Physiology of sweat gland function: The roles of sweating and sweat composition in human health

Hydrogel-based colorimetric power-saving sensors for on-site detection of chloride ions and glucose in sweat

Noninvasive diagnostics play a crucial role in health monitoring and disease detection. Sweat is a representative sample type containing various clinical biomarkers that provide information on certain disease risks. We developed a hydrogel-based colorimetric sensor for sweat analysis using a low-power battery. The hydrogel-based sensor comprised highly flexible bacterial cellulose (BC), highly water-absorbent carboxymethyl cellulose (CMC), and antibacterial chitosan (Ch), which functioned independently or in conjunction with a reusable three-dimensional printed polydimethylsiloxane-based microfluidic device. The highest tensile strength of 4.16 N for the hydrogel material of BC-CMC under the 0.6% Ch reaction indicated that this material had the best properties for absorbing sweat and measuring Cl- and glucose concentrations while attached to the surface of human skin. Our sensor was able to detect chloride ions (Cl-) and glucose concentrations in sweat. The sensor exhibited a linear relationship between the Cl- concentration and b∗ value with a detection limit of 0.56 mM and a detection range of 20-100 mM, encompassing the critical diagnostic window of cystic fibrosis. For glucose detection, color changes were observed visually, and there was a linear relationship between the glucose concentration and the -b∗ value. The detection limit of 0.1 μM and wide detection range of 6.25-500 μM were suitable for the diagnosis of diabetes. The as-prepared sensor maintained stability for one month under specific storage conditions, suggesting the potential of this analytical method for excellent water absorption and selectivity. The sensor can be used for real-time diagnostics to detect cystic fibrosis and its potential complications, such as diabetes, in clinical medicine.

Flexible epidermal wearable sensor for Athlete's sweat biomarkers monitoring

Wearable sweat sensors hold great promise for the monitoring of athletic sweat biomarkers that are reflective of physical status and the inimitable feature of wearable sensors to conduct dynamic sweat analysis in situ. However, the preparative methods of wearable patches for monitoring athlete's biomarkers are often complicated. Here, we demonstrate the first example of "sports lab-on-skin" as a fully integrated epidermal sweat sensor through simple laser engraving and laser cutting methods, which enables on-body and wirelessly measuring sweat Na+, sweat K+, sweat lactate, and initial sweat rate for physical status assessment. We test the performance of the "sports lab-on-skin" in both physically trained and un-trained groups under the same exercise intensity. We also validate the influence of different scenarios (water intake, breakfast, and exercise intensity) on dehydration time, sweat K+ level, sweat lactate level, and initial sweat rate.

Effects of Extreme Humidity and Heat on Ventricular Arrhythmia Risk in Patients With Cardiac Devices

Background

Climate change is increasing the frequency of high heat and high humidity days. Whether these conditions can trigger ventricular arrhythmias [ventricular tachycardia/ventricular fibrillation, VT/VF] in susceptible persons is unknown.

Objectives

The purpose of this study was to determine the relationship between warm-season weather conditions and risk of VT/VF in individuals with pacemakers and defibrillators.

Methods

Baseline clinical and device data from 5,944 patients in North Carolina (2010-2021) were linked to daily weather data geocoded to individuals' residential addresses. Associations between extreme humidity, temperature, and VT/VF overall and by patient, community, and built environment factors were estimated using a case time-series design with distributed lag nonlinear models, adjusting for temporal trends and individual factors.

Results

VT/VF events occurred on 4,486 of the 484,988 person-days. Extreme humidity (95th percentile: 90% relative humidity) increased odds of VT/VF in the 7 days following exposure (aOR 1.23 [95% CI: 1.00-1.51]). Humidity-associated VT/VF risk was highest among those who were male (aOR: 1.38 [95% CI: 1.08-1.76]), age 67 to 75 years (aOR: 1.65 [95% CI: 1.16-2.35]) with coronary artery disease (aOR: 1.79 [95% CI: 1.25-2.57]), heart failure (aOR: 1.72 [95% CI: 1.2-2.46]), diabetes (aOR: 3.01 [95% CI: 1.99-4.56]), hypertension (aOR: 2.06 [95% CI: 1.48-2.88]), and prior myocardial infarction (aOR: 1.75 [95% CI: 1.23-2.48]). Communities with high socioeconomic deprivation (aOR: 1.83 [95% CI: 1.28-2.62]), high income inequality (aOR: 1.56 [95% CI: 1.19-2.04]), and urban areas with less greenspace (aOR: 1.29 [95% CI: 0.93-1.78]) also had increased VT/VF risk. High temperatures were not associated with VT/VF.

Conclusions

In patients with preexisting cardiovascular disease, exposure to extreme humidity increased VT/VF risk, especially among vulnerable individuals, disadvantaged communities, and urban areas with less green space. These findings emphasize the need for policies that address environmental risks in susceptible individuals and communities.

Diagnosing cystic fibrosis in low- and middle-income countries: challenges and strategies

BACKGROUND

Cystic Fibrosis is caused by recessively inherited variants of the cystic fibrosis transmembrane regulator. It is associated with diverse clinical presentations that can affect the respiratory, digestive, and reproductive systems and inhibit nutrient absorption and growth.

MAIN BODY

The current estimation of people affected by Cystic Fibrosis is likely underestimated as this disease remains undiagnosed in countries with limited diagnostic capacity. Recent evidence indicates that Cystic Fibrosis is more common than initially thought and is likely underreported in low- and middle-income countries. The sweat chloride test remains the gold standard for diagnosing Cystic Fibrosis. However, the costs of commercially available instruments, consumables, and laboratory reagents remain relatively high for widespread implementation in low- and middle-income countries.

CONCLUSION

Alternative, cost-effective, and simpler approaches to sweat electrolyte measurement, may present more feasible options for CF diagnosis in the setting of low- and middle-income countries. Novel low-cost, point-of-care innovations for measuring sweat chloride should be explored and further validated as suitable alternatives. It will be important to consider how to implement these options and adjust the diagnostic algorithm to meet the needs of low- and middle-income countries. Future Cystic Fibrosis research in low- and middle-income countries should focus on finding a lower-cost and resource-intensive pathway for CF screening and diagnosis to improve its availability.

Current Strategies and Future Directions of Wearable Biosensors for Measuring Stress Biochemical Markers for Neuropsychiatric Applications

Most wearable biosensors aimed at capturing psychological state target stress biomarkers in the form of physical symptoms that can correlate with dysfunction in the central nervous system (CNS). However, such markers lack the specificity needed for diagnostic or preventative applications. Wearable biochemical sensors (WBSs) have the potential to fill this gap, however, the technology is still in its infancy. Most WBSs proposed thus far target cortisol. Although cortisol detection is demonstrated as a viable method for approximating the extent and severity of psychological stress, the hormone also lacks specificity. Multiplex WBSs that simultaneously target cortisol alongside other viable stress-related biochemical markers (SBMs) can prove to be indispensable for understanding how psychological stress contributes to the pathophysiology of neuropsychiatric illnesses (NPIs) and, thus, lead to the discovery of new biomarkers and more objective clinical tools. However, none target more than one SBM implicated in NPIs. Till this review, cortisol's connection to dysfunctions in the CNS, to other SBMs, and their implication in various NPIs has not been discussed in the context of developing WBS technology. As such, this review is meant to inform the biosensing and neuropsychiatric communities of viable future directions and possible challenges for WBS technology for neuropsychiatric applications.

Inhibition of Pseudomonas aeruginosa biofilm formation on copper-based thin foils

The development of Healthcare-Associated Infections (HAIs) represents an increasing threat to patient health. In this context, Pseudomonas aeruginosa is responsible for various HAIs, determining about 20% of the infections in hospitalized patients, which makes it one of the most effective pathogens due to its strong ability to form biofilms. Using Cu-based materials as foils on high-touch surfaces can help to prevent and mitigate P. aeruginosa contamination in biohazardous settings. However, the antibiofilm properties of Cu-based surfaces against P. aeruginosa may vary due to frequent touches combined with indoor environmental exposure. The main aim of this study is to investigate the impact of accelerated ageing, mimicking a high-touch frequency by cyclic exposure to artificial sweat solution as well as to temperature and relative humidity variations, on the efficacy of Cu-based thin foils against P. aeruginosa biofilms. Three Cu-based materials (rolled and annealed Phosphorous High-Conductivity (PHC) Cu, Cu15Zn brass, and Cu18Ni20Zn nickel silver) were evaluated. The ageing process enhanced the antibiofilm properties, due to an increment in Cu ion release: aged PHC Cu and Cu15Zn exhibited the highest Cu ion release and hence the highest biofilm inhibition (decrease in colony forming unit (CFU)) in comparison to their pristine counterpart, while aged Cu18Ni20Zn displayed the lowest biofilm formation reduction, despite showing the highest aesthetic and morphological stability. The Cu-based surface, which highlited the highest biofilm formation inhibition due to accelerated ageing, was Cu15Zn.

Descriptive study of sweat dermatitis: A rare dermatoses not so rare in tropics

Background

Sweat dermatitis is an irritant inflammatory dermatosis commonly encountered in tropics during summers. Profuse sweating triggered by high heat index, friction, clothing, outdoor activities, military training, overcrowding, prolonged working in ill-ventilated places, etc., are responsible or this dermatitis. Aim was to study the clinical, dermoscopic, vapometric, histopathological, and immunohistochemistry (IHC) findings in sweat dermatitis.

Methods

Twenty-five patients of sweat dermatitis attending out-patient department (OPD) of tertiary care hospital, were recruited over a period of three months (June to August 2022). A detailed history was followed by dermatological examination, dermoscopy, vapometry, histopathology, and IHC studies.

Results

Twenty-five patients were included in the study. There was male preponderance with male: female ratio of 2.1:1. The mean age of patients was 30.36 years. Dermatological examination in all patients revealed brownish "parchment"-like, shiny "crinkled cellophane paper"-like patches over the entire upper back and shoulder region with areas of exfoliation. Dermoscopy revealed increased skin markings, deep brown pigmentary changes with superimposed whitish scales with islands of eroded skin, and prominent eccrine duct openings. Vapometric analysis revealed increased transepidermal water loss (TEWL) in the affected area in 88% of patients. Histopathological examination showed features of spongiotic dermatitis. IHC with CK7 (cytoplasmic) highlighted the normal eccrine coils.

Conclusion

Sweat dermatitis is common seasonal dermatoses in tropics, but it remains undiagnosed due to lack of awareness. This study aims to sensitize medical doctors and dermatologists about sweat dermatitis and prevention strategies that can be helpful in mitigating it. The study also discusses the role of investigative modalities, such as dermoscopy, vapometry, histopathology, and IHC, in sweat dermatitis.

Machine learning-powered wearable interface for distinguishable and predictable sweat sensing

The constrained resources on wearable devices pose a challenge in meeting the demands for comprehensive sensing information, and current wearable non-enzymatic sensors face difficulties in achieving specific detection in biofluids. To address this issue, we have developed a highly selective non-enzymatic sweat sensor that seamlessly integrates with machine learning, ensuring reliable sensing and physiological monitoring of sweat biomarkers during exercise. The sensor consists of two electrodes supported by a microsystem that incorporates signal processing and wireless communication. The device generates four explainable features that can be used to accurately predict tyrosine and tryptophan concentrations, as well as sweat pH. The reliability of this device has been validated through rigorous statistical analysis, and its performance has been tested in subjects with and without supplemental amino acid intake during cycling trials. Notably, a robust linear relationship has been identified between tryptophan and tyrosine concentrations in the collected samples, irrespective of the pH dimension. This innovative sensing platform is highly portable and has significant potential to advance the biomedical applications of non-enzymatic sensors. It can markedly improve accuracy while decreasing costs.

Association between predicted level of water turnover deficit and all-cause and cause-specific mortalities among Japanese adults: The Japan Collaborative Cohort Study

BACKGROUND

Although water is essential for maintaining health and life, the association between water turnover as an indicator of daily water requirement and water deficit and mortality is unclear.

OBJECTIVES

We aimed to investigate this association in Japanese adults.

METHODS

A total of 63,488 (36,739 females and 26,749 males) Japanese aged 40-79 y in the Japan Collaborative Cohort Study in 1988-1990 were followed up their mortality through 2009. Water turnover was calculated considering lifestyle and environmental factors using an equation previously developed by the International Doubly Labeled Water Database Group. Participants were classified into sex-specific quintiles based on their water turnover. Water deficit levels were calculated from water turnover and dietary water consumption, which were estimated using a validated questionnaire.

RESULTS

The mean daily water turnovers were 2950 and 3466 mL in females and males, respectively. During 19.4 years of median follow-up (1,039,914 person-years), 12,551 deaths were recorded. After adjusting for lifestyle and medical history, the bottom quintile was associated with higher hazard ratios (HRs) of mortality from all causes (females-HR: 1.26; 95% CI: 1.12, 1.41; males-HR: 1.18; 95% CI: 1.07, 1.29) and cardiovascular disease (CVD). In spline analyses, the water turnover range with the lowest HR for all-cause mortality was 3000-3300 mL/d in females and the water turnover at which the HR for all-cause mortality plateaued was ∼3500-3700 mL/d in males. Water deficiency levels were associated with all-cause and CVD-related mortality in both sexes.

CONCLUSIONS

The association between water turnover and deficit and all-cause and CVD-related mortalities (especially coronary artery disease and ischemic stroke) in adults is L-shaped. These findings may be useful for setting the target values of water requirement, and differences between dietary requirements and actual intake may bridge the knowledge gap in water-mortality associations.

Applied body-fluid analysis by wearable devices

Wearable sensors are a recent paradigm in healthcare, enabling continuous, decentralized, and non- or minimally invasive monitoring of health and disease. Continuous measurements yield information-rich time series of physiological data that are holistic and clinically meaningful. Although most wearable sensors were initially restricted to biophysical measurements, the next generation of wearable devices is now emerging that enable biochemical monitoring of both small and large molecules in a variety of body fluids, such as sweat, breath, saliva, tears and interstitial fluid. Rapidly evolving data analysis and decision-making technologies through artificial intelligence has accelerated the application of wearables around the world. Although recent pilot trials have demonstrated the clinical applicability of these wearable devices, their widespread adoption will require large-scale validation across various conditions, ethical consideration and sociocultural acceptance. Successful translation of wearable devices from laboratory prototypes into clinical tools will further require a comprehensive transitional environment involving all stakeholders. The wearable device platforms must gain acceptance among different user groups, add clinical value for various medical indications, be eligible for reimbursements and contribute to public health initiatives. In this Perspective, we review state-of-the-art wearable devices for body-fluid analysis and their translation into clinical applications, and provide insight into their clinical purpose.

Advanced Wearable Devices for Monitoring Sweat Biochemical Markers in Athletic Performance: A Comprehensive Review

Wearable technology has advanced significantly, offering real-time monitoring of athletes' physiological parameters and optimizing training and recovery strategies. Recent developments focus on biosensor devices capable of monitoring biochemical parameters in addition to physiological ones. These devices employ noninvasive methods such as sweat analysis, which reveals critical biomarkers like glucose, lactate, electrolytes, pH, and cortisol. These biomarkers provide valuable insights into an athlete's energy use, hydration status, muscle function, and stress levels. Current technologies utilize both electrochemical and colorimetric methods for sweat analysis, with electrochemical methods providing higher precision despite potential signal interference. Wearable devices such as epidermal patches, temporary tattoos, and fabric-based sensors are preferred for their flexibility and unobtrusive nature compared to more rigid conventional wearables. Such devices leverage advanced materials and transmit real-time data to computers, tablets, or smartphones. These data would aid coaches and sports medical personnel in monitoring athletes' health, optimizing diets, and developing training plans to enhance performance and reduce injuries.

Rapid chemical detection and segmentation of latent fingerprints by means of a novel middle-infrared scanning method

The fast and reliable detection, segmentation and visualization of latent fingerprints are the main tasks in forensics. Currently, conventional fingerprints are searched for, recorded and subsequently analyzed via traditional destructive physical and chemical methods. For firmly defined crime objects and undefined crime scenes, the forensic process is very time-consuming and can take several hours for a single fingerprint. In this context, a laser-based measurement technique that records complete latent fingerprints under fifteen seconds in a non-destructive manner was developed that digitizes the fingerprint for postprocessing steps. The optical system is based on confocal measurements in the mid-infrared wavelength range (2 μm-4 μm) to analyze specific chemical substances at crime scenes. The resulting chemical segmentation allows molecule-dependent analysis of latent and visually invisible fingerprints, providing clear conclusions about the perpetrator or the course of the crime. In this study, the application of the developed measurement system (MIR scanner) to capture fingerprints in a molecule-dependent manner within few seconds is demonstrated, compared with reference methods such as FTIR (Fourier transform infrared spectroscopy) imaging, and extended to real crime objects.

Discretised microfluidics for noninvasive health monitoring using sweat sensing

Using sweat instead of blood for monitoring chemical biomarker concentrations of hospitalised patients offers several advantages for both the patients and healthcare workers. Unlike blood, sweat can be noninvasively and continuously sampled without direct involvement of a professional, and sweat contains a rich composition of biomarkers. However, patients in resting state have extremely low sweat rates and they produce correspondingly small sweat volumes, which makes sweat sensing of hospitalised patients highly challenging. We propose a unique solution that enables the use of sweat as a viable biofluid for noninvasive health monitoring, by actively transporting the sweat in a discretised manner. Our device uses electrowetting-on-dielectrics (EWOD) to create and move sweat droplets with a volume of around 1 nanolitre from a sweat gland to sensors integrated in the device. We present the first wearable device with integrated EWOD, and we show that it can collect and transport sweat on-body, while measuring sweat rate, under conditions typical for individuals at rest.

Estimation of the Number of Active Sweat Glands Through Discrete Sweat Sensing

Sweat is a biomarker-rich fluid with potential for continuous patient monitoring via wearable devices. However, biomarker concentrations vary with the sweat rate per gland, posing a challenge for sweat sensing. To address this, we propose an algorithm to compute both the number of active sweat glands and their individual sweat rates. We developed models of sweat glands and a discrete sweat-sensing device to sense sweat volume. Our algorithm estimates the number of active glands by decomposing the signal into patterns generated by the individual sweat glands, allowing for the calculation of individual sweat rates. We assessed the algorithm's accuracy using synthetic datasets for varying physiological parameters (sweat rate and number of active sweat glands) and device layouts. The results show that device layout significantly affects accuracy, with error rates below 0.2% for low and medium sweat rates (below 0.2 nL min-1 per gland). However, the method is not suitable for high sweat rates. The suitable sweat rate range can be adapted to different needs through the choice of device. Based on our findings, we provide recommendations for optimal device layouts to improve accuracy in estimating active sweat glands. This is the first study to focus on estimating the sweat rate per gland, which essential for accurate biomarker concentration estimation and advancing sweat sensing towards clinical applications.

Lack of sex-specific differences in the associations between the dimensions of great vessels and exercise performance in amateur cyclists

BACKGROUND

Endurance training enhances exercise capacity and triggers cardiovascular adaptations in both males and females. We investigated the relationship between the dimensions of great vessels and exercise capacity in amateur cyclists while considering sex differences.

METHODS

Using resting transthoracic echocardiography, we measured the dimensions of the main pulmonary artery (PA), aorta, and inferior vena cava (IVC) in 190 participants, who subsequently underwent a cardiopulmonary exercise test (CPET) until exhaustion.

RESULTS

The mean age of study participants was 30 years. Males (71%) exhibited a larger aortic annulus (approximately 3.5 mm, p<0.0001) and PA diameter (2.4 mm, p<0.0001) than females. No significant sex differences were found in expiratory or inspiratory IVC diameters. Males achieved greater peak exercise capacity, including workload, O2 consumption (VO2), and O2 pulse. Aortic and PA dimensions showed strong correlations with energy expenditure, workload, VO2, and O2 pulse. However, these correlations weakened when analyzed separately by sex. Multivariate linear regression revealed associations between CPET results, vessels size, and sex, with sex differences observed only in the intercepts-not in interactions between sex and vessels size. Despite males having better CPET results and larger vessels, the relationships between peak exercise capacity parameters and vessel dimensions were similar in both sexes.

CONCLUSION

Larger vessel dimensions (of the aorta, PA, and IVC) were associated with greater peak exercise capacity in amateur cyclists, with no significant sex differences in these associations.

Effects of individual characteristics and local body functions on sweating response: A review

In this study, we conducted a literature review to deepen our understanding of the sweating response of the thermoregulatory system, focusing on the influence of individual characteristics and local body functions. Among the factors related to individual characteristics, improvement in aerobic fitness had a positive effect on the sweating response, whereas aging exerted an inhibitory effect. Short-term artificial acclimation and seasonal heat acclimatization promoted sweating, whereas long-term geographical acclimatization suppressed sweating. Male exhibited higher sweat rates than female when the metabolic heat production was high. Individuals with smaller surface area-to-mass ratios tended to have higher sweat rates than those with larger ratios. Regarding local body functions, sweat distribution in the resting state showed high regional sweat rates in the lower limbs and torso, with higher values in the lower limbs when in the supine position and higher values in the torso when in the seated position. During exercise, the regional sweat rates was high in the torso, whereas the limbs exhibited relatively low sweat rates. These differences in sweat distribution stem from the thermoregulatory potential of each body region, which aims to efficiently regulate body temperature. Local effects have only been examined in the thigh and forearm, with temperature coefficient Q10 ranging from 2 to 5. Only the forehead showed significantly high thermosensitivity among all body regions.

A Passive Perspiration Inspired Wearable Platform for Continuous Glucose Monitoring

The demand for glucose monitoring devices has witnessed continuous growth from the rising diabetic population. The traditional approach of blood glucose (BG) sensor strip testing generates only intermittent glucose readings. Interstitial fluid-based devices measure glucose dynamically, but their sensing approaches remain either minimally invasive or prone to skin irritation. Here, a sweat glucose monitoring system is presented, which completely operates under rest with no sweat stimulation and can generate real-time BG dynamics. Osmotically driven hydrogels, capillary action with paper microfluidics, and self-powered enzymatic biochemical sensor are used for simultaneous sweat extraction, transport, and glucose monitoring, respectively. The osmotic forces facilitate greater flux inflow and minimize sweat rate fluctuations compared to natural perspiration-based sampling. The epidermal platform is tested on fingertip and forearm under varying physiological conditions. Personalized calibration models are developed and validated to obtain real-time BG information from sweat. The estimated BG concentration showed a good correlation with measured BG concentration, with all values lying in the A+B region of consensus error grid (MARD = 10.56% (fingertip) and 13.17% (forearm)). Overall, the successful execution of such osmotically driven continuous BG monitoring system from passive sweat can be a useful addition to the next-generation continuous sweat glucose monitors.

Textile sorption and release of odorous volatile organic compounds from a synthetic sweat solution

Body odorants typically transfer to clothing fabrics by way of liquid sweat, yet investigations of odor retention in textiles often neglect this route of exposure in their test procedures. This paper describes a novel method for transferring selected odorous volatile organic compounds to six types of textile fibers in yarn bundle form by an aqueous sweat solution. Headspace volatile organic compounds varying by chemical class (ketones, aldehydes, carboxylic acids) were monitored at discrete time intervals (30 min, 3 h, 24 h) using proton transfer reaction mass spectrometry. Lower intensities of ketones and aldehydes were detected in the headspace above cellulosic fibers (cotton, mercerized cotton, viscose) than above wool, nylon, and polyester fibers at 30 min. A rapid decrease in ketones occurred for all fibers, but lower intensities of ketones were released after 3 h for cellulosic and wool fibers. Nylon fibers typically released the highest amounts of ketones and aldehydes at 30 min, but by 24 h higher intensities of these compounds were released from polyester. Carboxylic acids exhibited minimal differences in intensities between 30 min and 3 h, with few differences evident among fiber types. Understanding the preferential sorption of odorants when clothing is exposed to volatile organic compounds in aqueous solutions such as sweat is enhanced from the results of this investigation.

3D Wetting Gradient Janus Sports Bras for Efficient Sweat Removal: A Strategy to Improve Women's Sports Comfort and Health

Developing Janus fabrics with excellent one-way sweat transport capacity is an attractive way for providing comfort sensation and protecting the health during exercise. In this work, a 3D wetting gradient Janus fabric (3DWGJF) is first proposed to address the issue of excessive sweat accumulation in women's breasts, followed by integration with a sponge pad to form a 3D wetting gradient Janus sports bra (3DWGJSB). The 3D wetting gradient enables the prepared fabric to control the horizontal migration of sweat in one-way mode (x/y directions) and then unidirectionally penetrate downward (z direction), finally keeping the water content on the inner side of 3DWGJF (skin side) at ≈0%. In addition, the prepared 3DWGJF has good water vapor transmittance rate (WVTR: 0.0409 g cm-2 h-1) and an excellent water evaporation rate (0.4704 g h-1). Due to the high adhesion of transfer prints to the fabrics and their excellent mechanical properties, the 3DWGJF is remarkably durable and capable of withstanding over 500 laundering cycles and 400 abrasion cycles. This work may inspire the design and fabrication of next-generation moisture management fabrics with an effective sweat-removal function for women's health.

Gold Nanowire Sponge Electrochemistry for Permeable Wearable Sweat Analysis Comfortably and Wirelessly

Electrochemistry-based wearable and wireless sweat analysis is emerging as a promising noninvasive method for real-time health monitoring by tracking chemical and biological markers without the need for invasive blood sampling. It offers the potential to remotely monitor human sweat conditions in relation to metabolic health, stress, and electrolyte balance, which have implications for athletes, patients with chronic conditions, and individuals for the early detection and management of health issues. The state-of-the-art mainstream technology is dominated by the concept of a wearable microfluidic chip, typically based on elastomeric PDMS. While outstanding sensing performance can be realized, the design suffers from the poor permeability of PDMS, which could cause skin redness or irritation. Here, we introduce an omnidirectionally permeable, deformable, and wearable sweat analysis system based on gold nanowire sponges. We demonstrate the concept of all-in-one soft sponge electrochemistry, where the working, reference, and counter electrodes and electrolytes are all integrated within the sponge matrix. The intrinsic porosity of sponge in conjunction with vertically aligned gold nanowire electrodes gives rise to a high electrochemically active surface area of ∼67 cm2. Remarkably, this all-in-one sponge-based electrochemical system exhibited stable performance under a pressure of 10 kPa and 300% omnidirectional strain. The gold sponge biosensing electrodes could be sandwiched between two biocompatible sweat pads, which can serve as natural sweat collection and outflow layers. This naturally biocompatible and permeable platform can be integrated with wireless communication circuits, leading to a wireless sweat analysis system for the real-time monitoring of glucose, lactate, and pH during exercise.

A physiological perspective of the relevance of sweat biomarkers and their detection by wearable microfluidic technology: A review

The great majority of published microfluidic wearable platforms for sweat sensing focus on the development of the technology to fabricate the device, the integration of sensing materials and actuators and the fluidics of sweat within the device. However, very few papers have discussed the physiological relevance of the metabolites measured using these novel approaches. In fact, some of the analytes present in sweat, which serve as biomarkers in blood, do not show a correlation with blood levels. This discrepancy can be attributed to factors such as contamination during measurements, the metabolism of sweat glands, or challenges in obtaining significant samples. The objective of this review is to present a critical and meaningful insight into the real applicability and potential use of wearable technology for improving health and sport performance. It also discusses the current limitations and future challenges of microfluidics, aiming to provide accurate information about the actual needs in this field. This work is expected to contribute to the future development of more suitable wearable microfluidic technology for health and sports science monitoring, using sweat as the biofluid for analysis.

From Sudoscan to bedside: theory, modalities, and application of electrochemical skin conductance in medical diagnostics

The human body has two main types of sweat glands: apocrine and eccrine. Eccrine glands are widely distributed across the skin, including areas with hair. While the eccrine glands on palms and soles help improve grip, those on the rest of the body primarily aid in thermoregulation. Sudomotor function, which controls sweating, is regulated by the sympathetic division of the autonomic nervous system through cholinergic and adrenergic pathways. The activation of eccrine glands involves intricate processes, including neurotransmitter binding, ion channel modulation, and voltage generation. Sudoscan technology utilizes electrochemical skin conductance (ESC) to non-invasively measure sudomotor function. This method, which has been standardized for accuracy, has established normative benchmarks and has proven reliable across diverse populations. Sudoscan's diagnostic performance is comparable to invasive methods such as intraepidermal nerve fiber density testing, making it a valuable tool for diagnosing small fiber neuropathy. Moreover, it has been shown to correlate with corneal nerve fiber length, providing insights into various neuropathic conditions. Compared to traditional sudomotor function tests, Sudoscan proves superior in terms of its accessibility, simplicity, and reliability, with the potential to replace or complement existing diagnostic methods. It is important to differentiate ESC, as measured by Sudoscan, from other skin conductance measures, such as galvanic skin response (GSR) or electrodermal activity (EDA). Although these methods share a common physiological principle, ESC is specifically designed for diagnosing sudomotor function, unlike GSR/EDA, which is typically used for continuous monitoring. Sudoscan's success has led to its integration into consumer health devices, such as the BodyScan from Withings, showcasing its versatility beyond clinical settings. Future research may explore ESC applications in diverse medical fields, leveraging real-world data from integrated consumer devices. Collaborative efforts between researchers and engineers promise to offer new insights into sudomotor function and its implications for broader health monitoring. This study provides a comprehensive overview of ESC, including topics such as eccrine gland physiology, sudomotor function, Sudoscan technology, normative benchmarks, diagnostic comparisons, and potential future applications.

Infrared thermal imaging for assessing human perspiration and evaluating antiperspirant product efficacy

In humans, perspiration regulates core body temperature. Therefore, objectively evaluating it is essential for studying sweat gland function and mechanisms, particularly in antiperspirant efficacy studies. Various approaches have been developed for measuring human perspiration and evaluating antiperspirant efficacy, but are unsuitable for robust and routine clinical testing applications. This paper shows how infrared thermography, utilizing both high- and low-resolution modes, functions as a multiscale imaging modality. The high-resolution mode extracts physiological parameters (respiratory ~ 0.3 Hz and heart rate ~ 1.0 Hz) and visualizes the reduction of the sweat pore radii (from 359 ± 155 μm to 161 ± 47 μm) after antiperspirant application, consistent with known mechanisms of pore plugging and constriction induced by aluminum salts. The low-resolution mode quantitatively maps sweat retention in underarm clothing. All study participants in a clinical trial showed reduced sweat retention on their T-shirts due to antiperspirants, with reductions ranging from approximately 37-97% and an average reduction of 77.7 ± 22.1% using the developed methodology and tested antiperspirant. Overall, this non-invasive technique presents significant potential for clinical and personal care product evaluations, particularly in the early stages of product development.

Iontophoresis Improves the Impact on the Quality of Life of Children with Primary Hyperhidrosis-A Prospective Study and a Short Review

BACKGROUND

Primary hyperhidrosis (PH) is a somatic and idiopathic pediatric skin disease. The eccrine glands are tiny and very numerous, with approximately 3 million distributed throughout the skin. There is no commonly accepted amount of sweating to define hyperhidrosis, but people with this disease suffer real limitations integrating into society, which can be quantified through quality of life measurement scales. We want to draw attention to this disease and its impact on children's quality of life because it is significant and there are no studies conducted on groups consisting solely of children.

METHODS

There are various quality of life evaluation questionnaires for hyperhidrosis. We studied 103 children with hyperhidrosis by monitoring their sweat severity and its impact on quality of life, using the Hyperhidrosis Disease Severity Scale. We compared the scale results before and after 10 days of iontophoresis. This study includes only children under 18 years old, treated with iontophoresis.

RESULTS

The average age of the group is 11.84 ± 2.89 years. Treatment success is recorded in 68 (66.02%) children, but a change in the score is recorded in 74 (71.84%) children. The average HDSS score at T0 is 2.95 ± 0.70, compared to the HDSS score at T1 of 1.92 ± 0.86.

CONCLUSIONS

Hyperhidrosis has a negative impact on daily life, especially self-esteem, occupational productivity, emotional well-being, and interpersonal relationships. Iontophoresis is a safe and effective treatment method that reduces the severity of hyperhidrosis and increases the quality of life.

Hydration Considerations to Improve the Physical Performance and Health of Firefighters

Background/Objectives: Firefighters are exposed to a high level of stress as they often perform physically challenging work in hazardous environments while responsible for rescuing and keeping those around them safe. To add to this stress, they are also required to work in heavy, unbreathable personal protective equipment which promotes dehydration. These occupational demands paired with dehydration may lead to increased core temperatures, cardiac strain, and overall risk for sudden cardiac events. Thus, it is important to include hydration assessments and determine fluid needs when firefighters are on shift to ensure their personal safety as well as the safety of those around them by optimizing physical performance by maintaining adequate hydration. Therefore, the purpose of this review is to identify markers of hydration, classifications of hydration status, current hydration recommendations, and hydration interventions that may contribute to the overall clarity of hydration protocols that may optimize performance and health of firefighters. In addition, the impact of common medications, exercise training, and health conditions on hydration status related to firefighters will be discussed. Methods: A comprehensive literature search was conducted to discuss the purpose statements. Results: Hydration recommendations for firefighters include (1) assessing hydration status with multiple measurements including body mass, urine specific gravity and thirst sensation, and (2) following general hydration recommendations on rest days and exercise hydration protocols during firefighting activities which may be altered according to hydration status measurements. Conclusion: Randomized controlled trials in firefighters are needed to determine the impact of maintaining adequate hydration on health markers.

Fabricated advanced textile for personal thermal management, intelligent health monitoring and energy harvesting

Fabrics are soft against the skin, flexible, easily accessible and able to wick away perspiration, to some extent for local private thermal management. In this review, we classify smart fabrics as passive thermal management fabrics and active thermal management fabrics based on the availability of outside energy consumption in the manipulation of heat generation and dissipation from the human body. The mechanism and research status of various thermal management fabrics are introduced in detail, and the article also analyses the advantages and disadvantages of various smart thermal management fabrics, achieving a better and more comprehensive comprehension of the current state of research on smart thermal management fabrics, which is quite an important reference guide for our future research. In addition, with the progress of science and technology, the social demand for fabrics has shifted from keeping warm to improving health and quality of life. E-textiles have potential value in areas such as remote health monitoring and life signal detection. New e-textiles are designed to mimic the skin, sense biological data and transmit information. At the same time, the ultra-moisturizing properties of the fabric's thermal management allow for applications beyond just the human body to energy. E-textiles hold great promise for energy harvesting and storage. The article also introduces the application of smart fabrics in life forms and energy harvesting. By combining electronic technology with textiles, e-textiles can be manufactured to promote human well-being and quality of life. Although smart textiles are equipped with more intelligent features, wearing comfort must be the first thing to be ensured in the multi-directional application of textiles. Eventually, we discuss the dares and prospects of smart thermal management fabric research.

Sexual effects and long-term outcomes of endoscopic lumbar sympathectomy for plantar hyperhidrosis in men: a cross-sectional study

Background

Plantar hyperhidrosis (PHH) is a disease with high psychosocial impact, and endoscopic lumbar sympathectomy (ELS) has been shown to be the best choice for treatment, but with some concerns such as compensatory sweating (CS) and sexual effects (SE), particularly in men.

Objectives

The aim of this study is to evaluate the long-term effectiveness of ELS for controlling PHH in men, its side effects, and perceived sexual modifications.

Methods

A cross-sectional study including only male patients operated for PHH with ELS between 2014-2022 at a private practice. During remote interviews, patients were asked about symptoms before and after ELS and about the postoperative effects on PHH. They were also objectively asked about any SE during the postoperative period. Validated quality of life for hyperhidrosis and erectile function questionnaires were also administered.

Results

10 male patients averaging 4.26±2.86 years post-ELS were interviewed. Eight of them (80%) achieved complete response (≥80% of sweat reduction) in the first month after surgery and this response was maintained up to the interview date. Two patients had partial response. In six patients, CS occurred, with 5 reporting it as non-troublesome. Six patients reported some type of SE, but none reported erectile dysfunction. Regarding the functional results, all patients rated ELS from good (10%) to very good (30%) or excellent (60%).

Conclusions

Endoscopic lumbar sympathectomy was effective for treatment of plantar hyperhidrosis in these patients, improving their quality of life and providing lasting PHH control, with some transient sexual dysfunctions that did not impair their sexual life.

Relative humidity, temperature, and hypertensive disorders of pregnancy: Findings from the Project Viva cohort

BACKGROUND

Preeclampsia is a multi-system hypertensive disorder of pregnancy that is a leading cause of maternal and fetal morbidity and mortality. Prior studies disagree on the cause and even the presence of seasonal patterns in its incidence. Using unsuitable time windows for seasonal exposures can bias model results, potentially explaining these inconsistencies.

OBJECTIVES

We aimed to investigate humidity and temperature as possible causes for seasonal trends in preeclampsia in Project Viva, a prebirth cohort in Boston, Massachusetts, considering only exposure windows that precede disease onset.

METHODS

Using the Parameter-elevation Relationships on Independent Slopes Model (PRISM) Climate Dataset, we estimated daily residential temperature and relative humidity (RH) exposures during pregnancy. Our primary multinomial regression adjusted for person-level covariates and season. Secondary analyses included distributed lag models (DLMs) and adjusted for ambient air pollutants including fine particulates (PM2.5). We used Generalized Additive Mixed Models (GAMMs) for systolic blood pressure (SBP) trajectories across hypertensive disorder statuses to confirm exposure timing.

RESULTS

While preeclampsia is typically diagnosed late in pregnancy, GAMM-fitted SBP trajectories for preeclamptic and non-preeclamptic women began to diverge at around 20 weeks' gestation, confirming the need to only consider early exposures. In the primary analysis with 1776 women, RH in the early second trimester, weeks 14-20, was associated with significantly higher odds of preeclampsia (OR per IQR increase: 1.81, 95% CI: 1.10, 2.97). The DLM corroborated this window, finding a positive association from weeks 12-20. There were no other significant associations between RH or temperature and preeclampsia or gestational hypertension in any other time period.

DISCUSSION

The association between preeclampsia and RH in the early second trimester was robust to model choice, suggesting that RH may contribute to seasonal trends in preeclampsia incidence. Differences between these results and those of prior studies could be attributable to exposure timing differences.

Diving into Sweat: Advances, Challenges, and Future Directions in Wearable Sweat Sensing

Sweat analysis has advanced from diagnosing cystic fibrosis and testing for illicit drugs to noninvasive monitoring of health biomarkers. This article introduces the rapid development of wearable and flexible sweat sensors, highlighting key milestones and various sensing strategies for real-time monitoring of analytes. We discuss challenges such as developing high-performance nanomaterial-based biosensors, ensuring continuous sweat production and sampling, achieving high sweat/blood correlation, and biocompatibility. The potential of machine learning to enhance these sensors for personalized healthcare is presented, enabling real-time tracking and prediction of physiological changes and disease onset. Leveraging advancements in flexible electronics, nanomaterials, biosensing, and data analytics, wearable sweat biosensors promise to revolutionize disease management, prevention, and prediction, promoting healthier lifestyles and transforming medical practices globally.

Skin-interfaced microfluidic biosensors for colorimetric measurements of the concentrations of ketones in sweat

Ketones, such as beta-hydroxybutyrate (BHB), are important metabolites that can be used to monitor for conditions such as diabetic ketoacidosis (DKA) and ketosis. Compared to conventional approaches that rely on samples of urine or blood evaluated using laboratory techniques, processes for monitoring of ketones in sweat using on-body sensors offer significant advantages. Here, we report a class of soft, skin-interfaced microfluidic devices that can quantify the concentrations of BHB in sweat based on simple and low-cost colorimetric schemes. These devices combine microfluidic structures and enzymatic colorimetric BHB assays for selective and accurate analysis. Human trials demonstrate the broad applicability of this technology in practical scenarios, and they also establish quantitative correlations between the concentration of BHB in sweat and in blood. The results represent a convenient means for managing DKA and aspects of personal nutrition/wellness.

Sweat-based stress screening with gas chromatography-ion mobility spectrometry and electronic nose

BACKGROUND

Diagnosis of stress generally involves uses of questionnaires which can provide biased results. The more reliable approach relies on observation of individual symptoms by psychiatrists which is time consuming and could not be applicable for massive scale screening tests. This research established alternative approaches with gas chromatography-ion mobility spectrometry (GC-IMS) and electronic nose (e-nose) to perform fast stress screening based on fingerprinting of highly volatile compounds in headspaces of sweat. The investigated samples were obtained from 154 female nurse volunteers who also provided the data of questionnaire-based mental health scores with the high stress cases confirmed by psychiatrists.

RESULTS

The interviews by psychiatrists revealed 14 volunteers with high stress. Their axillary sweat samples and that from 32 nurses with low/moderate stress (controls) were collected onto cotton rods and analysed with GC-IMS. The possible marker peaks were selected based on the accuracy data. They were tentatively identified as ammonia, diethyl ether, methanol, octane, pentane, acetone and dimethylamine which could involve different endogenous mechanisms or the relationships with the local microbiomes. The data were further analysed using partial least squares discriminant analysis with the receiver operating characteristic curves showing the optimum accuracy, sensitivity and selectivity of 87%, 86% and 88%, respectively. Providing that the samples were obtained from the nurses without deodorant uses, the high stress cases could be screened using e-nose sensors with the accuracy of 89%. The sensor responses could be correlated with the marker peak area data in GC-IMS with the coefficients ranging from -0.70 to 0.80.

SIGNIFICANCE

This represents the first investigation of highly volatile compound markers in sweat for high stress screening. The established methods were simple, reliable, rapid and non-invasive, which could be further adapted into the portable platform of e-nose sensors with the practical application to perform the screening tests for nurses in Phra Nakorn Si Ayutthaya hospital, Thailand.

The effect of 8-day oral taurine supplementation on thermoregulation during low-intensity exercise at fixed heat production in hot conditions of incremental humidity

PURPOSE

To determine the effect of taurine supplementation on sweating and core temperature responses, including the transition from compensable to uncompensable heat stress, during prolonged low-intensity exercise of a fixed-heat production (~ 200W/m2) in hot conditions (37.5 °C), at both fixed and incremental vapour-pressure.

METHODS

Fifteen females (n = 3) and males (n = 12; 27 ± 5 years, 78 ± 9 kg, V ˙ O2max 50.3 ± 7.8 mL/kg/min), completed a treadmill walking protocol (~ 200W/m2 heat production [Ḣprod]) in the heat (37.5 ± 0.1 °C) at fixed-(16-mmHg) and ramped-humidity (∆1.5-mmHg/5-min) following 1 week of oral taurine supplementation (50 mg/kg/bm) or placebo, in a double-blind, randomised, cross-over design. Participants were assessed for whole-body sweat loss (WBSL), local sweat rate (LSR), sweat gland activation (SGA), core temperature (Tcore), breakpoint of compensability (Pcrit) and calorimetric heat transfer components. Plasma volume and plasma taurine concentrations were established through pre- and post-trial blood samples.

RESULTS

Taurine supplementation increased WBSL by 26.6% and 5.1% (p = 0.035), LSR by 15.5% and 7.8% (p = 0.013), SGA (1 × 1 cm) by 32.2% and 29.9% (p < 0.001) and SGA (3 × 3 cm) by 22.1% and 17.1% (p = 0.015) during the fixed- and ramped-humidity exercise periods, respectively. Evaporative heat loss was enhanced by 27% (p = 0.010), heat-storage reduced by 72% (p = 0.024) and Pcrit was greater in taurine vs placebo (25.0-mmHg vs 21.7-mmHg; p = 0.002).

CONCLUSION

Taurine supplementation increased sweating responses during fixed Ḣprod in hot conditions, prior to substantial heat strain and before the breakpoint of compensability, demonstrating improved thermoregulatory capacity. The enhanced evaporative cooling and reduced heat-storage delayed the subsequent upward inflection in Tcore-represented by a greater Pcrit-and offers a potential dietary supplementation strategy to support thermoregulation.

Lactate threshold evaluation in swimming using a sweat lactate sensor: A prospective study

Since assessing aerobic capacity is key to enhancing swimming performance, a simple and widely applicable technology should be developed. Therefore, we aimed to noninvasively visualize real-time changes in sweat lactate (sLA) levels during swimming and investigate the relationship between lactate thresholds in sweat (sLT) and blood (bLT). This prospective study included 24 university swimmers (age: 20.7 s ± 1.8 years, 58% male) who underwent exercise tests at incremental speeds with or without breaks in a swimming flume to measure heart rate (HR), bLT, and sLT based on sLA levels using a waterproof wearable lactate sensor attached to the dorsal upper arm on two different days. The correlation coefficient and Bland-Altman methods were used to verify the similarities of the sLT with bLT and personal performance. In all tests, dynamic changes in sLA levels were continuously measured and projected onto the wearable device without delay, artifacts, or contamination. Following an initial minimal current response, with increasing speed the sLA levels increased substantially, coinciding with a continuous rise in HR. The speed at sLT strongly correlated with that at bLT (p < 0.01 and r = 0.824). The Bland-Altman plot showed a strong agreement (mean difference: 0.08 ± 0.1 m/s). This prospective study achieved real-time sLA monitoring during swimming, even with vigorous movement. The sLT closely approximated bLT; both were subsequently validated for their relevance to performance.

Multifunctional laser-induced graphene circuits and laser-printed nanomaterials toward non-invasive human kidney function monitoring

Faced with the increasing prevalence of chronic kidney disease (CKD), portable monitoring of CKD-related biomarkers such as potassium ion (K+), creatinine (Cre), and lactic acid (Lac) levels in sweat has shown tremendous potential for early diagnosis. However, a rapidly manufacturable portable device integrating multiple CKD-related biomarker sensors for ease of sweat testing use has yet to be reported. Here, a portable electrochemical sensor integrated with multifunctional laser-induced graphene (LIG) circuits and laser-printed nanomaterials based working electrodes fabricated by fully automatic laser manufacturing is proposed for non-invasive human kidney function monitoring. The sensor comprises a two-electrode LIG circuit for K+ sensing, a three-electrode LIG circuit with a Kelvin compensating connection for Cre and Lac sensing, and a printed circuit board based portable electrochemical workstation. The working electrodes containing Cu and Cu2O nanoparticles fabricated by two-step laser printing show good sensitivity and selectivity toward Cre and Lac sensing. The sensor circuits are fabricated by generating a hydrophilic-hydrophobic interface on a patterned LIG through laser. This sensor recruited rapid laser manufacturing and integrated with multifunctional LIG circuits and laser-printed nanomaterials based working electrodes, which is a potential kidney function monitoring solution for healthy people and kidney disease patients.

Behavior of Polymer Electrode PEDOT:PSS/Graphene on Flexible Substrate for Wearable Biosensor at Different Loading Modes

In recent years, flexible and wearable biosensor technologies have gained significant attention due to their potential to revolutionize healthcare monitoring. Among the various components involved in these biosensors, the electrode material plays a crucial role in ensuring accurate and reliable detection. In this regard, polymer electrodes, such as Poly(3,4 ethylenedioxythiophene): poly(styrenesulfonate), combined with graphene (PEDOT:PSS/graphene), have emerged as promising candidates due to their unique mechanical properties and excellent electrical conductivity. Understanding the mechanical behavior of these polymer electrodes on flexible substrates is essential to ensure the stability and durability of wearable biosensors. In this paper, PEDOT:PSS/graphene composite was spray-coated on flexible substrates at different growth conditions to explore the effect of the deposition parameters and mode of mechanical loading (longitudinal or transversal) on the electrical and mechanical behavior of the fabricated samples. It was found that the coating grown at lower temperatures and higher spraying pressure exhibited stable behavior no matter the applied stress type.

Biomarkers in Alzheimer's disease

Alzheimer's disease (AD) is among the most common neurodegenerative disorders. AD is characterized by deposition of neurofibrillary tangles and amyloid plaques, leading to associated secondary pathologies, progressive neurodegeneration, and eventually death. Currently used diagnostics are largely image-based, lack accuracy and do not detect early disease, ie, prior to onset of symptoms, thus limiting treatment options and outcomes. Although biomarkers such as amyloid-β and tau protein in cerebrospinal fluid have gained much attention, these are generally limited to disease progression. Unfortunately, identification of biomarkers for early and accurate diagnosis remains a challenge. As such, body fluids such as sweat, serum, saliva, mucosa, tears, and urine are under investigation as alternative sources for biomarkers that can aid in early disease detection. This review focuses on biomarkers identified through proteomics in various biofluids and their potential for early and accurate diagnosis of AD.

Self-assembly of cascade nanoenzyme glucose oxidase encapsulated in copper benzenedicarboxylate for wearable sweat-glucose colorimetric sensors with smartphone readout

BACKGROUND

With the advent of personalized medical approaches, precise and tailored treatments are expected to become widely accepted for the prevention and treatment of diabetes. Paper-based colorimetric sensors that function in combination with smartphones have been rapidly developed in recent years because it does not require additional equipment and is inexpensive and easy to perform. In this study, we developed a portable, low-cost, and wearable sweat-glucose detection device for in situ detection.

RESULTS

The sensor adopted an integrated biomimetic nanoenzyme of glucose oxidase (GOx) encapsulated in copper 1, 4-benzenedicarboxylate (CuBDC) (GOx@CuBDC) through a biomimetic mineralization process. CuBDC exhibited a peroxide-like effect, cascade catalytic effect with the encapsulated GOx, and increased the enzyme stability. GOx@CuBDC and 3,3,5,5-tetramethylbenzidine were combined to form a hybrid membrane that achieved single-step paper-based glucose detection.

SIGNIFICANCE AND NOVELTY

This GOx@CuBDC-based colorimetric glucose sensor was used to quantitatively analyze the sweat-glucose concentration with smartphone readings. The sensor exhibited a good linear relationship over the concentration range of 40-900 μM and a limit of detection of 20.7 μM (S/N = 3). Moreover, the sensor performed well in situ monitoring and in evaluating variations based on the consumption of foods with different glycemic indices. Therefore, the fabricated wearable sweat-glucose sensors exhibited optimal practical application performance.

Sunlight: Time for a Rethink?

UVR is a skin carcinogen, yet no studies link sun exposure to increased all-cause mortality. Epidemiological studies from the United Kingdom and Sweden link sun exposure with reduced all-cause, cardiovascular, and cancer mortality. Vitamin D synthesis is dependent on UVB exposure. Individuals with higher serum levels of vitamin D are healthier in many ways, yet multiple trials of oral vitamin D supplementation show little benefit. Growing evidence shows that sunlight has health benefits through vitamin D-independent pathways, such as photomobilization of nitric oxide from cutaneous stores with reduction in cardiovascular morbidity. Sunlight has important systemic health benefit as well as risks.

Sweat gland morphology and physiology in diabetes, neuropathy, and nephropathy: a review

Context: Sweat glands (SGs) play a vital role in thermal regulation. The function and structure are altered during the different pathological conditions.Objective: These alterations are studied through three techniques: biopsy, sweat analytes and electrical activity of SG.Methods: The morphological study of SG through biopsy and various techniques involved in quantifying sweat analytes is focussed on here. Electrical activities of SG in diabetes, neuropathy and nephropathy cases are also discussed, highlighting their limitations and future scope.Results and Conclusion: The result of this review identified three areas of the knowledge gap. The first is wearable sensors to correlate pathological conditions. Secondly, there is no device to look for its structure and quantify its associated function. Finally, therapeutic applications of SG are explored, especially for renal failure. With these aspects, this paper provides information collection and correlates SG with pathologies related to diabetes. Hence this could help researchers develop suitable technologies for the gaps identified.

Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males

PURPOSE

Caffeine is a commonly used ergogenic aid for endurance events; however, its efficacy and safety have been questioned in hot environmental conditions. The aim of this study was to investigate the effects of acute caffeine supplementation on cycling time to exhaustion and thermoregulation in the heat.

METHODS

In a double-blind, randomised, cross-over trial, 12 healthy caffeine-habituated and unacclimatised males cycled to exhaustion in the heat (35 °C, 40% RH) at an intensity associated with the thermoneutral gas exchange threshold, on two separate occasions, 60 min after ingesting caffeine (5 mg/kg) or placebo (5 mg/kg).

RESULTS

There was no effect of caffeine supplementation on cycling time to exhaustion (TTE) (caffeine; 28.5 ± 8.3 min vs. placebo; 29.9 ± 8.8 min, P = 0.251). Caffeine increased pulmonary oxygen uptake by 7.4% (P = 0.003), heat production by 7.9% (P = 0.004), whole-body sweat rate (WBSR) by 21% (P = 0.008), evaporative heat transfer by 16.5% (P = 0.006) and decreased estimated skin blood flow by 14.1% (P < 0.001) compared to placebo. Core temperature was higher by 0.6% (P = 0.013) but thermal comfort decreased by - 18.3% (P = 0.040), in the caffeine condition, with no changes in rate of perceived exertion (P > 0.05).

CONCLUSION

The greater heat production and storage, as indicated by a sustained increase in core temperature, corroborate previous research showing a thermogenic effect of caffeine ingestion. When exercising at the pre-determined gas exchange threshold in the heat, 5 mg/kg of caffeine did not provide a performance benefit and increased the thermal strain of participants.

Differential patterns of sweat and blood lactate concentration response during incremental exercise in varied ambient temperatures: A pilot study

Blood lactate concentration during exercise is a reliable indicator of energy metabolism and endurance performance. Lactate is also present in sweat, and sweating plays an important role in thermoregulation, especially in hot conditions. Recently, wearable sensors have enabled the real-time and noninvasive measurement of sweat lactate concentration, potentially serving as an alternative indicator of blood lactate response. However, the evidence regarding the relationship between sweat and blood lactate responses during incremental exercise in hot conditions is lacking. In a randomized cross-over design, six highly trained male runners completed two incremental treadmill tests under normal (20°C/50%RH) or hot (30°C/50%RH) conditions. The tests include 3-min running stages and 1-min recovery, starting at 12 km/h and increasing by 1 km/h at each stage. Blood and sweat lactate concentrations were measured at each stage to determine blood and sweat lactate thresholds (LT). Blood lactate concentrations were higher under hot conditions (p < 0.01), but there was no difference in the response pattern or velocity at blood LT between conditions. Significant early increase (p < 0.01) in sweat lactate and low velocity at sweat LT (p < 0.05) were observed under hot conditions. A significant correlation between blood and sweat lactate concentrations was found under normal conditions (p < 0.001) but not under hot conditions, and no significant correlations were observed between the velocity at blood and sweat LT. In conclusion, sweat lactate concentration does not consistently reflect blood lactate concentration during incremental exercise.

Simultaneous imaging of multi-pore sweat dynamics and evaporation rate measurement using wind tunnel ventilated capsule with infrared window

Sweat evaporation is critical to human thermoregulation, but current understanding of the process on 20 μm to 2 cm scale is limited. To this end, we introduce a wind-tunnel-shaped ventilated capsule with an infrared window for simultaneous infrared sweat imaging and evaporation rate measurement. Implementing the capsule in pilot human subject tests suggests that the common assumption of sweat being an isothermal film is only valid when the evaporation rate is low and sweat forms puddles on the skin. Before transitioning to this filmwise mode, sweating occurs in cyclic dropwise mode, displaying a 3x higher mass transfer coefficient in the same conditions. Imaging highlighted distinct phenomena occurring during and between these modes including out-of-duct evaporation, pulsating droplets, temporary and eventually lasting crevice filling, and individual drop-to-film spreading. In all, sweat evaporation is an impactful area that our results show is ripe for exploration, which can be achieved quantitatively using the introduced platform.

Comparative Study of 1444 nm Laser Monotherapy versus Integrated Liposuction in the Treatment of Axillary Osmidrosis

Background and Objectives: The 1444 nm wavelength Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser treatment is an efficient method for treating axillary osmidrosis (AO); however, it has a relatively low treatment persistence. To address this issue, we performed integrated liposuction surgery with a laser to treat AO and compared the results with those of a group treated only with a laser. Materials and Methods: This study compared the outcomes of AO treatment between the two groups up to six months postoperatively. The first group of 18 patients underwent laser treatment alone, and the second group of 12 patients underwent integrated liposuction surgery in addition to laser treatment. Outcomes were assessed using the following variables: degree of malodor (DOM), sweating area, patient satisfaction, pain levels, and complications, such as burns, swelling, and contractures. Results: Compared to the laser-only group, the integrated liposuction group demonstrated significantly superior outcomes in terms of DOM (p = 0.002) and patient satisfaction (p = 0.006), as well as a reduction in the sweating area (p = 0.012). The pain rating was higher in the liposuction group, but the difference was not statistically significant (p = 0.054). Compared with the patients in the integrated liposuction treatment group, those in the laser treatment group exhibited a significantly higher number of burns under the axillae (p = 0.025). However, no significant differences were observed in the swelling or contracture between the groups. Conclusions: Integrated liposuction with laser therapy significantly improved treatment outcomes, including malodor, patient satisfaction, sweat test results, and decreased complication rates.

The Acari Hypothesis, IV: revisiting the role of hygiene in allergy

Allergy and its manifestations were first appreciated in the 1870 s. Today, the mechanism by which specific substances elicit allergic reactions remains poorly understood. This is problematic from a healthcare perspective because the prevalence of allergic disease and its societal costs are substantial. Regarding mechanistic understanding of allergy, a new proposal, The Acari Hypothesis, has been forwarded. The Hypothesis, borne from consideration of alpha-gal syndrome, postulates that acarians, i.e., mites and ticks, are operative agents of allergy. By way of their pathogenic payloads and salivary pattern recognition receptor(s), acarians potentiate in human hosts the generation of IgE against acarian dietary elements. Those elements account for most, if not all, known human allergens. Inasmuch as acarian-human interactions occur on human epithelial surfaces, it is to be expected factors that influence the presence and/or operation of acarians on those surfaces influence the expression of allergic diseases. In this report, it is proposed that two adaptations of catarrhine primates, i.e., Old World monkeys, apes and humans, evolved to deter acarian species: firstly, the expansion of eccrine glands across the entirety of body surface area, and, secondly, the secretion of sweat by those glands. Contemporary hygienic practices that reduce and/or disrupt the operation of eccrine glands are likely responsible for the increase in allergic disease seen today.

DEMIGOD: A Low-Cost Microcontroller-Based Closed-Loop System Integrating Nanoengineered Sweat-Based Glucose Monitoring and Controlled Transdermal Nanoemulsion Release of Hypoglycemic Treatment with a Software Application for Noninvasive Personalized Diabetes Care

This study endeavored to design and develop an innovative closed-loop diagnostic and therapeutic system with the following objectives: (a) the noninvasive detection of glucose concentration in sweat utilizing nanonengineered screen-printed biosensors; (b) the management of measured data through a specialized computer system comprising both hardware and software components, thereby enabling the precise control of therapeutic responses via a patch-based nanomedicine delivery system. This initiative addresses the significant challenges inherent in the management of diabetes mellitus, including the imperative need for glucose-level monitoring to optimize glycemic control. Leveraging chronoamperometric results as a foundational dataset and the in vivo hypoglycemic activity of nanoemulsion formulations, this research underscores the efficacy and accuracy of glucose concentration estimation, decision-making mechanism responses, and transdermal hypoglycemic treatment effects, within the proposed system.

Skin Surface Sebum Analysis by ESI-MS

The skin surface is an important sample source that the metabolomics community has only just begun to explore. Alterations in sebum, the lipid-rich mixture coating the skin surface, correlate with age, sex, ethnicity, diet, exercise, and disease state, making the skin surface an ideal sample source for future noninvasive biomarker exploration, disease diagnosis, and forensic investigation. The potential of sebum sampling has been realized primarily via electrospray ionization mass spectrometry (ESI-MS), an ideal approach to assess the skin surface lipidome. However, a better understanding of sebum collection and subsequent ESI-MS analysis is required before skin surface sampling can be implemented in routine analyses. Challenges include ambiguity in definitive lipid identification, inherent biological variability in sebum production, and methodological, technical variability in analyses. To overcome these obstacles, avoid common pitfalls, and achieve reproducible, robust outcomes, every portion of the workflow-from sample collection to data analysis-should be carefully considered with the specific application in mind. This review details current practices in sebum sampling, sample preparation, ESI-MS data acquisition, and data analysis, and it provides important considerations in acquiring meaningful lipidomic datasets from the skin surface. Forensic researchers investigating sebum as a means for suspect elimination in lieu of adequate fingerprint ridge detail or database matches, as well as clinical researchers interested in noninvasive biomarker exploration, disease diagnosis, and treatment monitoring, can use this review as a guide for developing methods of best-practice.

The impact of nursing sustainable prevention program on heat strain among agricultural elderly workers in the context of climate change

BACKGROUND

This study assesses a geriatric nursing-led sustainable heat prevention program for elderly agricultural workers. It targets those aged 60 and above, addressing the heightened risk of heat strain in the era of climate change.

METHODS

A community-based quasi-experimental design involved 120 elderly agricultural workers, divided into intervention and control groups. The program, spanning three months, included education on hydration, rest, protective clothing, and recognition of heat-related illnesses.

RESULTS

The intervention led by geriatric nursing professionals showed significant improvements in heat strain metrics. The Heat Strain Score Index (HSSI) and the Observational-Perceptual Heat Strain Risk Assessment (OPHSRA) Index indicated increased safety levels and reduced risk categories among participants.

CONCLUSIONS

The study demonstrates the effectiveness of a geriatric nursing-led, tailored prevention program in reducing heat strain among elderly agricultural workers. It highlights the crucial role of nursing in adapting healthcare practices to the challenges posed by climate change.

TRIAL REGISTRATION

ClinicalTrials.gov, ID NCT06192069 retrospectively registered.

The Effect of Climate on the Dose Requirements of Botulinum Toxin A in Cosmetic Interventions

BACKGROUND

Botulinum toxin A to the glabella is a popular cosmetic intervention. Functional musculature differences may arise from chronic behavioral adjustment to high sun exposure levels, requiring greater doses. This could affect clinical practice globally. This study investigated the effect of climate on real-world doses.

METHODS

The authors conducted a comparative cohort study using data from a registry from a single provider practicing across two centers: the United Kingdom and Malta. They classified one center as low sun exposure (United Kingdom winter month treatment) and the other as high sun exposure (Malta summer months). Patients were followed up once every 3 weeks and received top-up doses until full clinical paralysis was achieved. To standardize the comparison, the study included only women aged 35 to 60 years undergoing glabellar botulinum toxin treatment by experienced clinicians following standard procedures from 2012 to 2019. Smokers, those not seeking maximal paralysis, those documented as not compliant with posttreatment advice, those with colds or fevers, and those with broken cold supply chains were excluded. Univariable and multivariable analyses were undertaken.

RESULTS

A total of 523 patients were included: 292 "high-sun" patients and 231 "low-sun" patients. Mean total doses were significantly higher in the high-sun group (29.2 units versus 27.3 units; P = 0.0031). When correcting for age in multivariable analysis, the low-sun group still had lower total dose requirements ( P = 0.00574).

CONCLUSION

Patients injected with glabellar botulinum toxin in high-sun climates may have significantly increased dose requirements to achieve maximal paralysis.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Whole blood multiplex measurements using electrochemical aptamer-based biosensors

Simultaneous measurements of various molecules ("multiplex") using electrochemical biosensors typically require multiple electrode implementations, which for neonates, hemophiliacs, etc. is problematic. Here, we introduce the oxazine ATTO 700 into electrochemical aptamer-based biosensors to achieve "true" multiplex, continuous and real-time measurements of two different molecules in undiluted whole blood using a single electrode.