Review of Wearable and Portable Sensors for Monitoring Personal Solar UV Exposure

Ultraviolet radiation thin film dosimetry: A review of properties and applications

Spectroradiometry, radiometry, and dosimetry are employed for the measurement of ultraviolet radiation (UVR) irradiance and non-ionizing exposure. Different types of UVR dosimeter have been developed for measuring personal and environmental UVR exposures since film dosimetry was pioneered in the 1970s. An important type of dosimeter is the thin film variant, which contains materials that undergo changes in optical absorbance when exposed to UVR. These changes can be measured at a specific wavelength using a spectrophotometer. Thin film dosimeters allow UVR exposure measurements on humans at various body sites during daily activities, as well as on plants, animals, and any sites of interest when utilized in a field environment. This review examines the properties and applications of five types of thin film UVR dosimeter that have different dynamic exposure limits and spectral responses. Polysulphone, with a spectral response approximating the human erythema action spectrum, was one of the first materials employed in thin film form for the measurement of UVR exposures up to 1 day, and up to 6 days with an extended dynamic range filter. Polyphenylene oxide has been characterized and employed for personal UVR exposure measurements up to approximately four summer days and has also been used for long-term underwater UVR exposures. Phenothiazine and 8-methoxypsoralen have been reported as suitable for the measurement of longer wavelength UVA exposures. Finally, polyvinyl chloride with an extended dynamic exposure range of over 3 weeks has been shown to have predominantly a spectral response in the UVB and extending up to 340 nm.

A model of ocular ambient irradiance at any head orientation

Exposure to ambient ultraviolet radiation is associated with various ocular pathologies. Estimating the irradiance received by the eyes is therefore essential from a preventive perspective and to study the relationship between light exposure and eye diseases. However, measuring ambient irradiance on the ocular surface is challenging. Current methods are either approximations or rely on simplified setups. Additionally, factors like head rotation further complicate measurements for prolonged exposures. This study proposes a novel numerical approach to address this issue by developing an analytical model for calculating irradiance received by the eye and surrounding ocular area. The model takes into account local ambient irradiance, sun position, and head orientation. It offers a versatile and cost-effective means of calculating ocular irradiance, adaptable to diverse scenarios, and serves both as a predictive tool and as a way to compute correction factors, such as the fraction of diffuse irradiance received by the eyes. Furthermore, it can be tailored for prolonged durations, facilitating the calculation of radiant dose obtained during extended exposures.

Novel elastomeric spiropyran-doped poly(dimethylsiloxane) optical waveguide for UV sensing

Novel poly(dimethylsiloxane) (PDMS) doped with two different spiropyran derivatives (SP) were investigated as potential candidates for the preparation of elastomeric waveguides with UV-dependent optical properties. First, free-standing films were prepared and evaluated with respect to their photochromic response to UV irradiation. Kinetics, reversibility as well as photofatigue and refractive index of the SP-doped PDMS samples were assessed. Second, SP-doped PDMS waveguides were fabricated and tested as UV sensors by monitoring changes in the transmitted optical power of a visible laser (633 nm). UV sensing was successfully demonstrated by doping PDMS using one spiropyran derivative whose propagation loss was measured as 1.04 dB/cm at 633 nm, and sensitivity estimated at 115% change in transmitted optical power per unit change in UV dose. The decay and recovery time constants were measured at 42 and 107 s, respectively, with an average UV saturation dose of 0.4 J/cm2. The prepared waveguides exhibited a reversible and consistent response even under bending. The sensor parameters can be tailored by varying the waveguide length up to 21 cm, and are affected by white light and temperatures up to 70 ℃. This work is relevant to elastomeric optics, smart optical materials, and polymer optical waveguide sensors.

E-Tattoos: Toward Functional but Imperceptible Interfacing with Human Skin

The human body continuously emits physiological and psychological information from head to toe. Wearable electronics capable of noninvasively and accurately digitizing this information without compromising user comfort or mobility have the potential to revolutionize telemedicine, mobile health, and both human-machine or human-metaverse interactions. However, state-of-the-art wearable electronics face limitations regarding wearability and functionality due to the mechanical incompatibility between conventional rigid, planar electronics and soft, curvy human skin surfaces. E-Tattoos, a unique type of wearable electronics, are defined by their ultrathin and skin-soft characteristics, which enable noninvasive and comfortable lamination on human skin surfaces without causing obstruction or even mechanical perception. This review article offers an exhaustive exploration of e-tattoos, accounting for their materials, structures, manufacturing processes, properties, functionalities, applications, and remaining challenges. We begin by summarizing the properties of human skin and their effects on signal transmission across the e-tattoo-skin interface. Following this is a discussion of the materials, structural designs, manufacturing, and skin attachment processes of e-tattoos. We classify e-tattoo functionalities into electrical, mechanical, optical, thermal, and chemical sensing, as well as wound healing and other treatments. After discussing energy harvesting and storage capabilities, we outline strategies for the system integration of wireless e-tattoos. In the end, we offer personal perspectives on the remaining challenges and future opportunities in the field.

MoOx-Based Colorimetric Sensor for Ultraviolet Visualization

Due to the depletion of the global ozone layer and the presence of ozone holes, humans are increasingly exposed to threats from solar ultraviolet radiation. Therefore, researching and developing a highly selective, sensitive, simple, and fast ultraviolet sensor is of significant importance for personal protection. In recent years, new nanomaterials have shown good application prospects in the research of ultraviolet sensors. MoOx nanostructures were prepared by a hydrothermal method. The experimental results show that, compared to traditional photochromic compounds, the new MoOx nanostructures exhibit high uniqueness, high selectivity, and excellent stability, and can perform rapid and accurate detection under full-band light. The beam sensor can not only detect through traditional electrical signal output, but also amplify, display, and analyze the beam through visualization and visual analysis, further improving the reliability and practicality of its application.

Utilizing Gold Nanoparticle Decoration for Enhanced UV Photodetection in CdS Thin Films Fabricated by Pulsed Laser Deposition: Exploiting Plasmon-Induced Effects

UV sensors hold significant promise for various applications in both military and civilian domains. However, achieving exceptional detectivity, responsivity, and rapid rise/decay times remains a notable challenge. In this study, we address this challenge by investigating the photodetection properties of CdS thin films and the influence of surface-deposited gold nanoparticles (AuNPs) on their performance. CdS thin films were produced using the pulsed laser deposition (PLD) technique on glass substrates, with CdS layers at a 100, 150, and 200 nm thickness. Extensive characterization was performed to evaluate the thin films' structural, morphological, and optical properties. Photodetector devices based on CdS and AuNPs/CdS films were fabricated, and their performance parameters were evaluated under 365 nm light illumination. Our findings demonstrated that reducing CdS layer thickness enhanced performance concerning detectivity, responsivity, external quantum efficiency (EQE), and photocurrent gain. Furthermore, AuNP deposition on the surface of CdS films exhibited a substantial influence, especially on devices with thinner CdS layers. Among the configurations, AuNPs/CdS(100 nm) demonstrated the highest values in all evaluated parameters, including detectivity (1.1×1012 Jones), responsivity (13.86 A/W), EQE (47.2%), and photocurrent gain (9.2).

Predictive analysis of the power spectral irradiance from blackbody radiation source using single pixel detector

Accurate spectral irradiance measurement in the near-infrared range is significant for the design and characterization of photodetector and photovoltaic cells. Approximation method is commonly used to solve for the input power using estimated spectral irradiance, where the dependency on wavelength and temperature remains uncertain. This study aims to determine the power spectrum at different radiation temperatures using a single pixel photodetector, taking into consideration factors such as transmission spectra of alumina radiator, CaF2 collimating lens, responsivity, and measured photocurrent information of photodetectors. Utilizing predictive mathematical model, five commercial photodetectors, including Silicon, Germanium, In0.53Ga0.47As, In0.73Ga0.27As, and In0.83Ga0.17As were used to solve for the power densities as a function of wavelengths at radiation temperatures of 1000 °C and 1500 °C. The spectral irradiance of photodetectors was determined with a percentage difference of <4.9 %, presenting an accurate power density estimation for the spectrum at a wide range of radiation temperatures. Power irradiance data obtained were validated in the narrow wavelength range with 1000 nm, 1400 nm, 1500 nm, and 2000 nm bandpass filters. The reported work demonstrates a simple and efficient way which could contribute to develop a cost-effective method of measuring and determining the spectrum irradiances of objects at different radiation temperatures. This predictive analysis method hopefully intensifies the progress of efforts to reduce the reliance on complex optoelectronic instruments in accurately solving power irradiance information.

Opportunities of Electronic and Optical Sensors in Autonomous Medical Plasma Technologies

Low temperature plasma technology is proving to be at the frontier of emerging medical technologies with real potential to overcome escalating healthcare challenges including antimicrobial and anticancer resistance. However, significant improvements in efficacy, safety, and reproducibility of plasma treatments need to be addressed to realize the full clinical potential of the technology. To improve plasma treatments recent research has focused on integrating automated feedback control systems into medical plasma technologies to maintain optimal performance and safety. However, more advanced diagnostic systems are still needed to provide data into feedback control systems with sufficient levels of sensitivity, accuracy, and reproducibility. These diagnostic systems need to be compatible with the biological target and to also not perturb the plasma treatment. This paper reviews the state-of-the-art electronic and optical sensors that might be suitable to address this unmet technological need, and the steps needed to integrate these sensors into autonomous plasma systems. Realizing this technological gap could facilitate the development of next-generation medical plasma technologies with strong potential to yield superior healthcare outcomes.

Comparison of three canine nose guards for reduction of ultraviolet (UVA and UVB) solar radiation

BACKGROUND

Protection from solar ultraviolet (UV) radiation is paramount for some dermatological conditions, yet there are no studies assessing UV nose guards for dogs.

OBJECTIVES

Compare the ability of three nasal guards to block solar UV radiation (UVR) from the canine nose, using two commercial products and one created by the authors.

ANIMALS

Four fabric model dogs were used in this prospective controlled trial.

MATERIALS AND METHODS

Each model had a UV dosimeter applied to the dorsal nose and anterior nasal planum. Three models had nose protectors applied: (1) a mesh hood (OutFox Field Guard, OutFox For Dogs); (2) a fabric nose shield (Nose Protector, Dog Nose Protectors); or (3) a basket muzzle with ultraviolet protection factor (UPF) 50+ fabric developed by the authors. The control had no protective device applied. All the models were placed in direct sunlight and measurements taken over nine 2 h time periods. Total cumulative UVR was analysed for each location and type of guard or control.

RESULTS

All guards provided statistically significant UV protection compared to control at all time points (p < 0.001). The basket muzzle with UPF 50+ guard was consistent in protecting the dorsal and anterior nose, blocking 94.2% and 94.3% UVR, respectively. The fabric nose protector blocked 99.2% UVR from the dorsal and 82.9% anterior. The mesh hood blocked 72.5% of UVR dorsal and 71.4% anterior.

CONCLUSIONS AND CLINICAL RELEVANCE

Two guards were superior in blocking UVR; however, the choice of UV guard in a clinical setting depends on an individual's disease location and tolerance of the device.

Functional Fiber Materials to Smart Fiber Devices

The development of fiber materials has accompanied the evolution of human civilization for centuries. Recent advances in materials science and chemistry offered fibers new applications with various functions, including energy harvesting, energy storing, displaying, health monitoring and treating, and computing. The unique one-dimensional shape of fiber devices endows them advantages to work as human-interfaced electronics due to the small size, lightweight, flexibility, and feasibility for integration into large-scale textile systems. In this review, we first present a discussion of the basics of fiber materials and the design principles of fiber devices, followed by a comprehensive analysis on recently developed fiber devices. Finally, we provide the current challenges facing this field and give an outlook on future research directions. With novel fiber devices and new applications continuing to be discovered after two decades of research, we envision that new fiber devices could have an important impact on our life in the near future.

Workplace exposure to UV radiation and strategies to minimize cancer risk

BACKGROUND

Workplace exposure to solar ultraviolet (UV) causes malignant melanoma and non-melanoma skin cancer. The evidence for beneficial effects of solar UV exposure in reducing the risks for other cancers is increasing. The intensity of UV radiation at the Earth's surface is dependent on latitude, but even in northern European countries exposure can be high enough for outdoor work to cause skin cancer.

GROWING POINTS

Awareness of the health risks and benefits of occupational solar UV exposure is poor. Actions to reduce the risk of skin cancer have been identified and employers should recognize their responsibility to actively manage these risks. There is evidence for reduced risks for breast, ovarian and colorectal cancer and possibly other cancers linked to solar UV exposure.

SOURCES OF DATA

This narrative review draws on published scientific articles and material designed to assist identifying strategies to protect workers from solar UV exposure.

AREAS OF AGREEMENT

Solar UV exposure can be harmful. Wavelengths in the UVB range are more effective in causing erythema and DNA damage. Solar UV is the main source of vitamin D for most people. Primary and secondary prevention for skin cancer can potentially eliminate these risks but the evidence for effectiveness is limited.

AREAS OF CONTROVERSY

Potential health benefits of UV exposure, particularly for reduced cancer risk. Determining and communicating optimal exposure to maximize health benefits. The risk of non-melanoma skin cancers may be more than doubled for some workers in temperate latitudes.

AREAS TIMELY FOR DEVELOPING RESEARCH

Exposure-response epidemiological studies; studies of the health benefits of occupational UV exposure; studies of the effectiveness of intervention strategies to prevent skin cancer. Use of low-cost UV sensors in workplaces.

Temperature and strain sensitivities of a groove bonded fiber Bragg grating at room and cryogenic temperatures

Optical fiber Bragg gratings (FBGs) are well suited for applications as temperature or/and strain sensors in harsh environments, e.g., detecting thermal hot spots in high-temperature superconductor (HTS) fusion energy magnets at cryogenic temperatures and high radiation environments. To maximize the signal-to-noise ratio (SNR) of the FBGs to a hot spot, we propose to have them mounted in V-shaped grooves of HTS' copper former. To investigate the differences between different adhesives on transferring strain and heat in this configuration, five arrays of FBGs are mounted in the V-shaped grooves of a copper dog-bone using Scotch-Weld epoxy, Stycast 2850 FT, Apiezon N, and Loctite 5145 silicone. The copper is cycled through tensile forces in a modified universal tensile tester, subjected to a thermal cycle between 293 K and 77 K, and exposed to heat pulse propagations at 293 K and 80 K. The FBGs that are bonded using Stycast show the highest temperature and strain sensitivities at room and cryogenic temperatures. No major differences in the temperature and strain sensitivities have been found between Ormocer and polyimide coated FBGs. Apiezon N is found to transfer strain consistently well below 245 K, which is comparable with other bonding materials in the temperature range between 77 K and 110 K. The FBGs bonded with the four adhesives in the V-groove configurations are shown to have comparable SNRs to a temperature rise of 20 K at 80 K. This paper emphasizes the importance of maximizing the thermal strain transferred from the host material through the bonding agents to achieve high temperature sensitivity of FBGs.

Applying the exposome concept to working life health

Exposures at work have a major impact on noncommunicable diseases (NCDs). Current risk reduction policies and strategies are informed by existing scientific evidence, which is limited due to the challenges of studying the complex relationship between exposure at work and outside work and health. We define the working life exposome as all occupational and related nonoccupational exposures. The latter includes nonoccupational exposures that may be directly or indirectly influenced by or interact with the working life of the individual in their relation to health. The Exposome Project for Health and Occupational Research aims to advance knowledge on the complex working life exposures in relation to disease beyond the single high exposure–single health outcome paradigm, mapping and relating interrelated exposures to inherent biological pathways, key body functions, and health. This will be achieved by combining (1) large-scale harmonization and pooling of existing European cohorts systematically looking at multiple exposures and diseases, with (2) the collection of new high-resolution external and internal exposure data. Methods and tools to characterize the working life exposome will be developed and applied, including sensors, wearables, a harmonized job exposure matrix (EuroJEM), noninvasive biomonitoring, omics, data mining, and (bio)statistics. The toolbox of developed methods and knowledge will be made available to policy makers, occupational health practitioners, and scientists. Advanced knowledge on working life exposures in relation to NCDs will serve as a basis for evidence-based and cost-effective preventive policies and actions. The toolbox will also enable future scientists to further expand the working life exposome knowledge base.

Recent Trends in Graphene/Polymer Nanocomposites for Sensing Devices: Synthesis and Applications in Environmental and Human Health Monitoring

Graphene-based nanocomposites are largely explored for the development of sensing devices due to the excellent electrical and mechanical properties of graphene. These properties, in addition to its large specific surface area, make graphene attractive for a wide range of chemical functionalization and immobilization of (bio)molecules. Several techniques based on both top-down and bottom-up approaches are available for the fabrication of graphene fillers in pristine and functionalized forms. These fillers can be further modified to enhance their integration with polymeric matrices and substrates and to tailor the sensing efficiency of the overall nanocomposite material. In this review article, we summarize recent trends in the design and fabrication of graphene/polymer nanocomposites (GPNs) with sensing properties that can be successfully applied in environmental and human health monitoring. Functional GPNs with sensing ability towards gas molecules, humidity, and ultraviolet radiation can be generated using graphene nanosheets decorated with metallic or metal oxide nanoparticles. These nanocomposites were shown to be effective in the detection of ammonia, benzene/toluene gases, and water vapor in the environment. In addition, biological analytes with broad implications for human health, such as nucleic bases or viral genes, can also be detected using sensitive, graphene-based polymer nanocomposites. Here, the role of the biomolecules that are immobilized on the graphene nanomaterial as target for sensing is reviewed.

Wearable Light Sensors Based on Unique Features of a Natural Biochrome

Overexposure to complete solar radiation (combined ultraviolet, visible, and infrared) is correlated with several harmful biological consequences including hyperpigmentation, skin cancer, eye damage, and immune suppression. With limited effective therapeutic options available for these conditions, significant efforts have been directed toward promoting preventative habits. Recently, wearable solar radiometers have emerged as practical tools for managing personal exposure to sunlight. However, designing simple and inexpensive sensors that can measure energy across multiple spectral regions without incorporating electronic components remains challenging, largely due to inherent spectral limitations of photoresponsive indicators. In this work, we report the design, fabrication, and characterization of wearable radiation sensors that leverage an unexpected feature of a natural biochrome, xanthommatin-its innate sensitivity to both ultraviolet and visible through near-infrared radiation. We found that xanthommatin-based sensors undergo a visible shift from yellow to red in the presence of complete sunlight. This color change is driven by intrinsic photoreduction of the molecule, which we investigated using computational modeling and supplemented by radiation-driven formation of complementary reducing agents. These sensors are responsive to dermatologically relevant doses of erythemally weighted radiation, as well as cumulative doses of high-energy ultraviolet radiation used for germicidal sterilization. We incorporated these miniature sensors into pressure-activated microfluidic systems to illustrate on-demand activation of a wearable and mountable form factor. When taken together, our findings encompass an important advancement toward accessible, quantitative measurements of UVC and complete solar radiation for a variety of use cases.

High-Frequency TiO2 Nanotube-Adapted Microwave Coplanar Waveguide Resonator for High-Sensitivity Ultraviolet Detection

Ultraviolet (UV) sensors are a key component in growing applications such as water quality treatment and environmental monitoring, with considerable interest in their miniaturization and enhanced operation. This work presents a passive gold coplanar waveguide split ring resonator integrated with anodic self-organized TiO₂ nanotube (TNT) membranes with a thickness of 20 μm to provide real-time UV detection. The resonator operated as a one-port device to capture the reflection coefficient (S₁₁) signal, with a center frequency of 16 GHz and a notch amplitude of -88 dB. It was experimentally analyzed for its UV sensing capability in the range of 36.5-463 μW/cm². The high-frequency resonator was improved through design choices including the addition of a tapered input transmission line, wire bonding for practical device design, and an interdigitated capacitive ring gap. The high frequency also helped mitigate noise due to water vapor or environmental contaminants. S₁₁ amplitude variation was found through both experiments and modeling to follow a linear trend with UV illumination intensity. The resonator exhibited over 45 ± 2 dB shift in the resonant amplitude under the highest UV illumination conditions, with a sensitivity of 0.084 dB/μW cm^-2 and the potential to sense UV intensity as low as 2.7 μW/cm². The presented device enabled a repeatable and accurate microwave response under UV illumination with very high sensitivity, entirely through the use of passive circuit elements.

Keratinocyte death by ferroptosis initiates skin inflammation after UVB exposure

The ultraviolet B radiation (UVB) causes skin inflammation, which contributes to the causality and the exacerbation of a number of cutaneous diseases. However, the mechanism of UVB-driven inflammation in the skin remains poorly understood. We show that ferroptosis, a non-apoptotic programmed cell death pathway that is promoted by an excessive phospholipid peroxidation, is activated in the epidermal keratinocytes after their exposure to UVB. The susceptibility of the keratinocytes to UVB-induced ferroptosis depends on the extent of pro-ferroptosis death signal generation and the dysregulation of the glutathione system. Inhibition of ferroptosis prevents the release of HMGB1 from the human epidermal keratinocytes, and blocks necroinflammation in the UVB-irradiated mouse skin. We show that while apoptosis and pyroptosis are also detectable in the keratinocytes after UVB exposure, ferroptosis plays a significant role in initiating UVB-induced inflammation in the skin. Our results have important implications for the prevention and the treatment of a broad range of skin diseases which are fostered by UVB-induced inflammation.

Affecting Young Children’s Knowledge, Attitudes, and Behaviors for Ultraviolet Radiation Protection through the Internet of Things: A Quasi-Experimental Study

Prolonged exposure to ultraviolet (UV) radiation is linked to skin cancer. Children are more vulnerable to UV harmful effects compared to adults. Children’s active involvement in using Internet of Things (IoT) devices to collect and analyze real-time UV radiation data is suggested to increase their awareness of UV protection. This quasi-experimental pre-test post-test control group study implemented light sensors in a STEM inquiry-based learning environment focusing on UV radiation and protection in primary education. This exploratory, small-scale study investigated the effect of a STEM environment implementing IoT devices on 6th graders’ knowledge, attitudes, and behaviors about UV radiation and protection. Participants were 31 primary school students. Experimental group participants (n = 15) attended four eighty-minute inquiry-based lessons on UV radiation and protection and used sensors to measure and analyze UV radiation in their school. Data sources included questionnaires on UV knowledge, attitudes, and behaviors administered pre- and post-intervention. Statistically significant learning gains were found only for the experimental group (t14 = −3.64, p = 0.003). A statistically significant positive behavioral change was reported for experimental group participants six weeks post-intervention. The study adds empirical evidence suggesting the value of real-time data-driven approaches implementing IoT devices to positively influence students’ knowledge and behaviors related to socio-scientific problems affecting their health.

Bringing Light into Darkness-Comparison of Different Personal Dosimeters for Assessment of Solar Ultraviolet Exposure

(1) Measuring personal exposure to solar ultraviolet radiation (UVR) poses a major challenges for researchers. Often, the study design determines the measuring devices that can be used, be it the duration of measurements or size restrictions on different body parts. It is therefore of great importance that measuring devices produce comparable results despite technical differences and modes of operation. Particularly when measurement results from different studies dealing with personal UV exposure are to be compared with each other, the need for intercomparability and intercalibration factors between different measurement systems becomes significant. (2) Three commonly used dosimeter types—(polysulphone film (PSF), biological, and electronic dosimeters)—were selected to perform intercalibration measurements. They differ in measurement principle and sensitivity, measurement accuracy, and susceptibility to inaccuracies. The aim was to derive intercalibration factors for these dosimeter types. (3) While a calibration factor between PSF and electronic dosimeters of about 1.3 could be derived for direct irradiation of the dosimeters, this was not the case for larger angles of incidence of solar radiation with increasing fractions of diffuse irradiation. Electronic dosimeters show small standard deviation across all measurements. For biological dosimeters, no intercalibration factor could be found with respect to PSF and electronic dosimeters. In a use case, the relation between steady-state measurements and personal measurements was studied. On average, persons acquired only a small fraction of the ambient radiation.

The Ultraviolet Index Is Well Estimated by the Terrestrial Irradiance at 310 nm

Ultraviolet (UV) exposure significantly contributes to non-melanoma skin cancer. In the context of health, UV exposure is the product of time and the UV Index (UVI), a weighted sum of the irradiance I(λ) over all wavelengths from λ = 250 to 400 nm. In our analysis of the United States Environmental Protection Agency’s UV-Net database of over 400,000 spectral irradiance measurements taken over several years, we found that the UVI is well estimated by 77 I₃₁₀. To further understand this result, we applied an optical atmospheric model to generate terrestrial irradiance spectra and found that it applies across a wide range of conditions. An accurate UVI radiometer can be built from a photodiode covered by a bandpass filter centered at 310 nm.

LPWAN and Embedded Machine Learning as Enablers for the Next Generation of Wearable Devices

The penetration of wearable devices in our daily lives is unstoppable. Although they are very popular, so far, these elements provide a limited range of services that are mostly focused on monitoring tasks such as fitness, activity, or health tracking. Besides, given their hardware and power constraints, wearable units are dependent on a master device, e.g., a smartphone, to make decisions or send the collected data to the cloud. However, a new wave of both communication and artificial intelligence (AI)-based technologies fuels the evolution of wearables to an upper level. Concretely, they are the low-power wide-area network (LPWAN) and tiny machine-learning (TinyML) technologies. This paper reviews and discusses these solutions, and explores the major implications and challenges of this technological transformation. Finally, the results of an experimental study are presented, analyzing (i) the long-range connectivity gained by a wearable device in a university campus scenario, thanks to the integration of LPWAN communications, and (ii) how complex the intelligence embedded in this wearable unit can be. This study shows the interesting characteristics brought by these state-of-the-art paradigms, concluding that a wide variety of novel services and applications will be supported by the next generation of wearables.