A wearable aptamer nanobiosensor for non-invasive female hormone monitoring

Interfacial engineering for biomolecule immobilisation in microfluidic devices

Microfluidic devices are used for various applications in biology and medicine. From on-chip modelling of human organs for drug screening and fast and straightforward point-of-care (POC) detection of diseases to sensitive biochemical analysis, these devices can be custom-engineered using low-cost techniques. The microchannel interface is essential for these applications, as it is the interface of immobilised biomolecules that promote cell capture, attachment and proliferation, sense analytes and metabolites or provide enzymatic reaction readouts. However, common microfluidic materials do not facilitate the stable immobilisation of biomolecules required for relevant applications, making interfacial engineering necessary to attach biomolecules to the microfluidic surfaces. Interfacial engineering is performed through various immobilisation mechanisms and surface treatment techniques, which suitably modify the surface properties like chemistry and energy to obtain robust biomolecule immobilisation and long-term storage stability suitable for the final application. In this review, we provide an overview of the status of interfacial engineering in microfluidic devices, covering applications, the role of biomolecules, their immobilisation pathways and the influence of microfluidic materials. We then propose treatment techniques to optimise performance for various biological and medical applications and highlight future areas of development.

Advances in wearable electronics for monitoring human organs: Bridging external and internal health assessments

Devices used for diagnosing disease are often large, expensive, and require operation by trained professionals, which can result in delayed diagnosis and missed opportunities for timely treatment. However, wearable devices are being recognized as a new approach to overcoming these difficulties, as they are small, affordable, and easy to use. Recent advancements in wearable technology have made monitoring information possible from the surface of organs like the skin and eyes, enabling accurate diagnosis of the user's internal status. In this review, we categorize the body's organs into external (e.g., eyes, oral cavity, neck, and skin) and internal (e.g., heart, brain, lung, stomach, and bladder) organ systems and introduce recent developments in the materials and designs of wearable electronics, including electrochemical and electrophysiological sensors applied to each organ system. Further, we explore recent innovations in wearable electronics for monitoring of deep internal organs, such as the heart, brain, and nervous system, using ultrasound, electrical impedance tomography, and temporal interference stimulation. The review also addresses the current challenges in wearable technology and explores future directions to enhance the effectiveness and applicability of these devices in medical diagnostics. This paper establishes a framework for correlating the design and functionality of wearable electronics with the physiological characteristics and requirements of various organ systems.

A fully integrated wireless microfluidic immunosensing system for portable monitoring of Staphylococcus aureus

The advanced devices that function fully without the need for external accessories are regarded as a pinnacle goal in the design and construction of modern ones. Staphylococcus aureus (S. aureus), a prominent human pathogen, is responsible for causing a wide variety of infections and chronic diseases. Herein, we present the first instance of a fully integrated wireless microfluidic immunosensing system (FIWMIS) capable of conducting point-of-care S. aureus monitoring in real samples of S. aureus-spiked commercial purified drinking water and S. aureus-spiked watermelon juice. The development of the proposed FIWMIS became a reality by conquering significant engineering hurdles in seamlessly integrating a microfluidic unit for liquid sample transport without the need of an external pump, an immunosensing unit for S. aureus monitoring, and an electronic control unit for signal conversion and wireless transmission. Such full integration culminated in a FIWMIS that upholds its pump-free, wireless, and low-cost characteristics for portable monitoring of S. aureus.

Power-Sustainable and Portable Electrochemical Sensing Platforms for Complex Outdoor Environment Applications

Portable sensor technologies are indispensable in personalized healthcare and environmental monitoring as they enable the continuous tracking of key analytes. Human sweat contains valuable physiological information, and previously developed noninvasive sweat-based sensors have effectively monitored single or multiple biomarkers. By successfully detecting biochemicals in sweat, portable sensors could also significantly broaden their application scope, encompassing non-biological fluids commonly encountered in daily life, such as mineral water. However, developing a portable electrochemical sensing system with sustainable power remains a challenge for real-time, on-site analysis in complex outdoor applications. Here, we present a power-sustainable and portable electrochemical sensing platform, composed of multiple electrochemical sensors, a multichannel data acquisition circuit, a microfluidic module, and a power supply module, that is designed to conform onto the human body for daily use. The device enables simultaneous and selective measurement of Na+, K+, and pH levels in sweat and outdoor environments wirelessly. Additionally, we utilize a dual power supply module composed of a lithium-ion battery and a solar cell, offering a sustainable power supply for various application scenarios. Looking forward, this novel platform can serve as a bridge between monitoring biological fluids and detecting nonbiological fluids in complex outdoor environments.

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.

Comprehensive and Sensitive Analysis of Total PAEs Using a Label-Free Zero-Voltage Photoelectrochemical Biosensor

The sensing of phthalate esters (PAEs) is vital for people's health and environmental protection. This study aimed to develop a highly sensitive and selective photoelectrochemical (PEC) biosensor for PAEs analysis in complex samples. The biosensor is based on a CdS nanoparticle/TiO2 nanotube (CdS NP/TiO2 NT) electrode substrate and a truncated PAEs aptamer (PAEs-apt). By exploiting spatial variations in the potential resistance of the sensing interface, the biosensor achieved superior sensitivity in determining the concentration of PAEs compared to the SELEX aptamer. It exhibited a linear correlation in the range of 0.005 to 1 ng/mL with a detection limit of 1.67 ng/L. Furthermore, the biosensor displayed excellent selectivity for PAEs, with an analysis error factor below 0.277 when the concentration of interfering species was 100 times that of the target. The high performance of the biosensor was attributed to the excellent photoelectronic properties of CdS NPs/TiO2 NTs, high density of PAEs-apt for PAEs, high affinity of PAEs-apt for PAEs, and specific recognition of PAEs. Notably, this PEC biosensor could be used for the PAEs assay in urine and water samples, providing a sensitive and simple analytical method for detecting the same class of compounds with similar chemical structures in complex samples.

Double hook-type aptamer-based colorimetric and electrochemical biosensor enables rapid and robust analysis of EpCAM expression

Epithelial cell adhesion molecule (EpCAM), which is overexpressed in breast cancer cells and participates in cell signaling, migration, proliferation, and differentiation, has been utilized as a biomarker for cancer diagnosis and therapeutic prognosis. Here, a dual-signal readout nonenzymatic aptasensor is fabricated for the evaluation of EpCAM at the level of three breast cancer cell lines. The central principle of this enzyme-free aptasensor is the use of double hook-type aptamers (SYL3C and SJ3C2)-functionalized magnetic iron oxide (Fe3O4) as capture probes and quasi-CoFe prussian blue analogs (QCoFe PBAs) as nonenzymatic signal probes for colorimetric and electrochemical analysis. Following ligand detachment, the CoFe PBA was transformed to QCoFe PBA (calcined at 350 °C for 1 h), with its metal active sites exposed by controllable pyrolysis. We found that the enhanced sensitivity was attributed to the resonance effect of QCoFe PBA with the remarkable enzymatic properties. The dual-signal readout nonenzymatic aptasensor exhibited limits of detection for EpCAM as low as 0.89 pg mL-1 and 0.24 pg mL-1, within a wide linear range from 0.001 to 100 ng mL-1, respectively. We successfully employed this nonenzymatic aptasensor for monitoring EpCAM expression in three breast cancer cell lines, which provides an economical and robust alternative to costly and empirical flow cytometry. The dual-signal readout nonenzymatic aptasensor provides rapid, robust, and promising technological support for the accurate management of tumors.

Surface-Functionalizing Strategies for Multiplexed Molecular Biosensing: Developments Powered by Advancements in Nanotechnologies

Multiplexed biosensing methods for simultaneously detecting multiple biomolecules are important for investigating biological mechanisms associated with physiological processes, developing applications in life sciences, and conducting medical tests. The development of biosensors, especially those advanced biosensors with multiplexing potentials, strongly depends on advancements in nanotechnologies, including the nano-coating of thin films, micro-nano 3D structures, and nanotags for signal generation. Surface functionalization is a critical process for biosensing applications, one which enables the immobilization of biological probes or other structures that assist in the capturing of biomolecules. During this functionalizing process, nanomaterials can either be the objects of surface modification or the materials used to modify other base surfaces. These surface-functionalizing strategies, involving the coordination of sensor structures and materials, as well as the associated modifying methods, are largely determinative in the performance of biosensing applications. This review introduces the current studies on biosensors with multiplexing potentials and focuses specifically on the roles of nanomaterials in the design and functionalization of these biosensors. A detailed description of the paradigms used for method selection has been set forth to assist understanding and accelerate the application of novel nanotechnologies in the development of biosensors.

MXene-based aptasensors: a perspective on recent advances

Recent advancements in science and technology have significantly enhanced public health by integrating novel materials and early diagnostic methods. A key focus is on MXenes, a class of materials known for their distinctive morphology and exceptional stability in diverse environments. MXenes possess notable structural engineering capabilities, enabling their design and synthesis into various forms tailored for specific applications. Their surface can be functionalized with different groups to enable chemical binding and physical attachment to various molecules, while variations in layer thickness and elemental composition influence their electrical conductivity and stability. This perspective article examines recent structural innovations in MXenes, particularly their application in biosensors. We highlight the role of aptamer surface decorations, which offer specific and selective binding for detecting a broad spectrum of analytes, thus underscoring MXenes' potential in advancing diagnostic technologies and improving public health.

Wearable Aptasensors

This Perspective explores the revolutionary advances in wearable aptasensor (WA) technology, which combines wearable devices and aptamer-based detection systems for personalized, real-time health monitoring. The devices leverage the specificity and sensitivity of aptamers to target specific molecules, offering broad applications from continuous glucose tracking to early diagnosis of diseases. The integration of data analytics and artificial intelligence (AI) allows early risk prediction and guides preventive health measures. While challenges in miniaturization, power efficiency, and data security persist, these devices hold significant potential to democratize healthcare and reshape patient-doctor interactions.

Active-reset protein sensors enable continuous in vivo monitoring of inflammation

Continuous measurement of proteins in vivo is important for real-time disease management and prevention. Implantable sensors for monitoring small molecules such as glucose have been available for more than a decade. However, analysis of proteins remains an unmet need because the lower physiological levels require that sensors have high affinities, which are linked to long complexation half-lives (t1/2 ~20 hours) and slow equilibration when concentrations decrease. We report active-reset sensors by use of high-frequency oscillations to accelerate dissociation, which enables regeneration of the unbound form of the sensor within 1 minute. When implemented within implanted devices, these sensors allow for real-time, in vivo monitoring of proteins within interstitial fluid. Active-reset protein sensors track biomarker levels on a physiological timescale for inflammation monitoring in living animals.

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.

Novel self-powered sandwich type Aptamer sensor for estrogen detection assisted with peroxidase mimic Cu-MOF

A novel self-powered and flexible enzymatic biofuel cell (EBFC)-based aptasensor was developed for the sensitive and selective detection of 17 β-estradiol (E2). A flexible polyvinyl alcohol (PVA)-tannic acid‑carbon nanotube/reduced graphene oxide (PTCR) substrate was modified with gold nanoparticles (AuNPs) and thiolated aptamer 1 (Apt1) to yield Apt1@AuNPs/PTCR. A copper-based metal-organic framework (Cu-MOF) with peroxidase mimicking activity was employed to anchor glucose oxidase (GOD) and Apt2, forming the Cu-MOF@GOD/Apt2 tag. When E2 was recognized by Apt1, the anchored E2 quantitatively recognized Cu-MOF@GOD/Apt2 to create a Cu-MOF@GOD/Apt2-E2-Apt1 sandwich structure for glucose oxidation to generate electrical power. Increased E2 concentrations enhanced Cu-MOF@GOD/Apt2 capture and amplified the electrical signal. The electrical power increased linearly as the E2 concentration increased from 1.0 pM to 1.0 nM. The sensor was successfully applied to various food samples and blood serum detection. This work promoted the application of novel self-powered biosensors for food safety analysis.

Core-Sheath Heterogenous Interlocked Stretchable Conductive Fiber Induced by Adhesive MXene Modulated Interfacial Soldering

Whereas high electrical conductivity and mechanical stretchability are both essentially required for flexible electronics, simultaneously achieving them remains a great challenge due to the "trade-off" effect. Herein, an ultrastretchable conductor with core-sheath heterogeneous interlocked structure was developed, induced by interfacial soldering silver nanowires (AgNWs) which gradually evolved into elastic conductive fiber. Adhesive polydopamine-functionalized MXene (PDM) was proposed as an interfacial solder to assemble AgNWs along fibers while induced strong cold-welding effect soldered them into superelastic interconnected network. In situ coaxial heterogeneous interlocking between core AgNWs and sheath PDM network gradually formed during the interfacial soldering process, which enables elastic conductor simultaneously owning large mechanical stretchability and high electrical conductivity. Stretchable conductive fiber with core-sheath heterogeneous interlocking structure not only exhibits excellent electrical conductivity (1.13 × 105 S/m) but also could maintain stability (ΔR/R0 < 0.19) even under large mechanical deformations (300%). Ultrastretchable fibrous conductor with core-sheath heterogeneous interlocked microstructure induced by adhesive PDM interfacial soldering holds great promise in soft electronics.

Nanomaterials for Flexible Neuromorphics

The quest to imbue machines with intelligence akin to that of humans, through the development of adaptable neuromorphic devices and the creation of artificial neural systems, has long stood as a pivotal goal in both scientific inquiry and industrial advancement. Recent advancements in flexible neuromorphic electronics primarily rely on nanomaterials and polymers owing to their inherent uniformity, superior mechanical and electrical capabilities, and versatile functionalities. However, this field is still in its nascent stage, necessitating continuous efforts in materials innovation and device/system design. Therefore, it is imperative to conduct an extensive and comprehensive analysis to summarize current progress. This review highlights the advancements and applications of flexible neuromorphics, involving inorganic nanomaterials (zero-/one-/two-dimensional, and heterostructure), carbon-based nanomaterials such as carbon nanotubes (CNTs) and graphene, and polymers. Additionally, a comprehensive comparison and summary of the structural compositions, design strategies, key performance, and significant applications of these devices are provided. Furthermore, the challenges and future directions pertaining to materials/devices/systems associated with flexible neuromorphics are also addressed. The aim of this review is to shed light on the rapidly growing field of flexible neuromorphics, attract experts from diverse disciplines (e.g., electronics, materials science, neurobiology), and foster further innovation for its accelerated development.

Wearable Electrochemical Biosensors for Advanced Healthcare Monitoring

Recent advancements in wearable electrochemical biosensors have opened new avenues for on-body and continuous detection of biomarkers, enabling personalized, real-time, and preventive healthcare. While glucose monitoring has set a precedent for wearable biosensors, the field is rapidly expanding to include a wider range of analytes crucial for disease diagnosis, treatment, and management. In this review, recent key innovations are examined in the design and manufacturing underpinning these biosensing platforms including biorecognition elements, signal transduction methods, electrode and substrate materials, and fabrication techniques. The applications of these biosensors are then highlighted in detecting a variety of biochemical markers, such as small molecules, hormones, drugs, and macromolecules, in biofluids including interstitial fluid, sweat, wound exudate, saliva, and tears. Additionally, the review also covers recent advances in wearable electrochemical biosensing platforms, such as multi-sensory integration, closed-loop control, and power supply. Furthermore, the challenges associated with critical issues are discussed, such as biocompatibility, biofouling, and sensor degradation, and the opportunities in materials science, nanotechnology, and artificial intelligence to overcome these limitations.

Modular Reconfigurable Approach Toward Noninvasive Wearable Body Net for Monitoring Sweat and Physiological Signals

In the realm of wearable technology, strategically placing sensors at various body locations enhances the detection of diverse physiological indicators crucial for remote medical care. However, current devices often focus on a single body part for specific physical parameters, which hinders the seamless integration of sensors across multiple body parts and necessitates redesign for new detection capabilities. Here, we propose a modular, reconfigurable circuit assembly method that can be adaptable for multiple body locations to construct the body net. By simply reassembling different child modules with the base module using flexible printed circuit board connectors, we can efficiently detect various parameters including sweat ion indicators, electrocardiogram signals, electromyography signals, motion data, heart rate, blood oxygen saturation, and skin temperature. These data can be transmitted to a mobile phone app via a Bluetooth Low Energy protocol for further evaluation. Comparative evaluations against established commercial devices substantiate the viability of our sensor technology. In addition, results from wearable body network detections using reconfigurable sensors across multiple body parts of volunteers also indicate promising application prospects, demonstrating the extensive potential for regular health monitoring and clinical applications.

Variable gain DNA nanostructure charge amplifiers for biosensing

Electronic measurements of engineered nanostructures comprised solely of DNA (DNA origami) enable new signal conditioning modalities for use in biosensing. DNA origami, designed to take on arbitrary shapes and allow programmable motion triggered by conjugated biomolecules, have sufficient mass and charge to generate a large electrochemical signal. Here, we demonstrate the ability to electrostatically control the DNA origami conformation, and thereby the resulting signal amplification, when the structure binds a nucleic acid analyte. Critically, unlike previous studies that employ DNA origami to amplify an electrical signal, we show that the conformation changes under an applied field are reversible. This applied field also simultaneously accelerates structural transitions above the rate determined by thermal motion. We tuned this property of the structures to achieve a response that was ≈2 × 104 times greater (i.e., a gain or amplification) than the value from DNA hybridization under similar conditions. Because this signal amplification is independent of DNA origami-analyte interactions, our approach is agnostic of the end application. Furthermore, since large signal changes are only triggered in response to desirable interactions, we minimize the deleterious effects of non-specific binding. The above benefits of self-assembled DNA origami make them ideally suited for multiplexed biosensing when paired with highly parallel electronic readout.

Vertical Graphene-Based Multiparametric Sensing Array for Integration of Smart Catheter to Electrochemically Monitor Peritoneal Dialysis

Renal failure is typical chronic kidney disease that required peritoneal dialysis as the primary treatment, but current catheter devices lack functionality to monitor changes in chemical analytes during peritoneal dialysis. Fabrication of miniatured sensing modules with good electrochemical performance in tiny catheter devices is the key to realize the smart monitoring of peritoneal dialysis. In this work, a vertical graphene-based multiparametric sensing array (VG-MSA) is developed to continuously measure fluctuations of various analyte concentrations for peritoneal dialysis monitoring. Vertical graphene (VG) electrode with good electrochemical properties serves as the core module in VG-MSA, allowing the development of miniatured sensing modules with sufficient electrochemical performance. The VG-MSA enables sensitive and multiplexed measurement of dialysate components like metabolites (reactive oxygen species, uric acid, and glucose) and ions (K+, Ca2+, and H+). The VG-MSA is demonstrated to effectively detect biochemical signals in peritoneal dialysate in vivo on rat models. The VG-MSA catheter can be inserted into abdominal cavity, allowing full contact with dialysate for in situ, real-time, and continuous collection of biochemical information during peritoneal dialysis. The VG-MSA catheter device offers a valuable tool for monitoring dialysis quality and facilitating treatment adjustments, potentially as a promising platform for high-quality therapy of renal failure.

DNA Nanomaterial-Based Electrochemical Biosensors for Clinical Diagnosis

Sensitive and quantitative detection of chemical and biological molecules for screening, diagnosis and monitoring diseases is essential to treatment planning and response monitoring. Electrochemical biosensors are fast, sensitive, and easy to miniaturize, which has led to rapid development in clinical diagnosis. Benefiting from their excellent molecular recognition ability and high programmability, DNA nanomaterials could overcome the Debye length of electrochemical biosensors by simple molecular design and are well suited as recognition elements for electrochemical biosensors. Therefore, to enhance the sensitivity and specificity of electrochemical biosensors, significant progress has been made in recent years by optimizing the DNA nanomaterials design. Here, the establishment of electrochemical sensing strategies based on DNA nanomaterials is reviewed in detail. First, the structural design of DNA nanomaterial is examined to enhance the sensitivity of electrochemical biosensors by improving recognition and overcoming Debye length. In addition, the strategies of electrical signal transduction and signal amplification based on DNA nanomaterials are reviewed, and the applications of DNA nanomaterial-based electrochemical biosensors and integrated devices in clinical diagnosis are further summarized. Finally, the main opportunities and challenges of DNA nanomaterial-based electrochemical biosensors in detecting disease biomarkers are presented in an aim to guide the design of DNA nanomaterial-based electrochemical devices with high sensitivity and specificity.

Development of a Graphene Oxide-Based Aptamer Nanoarray for Improved Neutralization and Protection Effects Against Ricin

Background/Objectives: Ricin's high toxicity and potential as a bioweapon underscore the need for effective antidotes. Monoclonal antibodies, though effective, are limited by complex production. This study aimed to develop a graphene oxide-based aptamer nanoarray (ARMAN) for improved neutralization and protection against ricin. Methods: High-affinity aptamers targeting ricin's RTA and RTB subunits were selected using SELEX technology and conjugated to graphene oxide (GO) via click chemistry. ARMAN's characteristics, including morphology, stability, and biosecurity, were assessed. Its performance was evaluated in terms of affinity for ricin, neutralization capacity, and therapeutic effects in cellular assays and a mouse model of ricin poisoning. Results: ARMAN exhibited a uniform morphology with an average particle size of 217 nm and demonstrated significantly enhanced affinity for ricin compared to free aptamers. ARMAN showed rapid and effective neutralization ability, significantly increasing cell viability in BEAS-2B, GES-1, and HL7702 cell lines exposed to ricin. In vivo, ARMAN treatment led to a notable prolongation of survival in ricin-poisoned mice, highlighting its potential for both pre- and post-exposure treatment. These findings indicate that ARMAN not only neutralizes ricin effectively but also provides a therapeutic window for treatment. Conclusions: ARMAN's superior binding affinity, serum stability, biocompatibility, and broad therapeutic efficacy make it a promising new antidote against ricin poisoning. This study's findings represent significant progress in the development of rapid-response antidotes, with ARMAN offering a potential solution for both military and civilian emergency response scenarios.

Sustainable Nanofibril Interfaces for Strain-Resilient and Multimodal Porous Bioelectronics

Porous soft bioelectronics have attracted significant attention due to their high breathability, long-term biocompatibility, and other unique features inaccessible in nonporous counterparts. However, fabricating high-quality multimodal bioelectronic components that operate stably under strain on porous substrates, along with integrating microfluidics for sweat management, remains challenging. In this study, cellulose nanofibrils (CNF) are explored, biomass-derived sustainable biomaterials, as nanofibril interfaces with unprecedented interfacial robustness to enable high-quality printing of strain-resilient bioelectronics on porous substrates by reducing surface roughness and creating mechanical heterogeneity. Also, CNF-based microfluidics can provide continuous sweat collection and refreshment, crucial for accurate biochemical sensing. Building upon these advancements, a multimodal porous wearable bioelectronic system is further developed capable of simultaneously detecting electrocardiograms and glucose and beta-hydroxybutyrate in sweat for monitoring energy metabolism and consumption. This work introduces novel strategies for fabricating high-quality, strain-resilient porous bioelectronics with customizable multimodalities to meet arising personalized healthcare needs.

Consumer wearables and personal devices for tracking the fertile window

The market for technology that tracks ovulation to promote conception is rapidly expanding in the United States, targeting the growing audience of technologically proficient, reproductive-age female consumers. In this narrative review, 23 different, nonprescription wearables and devices designed to help women track their fertile window were identified as currently, commercially available in the United States. The majority of these utilize measurements of basal body temperature or combinations of various urinary hormones. This clinical opinion characterizes the scant available research validating the accuracy of these technologies. It further examines research oversight, discusses the utility of these wearables and devices to consumers, and considers these technologies through an equity lens. The discussion concludes with a call for innovation, describing promising new technologies that not only harness unique physiologic parameters to predict ovulation, but also focus on cost-effectiveness with the hope of increasing access to these currently costly devices and wearables.

From Lab to Life: Self-Powered Sweat Sensors and Their Future in Personal Health Monitoring

The rapid development of wearable sweat sensors has demonstrated their potential for continuous, non-invasive disease diagnosis and health monitoring. Emerging energy harvesters capable of converting various environmental energy sources-biomechanical, thermal, biochemical, and solar-into electrical energy are revolutionizing power solutions for wearable devices. Based on self-powered technology, the integration of the energy harvesters with wearable sweat sensors can drive the device for biosensing, signal processing, and data transmission. As a result, self-powered sweat sensors are able to operate continuously without external power or charging, greatly facilitating the development of wearable electronics and personalized healthcare. This review focuses on the recent advances in self-powered sweat sensors for personalized healthcare, covering sweat sensors, energy harvesters, energy management, and applications. The review begins with the foundations of wearable sweat sensors, providing an overview of their detection methods, materials, and wearable devices. Then, the working mechanism, structure, and a characteristic of different types of energy harvesters are discussed. The features and challenges of different energy harvesters in energy supply and energy management of sweat sensors are emphasized. The review concludes with a look at the future prospects of self-powered sweat sensors, outlining the trajectory of the field and its potential to flourish.

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.

Ultrathin Self-Healing Nanofibrous Membrane with a Hierarchical Confined Structure for Biomimetic Epidermal Electrodes

Integrating self-healing capabilities into epidermal electrodes is crucial to improving their reliability and longevity. Self-healing nanofibrous materials are considered an ideal candidate for constructing ultrathin, long-lasting wearable epidermal electrodes due to their lightweight and high breathability. However, due to the strong interaction between fibers, self-healing nanofiber membranes cannot exist stably. Therefore, the development of self-healing and breathable nanofibrous epidermal electrodes still remains a major challenge. Here, a hierarchical confinement strategy that combines molecular and spatial confinement to overcome supramolecular hydrogen bonding between self-healing nanofibers is reported, and an ultrathin self-healing nanofibrous epidermal electrode with a neural net-like structure is developed. It can achieve real-time monitoring of electrophysiological signals through long-term conformal attachment to skin or plants and has no adverse effects on skin health or plant growth. Given the almost imperceptible nature of epidermal electrodes to users and plants, it lays the foundation for the development of biocompatible, self-healing, wearable, flexible electronics.

Stretchable Sweat Lactate Sensor with Dual-Signal Read-Outs

Innovations in wearable sweat sensors hold great promise to provide deeper insights into molecular level health information non-invasively. Lactate, a key metabolite present in sweat, holds immense significance in assessing physiological conditions and performance in sports physiology and health sensing. This paper presents the development and characterization of stretchable electrodes with ultrahigh active surface area of 648 % for lactate sensing. The as-printed stretchable electrodes were functionalized with an electron transfer layer comprising Toluidine Blue O and multi-walled carbon nanotubes (MWCNTs), and an enzymatic layer consisting of lactate dehydrogenase with β-Nicotinamide adenine dinucleotide as the cofactor for lactate selectivity. This sensor achieves a dual-signal read-out in which both electrochemical and fluorescence signals were obtained during lactate detection, demonstrating promising sensor performance in terms of sensitivity and reliability. We demonstrate the robustness of the dual-signal sensor under simulated conditions of physical deformation and shifted excitation. Under these compromised conditions, the performance of the stretchable electrodes remained largely unaffected, showcasing their potential for robust and adaptable sensing platforms in wearable health monitoring applications.

Integrated biosensor array for multiplex biomarkers cancer diagnosis via in-situ self-assembly carbon nanotubes with an ordered inverse-opal structure

To enhance the precision and reliability of early disease detection, especially in malignancies, an exhaustive investigation of multi-target biomarkers is essential. In this study, an advanced integrated electrochemical biosensor array that demonstrates exceptional performance was constructed. This biosensor was developed through a controllable porous-size mechanism and in-situ modification of carbon nanotubes (CNTs) to quantify multiplex biomarkers-specifically, C-reaction protein (CRP), carbohydrate antigen 125 (CA125), and carcinoembryonic antigen (CEA)-in human serum plasma. The fabrication process involved creating a highly ordered three-dimensional inverse-opal structure with the CNTs (pCNTs) modifier through microdroplet-based microfluidics, confined spatial self-assembly of nanoparticles, and chemical wet-etching. This innovative approach allowed for direct in-situ modification of nanomaterial onto the surface of electrode array, eliminating secondary transfer and providing exceptional control over structure and stability. The outstanding electrochemical performance was achieved through the synergistic effect of the pCNTs nanomaterial, aptamer, and horseradish peroxidase-labeled (HRP-) antibody. Additionally, the integrated biosensor array platform comprised multiple individually addressable electrode units (n = 11), enabling simultaneous multi-parallel/target testing, thereby ensuring accuracy and high throughput. Crucially, this integrated biosensor array accurately quantified multiplex biomarkers in human serum, yielding results comparable to commercial methods. This integrated technology holds promise for point-of-care testing (POCT) in early disease diagnosis and biological analysis.

Progress in nanoparticle-based electrochemical biosensors for hormone detection

Hormones are chemical messengers that regulate a wide range of physiological processes including metabolism, development, growth, reproduction and mood. The concentration of hormones that orchestrate the numerous bodily functions is very low (1 nM or less). Efforts have been made to develop highly sensitive tools to detect them. This review represents a critical comparison between different types of nanoparticle-based electrochemical biosensors for the detection of various hormones, namely cortisol, sex hormones (estradiol, progesterone, testosterone), insulin, thyroid-stimulating hormone (TSH) and growth hormone (GH). The electrochemical biosensors investigated for each hormone are first divided on the basis of the biological fluid tested for their detection, and successively on the basis of the electrochemical transducer utilized in the device (voltammetric or impedimetric). Focus is placed on the nanoparticles employed and the successive electrode modification developed in order to improve detection sensitivity and specificity and biosensor stability. Limit of detection (LOD), linear range, reproducibility and possibility of regeneration for continuous reuse are also investigated and compared. The review also addresses the recent trends in the development of wearable biosensors and point-of-care testing for hormone detection in clinical diagnostics useful for endocrinology research, and the future perspectives regarding the integration of nanomaterials, microfluidics, near field communication (NFC) technology and portable devices.

Fully Integrated Biosensing System for Dynamic Monitoring of Sweat Glucose and Real-Time pH Adjustment Based on 3D Graphene MXene Aerogel

The development of noninvasive glucose sensors capable of continuous monitoring without restricting user mobility is crucial, particularly for managing diabetes, which demands consistent and long-term observation. Traditional sensors often face challenges with accuracy and stability that curtail their practical applications. To address these issues, we have innovatively applied a three-dimensional porous aerogel composed of Ti3C2Tx MXene and reduced graphene oxide (MX-rGO) in electrochemical sensing. It significantly reduces the electron-transfer distance between the enzyme's redox center and the electrode surface while firmly anchoring the enzyme layer to effectively prevent any leakage. Another pivotal advancement in our study is the integration of the sensor with a real-time adaptive calibration mechanism tailored specifically for analyzing sweat glucose. This sensor not only measures glucose levels but also dynamically monitors and adjusts to pH fluctuations in sweat. Such capabilities ensure the precise delivery of physiological data during physical activities, providing strong support for personalized health management.

Microneedle sensors for dermal interstitial fluid analysis

The rapid advancement in personalized healthcare has driven the development of wearable biomedical devices for real-time biomarker monitoring and diagnosis. Traditional invasive blood-based diagnostics are painful and limited to sporadic health snapshots. To address these limitations, microneedle-based sensing platforms have emerged, utilizing interstitial fluid (ISF) as an alternative biofluid for continuous health monitoring in a minimally invasive and painless manner. This review aims to provide a comprehensive overview of microneedle sensor technology, covering microneedle design, fabrication methods, and sensing strategy. Additionally, it explores the integration of monitoring electronics for continuous on-body monitoring. Representative applications of microneedle sensing platforms for both monitoring and therapeutic purposes are introduced, highlighting their potential to revolutionize personalized healthcare. Finally, the review discusses the remaining challenges and future prospects of microneedle technology.

Graphical Abstract

One-pot assay using a target-driven split aptamer recognition and assembly strategy for convenient and rapid detection of gliotoxin

An aptamer targeting gliotoxin (GTX) was optimized to increase the binding affinity by approximately 20 times and achieve higher structural stability and targeting specificity. Molecular dynamics simulations were used to explore the molecular mechanism and key action sites underlying the recognition of GTX by the optimized aptamer. Subsequently, the optimized aptamer was split into two fragments and a convenient and rapid one-pot assay for GTX detection was successfully established using a target-driven split aptamer recognition and assembly strategy. The method exhibited a good linear range of 0.128 nM to 2 μM, a low detection limit of 0.07 nM, and excellent selectivity for GTX. Furthermore, the method had good accuracy and stability in real sample analysis. Therefore, the developed one-pot method provides a reliable, convenient, and cost-effective approach for the widespread application of GTX detection.

Programmable and ultra-efficient Argonaute protein-mediated nucleic acid tests: A review

With the attributes of high sensitivity, single-base resolution, multiplex detection capability, and programmability upon nucleic acid recognition, Argonaute (Ago)-based biosensing assays are increasingly recognized as one of the most promising tools for precise identification and quantification of target analytes. Employed as highly specific sequence recognition elements of these robust diagnostic methods, Agos are revolutionizing how nucleic acid targets are detected. A systematic and comprehensive summary of this emerging and rapid-advancing technology is necessary to give play to the potential of Ago-based biosensing assays. The structure and function of Agos were briefly overviewed at the beginning of the work, followed by a review of the recent advancements in employing Agos sensing for detecting various targets with a comprehensive analysis such as viruses, tumor biomarkers, pathogens, mycoplasma, and parasite. The significance and benefits of these platforms were then deliberated. In addition, the authors shared subjective viewpoints on the existing challenges and offered relevant guidance for the future progress of Agos assays. Finally, the future research outlook regarding Ago-based sensing in this field was also outlined. As such, this review is expected to offer valuable information and fresh perspectives for a broader group of researchers.

Recent advances in nonenzymatic electrochemical biosensors for sports biomarkers: focusing on antibodies, aptamers and molecularly imprinted polymers

Nonenzymatic electrochemical biosensors, renowned for their high sensitivity, multi-target analysis capabilities, and miniaturized integration, align well with the requirements of non-invasive, multi-index integrated, continuous monitoring, and user-friendly wearable biosensors in sports science. In the past three years, novel strategies targeting specific responses to sports biomarkers have opened new avenues for applications in sports science. However, these advancements also pose challenges in achieving adequate sensitivity and specificity for online analysis of complex sweat bio-samples. Our article focuses on three key nonenzymatic electrochemical biosensing strategies: antigen-antibody reactions, nucleic acid aptamer recognition, and molecular imprinting capture. We delve into strategies to enhance specificity and sensitivity in the application of biosensors in sports science, including shortening signal transduction paths through built-in signal probes, increasing reaction sites through increased surface area and the introduction of nanostructures, multi-target analyses, and microfluidic techniques.

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.

A Fully Integrated Conformal Wearable Ultrasound Patch for Continuous Sonodynamic Therapy

Cancer treatment is a continuous process, that the current therapy cannot meet the requirement well, including radiotherapy and chemotherapy. Wearable ultrasound device has the potential for continuous sonodynamic therapy due to its portability. However, the miniaturization of ultrasonic probe, system integration of device, and the strategy of continuous treatment are still urgent issues to be addressed. Herein, a portable wearable antitumor system is introduced, which utilizes a custom-developed multiplexed ultrasonic patch array (CWUS Patch) to accurately focus ultrasound on the lesion site and controllably stimulate sonosensitizer to produce a large amount of toxic reactive oxygen species (ROS). The system enables dynamic control of the ultrasound patches and allows real-time adjustments to optimize their performance in various applications, providing greater flexibility and precision in healthcare technology. Furthermore, the excellent penetration property of ultrasound into tumor tissues that induce synchronous apoptosis of tumor cells from the inside out is verified through a mouse model of breast cancer. This fully integrated conformal wearable ultrasound system provides a promising approach to noninvasively, continuously, and efficiently treat deep tumors.

Insertable Glucose Sensor Using a Compact and Cost-Effective Phosphorescence Lifetime Imager and Machine Learning

Optical continuous glucose monitoring (CGM) systems are emerging for personalized glucose management owing to their lower cost and prolonged durability compared to conventional electrochemical CGMs. Here, we report a computational CGM system, which integrates a biocompatible phosphorescence-based insertable biosensor and a custom-designed phosphorescence lifetime imager (PLI). This compact and cost-effective PLI is designed to capture phosphorescence lifetime images of an insertable sensor through the skin, where the lifetime of the emitted phosphorescence signal is modulated by the local concentration of glucose. Because this phosphorescence signal has a very long lifetime compared to tissue autofluorescence or excitation leakage processes, it completely bypasses these noise sources by measuring the sensor emission over several tens of microseconds after the excitation light is turned off. The lifetime images acquired through the skin are processed by neural network-based models for misalignment-tolerant inference of glucose levels, accurately revealing normal, low (hypoglycemia) and high (hyperglycemia) concentration ranges. Using a 1 mm thick skin phantom mimicking the optical properties of human skin, we performed in vitro testing of the PLI using glucose-spiked samples, yielding 88.8% inference accuracy, also showing resilience to random and unknown misalignments within a lateral distance of ∼4.7 mm with respect to the position of the insertable sensor underneath the skin phantom. Furthermore, the PLI accurately identified larger lateral misalignments beyond 5 mm, prompting user intervention for realignment. The misalignment-resilient glucose concentration inference capability of this compact and cost-effective PLI makes it an appealing wearable diagnostics tool for real-time tracking of glucose and other biomarkers.

Vaginal Sensors

The development and market emergence of vaginal sensors have begun to demonstrate their impact on women's healthcare. Until recently, in limited cases, these sensors have exhibited their capabilities in diagnosing and monitoring disorders of the vaginal tract during different stages of women's lives. This Perspective is a compilation of what has been accomplished so far in the landscape of vaginal sensors. The text explores the diverse types of vaginal sensor technologies, their applications, and their potential impact on women's healthcare. The review introduces the anatomy of the vagina and cervix and categorizes vaginal sensors that have been developed, highlighting the technologies and potential applications. The paper covers biomarkers of the vaginal tract and discusses their importance in maintaining the overall characteristics of the vaginal system. The text also explores the clinical implications of vaginal sensors in pregnancy monitoring, disease detection, and sexual health management. In the final step, the manuscript provides future perspectives and possibilities that can be incorporated in the emerging field of vaginal sensors.

Materials, Structure, and Interface of Stretchable Interconnects for Wearable Bioelectronics

Since wearable technologies for telemedicine have emerged to tackle global health concerns, the demand for well-attested wearable healthcare devices with high user comfort also arises. Skin-wearables for health monitoring require mechanical flexibility and stretchability for not only high compatibility with the skin's dynamic nature but also a robust collection of fine health signals from within. Stretchable electrical interconnects, which determine the device's overall integrity, are one of the fundamental units being understated in wearable bioelectronics. In this review, a broad class of materials and engineering methodologies recently researched and developed are presented, and their respective attributes, limitations, and opportunities in designing stretchable interconnects for wearable bioelectronics are offered. Specifically, the electrical and mechanical characteristics of various materials (metals, polymers, carbons, and their composites) are highlighted, along with their compatibility with diverse geometric configurations. Detailed insights into fabrication techniques that are compatible with soft substrates are also provided. Importantly, successful examples of establishing reliable interfacial connections between soft and rigid elements using novel interconnects are reviewed. Lastly, some perspectives and prospects of remaining research challenges and potential pathways for practical utilization of interconnects in wearables are laid out.

Designs and Applications for the Multimodal Flexible Hybrid Epidermal Electronic Systems

Research on the flexible hybrid epidermal electronic system (FHEES) has attracted considerable attention due to its potential applications in human-machine interaction and healthcare. Through material and structural innovations, FHEES combines the advantages of traditional stiff electronic devices and flexible electronic technology, enabling it to be worn conformally on the skin while retaining complex system functionality. FHEESs use multimodal sensing to enhance the identification accuracy of the wearer's motion modes, intentions, or health status, thus realizing more comprehensive physiological signal acquisition. However, the heterogeneous integration of soft and stiff components makes balancing comfort and performance in designing and implementing multimodal FHEESs challenging. Herein, multimodal FHEESs are first introduced in 2 types based on their different system structure: all-in-one and assembled, reflecting totally different heterogeneous integration strategies. Characteristics and the key design issues (such as interconnect design, interface strategy, substrate selection, etc.) of the 2 multimodal FHEESs are emphasized. Besides, the applications and advantages of the 2 multimodal FHEESs in recent research have been presented, with a focus on the control and medical fields. Finally, the prospects and challenges of the multimodal FHEES are discussed.

High-Fidelity Bioelectrodes with Bidirectional Ion-Electron Transduction Capability by Integrating Multiple Charge-Transfer Processes

Bioelectronics is an exciting field that bridges the gap between physiological activities and external electronic devices, striving for high resolution, high conformability, scalability, and ease of integration. One crucial component in bioelectronics is bioelectrodes, designed to convert neural activity into electronic signals or vice versa. Previously reported bioelectrodes have struggled to meet several essential requirements simultaneously: high-fidelity signal transduction, high charge injection capability, strain resistance, and multifunctionality. This work introduces a novel strategy for fabricating superior bioelectrodes by merging multiple charge-transfer processes. The resulting bioelectrodes offer accurate ion-to-electron transduction for capturing electrophysiological signals, dependable charge injection capability for neuromodulation, consistent electrode potential for artifact rejection and biomolecule sensing, and high transparency for seamless integration with optoelectronics. Furthermore, the bioelectrode can be designed to be strain-insensitive by isolating signal transduction from electron transportation. The innovative concept presented in this work holds great promise for extending to other electrode materials and paves the way for the advancement of multimodal bioelectronics.

Nucleic acid-based wearable and implantable electrochemical sensors

The rapid advancements in nucleic acid-based electrochemical sensors for implantable and wearable applications have marked a significant leap forward in the domain of personal healthcare over the last decade. This technology promises to revolutionize personalized healthcare by facilitating the early diagnosis of diseases, monitoring of disease progression, and tailoring of individual treatment plans. This review navigates through the latest developments in this field, focusing on the strategies for nucleic acid sensing that enable real-time and continuous biomarker analysis directly in various biofluids, such as blood, interstitial fluid, sweat, and saliva. The review delves into various nucleic acid sensing strategies, emphasizing the innovative designs of biorecognition elements and signal transduction mechanisms that enable implantable and wearable applications. Special perspective is given to enhance nucleic acid-based sensor selectivity and sensitivity, which are crucial for the accurate detection of low-level biomarkers. The integration of such sensors into implantable and wearable platforms, including microneedle arrays and flexible electronic systems, actualizes their use in on-body devices for health monitoring. We also tackle the technical challenges encountered in the development of these sensors, such as ensuring long-term stability, managing the complexity of biofluid dynamics, and fulfilling the need for real-time, continuous, and reagentless detection. In conclusion, the review highlights the importance of these sensors in the future of medical engineering, offering insights into design considerations and future research directions to overcome existing limitations and fully realize the potential of nucleic acid-based electrochemical sensors for healthcare applications.

DeltaGzip: Computing Biopolymer-Ligand Binding Affinity via Kolmogorov Complexity and Lossless Compression

The design of biosequences for biosensing and therapeutics is a challenging multistep search and optimization task. In principle, computational modeling may speed up the design process by virtual screening of sequences based on their binding affinities to target molecules. However, in practice, existing machine-learned models trained to predict binding affinities lack the flexibility with respect to reaction conditions, and molecular dynamics simulations that can incorporate reaction conditions suffer from high computational costs. Here, we describe a computational approach called DeltaGzip that evaluates the free energy of binding in biopolymer-ligand complexes from ultrashort equilibrium molecular dynamics simulations. The entropy of binding is evaluated using the Kolmogorov complexity definition of entropy and approximated using a lossless compression algorithm, Gzip. We benchmark the method on a well-studied data set of protein-ligand complexes comparing the predictions of DeltaGzip to the free energies of binding obtained using Jarzynski equality and experimental measurements.

Recent Advances in Materials, Devices and Algorithms Toward Wearable Continuous Blood Pressure Monitoring

Continuous blood pressure (BP) tracking provides valuable insights into the health condition and functionality of the heart, arteries, and overall circulatory system of humans. The rapid development in flexible and wearable electronics has significantly accelerated the advancement of wearable BP monitoring technologies. However, several persistent challenges, including limited sensing capabilities and stability of flexible sensors, poor interfacial stability between sensors and skin, and low accuracy in BP estimation, have hindered the progress in wearable BP monitoring. To address these challenges, comprehensive innovations in materials design, device development, system optimization, and modeling have been pursued to improve the overall performance of wearable BP monitoring systems. In this review, we highlight the latest advancements in flexible and wearable systems toward continuous noninvasive BP tracking with a primary focus on materials development, device design, system integration, and theoretical algorithms. Existing challenges, potential solutions, and further research directions are also discussed to provide theoretical and technical guidance for the development of future wearable systems in continuous ambulatory BP measurement with enhanced sensing capability, robustness, and long-term accuracy.

Framework Nucleic Acids Combined with 3D Hybridization Chain Reaction Amplifiers for Monitoring Multiple Human Tear Cytokines

Existing tear sensors are difficult to perform multiplexed assays due to the minute amounts of biomolecules in tears and the tiny volume of tears. Herein, the authors leverage DNA tetrahedral frameworks (DTFs) modified on the wireless portable electrodes to effectively capture 3D hybridization chain reaction (HCR) amplifiers for automatic and sensitive monitoring of multiple cytokines in human tears. The developed sensors allow the sensitive determination of various dry eye syndrome (DES)-associated cytokines in human tears with the limit of detection down to 0.1 pg mL-1, consuming as little as 3 mL of tear fluid. Double-blind testing of clinical DES samples using the developed sensor and commercial ELISA shows no significant difference between them. Compared with single-biomarker diagnosis, the diagnostic accuracy of this sensor based on multiple biomarkers has improved by ≈16%. The developed system offers the potential for tear sensors to enable personalized and accurate diagnosis of various ocular diseases.

Recent advances in smart wearable sensors for continuous human health monitoring

In recent years, the biochemical and biological research areas have shown great interest in a smart wearable sensor because of its increasing prevalence and high potential to monitor human health in a non-invasive manner by continuous screening of biomarkers dispersed throughout the biological analytes, as well as real-time diagnostic tools and time-sensitive information compared to conventional hospital-centered system. These smart wearable sensors offer an innovative option for evaluating and investigating human health by incorporating a portion of recent advances in technology and engineering that can enhance real-time point-of-care-testing capabilities. Smart wearable sensors have emerged progressively with a mixture of multiplexed biosensing, microfluidic sampling, and data acquisition systems incorporated with flexible substrate and bodily attachments for enhanced wearability, portability, and reliability. There is a good chance that smart wearable sensors will be relevant to the early detection and diagnosis of disease management and control. Therefore, pioneering smart wearable sensors into reality seems extremely promising despite possible challenges in this cutting-edge technology for a better future in the healthcare domain. This review presents critical viewpoints on recent developments in wearable sensors in the upcoming smart digital health monitoring in real-time scenarios. In addition, there have been proactive discussions in recent years on materials selection, design optimization, efficient fabrication tools, and data processing units, as well as their continuous monitoring and tracking strategy with system-level integration such as internet-of-things, cyber-physical systems, and machine learning algorithms.

A trivalent aptasensor by using DNA tetrahedron as scaffold for label-free determination of antibiotics

Owing to advantage in high sensitivity and fast response, aptamer based electrochemical biosensors have attracted much more attention. However, inappropriate interfacial engineering strategy leads to poor recognition performance, which ascribe to the following factors of immobilized oligonucleotide strand including steric hindrance, interchain entanglement, and unfavorable conformation. In this work, we proposed a DNA tetrahedron based diblock aptamer immobilized strategy for the construction of label-free electrochemical biosensor. The diblock aptamer sequence is composite of T-rich anchor domain and recognition domain, where T-rich domain enabling anchored on the edge of DNA tetrahedron via Hoogsteen hydrogen bond at neutral condition. The DNA tetrahedron scaffold offers an appropriate lateral space for target recognition of diblock aptamer. More importantly, this trivalent aptamer recognition interface can be regenerated by simply adjusting the pH environment to alkaline, resulting in the dissociation of diblock aptamer. Under the optimum condition, proposed electrochemical aptasensor manifested a satisfied sensitivity for aminoglycosides antibiotic, kanamycin with a limit of detection of 0.69 nM, which is 45-fold lower than traditional Au-S immobilization strategy. Moreover, the proposed aptasensor had also successfully been extended to ampicillin detection by changing the sequence of recognition domain in diblock aptamer. This work paves a new way for the rational design of aptamer-based electrochemical sensor.

Wireless and battery-free wearable biosensing of riboflavin in sweat for precision nutrition

Nutrition assessment is crucial for dietary guidance and prevention of malnutrition. Recent endeavors in wearable biochemical sensors have enabled real-time, in situ analysis of nutrients in sweat. However, the monitoring of riboflavin, an indispensable vitamin B involved in energy metabolism, remains challenging due to its trace level and variations in the sweat matrix. Herein, we report a wireless, battery-free, and flexible wearable biosensing system for the in situ monitoring of sweat riboflavin. Highly sensitive and selective electrochemical voltammetric detection is realized based on the synergistic effect of electrodeposited reduced graphene oxide (rGO) and platinum nanoparticles (PtNPs) with a low detection limit of 1.2 nM. The fully integrated system is capable of sweat sampling with the microfluidic patch, real-time riboflavin analysis and pH calibration with the flexible electrode array, as well as wirelessly simultaneous near field communication (NFC) energy harvesting and data transmission with the flexible circuit and a smartphone. On-body human sweat analysis demonstrates high accuracy cross-validated with gold-standard measurements, and reveals a strong correlation between sweat and urine riboflavin levels. The proposed wearable platform opens up attractive possibilities for noninvasive nutrient tracking, providing strong potential for personalized dietary guidance towards precision nutrition.

Flexible Multimodal Sensing System Based on a Vertical Stacking Strategy for Efficiently Decoupling Multiple Signals

Multisensory integration enables the simultaneous perception of multiple environmental stimuli while minimizing size and energy consumption. However, conventional multifunctional integration in flexible electronics typically requires large-scale horizontal sensing arrays (such as flexible printed circuit boards), posing decoupling complexities, tensile strain limitation, and spatial constraints. Herein, a fully flexible multimodal sensing system (FMSS) is developed by coupling biomimetic stretchable conductive films (BSCFs) and strain-insensitive communication interfaces using a vertical stacking integration strategy. The FMSS achieves vertical integration without additional adhesives, and it can incorporate individual sensing layers and stretchable interconnects without any essential constraint on their deformations. Accordingly, the temperature and pressure are precisely decoupled simultaneously, and tensile stress can be accurately discerned in different directions. This vertical stacking integration strategy is expected to offer a new approach to significantly streamline the design and fabrication of multimodal sensing systems and enhance their decoupling capabilities.