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Wearable sweat sensors exhibit significant promise in the realm of smart healthcare. Efficient and non‐contaminating continuous sweat collection, transport, and disposal are crucial for enhancing detection accuracy. In this study, a novel wearable sweat sensor is presented that integrates various biomimetic structures, including cactus‐inspired spine, shorebird‐inspired conical through‐holes, and frog‐foot‐inspired micro‐grooves. These structures facilitate sweat droplets to be automatically transported from the skin to the sensing chamber and discharged without external power. First, theoretical analysis, simulation, and experiments based on self‐driven droplet mechanisms to determine the optimal transport efficiency parameters for biomimetic structures are conducted. Next, a novel sweat transport module is fabricated through ultra‐precision 3D printing according to these optimal parameters. And this module has excellent sweat collection performance contrastively. Finally, the novel biomimetic sweat transport module is integrated with a high‐sensitivity glucose detection electrode, resulting in a wearable sweat glucose detection system. Human experiments monitoring glucose metabolism in sweat verify the correlation between glucose concentrations in blood and sweat, which proves the feasibility of reflecting changes in the body's circulatory system by monitoring changes in sweat composition. [ABSTRACT FROM AUTHOR]

Human sweat is intricately linked to human health, and unraveling its secrets necessitates a substantial volume of experimental data. However, conventional sensors fabricated via complex processes such as photolithography offer high detection precision at the expense of prohibitive costs. In this study, we presented a cost-effective and high-performance wearable flexible sweat sensor for real-time monitoring of K+ and Na+ concentrations in human sweat, fabricated using screen printing technology. Initially, we evaluated the electrical and electrochemical stability of the screen-printed substrate electrodes, which demonstrated good consistency with a variation within 10% of the relative standard deviation (RSD), meeting the requirements for reliable detection of K+ and Na+ in human sweat. Subsequently, we employed an "ion-electron" transduction layer and an ion-selective membrane to construct the sensors for detecting K+ and Na+. Comprehensive tests were conducted to assess the sensors' sensitivity, linearity, repeatability, resistance to interference, and mechanical deformation capabilities. Furthermore, we evaluated their long-term stability during continuous monitoring and storage. The test results confirmed that the sensor's performance indicators, as mentioned above, met the requirements for analyzing human sweat. In a 10-day continuous and regular monitoring experiment involving volunteers wearing the sensors, a wealth of data revealed a close relationship between K+ and Na+ concentrations in human sweat and hydration status. Notably, we observed that consistent and regular physical exercise effectively enhanced the body's resistance to dehydration. These findings provided a solid foundation for conducting extensive experiments and further exploring the intricate relationship between human sweat and overall health. Our research paved a practical and feasible path for future studies in this domain. [ABSTRACT FROM AUTHOR]

Extracting sufficient volumes of sweat consistently in various scenarios is necessary for next-generation wearable sweat sensors. Here, we developed a sensor patch for Joule-heating sweating and comfortable biofluid monitoring. The Ti 3 C 2 T x nanosheet provides silk fabrics with good electrical conductivity which can serve as an efficient low-voltage electrothermal platform. This biosensor can induce significant sweating in volunteers within just 5 minutes through mild heat stimulation, allowing real-time assessment of metabolic syndrome risks, including Na+, K+, pH, and uric acid levels. Unlike traditional sweat sensors that rely on iontophoresis or physical movement, our approach offered enhanced comfort and efficiency, particularly in sedentary scenarios. Such integration of Joule-heating sweating and sweat analysis endows its potential as a versatile and user-friendly tool in precision medicine and healthcare monitoring. • The patch uses Joule heating to induce sweat efficiently, ideal for sedentary situations. • The Ti 3 C 2 T x nanosheet-coated silk M-textile sensor has excellent electrothermal properties for sweat induction. • The sensor patch offers a comfortable, efficient alternative to iontophoresis and physical exercise. • The sensor enables real-time sodium, potassium, pH, and uric acid monitoring directly from sweat. [ABSTRACT FROM AUTHOR]

Sweat contains a wealth of health-related biomarkers, which has been a promising resource for personalized real-time monitoring at molecular level. Emergence of non-enzymatic electrochemical sensor that simulates the enzyme catalysis utilizing the functional material further promotes the development of wearable sweat sensor, successfully addressing the limitations of enzyme sensing in sensitivity and stability. Thus, there is an urgent need for centering on the regulation of the nanostructure, combination and preparation method of functional materials to enhance the catalytic activity for enzyme-free detection of sweat biomarkers. This review aims to present the superiors of enzyme-free sensing on wearable sweat sensor, and provides guidance for material innovation, sensor design and system integration. Firstly, we primarily focus on the recent advances of novel functional nanomaterials in wearable non-enzymatic electrochemical sensor, and briefly describe the sensing principles for detecting biomarkers in sweat. Subsequently, the correlation between the electrochemical strategy and functional material is elaborately interpreted by coupling with the diverse molecular structures of the biomarkers and the pH changes of test environments. Finally, challenges and opportunities for wearable non-enzymatic electrochemical sensor in sweat sensing are delineated in the development of future personalized healthcare.

Fabric-based sweat sensors based on colorimetric analysis have the characteristics of simple structure, small size, convenience, and comfort, which are more suitable for vigorous exercise. However, the realization of on-demand detection of colorimetric sweat sensors is difficult. It will be invalid immediately once the detection process is activated, which may easily lead to ineffective detection. Therefore, the design and controllable fabrication of the sweat sampling layer is the key to improving the practicality of colorimetric sweat sensors. In this article, the hydrophobic thermoplastic polyurethane (TPU) flexible microfibrous mesh was controllably constructed by melt electrowriting and used as a sweat sampling layer to realize on-demand detection of colorimetric sweat sensor. The gating of different amounts of water can be achieved by precisely and orderly depositing the TPU microfiber meshes with different pore sizes and stacking layer numbers. Simultaneously, the optimal parameters of the TPU mesh were determined by the calibration experiment of the running test, which greatly improved the use efficiency (22 times) of the colorimetric sweat sensor.Moreover, the stability of the optimal sweat sensor was improved by 418% compared with the unoptimized one. The comfort and applicability of wearable sweat sensors in vigorous sports can be enhanced greatly by the controllable preparation of the TPU flexible microfiber meshes, which is helpful to promote the development of sweat sensors. [ABSTRACT FROM AUTHOR]

Human sweat is intricately linked to human health, and unraveling its secrets necessitates a substantial volume of experimental data. However, conventional sensors fabricated via complex processes such as photolithography offer high detection precision at the expense of prohibitive costs. In this study, we presented a cost-effective and high-performance wearable flexible sweat sensor for real-time monitoring of K+ and Na+ concentrations in human sweat, fabricated using screen printing technology. Initially, we evaluated the electrical and electrochemical stability of the screen-printed substrate electrodes, which demonstrated good consistency with a variation within 10% of the relative standard deviation (RSD), meeting the requirements for reliable detection of K+ and Na+ in human sweat. Subsequently, we employed an “ion-electron” transduction layer and an ion-selective membrane to construct the sensors for detecting K+ and Na+. Comprehensive tests were conducted to assess the sensors’ sensitivity, linearity, repeatability, resistance to interference, and mechanical deformation capabilities. Furthermore, we evaluated their long-term stability during continuous monitoring and storage. The test results confirmed that the sensor’s performance indicators, as mentioned above, met the requirements for analyzing human sweat. In a 10-day continuous and regular monitoring experiment involving volunteers wearing the sensors, a wealth of data revealed a close relationship between K+ and Na+ concentrations in human sweat and hydration status. Notably, we observed that consistent and regular physical exercise effectively enhanced the body’s resistance to dehydration. These findings provided a solid foundation for conducting extensive experiments and further exploring the intricate relationship between human sweat and overall health. Our research paved a practical and feasible path for future studies in this domain.

Abstract Background Sweat, as an easily accessible bodily fluid, is enriched with a lot of physiological and health information. A portable and wearable sweat sensor is an important device for an on-body health monitoring. However, there are only few such devices to monitor sweat. Based on the fact that sweat is mainly composed of moisture and salt which is much more abundant than other trace ions in sweat, a new route is proposed to realize wearable sweat sensors using CdSSe nanowire-chips coated with a polyimide (PI) membrane. Results Firstly, the composition-graded CdS1−xSex (x = 0–1) nanowire-chip based sensor shows good photo-sensitivity and stress sensitivity which induces linear humidity dependent conductivity. This indicates good moisture response with a maximum responsivity (dI/I) 244% at 80% relative humidity (RH) even in the dark. Furthermore, the linear current decrease with salt increase illustrates the chip sensor has a good salt-sensing ability with the best salt dependent responsivity of 80%, which guarantees the high prediction accuracy in sweat sensing. The sensor current is further proven to nonlinearly correlate to the amount of sweat with excellent stability, reproducibility and recoverability. The wearable sweat sensor is finally applied on-body real-time sweat analysis, showing good consistence with the body status during indoor exercise. Conclusions These results suggest that this CdSSe nanowire-chip based PI-coated integrated sensor, combined with inorganic and organic functional layers, provides a simple and reliable method to build up diverse portable and wearable devices for the applications on healthcare and athletic status.

Levodopa (L -dopa) is an effective medication for Parkinson's disease. However, excess intake from overdose or the intake of natural sources of L -dopa can be dangerous, causing, for example, tardive dyskinesia. Therefore, in medicated individuals, it is important to monitor the levels of L -dopa in the body. In this paper, we report a simple, wearable, noninvasive, and portable metal−organic framework (MOF)-based electrochemical sensor with integrated enzymes for monitoring the concentration of levodopa in sweat, which can be used as a proxy for L -dopa levels in the body. Zeolitic imidazolate framework/graphene oxide (ZIF-8/GO) composites were prepared by the in-situ growth of ZIF-8 nanoparticles on the surface of GO, and, subsequently, tyrosinase was loaded onto the composite to yield the sensor. Integration with a wireless electronic circuit enabled communication between the sensor and a smartphone application for continuous analysis. The sensor was found to have a wide linear response range from 1 to 95 µM, a low limit of detection of 0.45 µM, satisfactory reproducibility, and excellent selectivity. In addition, the sensor showed high sensitivity and good stability as a result of the anchoring of the enzyme. Thus, the sensor shows promise for continuous, noninvasive point-of-care drug monitoring and management. • Noninvasive electrochemical sensor for levodopa determination in sweat developed. • Anchoring tyrosinase on ZIF-8/graphene oxide increases stability and active sites. • Linear electrochemical response over wide concentration range (1–95 µM). • Low limit of detection of 0.45 µM. • Continuous wireless monitoring of volunteers possible during exercise. [ABSTRACT FROM AUTHOR]