A wearable multisensing patch for continuous sweat monitoring

Abstract

In sport, exercise and healthcare settings, there is a need for continuous, non-invasive monitoring of biomarkers to assess human performance, health and wellbeing. Here we report the development of a flexible microfluidic platform with fully integrated sensing for on-body testing of human sweat. The system can simultaneously and selectively measure metabolite (e.g. lactate) and electrolytes (e.g. pH, sodium) together with temperature sensing for internal calibration. The construction of the platform is designed such that continuous flow of sweat can pass through an array of flexible microneedle type of sensors (50µm diameter) incorporated in a microfluidic channel. Potentiometric sodium ion sensors were developed using a polyvinyl chloride (PVC) functional membrane deposited on an electrochemically deposited internal layer of Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer. The pH sensing layer is based on a highly sensitive membrane of iridium oxide (IrOx). The amperometric-based lactate sensor consists of doped enzymes deposited on top of a semipermeable copolymer membrane and outer polyurethane layers. Real-time data were collected from human subjects during cycle ergometry and treadmill running. A detailed comparison of sodium, lactate and cortisol from saliva is reported, demonstrating the potential of the multi-sensing platform for tracking these outcomes. In summary, a fully integrated sensor for continuous, simultaneous and selective measurement of sweat metabolites, electrolytes and temperature was achieved using a flexible microfluidic platform. This system can also transmit information wirelessly for ease of collection and storage, with the potential for real-time data analytics.

CMOS Interfaces for Internet-of-Wearables Electrochemical Sensors: Trends and Challenges

“…Ideally, wearable chemical sensors should be non-invasive and, among candidate body fluids, such as sweat [6], saliva [8,9], urine and tears [10], sweat seems the most suitable medium to address biochemical parameters unobtrusively. This is reflected by the relatively higher number of works reporting sweat sensors [11][12][13][14][15] in the literature, compared to saliva or tears. Urine is a special case because, although it enables non-invasive determination of biochemical parameters, it does not lend itself for non-invasive monitoring applications.…”

“…This may be achieved through injury prevention and early detection [40], but also through the monitoring of effort and hydration in real time through sweat, which is the obvious sample medium to monitor, given its abundance during physical exertion [41]. In spite of this, sweat measurements also require choosing an adequate body area for sampling [17] and smart sweat management strategies [42], the most common of which are based on microfluidics [43][44][45] or on absorbents and lateral flow membranes [15,20,46].…”

Current technological trends in biosensors, nanoparticle devices and biolabels: Hi‐tech network sensing applications

“…Furthermore, capacitive textile‐insulted biosensors revolutionized wearable devices in health care and diagnostics (Ng & Reaz, ). Apart from these, ionic liquids and flexible microfluidics integrated sensors have also been successfully used for developing wearable diagnostic sensors for stable and specific detection of biological analytes from body fluids (Anastasova et al., ; Munje, Muthukumar, Jagannath, & Prasad, ). Conversely, optics‐based sensor was developed to detect alertness and drowsiness of human beings as a measure for driving ability of vehicles (He et al., ).…”

Wearable Chemosensors: A Review of Recent Progress

“…Humans weat, an easily accessible body fluid, contains av ariety of chemical biomarkers reflecting the state of human health. [62][63][64] Changes in the chemical compositiono fs weat can show av ariety of clinicalc onditions in the human body.M easurements of human sweat are noninvasive, easy,a nd can be done without risk of infection.R ecently,s everaln oninvasive methods have been designed to detect the chemical markers in sweat.…”