Date: 1st October 2020
Article in brief
Wearable biosensors have gained huge traction due to their potential for non-invasive health monitoring. They are used to detect the presence or concentration of a biological analyte, such as a biomolecule, a biological structure or a microorganism and are a means of extracting real-time physiological parameters indicative of health status. Now researchers have developed a battery-free, fully self-powered wearable system that can dynamically monitor key sweat biomarkers.
Sweat is an attractive biosensor medium as it contains a multitude of molecular biomarkers such as electrolytes, metabolites, amino acids, hormones, and drugs that a wearable system can analyse. However, how to power these wearables has been a challenge as continuous monitoring is concomitant with high energy consumption.
Now researchers from California Institute of Technology, US, and Peking University, China, have generated a highly robust, mass-producible, fully self-powered battery-free wearable system that can efficiently and reliably harvest energy from human motion during vigorous exercises and can monitor biomarkers that are present in sweat.
The system consisted of a highly efficient wearable freestanding-mode triboelectric nanogenerator (FTENG), low-power wireless sensor circuitry, and a microfluidic sweat sensor patch on a single flexible printed circuit board (FPCB) platform. An integrated Bluetooth Low Energy (BLE) module allowed sensor data to be transmitted to a mobile interface for health status tracking during exercise. The system was able to monitor real-time sweat pH and Na+ levels wirelessly during 30 minutes of exercise, showing stable pH levels and increasing Na+ levels.
Conclusions and future application
The work presented here represents the first demonstration of a fully integrated battery-free triboelectrically driven wearable system for multiplexed sweat sensing. It is a robust platform such that after intensive mechanical deformations and repeated washing cycles it remained mechanical and electrical stable. The team are hoping to further develop the technology as a self-powered wireless personalised health monitor.
Biosensing devices such as these have huge potential for a wide-range of areas in science and healthcare, from pharmacogenomics and drug discovery, to healthcare diagnostics and this technology would further accelerate personalised medicine, forensics and environmental monitoring to name but a few. Indeed, an ultra-sensitive biosensor which detects nucleic acids using crumpled graphene and can detect cancer markers in patient blood was recently developed, highlighting how far the field evolved. One crucial element which will determine how far-reaching and successful these wearable biosensors become will be the development of a more extensive and perhaps diagnostic range of biomarkers that can be detected.
Song, Y., J. Min, Y. Yu, H. Wang, Y. Yang, H. Zhang and W. Gao (2020). “Wireless battery-free wearable sweat sensor powered by human motion.” Science Advances 6(40): eaay9842.