Finger-actuated wireless-charging wearable multifunctional sweat-sensing system for levodopa and vitamin C

Efficient portable wearable sweat sensors allow the long-term monitoring of changes in the status of biomarkers in sweat, which can be useful in diagnosis, medication, and nutritional assessment. In this study, we designed and tested a wireless, battery-free, flexible, self-pumping sweat-sensing system that simultaneously tracks levodopa and vitamin C levels in human sweat and detects body temperature. The system includes a microfluidic chip with a self-driven pump and anti-reflux valve, a flexible wireless circuit board, and a purpose-designed smartphone app. The microfluidic chip is used for the efficient collection of sweat and the drainage of excess sweat. The dual electrochemical sensing electrodes in the chip are modified with functional materials and appropriate enzymatic reagents, achieving excellent selectivity and stability. The sensitivities of the levodopa sensor and the vitamin C sensor are 0.0073 and 0.0018 µA·µM −1 , respectively, and the detection correlation coefficients of both exceed 0.99. Both sensors have a wide linear detection range of 0–100 and 0–1000 µM, respectively, and low detection limits of 0.28 and 17.9 µM, respectively. The flexible wireless circuit board is equipped with the functions of wireless charging, electrical signal capture and processing, and wireless transmission. The data recorded from each sensor are displayed on a smartphone via a self-developed app. A series of experimental results confirmed the reliability of the sweat-sensing system in noninvasively monitoring important biomarkers in the human body and its potential utility in the comprehensive assessment of biological health.