A Wearable Sweat Sensor Powered by a Flexible Perovskite Solar Cell

Continuous monitoring of physiochemical biomarkers using wearable sensors has the potential to revolutionize personalized healthcare. While sweat sensing has emerged as a promising method for continuous biochemical screening, ensuring a sustainable power supply remains a challenge. Previous energy harvesting modules, such as biofuel cells and triboelectric nanogenerators, have relied on exercise-induced power and sweat generation, limiting their applicability to fitness monitoring. In this study, we propose a flexible perovskite solar cell (FPSC) powered autonomous sweat sensor that efficiently harvests energy from ambient light, enabling continuous and sustainable sweat monitoring throughout the day, even during sedentary activities. The wearable device integrates a long-term reusable FPSC and electronic system, alongside a cost-effective and replaceable microfluidic biosensor array produced through inkjet printing technology. The FPSC features a record-breaking power conversion efficiency (PCE) of 31% under indoor illumination conditions. Its exceptional performance is attributed to the incorporation of α-methylbenzylamine (MBA) as an organic spacer in the quasi-2D perovskite absorber layer, enhancing defect passivation and overall device functionality. Furthermore, the FPSC exhibits high durability, withstanding thousands of rigorous bending cycles, making it suitable for wearable applications. Its maintains a high power output under a wide range of illumination conditions, including dim indoor lighting, ensuring uninterrupted operation during various activities throughout the day. Our battery-free device was validated for on-body use by continuously extracting sweat and capturing real-time cross-calibrated sweat biomarker levels (glucose, sodium, pH, skin temperature, and sweat rate) throughout the day over 12 hours under various lighting conditions and daily activities raning from outdoor resting to indoor exercise.