Flexible piezo-electrocatalytic uric acid sensor

Non-invasive longitudinal monitoring of uric acid (UA) levels in human sweat could enable unprecedented diagnosis, therapy, and prognosis of numerous physiological and psychological conditions with societal and economic impacts. However, state-of-the-art flexible UA sensors are limited by their complicated fabrication processes, sophisticated instruments, expensive raw materials, and unsatisfactory detection performance. In this study, we designed and implemented for the first time a flexible piezo-electrocatalytic uric acid sensor (EPICS) based on ZnO nanorods. We demonstrated that the EPICS devices achieve a 4-fold enhancement in the UA sensing performance with a small compressive strain (−0.9%), boosted by piezo-electrocatalysis during the electrochemical oxidation of UA on the surfaces of mechanically deformed ZnO nanorods. The EPICS devices exhibited a superior sensitivity of 3.91 µA µM−1 cm−2 and a limit of detection of 0.086 µM, outperforming all reported flexible electrochemical UA sensors. Our design allows the possibility of non-invasive monitoring of UA with a boosted performance by otherwise wasted mechanical energy, such as that from the human body. The fundamental piezo-electrocatalytic principles can also be extended to other piezoelectric materials with catalytic properties for high-performance sensing in the biomedical, pharmaceutical, and agricultural areas.