Wearable Electrodes for Lactate: Applications in Enzyme-Based Sensors and Energy Biodevices

Wearable bioelectronics is a promising next-generation technology for its versatility in personalized applications. Measuring lactate is one of the growing trends in wearable biosensing research. To achieve this goal, enzymes capable of catalyzing reactions involving lactate must be coupled with bioelectrode components, creating a variety of biodevices such as biosensors, biofuel cells, and other devices harvesting energy from wearers. This review provides a brief history of noninvasive and minimally invasive enzyme-based lactate biosensors and energy biodevices. We introduce key principles of lactate oxidase and lactate dehydrogenase, together with immobilization strategies for efficient electrical contacts between redox enzymes and electrode supports. Additionally, we discuss recent examples of advanced wearable enzymatic lactate sensors and elaborate on a collection of self-powered wearable energy biodevices (e. g., biofuel cells, triboelectric nanogenerators, and piezoelectric devices). Lastly, we finish this review with discussions on challenges in developing lactate bioelectronics and provide our outlook on the prospects and future directions of this compelling technology.