A smart cup for wireless, biofuel-powered, sweat-based vitamin C sensing

Malnutrition poses a significant burden on the global healthcare system, in both loss of life and economic toll. Of particular interest is monitoring the regular intake of water-soluble vitamins, such as vitamin C, due to the body's inability to store them for extended periods. However, existing vitamin C monitoring conventionally relies on inconvenient, infrequent, and costly lab visits. Here, we describe an integrated touch-based disposable battery-free Smart Cup platform that harvests energy via a biofuel cell (BFC) that captures and converts metabolites naturally present on finger tips into electrical energy without requiring subject exertion or heating, and boosts the BFC's output voltage to a higher level needed to run on-board electronics that are used to sense, digitize, and wirelessly transmit data from an integrated potentiometric vitamin C sensor. Human subject testing was performed to validate the system's ability to monitor the temporal profile of vitamin C levels in natural perspiration, observing increased levels in response to an oral vitamin C supplement. The novel disposable cup-based system offers a unique opportunity for low-cost, unobtrusive, and regular real-time monitoring of vitamins, enabling individuals from all socioeconomic backgrounds to better optimize their diet and health.