Electrochemical reactions include the transformation of sugars into alcohol and carbon dioxide, and similar processes occur when the body breaks down food, drugs or other compounds. Monitoring these metabolic processes helps in testing, studying and combating disease, but they are difficult to study with normal equipment. In this week’s Review of Scientific Instruments, researchers discuss their work with a miniaturized potentiostat, which is compatible with most 3-electrode biosensors and can transmit its measurements via Bluetooth.