This invention is a wearable device for an arm with a plurality of close-fitting biometric sensors. These sensors can be spectroscopic sensors which project light onto an arm surface at different angles. Alternatively, these sensors can be electromagnetic energy sensors which measure tissue impedance, resistance, conductivity, or permittivity. These sensors can be on the circumference-center-facing wall of an elastic fluid, gel, or gas filled member. Data from these sensors can be used to measure a person's hydration levels, oxygen levels, glucose levels, or heart rate.
