Attachable Pulse Sensors Integrated with Inorganic Optoelectronic Devices for Monitoring Heart Rates at Various Body Locations.

Monitoring cardiovascular signals such as heart rate and blood flow provides critically important healthcare information about patients under medical care. However, when the sensors are worn for extended times, the sensors sometimes require higher mechanical compatibility with soft deformable tissues. In this paper, we report an attachable and flexible pulse sensor (bending radius: 2.4 mm), integrated with micro-inorganic photodetectors (thickness: 4.1 μm, photocurrent: 8.99 μA under 1.5 mW/cm2 ) and a red light emitting diode (620 nm), to monitor vital signals for extended times. Operating in a reflection mode, it can be attached and measure heart pulse waveforms from various locations on the human body including the finger, fingertip, nail, and forearm. The small form factor also enables integration on a finger ring. Electrical and mechanical performance assessments demonstrated the practical feasibility of the concept.