The MAX30102 pulse oximeter and heart rate integrated sensor module is claimed as the lowest power solution on the market today
The MAX30102 is an integrated pulse oximetry and heart-rate monitor module. It includes internal LEDs, photodetectors, optical elements, and low-noise electronics with ambient light rejection. The MAX30102 provides a complete system solution to ease the design-in process for mobile and wearable devices.
The MAX30102 operates on a single 1.8V power supply and a separate 5.0V power supply for the internal LEDs. Communication is through a standard I²C-compatible interface. The module can be shut down through software with zero standby current, allowing the power rails to remain powered at all times.
MAX30102 – High-Sensitivity Pulse Oximeter and Heart-Rate Sensor – [Link]