Optimum wavelengths in the near infrared for imaging photoplethysmography.

OBJECTIVE: The purpose of this contribution is to determine the ideal near infrared wavelength bands for monochromatic and dual-band remote heartbeat detection using imaging photoplethysmography of the forehead.

METHODS: Experimental data of 38 healthy volunteers has been recorded and analyzed. For the data acquisition a fast hyperspectral imager has been used. A new combination approach has been implemented which computes the quotient of the bands and therefore reduces motion artifacts.

RESULTS: With this dual-band method excellent results (1.67 beats per minute mean deviation from ECG measurements for 73 recordings) have been obtained using a simple algorithm to analyze images at 799 nm and 861 nm.

CONCLUSION: It can be concluded that excellent imaging PPG measurements can be performed at low cost using conventional siliconbased image sensors with invisible light in the near infrared region.

SIGNIFICANCE: This approach is a contribution to the development of non-contact heart rate measurement systems that can be used for medical diagnosis or other applications.