Wearable Sensor for Multi-wavelength Near-Infrared Spectroscopy of Skin Hemodynamics Along with Underlying Muscle Electromyography

Intermittent claudication in peripheral arterial disease (PAD) may be monitored with near-infrared spectroscopy (NIRS) of an exercising muscle and skin; however, skin NIRS data in conjunction with electromyography (EMG) of muscle activation has not been investigated. This paper presents the development of a wearable skin NIRS sensor to determine the changes in the blood oxygenation and blood volume of the skin tissue overlying the calf muscle in response to underlying muscle EMG activation during exercise. Skin NIRS sensor was based on the optode sensor configuration found using Monte Carlo-based simulations with a skin tissue model, that was compared with a state-of-the-art device frequency-domain NIRS system. A proof of concept experiment on a healthy volunteer showed promising results with future applications in monitoring critical limb ischemia in PAD during calf muscle exercise.