Embedded Barometric Pressure Sensor Unit for Force Myography in Exoskeletons

Exoskeletons and other wearable devices benefit from sensor systems that are based on biofeedback for detecting muscle activity. However, such sensor systems in wearable applications are often impractical due to the need for direct skin contact or due to non-linear signal output, both requiring extensive calibration and post-processing. This paper presents a compact and robust barometer-based pressure sensor unit for detecting surface muscle pressure in an exoskeleton interface shell that is light, thin and does not require direct contact with the skin. It consists of an array of five miniature barometric sensors mounted on a custom embedded printed circuit board enclosed in a silicon dome. Evaluation of this sensor unit in a controlled experimental setup showed high sensitivity and an almost linear response to the normal force applied to the silicon dome. Additionally, a pilot study was conducted with four participants in a wearable application to compare the performance of the proposed sensor with that of electromyography (EMG). The results showed higher robustness to positioning, consistent signal, low variance and inter-subject variability compared to EMG.