Optical muscle activation sensors for estimating upper limb force level

Muscle activation sensors are playing an important role in motion intention sensing of human-machine interaction system, such as human assisting manipulators or prosthetic devices. There are requirements of low-cost, reliability and portability for the device. This paper proposes an optical muscle activation sensor (oMAS) which measures the optical density in muscle by emitting and gathering the single wavelength light source. The oMAS was tested on the biceps brachii in isometric contraction condition, comparison with muscle activation level from surface electromyography. The results show that the optical density is enough to discriminable the muscle activation level. Therefore the oMAS is usable to measure the muscle contraction and it could offer a low-cost, reliable, portable and comfortable alternative for current muscle activation sensors.