Coaxial noncontact surface compliance distribution measurement for muscle contraction sensing

In this paper, we propose a coaxial noncontact surface compliance distribution measurement method for sensing human muscle contraction. Our measurement system is based on pressurization to a target object by acoustic radiation pressure and measuring of surface displacement. The directions of the ultrasound convergent beam and an optical beam for displacement measurement are identical in the proposed setup. This setup improves measurement accuracy especially for moving objects and bumpy surfaces. The effectiveness is examined by measuring human muscle compliance distribution for relaxed and contracted situations. This is the first evaluation of measurement time of human skin in vivo including moving situation.