The author of this paper explained that the crystal converts the vibration of ultrasound emitted outside the human body into electricity to drive a tiny transistor, which is directly attached to a nerve or muscle fibers, inside the device.
这篇论文的作者解释说，这个晶体将人体外发射的超声震动转化为电力，用以驱动器件内一个微小的晶体管，而这个晶体管直接连在一根神经或肌肉纤维上。