A Fully Implantable Subcutaneous EMG Sensor Powered by Transcutaneous Near-Infrared Light Irradiation

This paper presents a fully implantable electromyogram (EMG) sensing system for application with myoelectric prosthesis. The internal unit of the system, an EMG sensor consisting of recording electrodes, a bio-amplifier, a FM transmitter and a photodiode panel of six photovoltaic cells connected in series, is implanted subcutaneously and powered by transcutaneous near-infrared light irradiation. The external unit placed on the skin facing the internal unit has a near-infrared LED to illuminate the photodiode panel through the skin and a FM receiver to receive the EMG signals. The micro power circuit was designed for the implantable device. Internal units were implanted into rat thigh flexor muscle and examined. The system successfully recorded the EMG signals from the specific muscle of freely moving rats, and has been functioning normally in long-term recordings for more than twelve weeks. This system may offer a method to secure stable EMG signal sources for myoelectric prostheses by minimally invasive surgery.