Evaluation of Dedicated Bluetooth Low Energy Wireless Data Transfer for an Implantable EMG Sensor

Implantable EMG sensors can improve the control of myoelectric prostheses by providing a better signal-to-noise ratio, vicinity to muscle motor-unit, and fixed sensor placement. The adoption of the same radio frequency for both data transmission and power transfer can reduce system complexity. However, it prevents both contributions from being separately optimized. Lower frequencies benefit from lower tissue RF absorption and deeper signal penetration, but the achievable sensor data rate is lower. On the other hand, a higher data rate can be achieved at higher frequencies, which implies higher RF signal attenuation, causing lower power transfer and tissue heating. Task separation is thus beneficial, using lower frequencies for improving transferable power with reduced tissue damage, and higher frequencies for data transmission with a higher data rate. Considering this, the feasibility of transcutaneous data transmission using the Bluetooth Low Energy (BLE) protocol is demonstrated. Moreover, the use of a small system-in-package for system integration and sensor implantability is proposed. Systematic analysis, using a phantom for simulating a real scenario, demonstrates BLE data transmission by varying transmitted power, antenna distances, and sampling rate for minimizing packet retransmission and ensuring a stable data transmission rate.