A LONG-RANGE, IMPLANTABLE TELEMETRY SYSTEM FOR CHRONIC NEURAL RECORDING

Long-term neurophysiological studies of unanesthetized and freely moving animals require an implantable miniaturized telemetry system that can acquire and transmit neural firing patterns or other relevant physiological signals directly from inside the body. In this article, the design and in-vivo results of a long-range, chronic, implantable bio-telemetry system are presented. This system has three main features: wireless inductive powering capability with implanted rechargeable battery for long-term biosignal measurement, ultra-low power wireless stand-by mechanism, and long range data transmission (up to 70m) with a variable gain bio-amplifier. The design is based on commercial, off-the-shelf components and provides a solid framework for implementing similar systems by other research groups. The in-vitro experiment of our system was performed by submerging the internal module of the system in a saline container and applying a wide range of signals with different amplitudes and frequencies to verify its sensitivity and fidelity in capturing low-amplitude, large-bandwidth biosignals. In-vivo experiment of the system was performed by implanting the internal module in the inguinal region of a dog and inserting the measuring electrodes into its quadriceps femoris muscle. The system successfully recorded intramuscular activity in which motor unit activity could easily be distinguished. The module was in place for three months, after which it was removed from the animal and showed no sign of damage or corrupting tissue growth.