Ultrasound Intra Body Multi Node Communication System for Bioelectronic Medicine.

The coming years may see the advent of distributed implantable devices to support bioelectronic medicinal treatments. Communication between implantable components and between deep implants and the outside world can be challenging. Percutaneous wired connectivity is undesirable and both radiofrequency and optical methods are limited by tissue absorption and power safety limits. As such, there is a significant potential niche for ultrasound communications in this domain. In this paper, we present the design and testing of a reliable and efficient ultrasonic communication telemetry scheme using piezoelectric transducers that operate at 320 kHz frequency. A key challenge results from the multi-propagation path effect. Therefore, we present a method, using short pulse sequences with relaxation intervals. To counter an increasing bit, and thus packet, error rate with distance, we have incorporated an error correction encoding scheme. We then demonstrate how the communication scheme can scale to a network of implantable devices. We demonstrate that we can achieve an effective, error-free, data rate of 0.6 kbps, which is sufficient for low data rate bioelectronic medicine applications. Transmission can be achieved at an energy cost of 642 nJ per bit data packet using on/off power cycling in the electronics.