A Miniature Wireless 64-channel System for Monitoring Gastrointestinal Activity

We present a wireless recording system suitable for high-resolution mapping of gastric slow-wave signals. The system is composed of implantable (IU), wearable (WU) and stationary (SU) units. WU has the capability to wirelessly recharge the IU's battery through an inductive link. A load shift keying modulation with differential pulse position coding data communication with only 6.25% duty cycle is developed to guarantee consistent wireless downlink power transmission and uplink high data transfer rate, simultaneously. The IU sends the encoded recording data to the WU through the inductive path, where it demodulates and decodes the data. Finally, the retrieved data at the WU are either transmitted to the SU for real-time monitoring, or stored locally on a memory card. The measurements on the implemented system, demonstrate IU-WU 125kb/s and WU-SU 2Mb/s data transmission rate, while different signals recorded at IU and received by SU verified by a graphical user interface.