The purpose of this paper is to develop and validate a miniature system that can wirelessly acquire gastric electrical activity called slow waves, and deliver high energy electrical pulses to modulate its activity. The system is composed of a front-end unit, and an external stationary back-end unit that is connected to a computer. The front-end unit contains a recording module with three channels, and a single-channel stimulation module. Commercial off-the-shelf components were used to develop front- and back-end units. A graphical user interface was designed in LabVIEW to process and display the recorded data in real-time, and store the data for off-line analysis. The system was successfully validated on bench top and in vivo in porcine models. The bench-top studies showed an appropriate frequency response for analog conditioning and digitization resolution to acquire gastric slow waves. The system was able to deliver electrical pulses at amplitudes up to 10 mA to a load smaller than 880 Ω. Simultaneous acquisition of the slow waves from all three channels was demonstrated in vivo. The system was able to modulate –by either suppressing or entraining– the slow wave activity. This study reports the first high-energy stimulator that can be controlled wirelessly and integrated into a gastric bioelectrical activity monitoring system. The system can be used for treating functional gastrointestinal disorders.

High-resolution (HR) mapping of the gastrointestinal (GI) bioelectrical activity is an emerging method to define the GI dysrhythmias such as gastroparesis and functional dyspepsia. Currently, there is no solution available to conduct HR mapping in long-term studies. We have developed an implantable 64-channel closed-loop near-field communication system for real-time monitoring of gastric electrical activity. The system is composed of an implantable unit (IU), a wearable unit (WU), and a stationary unit (SU) connected to a computer. Simultaneous data telemetry and power transfer between the IU and WU is carried out through a radio-frequency identification (RFID) link operating at 13.56 MHz. Data at the IU are encoded according to a self-clocking differential pulse position algorithm, and load shift keying modulated with only 6.25% duty cycle to be back scattered to the WU over the inductive path. The retrieved data at the WU are then either transmitted to the SU for real-time monitoring through an ISM-band RF transceiver or stored locally on a micro SD memory card. The measurement results demonstrated successful data communication at the rate of 125 kb/s when the distance between the IU and WU is less than 5 cm. The signals recorded in vitro at IU and received by SU were verified by a graphical user interface.

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