A 32-Channel Wireless Configurable System for Electrical Stimulation of the Stomach.

We have designed and developed a configurable system that can generate and deliver a variety of electrical pulses suitable for gastrointestinal studies. The system is composed of a front-end unit, and a back-end unit that is connected to a computer. The front-end unit contains a stimulating module with 32 channels configured to generate two different current pulses, simultaneously. Commercial off-the-shelf components were used to develop front- and back-end units. A graphical user interface was designed in LabVIEW that allows configuration of the stimulation pulses through the back-end unit in real-time. The system was successfully validated on bench top. The bench-top studies showed the capability of the system to deliver bipolar, monopolar and unbalanced electrical pulses to a maximum load of 1.5 kΩ, at amplitudes up to ±10 mA with resolution of 10 µA, and pulse widths varying between 80 µs to 60 s with the resolution of 80 µs. This study reports the first multi-channel bipolar stimulator that is designed for gastrointestinal studies, and can be configured wirelessly. The system can be used for treating functional gastrointestinal disorders in future.

A Miniature Configurable Wireless System for Recording Gastric Electrophysiological Activity and Delivering High-Energy Electrical Stimulation.

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.

An inductive narrow-pulse RFID telemetry system for gastric slow waves monitoring.

We present a passive data telemetry system for real-time monitoring of gastric electrical activity of a living subject. The system is composed of three subsystems: an implantable unit (IU), a wearable unit (WU), and a stationary unit (SU). Data communication between the IU and WU is based on a radio-frequency identification (RFID) link operating at 13.56 MHz. Since wireless power transmission and reverse data telemetry system share the same inductive interface, a load shift keying (LSK)-based differential pulse position (DPP) 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 clock and data are encoded into one signal by an MSP430 microcontroller (MCU) at the IU side. This signal is sent to the WU through the inductive link, where decoded by an MSP432 MCU. Finally, the retrieved data at the WU are transmitted to the SU connected to a PC via a 2.4 GHz transceiver for real-time display and analysis. The results of the measurements on the implemented test bench, demonstrate IU-WU 125 kb/s and WU-SU 2 Mb/s data transmission rate with no observed mismatch, while the data stream was randomly generated, and matching between the transmitted data by the IU and received by the SU verified by a custom-made automated software.