Batteryless wireless gastric implants

In this paper, development of batteryless wireless implantable devices and systems for gastric applications at the University of Texas - Arlington is reviewed. The systems are based on near-field inductive coupling to wirelessly transfer energy across thick tissues. The process enables batteryless operation of miniature electrical and electrochemical sensors and wireless transduction of sensor data. Batteryless endoluminal sensing telemetry architecture of an esophagus implant for remote diagnosis of gastroesophageal reflux disease (GERD) is discussed. The implant can detect both impedance and pH variations accurately inside the esophagus in real time with high sampling rates. The similar wireless power transfer process also enables batteryless operation for tissue stimulation inside body. An endoscopically-implantable wireless gastrostimulator for gastroparesis and obesity management has been demonstrated. In both cases, electromagnetic energy has to pass through thick heterogeneous layers of tissues to provide sufficient powers to the implants, while transmitting powers have to be minimized in order to limit energy exposure to tissues. Various live animal experiments have been conducted to demonstrate the feasibility and performance of these systems. The GERD sensor implant can detect occurrence and pH nature of each reflux event accurately while the gastrostimulator can modulate the electrogastrogram signals indicating changes of motility in the stomach. Design strategies focusing on antennas are proposed for various physiological scenarios. The demonstrations provide new means in clinical practices to improve care quality and assist better living.