A Tetrapolar Bioimpedance Sensor-Integrated Capsule Toward Targeted Real-Time Monitoring of Intestinal Tissues

We present the simulation, fabrication, and validation of a novel, Bluetooth®-enabled ingestible sensing capsule utilizing a flexible tetrapolar bioimpedance sensor toward real-time monitoring of tissue integrity in the gastrointestinal (GI) tract. This work advances ingestible bioimpedance sensor design using four-probe measurements to minimize contact resistance and optimizes geometry to target specific tissue depths and, consequently, intestinal layers. An electrode diameter of 500 μm and inner spacing of 4 mm was empirically determined to isolate epithelial impedance contributions from surrounding media. The field confinement was then validated on porcine intestinal tissue ex vivo. This system is a major step toward localized characterization of compromised intestinal tissues for real-time monitoring of GI tissue.