Batteryless implantable dual-sensor capsule for esophageal reflux monitoring

Background: Chronic GERD affects approximately 15% of adults in the United States and is one of the most prevalent clinical conditions involving the GI tract. The commercial tools for monitoring GERD include multichannel intraluminal impedance (MII) probes and pH-sensing capsules. However, MII probes cause discomfort, which alters patients' regular activities, whereas the pH-sensing capsule lacks the ability to detect weak or nonacid episodes, misses reflux episodes with similar pH values, and has a limited sampling rate and battery life. Objective: To develop and test an implantable batteryless dual-sensor capsule that can be used to diagnose and monitor GERD. Design: The implanted capsule is wirelessly powered by an external device. Simulated reflux episodes were created in 3 live porcine models. Impedance and pH data were continuously measured and recorded. Intervention: The implant capsule was placed in the esophagus along with a commercial pH-sensing capsule for comparison. Main Outcome Measurements: Precise impedance and pH readouts were obtained and compared with those from a commercial pH-sensing capsule. Results: The wireless energy supplied by the external unit was strong enough to power the implant. The pH sensor accurately measured pH levels and the impedance sensor precisely located the reflux episodes. Limitation: Simulated reflux events in a pig model. Conclusion: Our wireless sensors are reliable in operation and provide accurate assessment of simulated reflux episodes. The entire device can potentially be used to diagnose and monitor GERD.