@article{5851ecbac6244321b6e1454aae5dfcf6,
title = "An implantable, batteryless, and wireless capsule with integrated impedance and pH sensors for gastroesophageal reflux monitoring",
abstract = "In this study, a device for gastroesophageal reflux disease (GERD) monitoring has been prototyped. The system consists of an implantable, batteryless and wireless transponder with integrated impedance and pH sensors; and a wearable, external reader that wirelessly powers up the transponder and interprets the transponded radio-frequency signals. The transponder implant with the total size of 0.4cm ×0.8cm ×3.8cm harvests radio frequency energy to operate dual-sensor and load-modulation circuitry. The external reader can store the data in a memory card and/or send it to a base station wirelessly, which is optional in the case of multiple-patient monitoring in a hospital or conducting large-scale freely behaving animal experiments. Tests were carried out to verify the signal transduction reliability in different situations for antenna locations and orientation. In vitro, experiments were conducted in a mannequin model by positioning the sensor capsule inside the wall of a tube mimicking the esophagus. Different liquids with known pH values were flushed through the tube creating reflux episodes and wireless signals were recorded. Live pigs under anesthesia were used for the animal models with the transponder implant attached on the esophageal wall. The reflux episodes were created while the sensor data were recorded wirelessly. The data were compared with those recorded independently by a clinically used wireless pH sensor capsule placed next to our implant transponder. The results showed that our transponder detected every episode in both acid and nonacid nature, while the commercial pH sensor missed events that had similar, repeated pH values, and failed to detect pH values higher than 10. Our batteryless transponder does not require a battery thus allowing longer diagnosis and prognosis periods to monitor drug efficacy, as well as providing accurate assessment of GERD symptoms.",
keywords = "Gastroesophageal reflux disease (GERD), impedance sensor, implantable, pH sensor, wireless powering",
author = "Hung Cao and Vaibhav Landge and Uday Tata and Seo, {Young Sik} and Smitha Rao and Tang, {Shou Jiang} and Tibbals, {H. F.} and Stuart Spechler and Chiao, {J. C.}",
note = "Funding Information: Instruments, Texas Ignition Fund and National Science Foundation under Grant The MII probe is a catheter that harbors a number of metal ∗NSF#1046488.Asteriskindicatescorrespondingauthor. impedance and antimony pH sensing electrodes for detecting TexasatArlington,Arlington,TX76010USA(e-mail:hcao@uta.edu).H.CaoiswiththeDepartmentofElectricalEngineering,TheUniversityof variations at multiple levels throughout the esophagus. Unlike V. Landge, U. Tata, and Y.-S. Seo are with the Department of Electri- conventional esophageal pH monitoring, which detects only calEngineering,TheUniversityofTexasatArlington,Arlington,TX76010 episodes of acid reflux, MII monitoring detects the reflux of any seo@mavs.uta.edu).USA(e-mail:vaibhav.landge@mavs.uta.edu;tatauday@gmail.com;young-sik. material within the esophagus that alters impedance. Presently, S. Rao is with Med-Worx, Grand Prairie, TX 75050 USA (e-mail: MII monitoring involves the passage of the catheter probe smithamn7@gmail.com). through the nose and throat into the esophagus. The catheter sissippiMedicalCenter,Jackson,MS39216USA(e-mail:STang@umc.edu).S.-J.TangiswiththeDepartmentofDigestiveDiseases,UniversityofMis- is taped to the nose, connected to an electronic recording unit H. F. Tibbals is with Department of Material Science and Engineering, The that the patient wears on a belt, and left in place for the 24-h UniversityofTexasatArlington,Arligton,TX76010USA(e-mail:HFTibbals@ or longer monitoring period. The resultant discomfort, inconve-S.SpechleriswiththeDepartmentofInternalMedicine,Universityofuta.edu). nience, and embarrassment severely limit patient tolerability for Texas Southwestern Medical Center, Dallas, TX 75390 USA (e-mail: Stuart. the test [7], [8]. In addition, patients often alter their usual daily Spechler@UTSouthwestern.edu). activities during the monitoring period, which raises questions versityofTexasatArlington,Arlington,TX76010USA,andalsowiththeJ.-C.ChiaoisalsowiththeDepartmentofElectricalEngineering,TheUni- regarding the validity of the results.",
year = "2012",
doi = "10.1109/TBME.2012.2214773",
language = "English (US)",
volume = "59",
pages = "3131--3139",
journal = "IEEE Transactions on Biomedical Engineering",
issn = "0018-9294",
publisher = "IEEE Computer Society",
number = "12 PART2",
}