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Researchers Develop RFID System to Monitor Acid Reflux

April 24, 2007

A collaborative effort between researchers at the University of Texas at Arlington and the University of Texas Southwestern Medical Center in Dallas has resulted in an innovative approach to diagnose and monitor the effects of gastroesophageal acid reflux, sometimes called gastroesophageal reflux disease (GERD). Their solution involves placing a battery-less sensor in the patient’s esophagus.

According to a 1997 study published in Gastroenterology, GERD affects an estimated 5% to 7% of men, women, and children. Persistent heartburn is the most frequent symptom of GERD. If left untreated or treated incorrectly, chronic acid reflux can result in serious damage or even esophageal cancer.

Current tests for GERD require a wired sensor that runs through the patient's nostril and into the esophagus. The wires are attached externally to a recording devise worn by the patient, who is instructed to follow his or her normal dietary and activity routine for the next 24 to 48 hours. This uncomfortable procedure makes it very difficult for a patient to eat and behave normally, which is required for accurate testing.

Dr. Shou Tang, an Assistant Professor of Medicine at UT Southwestern, mentioned this problem to J.-C. Chiao, an Associate Professor in UT Arlington's Electrical Engineering Department, in 2005. They met in a seminar, becoming friends immediately and often having brainstorming conversations about modern medicine. “He asked me, ‘Can this be made wireless?’” Chiao recalled. That comment inspired Dr. Chiao and led to a two-year challenge to develop a wireless prototype.

A team of faculty and students led by Dr. Chiao at the Automation & Robotics Research Institute then created an RFID-enabled sensor that can be inserted into the esophagus and attached to the esophagus wall, where it transmits to an RFID reader around the patient's neck. Their first designs were tested with simulated stomach acid in a test tube; the second generation was tested on pork tissue. They are preparing to conduct tests on animals later this year.

The two-centimeter-square sensor is enclosed in a flexible substrate made of Kapton, a plastic film that is not felt in the esophagus. The sensor is designed to measure the presence of stomach acid, gas and water in the esophagus.

The physician will use an endoscope to remove the tag at the completion of the test. Eventually, Dr. Chiao would like to develop a sensor that could be dissolved or flushed through the body's digestive tract. More immediately, he hopes to bring the size of the RFID sensor-tag down further before human testing begins soon.