Editors' ChoiceBiosensors

Getting in touch with your inner stomach

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Science Translational Medicine  08 Nov 2017:
Vol. 9, Issue 415, eaaq1229
DOI: 10.1126/scitranslmed.aaq1229

Abstract

An ingestible and mechanically flexible piezoelectric device enables sensing of changes in the GI tract of pigs.

Everybody has experienced an embarrassing stomach growl during a lull in conversation or the satisfying and uncomfortable fullness after dessert. These are illustrations of our stomach communicating—through muscle contractions—some of the most fundamental cues to our survival: when to eat. Gaining even more information about what is happening in the stomach and gastrointestinal (GI) tract has been an important clinical goal. For example, ingestible electronics have revolutionized GI imaging through wireless endoscopy pills, and as sensors that detect changes in pressure or other indicators of stomach, esophageal, and GI tract disorders.

More widespread use of ingestible electronics has been hindered by rigid devices that could cause GI obstruction and by limited battery life. Now Dagdeviren and co-workers have created a flexible, ingestible sensor comprised of an array of piezoelectric ribbons with a polymeric coating to provide protection from the GI environment. Piezoelectric materials have low power requirements and offer flexibility. Thus, in mechanical fatigue studies, the device could detect voltage changes even after 10,000 stretching cycles. In a physical model of the stomach, the device sensed voltage changes associated with fluid entry and stomach shape changes. Next, the sensor was packaged in a capsule and introduced into the stomach of sedated pigs. This capsule quickly dissolved, allowing the sensor array to uncoil and settle in conformal contact with the stomach lining. Subsequently, inflation and deflation of the stomach with air could be detected, as well as fluid entry and movement mimicking a walking motion. In nonsedated pigs, the sensor was also able to measure voltage changes after feeding. The prototype in these studies lacked a power supply and was deployed endoscopically to maintain an electrical connection. However, the conformal contact with the tissue enabled by the flexibility of the piezoelectric design could allow harvesting of mechanical energy to power future ingestible devices.

Some of the open questions include the host response to the device, the efficiency of energy harvesting for self-powering, and whether the device would eventually need to be retrieved after stomach deployment. Still, wireless ingestible devices could provide new lines of communication between you and your stomach to help identify and treat stomach motility disease, GI conditions, or even for monitoring diet or eating disorders.

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