Development of a wireless swallowable capsule with potentiostatic electrochemical sensor for gastrointestinal track investigation

Abstract

The gastrointestinal (GI) tract, especially the small intestine, remains largely inaccessible to modern medical science. While swallowable capsule technologies are emerging, endoscopy and colonoscopy remain the primary method for GI tract analysis. This paper presents an alternative wireless device, with electrochemical sensing technique, which behaves autonomously as it travels through the GI tract. The capsule includes a direct access, multi electrode electronic tongue sensor that enables non-specific characterization of gut fluids, aiding in the diagnosis of gastrointestinal diseases such as Crohn's and ulcerative colitis. The sensor, interfaced through a potentiostatic circuit, is capable of performing various voltammetries such as cyclic, square wave and differential pulse techniques. A wireless communication link, operating at 433MHz, delivers measured data to a base station receiver located outside the body. The capsule, powered by a single lithium-ion cell and implemented on a polyimide flexible substrate, is encapsulated in polyether ether ketone (PEEK) material to measure 12mm in diameter and 28mm in length taking volume of approximately 4cm3. The capsule's front end potentiostat compares well with commercial laboratory equipment under the same cell and voltammetry conditions. The electrochemical characterization of the system and its application for electrochemical examination of faecal waters proves its potential as an in vivo GI tract diagnostic tool and other biomedical applications requiring a miniaturized low power sensing device.