Continuous biochemical profiling of the gastrointestinal tract using an integrated smart capsule

Abstract

The gastrointestinal tract contains a wealth of chemical information that can be used to decipher the health of the digestive and nervous systems. Traditional methods of analysis, such as faecal analysis and biopsies, are invasive, costly and incapable of providing real-time metabolic and hormone profiling across the gastrointestinal tract. Commercial ingestible capsule sensors have been developed, but only monitor basic markers, such as pH and pressure, neglecting detailed chemical analysis. Here we report an integrated smart capsule that can simultaneously detect a spectrum of biochemical markers, including electrolytes, metabolites and hormones. The capsule, which is termed PillTrek, is 7 mm in diameter and 25 mm in length, and houses a miniaturized wireless electrochemical workstation capable of executing a range of electrochemical measurement techniques (potentiometry, amperometry, voltammetry and impedimetry), allowing it to interface with a variety of electrochemical sensors and detect various parameters in the gut. Using an array of sensors (serotonin, glucose, pH, ionic strength and temperature), we illustrate the capabilities of the system in vitro and in vivo in animal studies involving rat and rabbit models, monitoring the dynamic profile of these crucial biomarkers and their responsiveness to different dietary intakes.