Biosensing with Ingestible Pill for Gut Health Monitoring

Gut health is crucial for overall human physiological well-being, representing digestion, immune functions, early detection of chronic diseases, and mental health. Hence, monitoring gut health is beneficial for the early detection of critical health issues and guided interventions to maintain physical and mental health. Traditional methods for determining gut conditions require hospital-based invasive measurements in the human gastrointestinal (GI) tract. We introduce an ingestible pill to unleash the potential of utilizing information from gut health monitoring for overall health assessment. Our ingestible pill presents convenient, non-invasive measurements through comprehensive real-time data collection in the GI tract. We precisely measure the composition of gases (oxygen O₂, ammonia NH₃) and articulate the variations in pH levels at different segments of the GI tract. We fabricate the gas sensors based on the principle of fluorescence quenching. In our custom-made ingestible pill, the gas-sensitive membrane is excited by a wavelength-specific LED (440nm for O₂, 530nm for NH₃). In response, the membrane produces fluorescence in the red spectrum (580 nm and 640 nm), with the intensity varying according to the target gas concentration. Our gas sensor in the ingestible pill can detect O₂ in 0-20% and NH₃ in 0-100 ppm. We use the 3-electrode sensing mechanism for detecting pH. We fabricate the 3-electrode sensors by inkjet printing the gold (Au) nanoparticle ink in a flexible substrate, while the reference electrode is by direct 3D writing of Ag/AgCl. We modify the working electrode using an H+ ion selective membrane. Our pH sensor is capable of measuring pH 1 to 7. Our ingestible pill supports bi-directional operation, which is necessary for measuring reduction and oxidation currents in amperometry and voltammetry. We envision this ingestible pill will bridge the gap between gut health and overall health monitoring, providing a powerful tool for personalized healthcare.