Even, AniekAniekEvenMinderhoud, RoseanneRoseanneMinderhoudTorfs, TomTomTorfsLeonardi, FrancescaFrancescaLeonardiVan Heusden, ArjanArjanVan HeusdenSijabat, RiaRiaSijabatFirfilionis, DimitriosDimitriosFirfilionisCastro Miller, Ivan DarioIvan DarioCastro MillerRammouz, RamzyRamzyRammouzTeichmann, TobiasTobiasTeichmannvan Bergen, RubenRubenvan BergenVermeeren, GunterGunterVermeerenCapuano, EdoardoEdoardoCapuanoArmstrong, RachelRachelArmstrongMathwig, KlausKlausMathwigde Vries, SonjaSonjade VriesGoris, AnneliesAnneliesGorisVan Helleputte, NickNickVan HelleputteHooiveld, GuidoGuidoHooiveldVan Hoof, ChrisChrisVan Hoof2025-07-242025-07-2420252520-1131WOS:001530182100001https://imec-publications.be/handle/20.500.12860/45928Redox balance—the equilibrium between oxidants and reductants—is a key modulator of a healthy gut and consequently overall well-being. Excess reactive species, resulting in oxidative stress, are linked to deleterious processes including inflammation and microbiome dysbiosis. However, a lack of suitable in vivo methods has restricted measurements of redox balance in the human gut. Here we report a miniaturized ingestible sensor that is equipped with an oxidation–reduction potential sensor, an electrochemical reference electrode and pH and temperature sensors. We preclinically validate our wireless gastrointestinal (GI) smart module (GISMO) in GI fluids and an animal model and report in-human measurements in 15 healthy individuals. Our high-temporal-resolution data, measured every 20 s, reveal consistent profiles from an oxidative environment in the stomach to a strongly reducing environment in the large intestine. This non-intrusive method has the potential to advance (GI) disease monitoring and offer insights into the gut microbiome.Journal article10.1038/s41928-025-01411-4WOS:001530182100001OXIDATIVE STRESSCAPSULEPHCHEMILUMINESCENCEBIOLOGYHUMANS