biostudies-literatureHwang CNational Research Foundation of Korea30772https://www.ebi.ac.uk/biostudies/studies/S-EPMC11680892biostudies-literatureUnknown14(1)pH sensing technology is pivotal for monitoring aquatic ecosystems and diagnosing human health conditions. Indium-gallium-zinc oxide electrolyte-gated thin-film transistors (IGZO EGTFTs) are highly regarded as ion-sensing devices due to the pH-dependent surface chemistry of their sensing membranes. However, applying EGTFT-based pH sensors in complex biofluids containing diverse charged species poses challenges due to ion interference and inherently low sensitivity constrained by the Nernst limit. Here, we propose a dual-biased (DB) EGTFT pH sensing platform, acquiring back-gate-assisted sensitivity enhancement and recyclable redox-coupled protonation at the semiconductor-biofluid interface. A solution-processed amorphous IGZO film, used as the proton-sensitive membrane, ensures scalable uniformity across a 6-inch wafer. These devices demonstrate exceptional pH resistivity over several hours when submerged in solutions with pH levels of 4 and 8. In-depth electrochemical investigations reveal that back-gate bias significantly enhances sensitivity beyond the Nernst limit, reaching 85 mV/pH. This improvement is due to additional charge accumulation in the channel, which expands the sensing window. As a proof of concept, we observe consistent variations in threshold voltage during repeated pH cycles, not only in standard solutions but also in physiological electrolytes such as phosphate-buffered saline (PBS) and artificial urine, confirming the potential for reliable operation in complex biological environments.Scientific reportsDual-biased metal oxide electrolyte-gated thin-film transistors for enhanced protonation in complex biofluids.PMC11680892RS-2023-00213089Hwang CChoi JGPark SBaek SSong YfalseDual-biased metal oxide electrolyte-gated thin-film transistors for enhanced protonation in complex biofluids.pH sensing technology is pivotal for monitoring aquatic ecosystems and diagnosing human health conditions. Indium-gallium-zinc oxide electrolyte-gated thin-film transistors (IGZO EGTFTs) are highly regarded as ion-sensing devices due to the pH-dependent surface chemistry of their sensing membranes. However, applying EGTFT-based pH sensors in complex biofluids containing diverse charged species poses challenges due to ion interference and inherently low sensitivity constrained by the Nernst limit. Here, we propose a dual-biased (DB) EGTFT pH sensing platform, acquiring back-gate-assisted sensitivity enhancement and recyclable redox-coupled protonation at the semiconductor-biofluid interface. A solution-processed amorphous IGZO film, used as the proton-sensitive membrane, ensures scalable uniformity across a 6-inch wafer. These devices demonstrate exceptional pH resistivity over several hours when submerged in solutions with pH levels of 4 and 8. In-depth electrochemical investigations reveal that back-gate bias significantly enhances sensitivity beyond the Nernst limit, reaching 85 mV/pH. This improvement is due to additional charge accumulation in the channel, which expands the sensing window. As a proof of concept, we observe consistent variations in threshold voltage during repeated pH cycles, not only in standard solutions but also in physiological electrolytes such as phosphate-buffered saline (PBS) and artificial urine, confirming the potential for reliable operation in complex biological environments.2024-01-01T00:00:00Z2024 Dec2025-04-19T21:28:21.215Z2025-04-19T21:28:21.215ZS-EPMC116808923973046210.1038/s41598-024-80005-0