An Affordable Amperometric\nGas Sensor Based on Polyvinylidene\nFluoride Solid-State Electrolyte for Highly Selective Detection of\nppm-Level H<sub>2</sub> at Room Temperature

Currently, the assessment of irritable bowel syndrome\n(IBS) through\nthe detection of H<sub>2</sub> levels in exhaled breath using commercial\ngas sensors remains a challenging task. In this work, we presented\na cost-effective amperometric gas sensor capable of monitoring parts\nper million-level H<sub>2</sub> at room temperature by grafting polystyrene\nsulfonic acid onto polyvinylidene fluoride (PVDF-<i>g</i>-PSSA), creating a thermal stable and highly adaptable solid polymer\nelectrolyte. This PVDF-<i>g</i>-PSSA exhibited a high tensile\nstress value of 9.72 MPa and ionic conductivity of 2.73 × 10<sup>–2</sup> S cm<sup>–1</sup>, which is comparable with\nthat of the Nafion N115 membrane. The amperometric gas sensor based\non the PVDF-<i>g</i>-PSSA membrane exhibited preferable\nsensing performance, including a response current of 174.3 nA to 50\nppm of H<sub>2</sub> at room temperature and 50% relative humidity.\nAdditionally, it also displayed an acceptable response–recovery\ntime of 96 and 54 s, limit of detection (LOD) of 1 ppm H<sub>2</sub>, and selectivity for H<sub>2</sub> over other interfering gases.\nRemarkably, this sensor demonstrated a highly linear relationship\n(4.6 nA/ppm H<sub>2</sub>) with a correlation coefficient of 0.9998.\nFurthermore, we also applied this sensor to distinguish parts per\nmillion-level H<sub>2</sub> concentrations in simulated exhaled breath.\nThese findings demonstrated an affordable amperometric H<sub>2</sub> gas sensor for detecting ppm-level H<sub>2</sub> at room temperature,\neven without requiring a bias, thereby promising for biomarker detection\nin exhaled breath.