High-κ Tm₂Ti₂O₇ electrolyte- insulator-semiconductor creatinine biosensor

In this study, we developed an electrolyte-insulator-semiconductor (EIS) device - incorporating a high-κ Tm₂Ti₂O₇ sensing membrane deposited on a Si substrate through co-sputtering - for pH measurement and creatinine detection. We used X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy to investigate the structural and morphological features of the Tm₂Ti₂O ₇ film. For pH measurement, this high-κ Tm₂Ti ₂O₇ EIS device exhibited high sensitivity [58.45 mV/pH (at values of solution pH from 2 to 12)], a low hysteresis voltage [4.3 mV (pH 7 → 4 → 7 → 10 → 7)], a small drift rate [0.595 mV/h (in buffer solution at pH 7)], and good stability (operation time: 120 days). The sensitivity of a creatinine deiminase-immobilized EIS biosensor was 82.39 mV/pC_creatinine for creatinine concentrations ranging from 0.01 to 15 mM.