High-$\kappa$ ${\rm Tm}_{2}{\rm Ti}_{2}{\rm O}_{7}$ Electrolyte-Insulator-Semiconductor Creatinine Biosensor

In this study, we developed an electrolyte-insulator-semiconductor (EIS) device-incorporating a high-κ Tm
₂
Ti
₂
O
₇
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 Tm
₂
Ti
₂
O
₇
film. For pH measurement, this high-κ Tm
₂
Ti
₂
O
₇
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.