Development of High-kappa Eu2Ti2O7 EIS Devices Using Poly-N-isopropylacrylamide as an Enzyme Encapsulation Material for pH Detection and Uric Acid Biosensing

Abstract

In this study, we proposed an electrolyte-insulator-semiconductor (EIS) device fabricating a high-kappa Eu2Ti2O7 sensing membrane deposited on Si substrates through cosputtering for pH detection and uric acid biosensing applications. The EIS device incorporating a high-kappa Eu2Ti2O7 sensing membrane annealed at 900 degrees C exhibited a higher sensitivity of 59.03 mV/pH, a smaller hysteresis voltage of 2.8 mV, and a lower drift rate of 0.586 mV/h compared to those of the other annealing temperatures. These results are attributed to the small number of crystal defects and the large surface roughness. Furthermore, for high-kappa Eu2Ti2O7 EIS-based biosensing application, a phase tunable poly-N-isopropylacrylamide (PNIPAAm) was used as an enzyme encapsulating material, making the loading and removal of a biological recognition element on a biosensor easily. In this study, a hybrid configuration of the high-kappa Eu2Ti2O7 EIS biosensor with an unease-immobilizing PNIPAAm film attached was established and was demonstrated for uric acid biosensing. The sensitivity of a Eu2Ti2O7 EIS biosensor was 17.6 mV/mM for uric acid concentrations ranging from 2 to 8 mM.