Alternative sensor materials for light-addressable potentiometric sensors

Ta2O5 and porous Si were investigated as alternative sensor materials for the light-addressable potentiometric sensor (LAPS). The Ta2O5 LAPS, prepared by the pulsed laser deposition (PLD) technique, showed a high pH sensitivity of 57.5 mV/pH and a good linearity. Porous Si was prepared by anodic etching of Si in a mixture of HF and ethanol. The porous Si LAPS with a Si3N4 layer showed a pH sensitivity of 57.3 mV/pH. As an application of the porous Si LAPS, a penicillin LAPS was fabricated by immobilization of penicillinase on the surface. The pH change due to the enzymatic reaction was detected for the penicillin concentration between 250 μM and 10 mM.