Alternative sensor materials for light-addressable potentiometric sensors

Ta2O5 and porous Si were investigated as alternative sensor materials for t he light-addressable potentiometric sensor (LAPS). The Ta2O5 LAPS, prepared by the pulsed laser deposition (PLD) technique, showed a high pH sensitivi ty of 57.5 mV/pH and a good linearity. Porous Si was prepared by anodic etc hing 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 porou s Si LAPS, a penicillin LAPS was fabricated by immobilization of penicillin ase on the surface. The pH change due to the enzymatic reaction was detecte d for the penicillin concentration between 250 muM and 10 mM. (C) 2001 Else vier Science B.V. All rights reserved.