A CAPACITANCE-TYPE CHEMICAL SENSOR THAT EMPLOYS VAPO-5, MNAPO-5 AND MAPO-36 MOLECULAR-SIEVES AS THE DIELECTRIC PHASE

We have developed a chemical sensor based on a capacitor design that u tilizes molecular sieves as the dielectric phase. In this study, thin films of vanadium aluminum phosphate (VAPO-5), the isostructural manga nese aluminum phosphate (MnAPO-5) and magnesium aluminum phosphate (MA PO-36) were deposited onto titanium nitride-coated silicon wafers by l aser ablation. The molecular sieve films function as the dielectric ph ase and were patterned with Au/Pd to complete the capacitor. The molec ular sieve-based sensors exhibited capacitance changes upon exposure t o CO2, CO, N-2 and H2O at room temperature. Significant responses to C O2 and CO were registered at levels as low as 50 and 100 ppm, respecti vely. (C) 1997 Elsevier Science S.A.