Nanogap-based electrical hydrogen sensors fabricated from Pd-PMMA hybrid thin films

Hybrid thin films, in which a Pd thin film was sandwiched between thin poly(methyl methacrylate) PMMA layers, were prepared on a flexible substrate using a combination of sputtering and spin coating. In real-time electrical response tests to H-2, Pd-PMMA hybrid nanogap sensors operated in an on-off manner for both air and N-2 carriers. Due to the selective penetration of H-2 and the density reduction of the cracks that formed in the trilayer of the hybrid thin films, the detection limit of the hybrid nanogap sensors( 6000 ppm H-2 in air and 600 ppm H-2 in N-2) was drastically reduced compared to that of Pd nanogap sensors without PMMA layers. Hybrid thin films have great promise in realizing sensors that can be used in air without additional filter system. (C) 2013 Elsevier B. V. All rights reserved.