Kinetic control of nanocrack formation in a palladium thin film on an elastomeric substrate for hydrogen gas sensing in air

• The effects of various tensile velocities on nanocrack formation were studied.
• A tunable nanocrack was created by mechanical stretching/compression cycles.
• The tensile velocity was found to have a significant effect on the crack density.
• A low detection limit of 500 ppm of H2 in air was demonstrated.
• Narrow nanocracks (w: 55–100 nm) and high crack density provides enhanced sensing properties in air.

We report the effects of various tensile velocities on the nanocrack formation in a Pd thin film on an elastomeric polydimethylsiloxane substrate and its H2 sensing properties. A tunable nanocrack along the x and y axes was created by mechanical stretching/compression cycles with varying tensile velocities. From the microstructural analyses, we found that the tensile velocity has a significant effect on the crack density but little effect on the average crack width. The Pd nanogap sensor prepared under a high tensile velocity showed a high performance with a low detection limit of 500 ppm of H2 in air. Our results indicate that the higher crack density with the narrow nanocrack width (55–100 nm) propagated over the entire film provides the enhanced H2 sensing properties in air.