Sensing performance of Pd nanogap supported on an elastomeric substrate in a wide temperature range of –40 to 70 °C

Abstract

We examined the effect of environmental temperature (–40 to 70 °C) on the hydrogen sensing performance of a Pd nanogap sensor supported on an elastomeric polydimethylsiloxane (PDMS) substrate. Sensing tests were conducted using various sensors with different gap widths, prepared with different tensile strains. All sensors operated in an “On-Off” mode with a rapid response time of ~1 s at the operating temperatures. The sensing performance was significantly influenced by the high thermal contraction/expansion properties of the PDMS substrate, depending on the environmental temperature. At subzero temperatures (0, –20, and −40 °C), the sensing performance was improved owing to the gap narrowing. At high temperatures (above 40 °C), it decreased owing to the gap broadening. The detection limit was 300 ppm at subzero temperatures but >1% at high temperatures. The results reveal that the Pd nanogap sensor on PDMS is more suitable for detecting H2 at subzero temperatures. In addition, the sensor showed excellent reproducibility for hundreds of sensing cycles at 25 °C and −40 °C. Furthermore, the sensor was stable to high humidity (above 70 RH%) at 25 °C. Our study demonstrated that the Pd nanogap sensor on a PDMS substrate is a possible candidate for use as an on-board safety H2 sensor in hydrogen-electric vehicles.