Batch fabrication of nanogap electrodes arrays with controllable cracking for hydrogen sensing

Hydrogen sensor based on Pd nanogap arrays was fabricated using the swelling induced cracking method. The square hole Pd array is patterned on the polymer to define the position of the nanogaps. We discuss the influence of the size and the shape of the holes on the formed nanogaps. The structural and morphological characteristics of the metal array and the nanogaps were investigated using laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM). To illustrate an application of the nanogap structure, the Pd nanogap array was deposited on epoxy and polyimide (PI) substrate and used as H₂ sensor, showing a good sensitivity and stability at room temperature. Moreover, the performance of the nanogap array on PI substrate remains stable after annealing at 80-180 °C. This effect is attributed to the high thermal stability of the PI substrate. The effective fabrication method, good sensitivity and the high stability of the Pd nanogap arrays show promising application for H₂ sensing.