Laser-induced colloidal writing of repeatable and ultrafast Pd-Ni hydrogen sensor

The advent of hydrogen economy brings new challenges in terms of safety and sensing with a need for fast and low-cost monitoring of hydrogen concentration. Herein, we present a repeatable process for the fabrication of ultrafast Pd based hydrogen sensor. In a first step, organometallic Pd and Ni precursors yield after a fast reaction at room temperature a colloidal ink of Pd/Ni alloyed nanoparticles. This organic based ink displays a relatively high metal content (around 1 wt%) and stability over months. Then, Laser induced micro-bubble patterns metallic wires from a micro-droplet colloidal solution on a glass slide with gold pads. An optical microscope monitors the wire writing process and a simple multimeter measures the sensor conductance, assessing the success of the fabrication process. We tested the sensing performances of the as-fabricated metallic wires and demonstrate a high repeatability and fast response time in air at room temperature. The sensors show great performance in terms of response time (6 msec), low detection limit and good stability. This unique and novel process displays a few advantages compared to existing techniques, the integration of organometallic precursors based colloids and Laser induced micro-bubble technique opens an avenue for the writing of sensors on simple substrates.