Low Concentration Response Hydrogen Sensors Based on Wheatstone Bridge

Abstract

The PdNi film hydrogen sensors with Wheatstone bridge structure were designed and fabricated with the micro-electro-mechanical system (MEMS) technology. The integrated sensors consisted of four PdNi alloy film resistors. The internal two were shielded with silicon nitride film and used as reference resistors, while the others were used for hydrogen sensing. The PdNi alloy films and SiN films were deposited by magnetron sputtering. The morphology and microstructure of the PdNi films were characterized with X-ray diffraction (XRD). For efficient data acquisition, the output signal was converted from resistance to voltage. Hydrogen (H2) sensing properties of PdNi film hydrogen sensors with Wheatstone bridge structure were investigated under different temperatures (30 °C, 50 °C and 70 °C) and H2 concentrations (from 10 ppm to 0.4%). The hydrogen sensor demonstrated distinct response at different hydrogen concentrations and high repeatability in cycle testing under 0.4% H2 concentration. Towards 10 ppm hydrogen, the PdNi film hydrogen sensor had evident and collectable output voltage of 600 μV.

Flexible nanofiber sensor for low-concentration hydrogen detection

“…The good surface crystal structure shows the significant effect on gas sensing. The good crystallinity of Pd can help to eliminate the phenomenon of base resistance drift during testing, which leads to a more stable device performance [6].…”

“…Hence, the key role of the hydrogen sensor is evidently to detect the leakage of hydrogen. However, in the field of space exploration, hydrogen is very thin in space, and the temperature of space is variable [6]. Thus the development of high-performance hydrogen sensors, especially for low-concentration hydrogen detection, is desired to ensure the safe use of hydrogen in future society [7].…”

“…During the last decades, in order to detect hydrogen timely and reliably, different hydrogen sensors have been developed, including metal oxide-based sensors [8][9][10][11][12], palladium (Pd) film sensors on solid silicon substrate [6,13] and flexible sensors based on polymer film [14][15][16][17][18]. Various detecting mechanisms have been derived from these functional sensors, like electric resistance [19,20], Schottky contact [21][22][23][24], optical type and surface acoustic wave, etc [5,25].…”

Multi-Agent Approach Using LoRaWAN Devices: An Airport Case Study

“…Wheatstone bridges are low cost sensors that are used for measuring the very low resistance values precisely. Applications include calculations of hydrogene levels or gases levels in a recipient [38,39], in order to measure the wind speed and direction [40] or for tactile touch monitoring [41]. Accordingly, with these sensors, the system obtained the state of the bathrooms.…”

Optimizing the Performance of a Pd Film-Based Room-Temperature H2 Sensor by Eliminating the Clamping Effect with Cr Nanoparticles

“…Moreover, the expansion of the Pd film may cause their detachment from the substrate, leading to the failure of the sensor . To overcome this drawback, various methods have been reported including doping a second metal, − changing the substrate, , modifying the microstructure, , and adding a buffer layer. , Among them, adding a buffer layer between the substrate and the Pd film has been proven to be an effective method. Recently, Anasthasiya et al had fabricated a Pd film on an alumina substrate and included a Cr buffer layer.…”