Hydrogen Detection with SAW Polymer/Quantum Dots Sensitive Films

Abstract

Regarding the use of hydrogen as a fuel, it is necessary to measure its concentration in air at room temperature. In this paper, sensitive composite films have been developed for surface acoustic wave (SAW) sensors, using quantum dots (QDs) and polymers. Si/SiO2 QDs were used due to having a high specific surface area, which considerably improves the sensitivity of the sensors compared to those that only have a polymer. Si/SiO2 QDs were obtained by laser ablation and analyzed by X-ray diffraction and transmission electron microscopy (TEM). Two types of polymers were used: polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA). Polymer and polymer with QDs compositions were deposited on the sensor substrate by drop casting. A heat treatment was performed on the films at 80 °C with a thermal dwell of two hours. The sensors obtained were tested at different hydrogen concentrations at room temperature. A limit of detection (LOD) of 452 ppm was obtained by the sensor with PDMS and Si/SiO2 QDs, which was heat treated. The results demonstrated the potential of using QDs to improve the sensitivity of the SAW sensors and to achieve a heat treatment that increases its adsorption capacity of the gas molecules.

Development of Pd/TiO2 Porous Layers by Pulsed Laser Deposition for Surface Acoustic Wave H2 Gas Sensor

“…This type of sensors has attracted attention through their features as small size, low cost, ease of fabrication, fast response, remarkable sensitivity, satisfactory stability, wireless operation [15,16]. SAW sensors have been developed for the detection of hydrogen [15,17] volatile organic compounds [18], ammonia [16], hydrogen sulfide [1], explosives [19], toxic gases [20], etc.…”

Equivalent Circuit Model Extraction for a SAW Resonator: Below and above Room Temperature

“…Such variations can be measured with high-accuracy frequency estimation algorithms [ 17 ] and easily related to the physical quantity of interest [ 18 ]. SAW resonators have been successfully employed for temperature and humidity sensing [ 15 , 19 , 20 , 21 ], as pressure sensors [ 16 , 22 , 23 ], biosensors [ 24 ], and for VOC and gas sensing [ 25 , 26 , 27 , 28 ]. They have also been employed in harsh environments [ 14 , 29 , 30 ].…”

Effect of Pd/ZnO Morphology on Surface Acoustic Wave Sensor Response

“…Surface acoustic wave (SAW) sensors are notable due to their very high sensitivity, short response and recovery times, the possibility of wireless operation, small size and ease of fabrication [8,9]. The principle of operation of this type of sensor is based on the transformation of an electrical signal into a mechanical wave that travels at the surface of the sensor, which includes a sensitive area.…”

“…Depending on the type of gas to be detected, both the type and the morphology of the sensitive material are important. For the detection of hydrogen, SAW sensors with different types of sensitive layers have been developed: metal oxide semiconductors (ZnO, SnO 2 , TiO 2 ) [15][16][17][18], metals (Pd and Pt) [19] and composite materials [9,13,20]. The morphology of these materials has a very important role in ensuring the interaction of gas molecules with the sensitive film over a large surface.…”