Design and Fabrication Challenges of a Highly Sensitive Thermoelectric-Based Hydrogen Gas Sensor

Abstract

This paper presents a highly sensitive thermoelectric sensor for catalytic combustible gas detection. The sensor contains two low-stress (+176 MPa) membranes of a combination of stoichiometric and silicon-rich silicon nitride that makes them chemically and thermally stable. The complete fabrication process with details, especially the challenges and their solutions, is discussed elaborately. In addition, a comprehensive evaluation of design criteria and a comparative analysis of different sensor designs are performed with respect to the homogeneity of the temperature field on the membrane, power consumption, and thermal sensitivity. Evaluating the respective tradeoffs, the best design is selected. The selected sensor has a linear thermal characteristic with a sensitivity of 6.54 mV/K. Additionally, the temperature profile on the membrane is quite homogeneous (20% root mean standard deviation), which is important for the stability of the catalytic layer. Most importantly, the sensor with a ligand (p-Phenylenediamine (PDA))-linked platinum nanoparticles catalyst shows exceptionally high response to hydrogen gas, i.e., 752 mV at 2% concentration.

Critical Sensing Modalities for Hydrogen: Technical Needs and Status of the Field to Support a Changing Energy Landscape

“…144 The robust selectivity was achieved by embedding the nanowires in a hydrophobic poly(methyl methacrylate) (PMMA) matrix, which likely contributes to the longer response times. 143 Other designs that exploit the thermoelectric effect are emerging due to advances in microfabrication 145,146 techniques that support the production of new intricate thermopiles 142,145,146 consisting of n ∼ 20−30 microthermocouples wired in series. Thermopiles improve the sensitivity to temperature changes by amplifying the associated electrical potential: 149,150 = V n T (19) Zhang et al 146 fabricated thermopiles made from singlecrystalline silicon with a Pt NP@Al 2 O 3 catalyst.…”

“…Other catalytic sensors exploit the Seebeck effect to generate a change in potential, Δ V , due to the associated temperature change of a thermoelectric device: − Δ V = α Δ T where α is the Seebeck coefficient. , Hwang et al and Kim et al studied thermochemical hydrogen sensors using Pt-decorated exfoliated graphene sheets and a tellurium nanowire-based thermoelectric (TNTE) layer that is operable at ambient temperature and relative humidity. When hydrogen is present, the Pt nanoparticles catalyze the exothermic combustion of H 2 to create water vapor (Equation ) thereby increasing the TNTE temperature and causing the potential drop as indicated in Equation .…”

Construction of trace hydrogen detection system based on distributed feedback fiber laser

“…Multiple hydrogen sensing technologies have been reported, such as electrochemical sensors, 3 – 5 semiconductor sensors, 6 – 8 and thermoelectric sensors 9 – 11 These sensors have high precision and stability while risk of ignition due to potential sparks. Optical hydrogen sensors, 12 – 17 which are intrinsic safety, resistant to electromagnetic interference, and spark-free, have great potential in hydrogen sensing 18 …”

Low-Concentration Ammonia Gas Sensors Manufactured Using the CMOS–MEMS Technique

“…Gas sensors that are used to detect hydrogen sulfide [4], carbon dioxide [5], hydrogen [6], nitrogen dioxide [7], and formaldehyde [8] have been miniaturized using microelectromechanical system (MEMS) technology. Gas microsensors that use this technology are quiet and highly sensitive, feature low power consumption, and can be mass-produced easily.…”

“…The oxidation-reduction method is used to synthesize the sensing film, which consists of PPy/RGO. Most gas sensors [6][7][8][9][10][11][12] have a heater to generate the WT for the sensitive film, but this study produced an AGS without a micro-heater. This AGS operates at room temperature, so it is more efficient in terms of power consumption.…”