Design and Experimentation with Sandwich Microstructure for Catalytic Combustion-Type Gas Sensors

Abstract

The traditional handmade catalytic combustion gas sensor has some problems such as a pairing difficulty, poor consistency, high power consumption, and not being interchangeable. To address these issues, integrated double catalytic combustion of alcohol gas sensor was designed and manufactured using silicon micro-electro-mechanical systems (MEMS) technology. The temperature field of the sensor is analyzed using the ANSYS finite element analysis method. In this work, the silicon oxide-PECVD-oxidation technique is used to manufacture a SiO2-Si3N2-SiO2 microstructure carrier with a sandwich structure, while wet etching silicon is used to form a beam structure to reduce the heat consumption. Thin-film technology is adopted to manufacture the platinum-film sensitive resistance. Nano Al2O3-ZrO-ThO is coated to format the sensor carrier, and the sensitive unit is dipped in a Pt-Pd catalyst solution to form the catalytic sensitive bridge arm. Meanwhile the uncoated catalyst carrier is considered as the reference unit, realizing an integrated chip based on a micro double bridge and forming sensors. The lines of the Pt thin-film resistance have been observed with an electronic microscope. The compensation of the sensitive material carriers and compensation materials have been analyzed using an energy spectrum. The results show that the alcohol sensor can detect a volume fraction between 0 and 4,500 × 10−6 and has good linear output characteristic. The temperature ranges from −20 to +40 °C. The humidity ranges from 30% to 85% RH. The zero output of the sensor is less than ±2.0% FS. The power consumption is ≤0.2 W, and both the response and recovery time are approximately 20 s.

Programmable and Modularized Gas Sensor Integrated by 3D Printing

“…This sensing element enables the selective adsorption and subsequent catalytic combustion of analytes on the surface of the Pt wire. The heat generated by the combustion induces changes in the electrical properties of the Pt wire, which are then translated into measurable electrical signals. , These sensors are characterized by their high sensitivities to a wide array of combustible gases and their high selectivities, realized by the use of specific catalysts. However, it is noteworthy that the performances of these sensors can be compromised in environments with insufficient oxygen, highlighting their dependency on the surrounding atmospheric conditions.…”

Adsorption/combustion-type VOC sensors employing mesoporous γ-alumina co-loaded with noble-metal and oxide

“…The appropriate amount of the mp-Al 2 O 3 or lMO/mp-Al 2 O 3 powder obtained was added into the colloidal dispersion containing the noble metal nanoparticles, and then the pH was adjusted to about 4. After the noble metal nanoparticles were adsorbed on the powders, the powders obtained were filtered and dried at 40 • C for 12 h. The obtained mp-Al 2 O 3 powders loaded with mN 1 /nN 2 were denoted as mN 1 /nN 2 /mp-Al 2 O 3 (N 1 and N 2 : noble metal loaded (Au, Pd and Pt), m and n: the amount of N 1 and N 2 nanoparticles loaded, m + n = 1.0 (wt%), mN 1 /mp-Al 2 O 3 for one kind of noble metal nanoparticles loaded) [33][34][35][36]. The Pt nanoparticle only was also loaded on the lMO/mp-Al 2 O 3 powders by the same technique stated above.…”

“…The sensor structure is similar to that of catalytic combustion-type gas sensors [34][35][36], but the sensor-operating conditions are quite different from that of the catalytic combustion-type gas sensors. Namely, the general catalytic combustion-type gas sensors are operated at a given temperature (typically, 100-350 • C), and thus the sensitivity and selectivity to VOC are relatively poor in comparison with other sensors.…”

Hydrogen Sensor Based on NTC Thermistor with Pt-Loaded WO3/SiO2 Coating

“…Various types of hydrogen sensors have been developed thus far. The traditional handmade catalytic combustion gas sensor is not influenced by humidity changes, but these sensors have some drawbacks, including difficulty in pairing, poor consistency, high power consumption, and non-interchangeability, and they are vulnerable to poisoning because they have molecules containing siloxane and sulfur [4][5][6]. Semiconductor-type sensors have good stability, selectivity, and sensitivity, but they only work well at high temperatures [7], necessitating the use of an additional high-temperature thermostatic control.…”