This paper describes a fast and flexible microfabrication method for thermal conductivity gas sensors useful in high-temperature applications. The key parts of the sensor, the microheater and the package, were fabricated from glass-coated platinum wire and the combination of laser micromilling (ablation) of already-sintered monolithic ceramic materials and thick-film screen-printing technologies. The final thermal conductivity gas sensor was fabricated in the form of a complete MEMS device in a metal ceramic package, which could be used as a compact miniaturized surface-mounted device for soldering to standard PCB. Functional test results of the manufactured sensor are presented, demonstrating their full suitability for gas sensing applications and indicating that the obtained parameters are at a level comparable to those of standard industrially produced sensors. The results of the design and optimization principles of applied methods are discussed with regard to possible wider applications in thermal gas sensor prototyping in the future. The advantage of the developed sensors is their ability to operate in air environments under high temperatures of 900 °C and above. The sensor element material and package metallization were insensitive to oxidation compared with classical sensor-solution-based metal–glass packages and silicone MEMS membranes, which exhibit mechanical stress at temperatures above 700 °C.

The features of the wide band gap SiC semiconductor use in the capacitive MOSFE sensors’ structure in terms of the hydrogen gas sensitivity effect, the response speed, and the measuring signals’ optimal parameters are studied. Sensors in a high-temperature ceramic housing with the Me/Ta₂O₅/SiCⁿ⁺/4H-SiC structures and two types of gas-sensitive electrodes were made: Palladium and Platinum. The effectiveness of using Platinum as an alternative to Palladium in the MOSFE-Capacitor (MOSFEC) gas sensors’ high-temperature design is evaluated. It is shown that, compared with Silicon, the use of Silicon Carbide increases the response rate, while maintaining the sensors’ high hydrogen sensitivity. The operating temperature and test signal frequency influence for measuring the sensor’s capacitance on the sensitivity to H₂ have been studied.

A prototype of a nitro compound vapor and trace detector, which uses the pyrolysis method and a capacitive gas sensor based on the metal–insulator–semiconductor (MIS) structure type Pd–SiO₂–Si, was developed and manufactured. It was experimentally established that the detection limit of trinitrotoluene trace for the detector prototype is 1 × 10⁻⁹ g, which corresponds to concentration from 10⁻¹¹ g/cm³ to 10⁻¹² g/cm³. The prototype had a response time of no more than 30 s. The possibility of further improving the characteristics of the prototype detector by reducing the overall dimensions and increasing the sensitivity of the MIS sensors is shown.

A reduced size thermocatalytic gas sensor was developed for the detection of methane over the 20% of the explosive concentration. The sensor chip is formed from two membranes with a 150 µm diameter heated area in their centers and covered with highly dispersed nano-sized catalyst and inert reference, respectively. The power dissipation of the chip is well below 70 mW at the 530 °C maximum operation temperature. The chip is mounted in a novel surface mounted metal-ceramic sensor package in the form-factor of SOT-89. The sensitivity of the device is 10 mV/v%, whereas the response and recovery times without the additional carbon filter over the chip are <500 ms and <2 s, respectively. The tests have shown the reliability of the new design concerning the hotplate stability and massive encapsulation, but the high degradation rate of the catalyst coupled with its modest chemical power limits the use of the sensor only in pulsed mode of operation. The optimized pulsed mode reduces the average power consumption below 2 mW.

We examined the feasibility of alumina substrate metallization by magnetron deposition of copper coatings with thickness of several tens µm for its prospective applications in production of ceramic PCBs and packaging. The films were prepared in magnetron sputtering systems with cooled and thermally insulated (hot) targets. Substrates with different geometries were used, including those with through-holes. Thickness, adhesive properties, and electrical resistivity of produced coatings were analyzed. If the film thickness exceeded ~20 µm, we observed its systematic delamination, unless the dedicated Cu_xO_y sub-layer of was introduced between the substrate and the main Cu film. Intermediate copper oxide films were investigated separately by SEM, EDS, and XRD methods, and deposition conditions for predominant growth of favorable tenorite CuO were determined. Prepared composite two-layer CuO + Cu coatings with total thickness of ~100 µm demonstrated good adhesion to alumina substrates in scratch-testing and performed much better than Cu-only films both in soldering and thermal cycling tests. We discuss an approach for constructing a reliable metallizing coating by plasma-assisted PVD methods that could be beneficial for complex-shaped ceramic PCBs and packaging.

The technological approach for the low-scale production of field-effect gas sensors as electronic components for use in non-lab ambient environments is described. In this work, in addition to the mechanical protection of a gas-sensitive structure, an emphasis was also placed on the very topical issue of thermal stabilization around the one temperature point, even if it is several degrees higher than the surrounding one, which will probably also be useful for any type of application for many types of field-effect sensors. Considerable attention was paid to the characterization of the results obtained by various invasive and non-invasive methods for diagnosing the manufactured construction. The technology described in this article occupies an intermediate position between laboratory samples tested in clean rooms with stable ambient atmospheres, and experimental and small-scale production sensors designed for real operating conditions to solve the narrow application of measuring low concentrations of hydrogen.