The Microsystems Laboratory of the ELKH Centre Energy for Research (EK-CER) and the Moscow Engineering Physics Institute (MEPhI) of the National Nuclear Research University of Russia have developed a microscale gas sensor for natural gas leak detection as part of a joint Hungarian-Russian project. The microheater unit, which is the basis of the device, is protected by a sample seal to ensure a uniform surface temperature.
The uniform temperature of the 0.15 mm diameter surface of the microheater on which the sensors are based is within ±1 percent and its stability up to 530 °C is 5,000 hours, making it operational for 5 years in the intermittent mode used in gas sensors. The heater reaches 500 °C at 1.5 V with a power of only 27 mW, making it ideal for use in portable personal protection devices.
Another element of the newly developed device is the ceramic case for explosion-proof mechanical protection of the chip, which is printed on a circuit board using SMD technology and produced with laser technology. Catalytic gas sensors are based on the measurement of heat generated during the controlled oxidation of combustible gases. In their development, nanoparticle catalysts were produced by classical chemical procedures and atomic layer separation. Although the long-term stability of catalysts still falls below requirements, the refinement of new techniques and material systems will enable the production of marketable sensors. The first element is a sensor measuring the required thermal conductivity, which is made up of the elements mentioned above. There are plans to build a robust and reliable methane alarm system by combining sensors based on thermal conductivity measurement and the catalyst principle.
The early-warning signal from the newly developed device is primarily used to prevent the formation of explosive concentrations of natural gas and other flammable gases. The project "Low-power calorimetric nanosensors for gas sensing in hazardous media", under project ID 2017-2.3.4-TÉT-RU-2017-00006, was funded by the Hungarian Government with support from the Research and Technology Innovation Fund.
Gas sensor chip and optical microscope images of laser-cut ceramic cases. On the left, the catalytically active (black) and passive (white) reference coatings separated from the suspensions on the two heating elements of the integrated 1x1 mm micro-pellistor chip. The picture on the right shows the SMD-mounted, ceramic-encapsulated sensors.