Belarusian university offers scientific and technical cooperation on the joint development and testing of low-power gas microsystems on a nanostructured substrate to detect extremely low concentrations of toxic and explosive gases

Summary

Belarusian university has developed a two-sensor gas microsystem on a nanostructured substrate of anodic alumina for monitoring the gas environment. The university is interested in research and technical cooperation with industrial and scientific partners for the joint development and testing of semiconductor gas microsystems.

Description

Belarusian university with strong expertise in microelectronics and nanotechnologies has developed the two-sensor gas microsystem on nanostructured substrate of anodic alumina, designed to determine extremely low concentrations of toxic and explosive gases.

The microsystem can be used as:
- sensitive component of fire alarm systems,
- in systems for analyzing multicomponent gas media,
- for environmental monitoring (e.g., in the automotive industry to control the emission of CO into the atmosphere),
- for monitoring the working environment of industrial enterprises (e.g., in chemical laboratories to control the leakage of toxic gases).

Modern sensor devices to monitor and control technological gas media and complex compositions in limited space have number of unsolved problems:
1) increasing the sensitivity of gas layers without compromising the selectivity of gas components in a gas mixture
2) increasing the thermomechanical properties of the layers used, that allow the devices to operate at elevated temperatures up to 500-600 C,
3) reducing energy consumption to the microwave range in continuous operation.

The use of nanoporous anodic alumina with increased mechanical characteristics, elasticity and wear resistance as a passive dielectric substrate or membrane allows one to ensure:
- fast response, low power consumption, sensitivity to extremely low concentrations of toxic gases;
- selectivity to certain types of gases depending on the material and structuring of the active layers;
- minimized heat losses due to the sensor design;
- consistency of the thermomechanical properties of the materials in use;
- simultaneous formation of several different-type sensors on a single microsystem crystal while maintaining the size of a single-crystal structure, which allows for the recognition of the composition of multicomponent gas media.

Structurally, the microsystem consists of two crystals of anodic alumina with thickness of 55-60 microns and pores with diameter of 50 nm. The planar side of the crystals has two pairs of platinum information electrodes with sensitive layers deposited in between, which are nanostructured metal oxide films with thickness of 150-400 nm. Heating elements in the meander form are on the reverse side of the crystals.

The operating principle of the two-sensor gas microsystem is based on changing in the electrophysical characteristics of heated metal oxide sensitive layers during their interaction with the gas medium. Sensors with gas-sensitive layers working in parallel and detecting one gas, as well as sensors with gas-sensitive layers working in series and detecting gases of different composition can be located on one chip. The sensors of the developed microsystem are calibrated for certain concentrations of the following gases or their mixtures: ethanol, СО, Н2, С3Н8, NO2, NH3. The operating temperature of the structures is from 200 to 450 C, the power consumption is up to 40 mW.

The university is seeking for partners (scientific organizations, universities, production facilities, and private companies) to develop and test new designs and manufacturing technology of gas microsystems consisting of 16 or more sensors, in which the problem of processing and separating signals from different sensors is eliminated.

The proposal aims to establish research cooperation agreement with industrial and scientific partners in order to improve the current manufacturing technology of the semiconductor gas microsystems, as well as to research and develop new designs of these microsystems with improved parameters.

Collaboration with an industrial partner within technical cooperation agreement is possible for carrying out joint pilot testing of the developed two-sensor gas microsystem.

Advantages & innovations

For the first time, the crystal was designed with the nanoporous base made by the developed technology of anodized aluminum micromachining with no analogues in the world. This solved the number of technological and design problems of thin-film chemoresistive sensors, and at the same time increased their functional characteristics. Advantages: Technical: gas-sensitive layers with the composition determined by the type of gas under analysis and applied to nanoporous surface have tens of times larger effective surface than on smooth silicon or glass surface, which made it possible to significantly increase the sensitivity of sensors at the same time while reducing their dimensions. The developed porous surface significantly improved the thermal and mechanical characteristics of the microsystem: significant reduction in heat losses, increase in the reaction rate and regeneration of the sensor, increase in the thickness of the heater and, as result, increase in the reliability of the sensor. The structured surface of the substrate with the same pores allows nanostructuring the active gas-sensitive layers deposited on it, which makes the film homogeneous system of equal-sized grains of certain composition. This made it possible to increase the selectivity of the sensors. Microengineering of the substrate allowed us to localize heat in limited area of the membrane, significantly reduce energy consumption to tens of microwatts, and increase the speed to tens of seconds and the regeneration rate to units of minutes. Energy saving: The electrochemical anodizing process consumes little power, which makes the technology energy-saving compared to the production of silicon substrates. Resource saving: the technology uses low-harmful reagents and weak acid solutions with no need to dispose. Cost reduction: 3D liquid etching of substrates made of anodic aluminum oxide allows one to avoid purchasing expensive equipment.

Stage of development

Available for demonstration

Contact/ source: Enterprise Europe Network (europa.eu)