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SiC-FET gas sensors for environmental monitoring and air quality control

Applied Sensor Science launched the silicon carbide field effect transistor, SiC-FET, chemical gas sensors 18 years ago.

The devices have been already commercialized for certain applications by the spin off company SenSiC AB. The SiC-FETs are tailor made for different applications through the choice of catalytic gate material of the transistor and the operation temperature, 200-500°C. They are demonstrated for applications like combustion and emission control, engine exhaust after-treatment and, through the EU project SENSIndoor (#604311), for indoor air quality control related to VOCs like formaldehyde, benzene and naphthalene at ultra-low concentrations (sub-ppb). The group has strong collaboration with University of Oulu, Finland, especially related to LTCC (low temperature co-fired ceramic), advanced packaging of the SiC-FETs, and Saarland University, Germany (double PhD students), related to advanced operation of the SiC-FETs in terms of temperature and gate bias cycling, and real time sensor signal algorithm development through advanced data processing and data evaluation based on multivariate statistics.

Detection of hazardous indoor air pollutants at sub-ppb level

We develop SiC-FET gas sensors for highly sensitive and selective detection of hazardous volatile organic compounds (VOCs), such as formaldehyde, naphthalene, and benzene, at the ultra-low concentration level (down to sub-ppb).

The optimization of the sensor performance is studied through development of novel sensing materials for the gate contact as well as smart operation combined with advanced data evaluation based on multivariate statistics.

Major outcomes of this research are from the EU-project SENSIndoor.

The SENSIndoor project (2014-2016) was supported by the European Union's Seventh Programme for research, technological development and demonstration, under grant agreement no. 604311.

Other financial supports were received by the COST Action TD1105 EuNetAir (two-week Short Term Scientific Mission, STSM, at Saarland University, Germany), by the Knut and Alice Wallenberg Foundation, KAW (travel grant to attend the IMCS Conference, 16-19 March 2014, Buenos Aires, Argentina, oral presentation), and by the Royal Swedish Academy of Sciences, KVA (travel grant to attend the Indoor Air Conference, 3-8 July 2016, Ghent, Belgium, poster presentation with short oral introduction).

Figure: Sensor response to formaldehyde (CH2O) using Ir-gated SiC-FET (D. Puglisi et al., J. Sens. Sens. Syst. 4, 1-8, 2015).

SiC-based ammonia sensors for control of SNCR

This project was initially supported by Värmeforsk involving the industrial partners Tekniska Verken, SenSiC AB, Vattenfall and Alstom Power Sweden AB. It concerned development of a SiC based ammonia sensor system to control selective non catalytic reduction (SNCR), i.e. injection of ammonia (or urea) in hot flue gases in order to convert nitrogen oxide gases to nitrogen and water. It continued partly on faculty support during 2012. Now an ammonia sensor, also intended for stationary engines, is commercially available through SenSiC AB.

Figure: The figure shows that it is possible to fine-tune the operation parameters when using the ammonia sensors for alarm purposes simply by adjusting an offset voltage.

Upper panel: flue gas emissions of CO (red) and ammonia slip (blue). Lower panel: The corresponding sensor signal (gate electrode, iridium) set to an alarm level of 15-20 ppm ammonia.

WOV - Working on Venus

This project has started on January 2014 and has eight PhD students in different work packages. Applied Sensor Science contributes to this project with the development of SiC-FET sensors capable to operate in harsh conditions compatible with the Venus target, i.e., high temperature up to 550°C, high pressure (92 bar) and high CO2 concentration.
Lida Khajavizadeh is doing her PhD within this project under the supervision of Mike Andersson.

NOx sensing

SenSiC AB has coordinated a FFI-project (Fordonsstrategisk Forskning och Innovation) where Applied Sensor Science and Chalmers together with industrial partners VOLVO AB and SCANIA develop a NOx sensor for after treatment of diesel engine exhausts.

SO2 sensing

In a research project within FunMat and in collaboration with Alstom Power Sweden AB in Växjö we have developed SO2 sensors for control of the desulphurization unit in power plants. We demonstrated that the SiC-FET sensor can detect the SO2 target concentration in a small heating plant when operated in temperature cycling operation mode.

Zhafira Darmastuti defended her PhD thesis on this project in June 2014.

Particle detection

Ammonia containing ash particles were heated to 430°C and the release of ammonia detected by SiC-FET devices. Heating particles and detecting the emissions by gas sensors may give
a fingerprint of the content/ adsorbents of the particles.

This research project has been running in collaboration with Saarland University, Saarbrücken, Germany, and University of Oulu, Finland.

Responsible for this page: Donatella Puglisi

Last updated: 03/10/17