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. 2016 Sep 29;16(10):1612.
doi: 10.3390/s16101612.

Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors

M Cihan Çakır  1   2 , Deniz Çalışkan  3 , Bayram Bütün  4 , Ekmel Özbay  5   6
Affiliations

Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors

M Cihan Çakır et al. Sensors (Basel). .

Abstract

Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO) heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption-dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively.

Keywords: Heat distribution; Indium tin oxide; Metal oxide gas sensor; Micro hot-plate; SnO2.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Cross-section of the gas sensor.
Figure 2
Figure 2
Fabricated sensor’s optical microscope photograph.
Figure 3
Figure 3
Power consumption versus measured maximum metal oxide film temperature.
Figure 4
Figure 4
Temperature distribution image taken by a thermal microscope (a) and temperature distribution line scan through center of the device at 80 mW (b).
Figure 5
Figure 5
Heat-up and cool-down times as measured at 100 °C, 150 °C, and 200 °C average active area temperature.
See this image and copyright information in PMC

References

    1. Wang C. Metal Oxide Gas Sensors: Sensitivity and Influencing Factors. Sensors. 2010;10:2088–2106. doi: 10.3390/s100302088. - DOI - PMC - PubMed
    1. Çalışkan D., Bütün B., Çakır M.C., Özcan Ş., Özbay E. Low dark current and high speed ZnO metal–semiconductor–metal photodetector on SiO2/Si substrate. Appl. Phys. Lett. 2014;105:161108. doi: 10.1063/1.4899297. - DOI
    1. Razeghi M., Rogalski A. Semiconductor ultraviolet detectors. J. Appl. Phys. 1996;79:7433–7473. doi: 10.1063/1.362677. - DOI
    1. Hwang W., Shin K., Roh J., Lee D., Choa S. Development of Micro-Heaters with Optimized Temperature Compensation Design for Gas Sensors. Sensors. 2010;11:2580–2591. doi: 10.3390/s110302580. - DOI - PMC - PubMed
    1. Manginell R.P., Smith J.H., Ricco A.J. An overview of micromachined platforms for thermal sensing and gas detection. Proc. SPIE. 1997;3046 doi: 10.1117/12.276616. - DOI