| 摘 要： | A highly reliable and selective ethanol gas sensor working in realistic environments based on alpha-Fe_2O_3(α-Fe_2O_3)nanorhombs is developed. The sensor is fabricated by integrating α-Fe_2O_3 nanorhombs onto a low power microheater based on micro-electro-mechanical systems(MEMS) technology. The α-Fe_2O_3 nanorhombs, prepared via a solvothermal method, is characterized by transmission electron microscopy(TEM), Raman spectroscopy, x-ray diffraction(XRD), and x-ray photoelectron spectroscopy(XPS). The sensing performances of the α-Fe_2O_3 sensor to various toxic gases are investigated. The optimum sensing temperature is found to be about 280℃. The sensor shows excellent selectivity to ethanol.For various ethanol concentrations(1 ppm–20 ppm), the response and recovery times are around 3 s and 15 s at the working temperature of 280℃, respectively. Specifically, the α-Fe_2O_3 sensor exhibits a response shift less than 6% to ethanol at280℃ when the relative humidity(RH) increases from 30% to 70%. The good tolerance to humidity variation makes the sensor suitable for reliable applications in Internet of Things(IoT) in realistic environments. In addition, the sensor shows great long-term repeatability and stability towards ethanol. A possible gas sensing mechanism is proposed.
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