Gas sensing based on the dynamic nonlinear responses of a semiconductor gas sensor: dependence on the range and frequency of a cyclic temperature change

Transient response analysis for temperature-modulated chemoresistors

“…The authors used a Figaro sensor with a sinusoidal heater voltage, and analyzed selectivity and sensitivity as a function of the frequency and the heater voltage for different analyte concentrations. For more than a decade, Nakata and co-workers [5][6][7][8][9] have also used a sinusoidal heater voltage for temperature modulation purposes. The authors transform the sensor response into the frequency domain by means of the fast Fourier transform (FFT), and use the coefficients of higher harmonics to discriminate various analytes [6][7][8][9].…”

“…For more than a decade, Nakata and co-workers [5][6][7][8][9] have also used a sinusoidal heater voltage for temperature modulation purposes. The authors transform the sensor response into the frequency domain by means of the fast Fourier transform (FFT), and use the coefficients of higher harmonics to discriminate various analytes [6][7][8][9]. Nakata et al [7], and Nakata and Yoshikawa [8] have also applied these procedures to qualitatively characterize the mixtures of two gases.…”

Chemical Sensor Based on Nonlinearity: Principle and Application

“…6,[15][16][17]20,21,24 In general, the relationship between the d.c. value of the response (one-dimensional information) and the concentration, R0-C, is used for the calibration curve. As for the present system based on nonlinearity, characteristic calibration curves based on multi-dimensional information (R0-C, R1-C, R2-C, R3-C, …, I1-C, I2-C, I3-C, …) were used to define the concentration of the sample species.…”

“…We recently reported that the effect of the range and frequency of temperature modulation is examined 16 and that the nonlinear responses exhibit characteristic changes depending on the gas species and on the composition of the semiconductor 17 to enhance the selectivity. We also reported that the nonlinear dynamic response can be used to determine the concentration of a specific gas, even in the presence of an interfering gas.…”

“…Figure 2 shows a schematic representation of a measurement for detecting and evaluating the nonlinearity of a system. Experimental and analytical profiles are as follows: [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] (1) a sinusoidal perturbation (X: e.g., temperature, voltage, flow rate, or surface area) is applied to the experimental system; (2) the output signal is recorded; and (3) a time trace of the output signal (Y) is Fourier transformed to the frequency domain. The deformation of the output signal from the sinusoidal input corresponds to the nonlinearity of the experimental system, and is quantitatively evaluated as higher harmonics of a Fourier transformation.…”