Chemical analysis based on nonlinearity : Evaluation of a target species in a mixture sample.

在这项研究中，我们研究了在周期性温度变化中，传感器对样品气体的动态响应因高次谐波扰动而显著增强。这些效应反映在场效应管的幅值上，即传感器响应的性质可以通过高次谐波来评估。基于半导体传感器表面的反应扩散模型，从理论上模拟了二次谐波扰动下传感器的动态响应特性。我们还证明了温度扰动增强的传感器的非线性响应可以为样品气体的分析提供有用的信息。虽然我们只证明了θ_2=π/6时的二次谐波扰动，但选择其他更高的谐波扰动将提高传感器响应的选择性，因为非线性响应随化学物质的变化而变化。为了从理论上找到最佳条件，需要进一步研究温度扰动对传感器响应的影响，例如，在本模型中，应考虑样品气体在传感器表面的反应，以及半导体势垒高度与吸附气体状态和德拜长度的关系。

In this study, we investigated that the dynamic sensor responses to sample gases tinder a periodic temperature change were characteristically enhanced by higher-harmonic perturbation. These effects are reflected by the amplitude in FET, i.e., the nature of sensor response can be evaluated by the higher harmonics. The characteristic dynamic sensor response stimulated by the second-harmonic perturbation was theoretically simulated based on a reaction-diffusion model for the semiconductor sensor surface. We also demonstrated that the nonlinear sensor response enhanced by temperature perturbation can provide useful information for the analysis of a sample gas.Although we have demonstrated only the second harmonic perturbation at θ_2=π/6 in addition to the fundamental harmonic, the selectivity of the sensor response will be enhanced by choosing other higher harmonic perturbation because the nonlinear response changes depending on the chemical species. In order to find the optimal condition from the theoretical point of view, the effects on the sensor responses under the temperature perturbation should be clarified by further investigation, e.g., the reactions between sample gases on the sensor surface should be considered along with the dependence of the semiconductor barrier height on the status of the adsorbed gas and the Debye length [21,32] in the present model.