Gas sensing is nowadays a key actor in pollution observation and detection of chemical toxic agents or explosives. All these applications require the shortest possible time response. Very recently, a control of the surface potential in gas sensors based on metal oxides has experimentally shown to dramatically improve the time response of metal-oxide gas sensors. The proposed control is inspired in sigma-delta modulators. This paper aims at studying the resulting dynamics in the sensor from a theoretical point of view. Using state space models, it is shown how the state variables, namely the concentrations of ionized species in the sensing layer, evolve with time in open and closed loop configuration. This analysis studies how it is possible to alter the dynamics of the overall system, while at the same time keeping some important characteristics of sigma-delta modulators, such as quantization noise-shaping. Numerical simulations validate the obtained results.

如今，气体感测是污染观察和化学有毒物质或爆炸物检测中的关键角色。所有这些应用都需要最短的时间响应。最近，实验表明，基于金属氧化物的气体传感器表面电位的控制可显着改善金属氧化物气体传感器的时间响应。所建议的控制受到sigma-delta调制器的启发。本文旨在从理论的角度研究传感器中产生的动力学。使用状态空间模型，显示了状态变量（即传感层中电离物质的浓度）在开环和闭环配置中如何随时间变化。这项分析研究了如何改变整个系统的动力，同时保留了sigma-delta调制器的一些重要特性，例如量化噪声整形。数值模拟验证了所获得的结果。