The resistive particulate matter sensor is a simple device that transduces the presence of soot through impedance change across inter-digital electrodes (IDEs). We investigate the information provided by impedance spectroscopy over the frequency range from 100 Hz to 10 kHz for two purposes. The first is to investigate the opportunities for an improved sensor response to particulate matter (PM), based on the additional information provided by the measurement of both the in-phase (resistive) and out-of-phase (capacitive) components of the change in impedance over this frequency range as compared to DC resistance measurement only. Secondly, the origin of the capacitive response of the device is investigated from the perspective that soot on the device is in the form of bendable dendrites that grow in three dimensions. An IDE structure with the housing acting as an additional suspended electrode for introducing a controllable vertical electric field component has been used for this purpose. The formation of dipoles, due to bending of the charged dendrites, is found to be the source of the capacitive response. Simulation of electrostatic soot deposition reinforces dendritic self-assembly mechanisms, driven by charged particle trajectories along electric field lines. Optical microscopy confirms that dendrites growing out of the substrate plane are sensitive to electric and flow forces, bending when force balances are appropriate. We also apply impedance spectroscopy under varying electric field strengths, showing that capacitive response is only observed when conditions are conducive to dendrite bending in response to the applied AC electric fields.

中文翻译：

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探索电阻式烟尘传感器对交流电激励的响应

电阻式颗粒物传感器是一种简单的设备，它通过叉指电极 (IDE) 上的阻抗变化来转换碳烟的存在。我们研究阻抗谱在 100 Hz 到 10 kHz 的频率范围内提供的信息有两个目的。第一个是基于测量变化的同相（电阻）和异相（电容）分量所提供的附加信息，研究改进传感器对颗粒物 (PM) 响应的机会与仅直流电阻测量相比，在此频率范围内的阻抗。其次，从器件上的烟灰以在三个维度上生长的可弯曲枝晶的形式来研究器件的电容响应的起源。为此目的，使用了一种 IDE 结构，其外壳用作附加的悬置电极，用于引入可控的垂直电场分量。由于带电树突弯曲，偶极子的形成被发现是电容响应的来源。静电烟尘沉积的模拟加强了由沿电场线的带电粒子轨迹驱动的树枝状自组装机制。光学显微镜证实，从基板平面长出的枝晶对电力和流动力敏感，当力平衡合适时会弯曲。我们还在不同电场强度下应用阻抗谱，表明仅当条件有利于响应施加的 AC 电场而导致枝晶弯曲时才观察到电容响应。