Department of Functional Materials, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
Sensors (Basel). 2019 Sep 23;19(19):4104. doi: 10.3390/s19194104.
A novel sensor operation concept for detecting ppb-level NO concentrations at room temperature is introduced. Today's research efforts are directed to make the sensors (low response and recovery times). Nevertheless, hourly mean values can hardly be precisely calculated, as the sensors are still too slow and show baseline drifts. Therefore, the integration error becomes too large. The suggested concept follows exactly the opposite path. The sensors should be made and operated as resistive gas dosimeters. The adsorption/desorption equilibrium should be completely shifted to the adsorption side during a sorption phase. The gas-sensitive material adsorbs each NO molecule (dose) impinging and the sensor signal increases linearly with the NO dose. The actual concentration value results from the time derivative, which makes the response very fast. When the NO adsorption capacity of the sensor material is exhausted, it is regenerated with ultraviolet (UV) light and the baseline is reached again. Since the baseline is newly redefined after each regeneration step, no baseline drift occurs. Because each NO molecule that reaches the sensor material contributes to the sensor signal, a high sensitivity results. The sensor behavior of ZnO known so far indicates that ZnO may be suitable to be applied as a room-temperature chemiresistive NO dosimeter. Because UV enhances desorption of sorbed gas species from the ZnO surface, regeneration by UV light should be feasible. An experimental proof demonstrating that the sensor concept works at room temperature for ppb-level NO concentrations and low doses is given.
介绍了一种用于在室温下检测 ppb 级 NO 浓度的新型传感器工作原理。目前的研究工作旨在使传感器（响应和恢复时间短）。然而，由于传感器仍然太慢并且存在基线漂移，因此几乎不可能精确计算小时平均值。因此，积分误差变得太大。所提出的概念完全遵循相反的路径。传感器应该被制造成电阻式气体剂量计并进行操作。在吸附阶段，吸附/解吸平衡应完全转移到吸附侧。气体敏感材料吸附每个撞击的 NO 分子（剂量），并且传感器信号随 NO 剂量线性增加。实际浓度值来自时间导数，这使得响应非常快。当传感器材料的 NO 吸附容量耗尽时，它会用紫外线（UV）光再生，并且再次达到基线。由于在每次再生步骤后重新定义了基线，因此不会发生基线漂移。由于到达传感器材料的每个 NO 分子都有助于传感器信号，因此灵敏度很高。迄今为止已知的 ZnO 传感器行为表明，ZnO 可能适合用作室温化学电阻式 NO 剂量计。由于 UV 增强了从 ZnO 表面解吸被吸附气体的物种，因此通过 UV 光进行再生应该是可行的。给出了实验证明，证明该传感器概念在室温下适用于 ppb 级 NO 浓度和低剂量。
