Radio-frequency-based high-temperature nitrogen oxide sensor for dosimeter-type detection of NOx in the ppb range for continuous air quality monitoring

该项目的总体目标是建立一个自热式高温射频传感器平台(HT-RF-Platform)，用于像剂量计一样检测最低的NO和NO2浓度，用于空气质量监测。同时电读出的基本累积原理是基于储存NOx的薄膜在几GHz处与负载有关的介电性质。在项目结束时，可以使用射频NOx剂量计的工作演示器，它由一个涂有NOx存储材料的高温射频传感器平台组成。在进一步的工作中，传感器平台被设想用于其他敏感层和分析物或作为材料表征工具。以下科学问题将被解决：1.开发和建造具有用于高温GHz测量的衬底材料和谐振器结构的自加热HTRF传感器平台。-哪些衬底材料适合于高达600°C的射频研究？-什么样的共面波导布置提高了传感器的灵敏度？-应如何确定加热器结构和衬底几何尺寸，以使敏感层的温度均匀并最大限度地减少对连接垫的热传递？-如何将来自背面加热器结构的干扰降至最低？2.通过RF分析评估含Ba2+的NOx存储材料对介质NOx剂量测量的适用性在NO或NO2气氛中，取决于温度。-在NOx负载过程中，含Ba2+的NOx存储材料的介电性能如何变化？哪些被测物适合作为传感器信号？-哪些材料成分适合用于空气质量的射频监测？-随温度变化的线性测量范围有多大？无再生间隔和峰值的日平均信号能以足够的精度确定吗？-储氧材料部分的负载对测量变量有什么影响？-交叉敏感性是什么，它们能被消除吗？-传感器的热再生应该在什么时候开始？3.通过组合的操纵面射频漂移光谱分析NOx吸附和解吸过程中的介电性质与化学过程的相关性。-可以对自热传感器平台进行操纵面漂移分析吗？-介电性质(HF)如何与NOx负载量(漂移)相关？-根据剂量种类和工作温度，哪些NOx吸附部位可以被识别？亚硝酸盐和硝酸盐形成的影响是什么？-测量变量和NOx储存库的化学成分是如何关联的？-线性测量范围是否受电气或化学过程的限制？-哪种温度-时间分布永久适合热再生？

The overall project goal is a self-heated high-temperature radio-frequency sensor platform (HT-RF-platform) for dosimeter-like detection of lowest NO and NO2 concentrations for air quality monitoring. The underlying accumulation principle with simultaneous electrical readout is based on the load-dependent dielectric properties at several GHz of a NOx-storing film. At the end of the project, a working demonstrator of a RF NOx dosimeter is available, which consists of a HT-RF-sensor platform coated with a NOx storage material. In further work, an application of the sensor platform for other sensitive layers and analytes or as a material characterization tool is envisaged.Divided into three thematic complexes, the following scientific questions are to be addressed:1. Development and construction of a self-heated HT RF sensor platform with qualification of substrate materials and resonator structures for high-temperature GHz measurements.- Which substrate materials are suitable for RF investigations up to 600 °C?- What coplanar waveguide arrangement enhances sensor sensitivity?- How should the heater structure and substrate geometry be dimensioned for homogeneous temperature of the sensitive layer and minimal heat transport to the connection pads?- How can interferences from the backside heater structure be minimized?2. Evaluation of the suitability of barium-containing NOx storage materials for dielectric NOx dosimetry by RF analysis in NO or NO2 atmospheres depending on temperature.- How do the dielectric properties of barium-containing NOx storage materials change during NOx loading? Which measurands are suitable as sensor signals?- Which material compositions are suitable for RF monitoring of air quality? - How large is the temperature-dependent linear measuring range? Can daily mean signals without regeneration interval and peak values be determined with sufficient accuracy?- What influence does the loading of the oxygen storage material part have on the measured variables?- What are the cross-sensitivities and can they be eliminated?- When should the thermal regeneration of the sensor be initiated?3. Correlation of dielectric properties with chemical processes during NOx adsorption and desorption by combined operando RF-DRIFT spectroscopy.- Is operando DRIFT analysis of self-heated sensor platforms possible? - How do dielectric properties (HF) correlate with NOx loading (DRIFTS)?- Which NOx sorption sites can be identified depending on the dosed species and the operating temperature? What is the influence of nitrite and nitrate formation?- How do measured variables and chemical composition of the NOx reservoir correlate?- Is the linear measurement range limited by electrical or chemical processes?- Which temperature-time profile is permanently suitable for thermal regeneration?