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

总体项目目标是一个自加热高温射频传感器平台（HT-RF-platform），用于空气质量监测中最低NO和NO2浓度的剂量计式检测。同时电读出的潜在积累原理是基于在几GHz的NOx存储膜的负载依赖的介电性质。在项目结束时，RF NOx剂量计的工作演示器可用，其包括涂有NOx存储材料的HT-RF传感器平台。在进一步的工作中，传感器平台的应用程序为其他敏感层和分析物或作为材料表征tool被设想。分为三个主题复合体，以下科学问题是要解决的：1。开发和构建自加热HT RF传感器平台，并对用于高温GHz测量的基板材料和谐振器结构进行鉴定。哪些基板材料适用于高达600 °C的RF研究？-哪种共面波导结构可提高传感器的灵敏度？加热器结构和基板几何形状的尺寸应如何确定，以使敏感层的温度均匀，并使到连接焊盘的热传输最小？如何将来自背面加热器结构的干扰最小化？2.在取决于温度的NO或NO2气氛中通过RF分析评估含钡NOx储存材料用于介电NOx剂量测定的适用性。含钡NOx储存材料的介电性质在NOx负载期间如何变化？哪些被测变量适合作为传感器信号？哪些材料成分适用于射频空气质量监测？- 温度相关线性测量范围有多大？没有再生间隔和峰值的日平均信号是否能够以足够的精度确定？储氧材料部分的装载对测量变量有什么影响？-什么是交叉敏感性，它们可以被消除吗？传感器的热再生应在何时启动？3.通过组合操作RF-DRIFT光谱学研究NOx吸附和脱附过程中介电性质与化学过程的相关性。自热传感器平台的可操作漂移分析是否可行？- 介电性能（HF）与NOx负载（DRIFTS）之间有何关联？根据投加的物质和操作温度，可以识别哪些NOx吸附位点？亚硝酸盐和硝酸盐的形成有什么影响？测量的变量和氮氧化物储层的化学成分如何相互关联？线性测量范围是否受到电气或化学过程的限制？哪种温度-时间曲线永久适用于热再生？

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?