覆盖敏感膜的声表面波气体传感器中的关键科学问题及应用技术研究

Because of their high sensitivity, small size and low cost, surface acoustic wave (SAW) sensors have demonstrated strong competitiveness in a variety of gas monitoring fields and attract many researchers’ interest. However, some related scientific problems still need further researches. Based on our previous studies, in this project we will carry out the following studies: the changes of SAW propagation properties and coupling-of-mode (COM) parameters after a sensitive film coated, the adsorption and desorption mechanisms of gasses in porous solids, the physical and chemical nature of the selectivity of sensitive films adsorbing gas, the changes in the material parameters of the sensitive film after adsorbing gas, and the changes in SAW propagation characteristics when the gas being adsorbed, etc. The aim of this project is to establish a theoretical model which can describe the relationship between the sensor output and the gas concentration or pressure. To set up the experimental platform, a SAW detector with low-loss and high Q-value will be designed and fabricated, a corresponding polymer or graphene oxide (GO) film will be coated on the detector surface respectively, and a high-frequency oscillating circuit will be developed. By using the platform, gas detection experiments will be performed to verify the theoretical model and modify the model parameters. The researches in this project will be helpful to complete the theoretical models on the response mechanism of SAW gas sensors and to accelerate the development of practical sensors.

由于具有灵敏度高、体积小、成本低等优点，声表面波传感器在多种气体监测领域展现了强烈的竞争力，成为当前研究热点之一，吸引着众多学者投身其中，但与其有关的科学问题尚需深入研究。在已有研究基础之上，本项目将要开展的研究包括：覆盖敏感膜后声波传播特性的改变及对耦合模模型参数的影响，多孔固体中气体的吸附及脱附机制，敏感膜选择性吸附的成因及选定方法，吸附气体后敏感膜的变化及其对声波传播机制的影响等。依据前述理论研制一种低损耗高Q值的检测器，在其表面发分别涂覆聚合物和氧化石墨烯敏感膜，结合高频电路组成一种高稳定性的振荡器，以此作为实验测试平台开展DMMP气体检测实验以验证理论、修正模型参数。通过这些研究建立一种能够全面、准确的分析气体传感器响应机制及敏感膜选定原则的理论模型与实用方案。本项目的开展对完善声表面波气体传感器的理论模型、加速实用传感器的开发等具有重要意义。

声表面波传感器在多种气体监测领域具有较强的竞争力，是当前研究热点之一。针对SAW气体传感器中现存的一些瓶颈问题，本项目开展了以下研究。首先构建了一种能够描述SAW气体传感器吸附、脱附全过程的实时响应模型，该模型能充分考虑气体浓度、流动速度、敏感膜大小和位置、气室结构等因素对吸附效率的影响，可用于优化传感器结构设计、缩短检测时间。研制了基于氧化锌量子点敏感膜的SAW气体传感器芯片，结合相移网络、放大器、混频器、SAW延迟线等构建了声表面波振荡器；实测结果表明，装置对于浓度为0~40 ppm的DMMP气体的响应线性度较好，且具有良好的重复性，验证了所建立的SAW气体传感器实时响应模型。采用横向耦合谐振结构，研制了一种高Q值、低损耗、单一峰值的SAW气体传感器检测芯片，得到的SAW芯片的Q值 >3000、插入损耗 <3 dB、旁瓣抑制 >30 dB，指标优于目前通常采用的延迟线和纵向耦合结构。本项目基本完成了预定研究目标。