ACT/SGER: Resonant Toxic Chemical Sensor Platform

这个项目是响应国家科学基金会03-569：“打击恐怖主义的方法”而发起的，将研究压电体声波谐振传感器作为探测各种化学和生物物种的敏感平台的潜力。 主要研究者（PI）小组先前已经证明，基于镧镓石（La 3Ga 5SiO 14）的谐振器可以在宽范围的压力下有效地工作到600 ℃。 因此，基于这种设备的传感器可能能够在各种恶劣环境中工作，例如战场或工业生产设施。 这种谐振器可以与多孔Si或沸石膜集成，其可以涂覆有催化剂或功能性表面基团以检测广泛的化学或生物物种。 PI将构建基于镧系元素的谐振器，其与被光电化学蚀刻以形成孔的多孔Si膜集成，从而提供高活性表面积。 他将研究传感器对化学神经战剂模拟物的响应，确定灵敏度和响应时间作为Si孔隙率和表面催化剂负载的函数。 此外，他还将研究传感器对湿度、压力和其他化学和生物物种的交叉敏感性。根据该计划开发的鲁棒谐振器将使薄膜的氧化还原研究，原位薄膜沉积监测和高精度TGA分析成为可能。这将影响催化领域，因为能够原位监测吸附/解吸动力学和许多技术应用，例如监测汽车和工厂排放，检测有毒物质以及化学和其他工业过程中的反馈控制。 由于这项工作的广泛适用性，它得到了美国情报界和数学和物理科学局多学科活动办公室的资助。 化学武器和生物武器是对国家安全的严重威胁，对平民和军事人员都构成潜在危险。根据该计划开发的传感器提供了在恶劣环境下远程监测此类威胁的可能性。 更一般地，压电谐振器可用于执行精确且高分辨率的质量测量。 压电体声波谐振器（本质上是一个微小的鼓）的频率取决于谐振器的尺寸和表面层或膜的质量。 通过创建对特定类型的化学或生物物种具有亲和力的表面层，可以创建能够检测该物种的存在或不存在的传感器。 在不存在特定物质的情况下，谐振器具有一个频率，并且当存在这样的物质时，它具有不同的频率。 在本项目中，PI将构建各种此类传感器并研究其特性。 特别是，他将确定产生可检测响应所需的材料量，研究响应速度，并检查其他因素（如湿度，压力和其他物种的存在）对传感器性能的影响。 该计划还受益于与德国同事的合作，并为研究生提供了访问相关领域专家并与之互动的机会。 本科生通过麻省理工学院的UROP计划融入研究活动，PI向科学高中教师讲授传感器和能源相关材料研究的进展。

This project, initiated in response to NSF 03-569: "Approaches to Combat Terrorism," will investigate the potential of piezoelectric bulk acoustic wave resonant sensors as sensitive platforms for the detection of various chemical and biological species. The Principal Investigator's (PI's) group has previously demonstrated that langanite (La3Ga5SiO14) based resonators can operate effectively to 600 C over a wide range of pressures. For this reason, sensors based on such devices are potentially capable of operating in a variety of hostile environments, such as battlefields or industrial production facilities. Such resonators can be integrated with porous Si or zeolite films, which can be coated with catalysts or functional surface groups to detect a wide range of chemical or biological species. The PI will construct langanite-based resonators integrated with porous Si films that are photoelectrochemically etched to form pores, thus providing high active surface areas. He will study the response of the sensor to a simulant for chemical nerve warfare agents, determining the sensitivity and response time as functions of the Si porosity and surface catalyst loading. In addition, he will study the cross-sensitivity of the sensors to humidity, stress, and other chemical and biological species. Robust resonators developed under this program will enable redox studies of films, in-situ thin film deposition monitoring, and high precision TGA analysis. This will impact the field of catalysis, given the ability to monitor, in situ, adsorption/desorption kinetics and many technological applications, such as monitoring of automotive and factory emissions, detection of toxic agents and feedback control in chemical and other industrial processes. Because of the broad applicability of this work, it is supported both by funding from the U.S. intelligence community and by the Office of Multidisciplinary Activities in the Directorate for Mathematical and Physical Sciences. %%%Chemical and biological weapons are a serious threat to national security and pose a potential danger to both civilians and military personnel. Sensors developed under this program provide the potential to monitor such threats remotely and under harsh environments. More generally, piezoelectric resonators can be used to perform precise and high-resolution mass measurements. The frequency of a piezoelectric bulk acoustic wave resonator (essentially a tiny drum) depends upon the dimensions of the resonator and the mass of the surface layer or membrane. By creating a surface layer that has an affinity for a specific type of chemical or biological species, one can create a sensor capable of detecting the presence or absence of that species. In the absence of the particular species the resonator has one frequency, and when such species are present, it has a different frequency. In this project, the PI will construct a variety of sensors of this type and study their characteristics. In particular, he will determine the amount of material necessary to produce a detectable response, study the speed of the response, and examine the effects of other factors - such as humidity, stress, and the presence of other species - upon the performance of the sensor. This program also benefits from collaboration with German colleagues and provides an opportunity for graduate students to visit and interact with experts in related fields. Undergraduate students are integrated into the research activities via MIT's UROP program, and the PI lectures about advances in sensor and energy related materials research to Science High School teachers.