GOALI: MEMS-Based Preconcentrators with Nano-Structured Adsorbents for Micro Gas Chromatography

0854242 Agah自20世纪50年代以来，气相色谱法（GC）一直是分析挥发性混合物的常用方法。使用微机电系统（MEMS）技术用于GC开发（MEMS GC）是用于开发微仪器的一种有前途的方法，与传统的对应物相比，所述微仪器具有更低的成本、更小的尺寸、更低的功耗、更快的分析和更大的现场使用的便携性。这些仪器在国土安全、工业过程控制、生物监测和改善环境质量方面都有应用。由于挥发性和半挥发性有机化合物（VOC）的低浓度的CRTGC，一个预浓缩步骤之前，实时化学传感器测量是必要的。理想的预浓缩器将自动采样环境气体，并将测量灵敏度提高10-1000倍，同时具有低功耗。我们将通过结合和弥合自上而下的小型化处理（MEMs）和自下而上的自组装方法（纳米技术）之间的差距来应对这一挑战。这项工作的目的是采用MEMS技术开发集成的热解吸能力和高的表面积体积比的VOC预浓缩器芯片，并利用纳米技术涂覆纳米结构的吸附剂。提出了四个具体目标：1）制造低质量使用高纵横比硅蚀刻技术和玻璃上硅晶片工艺的具有片上加热器和温度传感器的（低功率）预浓缩器，2）在基于MEMS的预浓缩器的所有表面上以纳米分辨率沉积存款离子自组装多层（ISAM）或烷烃官能化的金纳米颗粒，3）用常规吸附剂如OV-1和Tenax涂覆MEMS预浓缩器，并在解吸宽度、穿透体积和温度分布方面评估它们相对于涂覆有纳米结构材料的那些预浓缩器的性能，以及开发新模型来预测这种预浓缩器的行为，以及4）通过与Convergent Engineering Inc.合作，表征用于监测呼吸中存在的生物分析物的微芯片及其相应吸附剂的性能，并将微芯片的性能与常规工业标准预浓缩器进行比较。（CE）.我们期望通过实现200的浓缩因子、0.2s的解吸宽度和在50°C/sec温度梯度下1 W的功耗来证明正构烷烃（C5-C16）和多环芳烃以及环尺寸不同的呼吸分析物的浓缩和解吸。自组装极性和非极性吸附材料的能力将使我们能够在广泛的应用中选择性地浓缩分析物，即环境监测，国土安全和生物医学。该项目的成果将树立一个杰出的例子，说明MEMS和纳米技术如何成为开发低成本、低功耗、高性能设备的高度互补方法，这些设备将影响地球仪的行业，因为全球GC仪器市场估计每年约为10亿美元。这项研究还将推进发现，同时促进高中，本科和研究生水平的教学和学习。这包括：1）开发气相色谱演示使用MEMS为基础的预浓缩器与纳米结构的吸附剂弗吉尼亚理工大学？的物理学生的社会推广计划，以农村，弗吉尼亚州西南部的高中学生，2）在弗吉尼亚理工大学（VT）和威廉和玛丽学院（W M）的本科生的研究机会&，3）从代表性不足的群体招募研究生到一个高度跨学科的研究计划，和4）在由PI在不同部门/机构教授的课程中纳入项目结果，即VT？的MEMS：从制造到应用和纳米技术，和W M？的仪器分析和高级分析化学和4）由VT，W M和CE的年度联合研讨会上微系统在生物医学中的应用。此外，这项研究的成果将在同行评审的期刊上广泛传播给工程和科学界，并在多学科会议上发表，以CE和其他使用或开发气相色谱和VOC预浓缩器的行业（微陷阱），在网页上，将作为资源，为关闭-教授本科生和研究生分析化学课程，涉及分离科学的校园教师

0854242AgahSince the 1950s, gas chromatography (GC) has been a common approach for analysis of volatile mixtures. The use of microelectromechanical systems (MEMS) technology for GC development (ìGC) is a promising approach for developing micro-instruments having lower cost, smaller size, lower power consumption, faster analysis, and greatly increased portability for in-field use compared to their conventional counterparts. These instruments have applications in homeland security, industrial process control, bio-monitoring, and in improving environment quality. Due to the low concentration of volatile and semi-volatile organic compounds (VOC) in ìGCs, a preconcentration step prior to real-time chemical sensor measurement is needed. The ideal preconcentrator would automatically sample the ambient gas and improve the measurement sensitivity by 10-1000 fold while having low power consumption. We will address this challenge by combining and bridging the gap between top-down miniaturized processing (MEMs) and bottom-up self-assembly approaches (nanotechnology). The objective of this work is to employ MEMS technology to develop VOC preconcentrator chips with integrated thermal desorption capability and high surface-to-volume-ratio and to utilize nanotechnology to coat them with nano-structured adsorbents. Four specific goals are proposed: 1) fabricate low-mass (low-power) preconcentrators with on-chip heaters and temperature sensors using high-aspect-ratio silicon etching techniques and a silicon-on-glass wafer process, 2) deposit ionic self-assembled multilayers (ISAM) or alkane functionalized gold nanoparticles on all surfaces of the MEMS-based preconcentrators with nanometer resolutions, 3) coat MEMS preconcentrators with conventional adsorbents such as OV-1 and Tenax and evaluate their performance against those coated with nano-structured materials in terms of desorption width, breakthrough volume, and temperature profile as well as develop new models to predict the behavior of such preconcentrators, and 4) characterize the performance of ìPCs and their corresponding adsorbents for monitoring bioanalytes present in breath and compare the performance of the microchips with conventional industry-standard preconcentrators through collaboration with Convergent Engineering Inc. (CE). We expect to demonstrate the concentration and desorption of n-alkanes (C5-C16) and polyaromatic hydrocarbons as well as breath analytes that vary in ring-size by achieving a concentration factor of 200, desorption widths 0.2s, and power consumptions 1W at 50°C/sec temperature ramps. The ability to self-assemble both polar and non-polar adsorbent materials will enable us to have selective concentration of analytes in a wide range of applications, namely environmental monitoring, homeland security, and biomedicine. The outcome of this project will set an outstanding example of how MEMS and Nanotechnology can become highly complementary methodologies for developing low-cost, low-power, high-performance devices that impact industries across the globe, considering that the worldwide market for GC instruments is estimated to be around $1 billion annually. This research will also advance discovery while promoting teaching and learning at the high school, undergraduate, and graduate levels. This includes: 1) development of gas chromatographic demonstrations using the MEMS-based preconcentrators with nano-structured adsorbents for Virginia Tech?s Society of Physics Students outreach programs to rural, southwestern Virginia high school students, 2) research opportunities for undergraduates at Virginia Tech (VT) and the College of William and Mary (W&M), 3) recruiting of graduate students from under-represented groups into a highly interdisciplinary research program, and 4) incorporation of the project results in the courses taught by the PIs in different departments/institutions, namely VT?s MEMS: from fabrication to application and Nanotechnology, and W&M?s Instrumental Analysis and Advanced Analytical Chemistry and 4) annual joint seminars by VT, W&M, and CE on microsystems applications in biomedicine. Additionally, the outcome of this research will be widely disseminated to the engineering and scientific communities in peer-reviewed journals and in presentation at multidisciplinary conferences, to CE and other industries that use or develop gas chromatography and VOC preconcentrators (microtraps), and in web pages that will serve as resources for off-campus faculty who are teaching undergraduate and graduate analytical chemistry courses that deal with separation science