SBIR Phase I: Ultrasensitive Elemental Mercury Pollution Monitor

这一小型企业创新研究第一阶段项目将利用微电子杠杆的最新发展开发一种新型微型汞传感器。基于这项技术的传感器将比现有的汞传感器小103倍，灵敏度高得多，而且价格便宜。 50-200 μ m长、10-40 μ m宽、0.3-3 μ m厚、共振频率在10-300 kHz范围内的微悬臂梁最近已用于扫描力显微镜，以检测10-12-10-9 N范围内的极小力变化。微悬臂梁的共振频率（和弯曲）由于分子在悬臂梁表面上的吸附而可再现地和灵敏地变化，使其成为具有皮克灵敏度和十亿分之一检测的理想化学传感器。初步的汞检测研究已证明可检测到ppb的汞，并表明汞在镀金杠杆上的选择性吸附（端部加载）产生共振频率的线性变化，灵敏度为0.8 pg/Hz。同时弯曲测量导致0.6 pg/mV的灵敏度。汞传感器的可回收性将通过加热传感器去除吸附的汞来证明。利用微悬臂梁响应，结合使用过滤器选择性去除干扰分子（如H2S），微悬臂梁将被证明是非常通用的和新颖的汞污染传感器。我们计划证明传感器可以在液体环境中以合理的Q振动，使其能够用于检测这些环境中汞的存在。此外，由于传感器的尺寸非常小，因此可以开发高度灵敏的个人监视器。这项工作将为微悬臂梁传感器技术提供一个非常重要的进步，并有可能为其他化学品开发新的传感器。 汞传感器的商业应用包括工业卫生、空气和水污染控制、采矿业、潜艇、空气质量监测等。

This Small Business Innovative Research Phase I project will develop a novel type of miniature mercury sensor utilizing very recent developments in microcantilevers. Sensors based on this technology will be up to 103 times smaller, considerably more sensitive, and less expensive than currently available mercury sensors. Microcantilevers that are 50-200 (m long, 10-40 (m wide, and 0.3-3 (m thick and possessing resonance frequencies in the range 10-300 kHz, have recently been used in scanning force microscopy to detect extremely small changes in force in the range of 10-12-10-9 N. The resonance frequency (and bending) of the microcantilever varies reproducibly and sensitively due to adsorption of molecules on the cantilever surfaces making it an ideal chemical sensor with picogram sensitivity and parts per billion detection. Preliminary mercury detection studies, have demonstrated detection of ppb of Hg, and have shown that selective adsorption of mercury on gold coated cantilevers (end loading) produces a linear variation in resonance frequency with a sensitivity of 0.8 pg/Hz. Simultaneous bending measurements resulted in a sensitivity of 0.6 pg/mV. The recyclability of the mercury sensor will be demonstrated by removing the adsorbed mercury by heating the sensor. Exploiting the microcantilever response, combined with selective removal of interfering molecules (such as H2S) using filters, microcantilevers will be shown to be extremely versatile and novel mercury pollution sensors. We plan to demonstrate that the sensor can be vibrated in liquid environments with a reasonable Q, allowing it to be used to detect the presence of mercury in these environments. Additionally, due to the extremely small size of the sensor, the development of a personal monitor that is highly sensitive may be possible. The proposed work will provide a highly significant advance in microcantilever sensor technology with possibilities of developing new sensors for other chemicals. Commercial applications of mercury sensors include industrial hygiene, air and water pollution control, mining industry, submarines, air quality monitoring, etc.