奈米流體(nanofluids)為近幾年相當熱門的研究議題，部分研究顯示在流體中加入奈米球 (nanoparticles)可大幅增加流體之熱傳效應，在許多散熱系統的應用上有非常大的潛力。奈米流體也可應用於生醫、生物分子檢測，如生醫晶片(Bio-MEMS, Lab-on-a-Chip)等元件，可利用功能化之奈米球與所需之巨分子(macromolecular)結合，再利用電性或光學等方式來檢測。若再進一步去思考，存在巨分子或生物分子的流體本身就可視為一奈米流體，了解其中的傳輸現象將有助於未來突破性的應用。目前相關的奈米流體熱傳理論目前仍處於研究初期，許多理論相繼提出，包括 Brownian 運動、奈米的尺度效應及介面效應等，不過也有部分實驗研究顯示熱傳增加現象並不如預期的大。造成這些不確定的主要原因之一在於實驗設計與量測的困難，以致於有些實驗數據並不能完全顯示預期的目標效應。致於巨分子或生物流體的奈米熱傳現象實驗數據則是非常缺乏，其主要的原因除了面臨與奈米流體研究一樣的實驗設計量測之困難，另外傳統量測方法需要百毫升(milliliter)以上的量測樣品，使高價位的生物分子實驗面臨極大的挑戰。本計畫的目的即是利用微機電技術(MEMS)，設計製造一熱傳量測分析元件，以微升體積 (microliter)的流體取樣來進行奈米流體與巨分子相關的熱傳輸現象基礎研究。利用量測微量的體積，將量測變異性縮小，不僅可減少量測所需要的樣品量，也減少了量測所需要的時間。而量測微量樣品所需要高精度，則靠微機電技術製造之微感應器配合精密量測方法來克服。此元件主要為一微製造之懸浮薄膜結構，並於薄膜上製作一金屬薄膜溫度感應器，應用改良之熱線法及諧波暫態法原理將可量測微量液體的熱傳導係數，經由實驗設計將可分析其介面熱阻。本計畫分三年來執行，第一年為微量測元件之設計、製作與驗証，包括量測方法的建立與數值模擬。第二年為奈米流體之介面熱阻基礎研究，利用所建立之微元件量測探討奈米球與液體固液之有效(effective) 介面效應，並利用諧波暫態法量測探討本質(intrinsic)的固液介面效應。第三年則為巨分子流體之熱傳量測與分析，探討分子型貌及折疊展開(folding/unfolding)行為對熱傳的影響。整個計畫的研究將有助於了解流體中的奈米傳輸現象，對未來微元件散熱及生醫晶片的應用將有重要的貢獻。Traditional biological molecule detection and analysis usually require complex and tedious processes, which consume huge amount of time and manpower. With the advancing of MEMS (Microelectromechanical systems) technology, many MEMS and micro-machined devices and systems have been proposed. As we know, Bio-MEMS or Lab-on-a-Chip is now a popular topic. Miniaturization technique can integrate many devices into on chip, which not only saves the spaces but also minimizes the use of testing samples and reagents. So far, most of the biological detection or analysis techniques use optical, biological, chemical, and electrical approaches. These methods usually requires lasers or microscopes. Some analysis may have bad interferences with chemical and electrics. In this study, we propose a method using thermal conductivity as a probe for detecting biological activities. Using the thermal approach does not require the use of laser and microscope. The heat caused by the measurement also has no influence on the biological samples. We plan to use a microfabricated free standing membrane structure for the thermal conductivity measurement of small volume fluid samples. By applying the hot-wire technique, we can study the effects of biological structure changes to the thermal conductivity. In the study, we will perform the numerical simulations to realize some of the errors caused by the imperfect model of hot-wire. The simulation results are also for the correction and design improvement of the device. The denaturization of DNA and the unfolding of proteins will be studied using the developed device. The technique has potential to integrate with real-time micro-PCR (Polymerase Chain Reaction). 研究期間：10008 ~ 10107
