以焦耳加熱法於介電濕潤數位微流體平台實現DNA之聚合酶連鎖反應

Abstract

本論文藉由整合加熱功能於微流體介電濕潤帄台上，使之同時具有加熱以及驅動微流體 的功能，並利用焦耳加熱原理處理微量的生物性檢體(如: DNA)。其不但能有效減少反應試劑 量，更能減少元件體積，加速升降溫速率；更進一步地，我們將此加熱功能應用於聚合酶連 鎖反應，藉由快速的升降溫，完成核酸的序列放大。傳統實驗機台在熱處理生化檢體時，因 為熱質量大導致升降溫緩慢，且需要較多的生化檢體以及足量的反應試劑，反觀本介電濕潤 數位微流體帄台，不但能有效減少生化反應體積從傳統機台所需之50 □l 減低至□ □l，更能 於低功率的情況下如8.5 x 10-3 W，達到2.46 oC/s 的升溫速率，而降溫速率更達到6.94 oC/s。 本實驗透過焦耳加熱的方式操控平行電極板中微液滴的溫度，非理想電容所損耗的能量能以 熱能形態釋放而加熱微液滴，另外利用介電濕潤(Electrowetting-on-dielectric, EWOD)驅動之， 於測試中發現，頻率為1 kHz 之交流電壓源可以介電濕潤機制驅動微液滴，且此時微液滴並 無溫度變化；而頻率為100 kHz 以上之交流電壓源除了在液體中形成一電場外，當頻率升高 至300 kHz 時，可使微液滴產生80 oC 以上的溫度變化(校正後溫度變化24.3 oC□105.6 oC)。 由實驗結果顯示，在高頻電場時，微液滴溫度隨外加電壓增加而上升，而微液滴溫度也與頻 率有關。因此，本系統可藉由調整外加電壓與交流電場頻率來驅動或加熱微液滴形式之聚合 酶連鎖反應試劑，並成功完成DNA 聚合酶連鎖反應。

We investigated joule heating to treat a small amount of biochemical sample driven by electrowetting-on-dielectric (EWOD) on a digital microfluidic platform. For the decreased reagent volume and reduced device size, the heating and cooling rates are thus increased. With the heating and driving abilities, we utilize this platform to realize polymerase chain reaction of DNA with fast heating and cooling rates. On the contrary, conventional equipments usually give lower heating and cooling rates because large amounts of biochemical samples and reagents are required. The reported digital microfluidic system with the joule heating ability would provide an approach to solve the heating/cooling rate issues by reducing the reaction volume from conventional 50 □l to 3 □l at a heating rate of 2.46 oC/s and a cooling rate of 6.94 oC/s The system consumes a much lower power 8.5 x 10-3 W than that consumed in traditional PCR machines. In the experiment, the external voltage at low frequency (1 kHz) can drive droplet by EWOD without temperature change. At high frequency (higher than 100 kHz), the AC electric field heats the droplet and causes an 80 oC temperature change to the temperature of 105.6 oC. The temperature of the tested droplet rises when the external voltage increases. In addition, the heating is also frequency-related. Therefore, this system can control the temperature and position of the droplet for realizing the polymerase chain reaction- by tuning the amplitude and frequency of the applied voltage.