5.1 加熱與操控流體於同一電極
5.1.1 熱電阻式
藉由著電極曲繞形的設計，同個電極可以擁有電溼潤或是加熱效應，並稱之為多功 能電溼潤電極。當在電極兩端給予直流電時，電極會因熱阻產生熱量加熱在上面的流 體；而當給予兩端等電位並與上板電極有一交流電的壓差時，電極會產生電溼潤效應而 可操控流體。流體的溫度與直流電的功率與電極的電阻成正比。
5.1.2 介電式
利用傳統電溼潤電極類似平行板的電容性值，來加熱之間的流體，以水為例，水珠 的溫度與交流電100 kHz 以上的頻率成正比。在兩板距離固定下，也隨電壓上升而上升。
而交流電1 kHz 的頻率只有操控水珠的能力，沒有加熱效果。介電損失低的東西，如油，
與水比起來(介電損失差 20~400 倍)，比較不容易被加熱[45]。以水為例，在 1×10-8 kHz 下介質損失為400，而汽油為 1，絕緣油為 17。
5.2 加熱與操控流體同時運作
5.2.1 熱電阻式
利用電路板的設計，給予下板多功能電極直流電的同時，把其與交流電共地，並在 要操控流體的電極端通予交流電火線，如此可以達到隨時加熱，又可操控流體的驅動位 子。藉由電路板上的可變電阻調整分壓來控制電極產熱來達到流體所需的溫度。直流電 的電壓以不影響水珠操控為主(最基本是直流電電壓不能大過交流電電壓)，交流電電壓 以不破壞介電層為主。
5.2.2 介電式
利用兩種訊號(例如、以水為例的兩種訊號，一為 100 kHz 以上加熱能力的交流電訊 號，一為100 和 1 kHz 的混合訊號)來加熱與操控，讓流體可以隨時被加熱，並藉由電路 板的控制來切換來操作水珠。雖然有些加熱訊號也有操作流體的能力，但在移動的過程 中會因部份流體不在電極內部的關係，會使得加熱不均勻，使用兩種訊號的方式可以減 少熱能的損失。以下兩種方式除了論文中兩個優點外的比較：
表5.1 熱電阻式與介電式表較
優點 缺點
熱電阻式 1.可加熱任何液體。 1.電極比介電式多出許多。
2.加熱的直流電有所限制。
介質式 1.更改頻率即可決定是否要加熱。
2.不需變更電極設計即可加熱。
1.加熱流體的限制。
(介質損失過小不適用，例如矽油。)
5.3 熱電阻式在 PCR 的應用
利用可變電阻來調整下板多功能電溼潤電極，使其達到95oC、55 oC、77 oC 三個反 應所需溫度，並以上板來操控流體在電極上進行PCR 的反應。實驗中發現，DNA 溶液 或者是水在超過高溫區(80~83 oC)後會開始產生氣泡而影響其前進的能力。使的反應並 不理想。過程使用黏滯系數低的油(20 cSt)來防止 DNA 溶液被汙染及蒸散。產生氣泡在 加熱去離子水時也有發生，原因有可能是因為表面不夠平坦，使得局部溫度過高，如下 圖。這狀況在熱電阻式最為明顯。
圖5.1 晶片平坦問題
5.4 未來工作
實驗平台中最大的問題在於，1、需以微熱電偶來量測溫度，會阻礙流體操控。2、
缺乏溫控回饋系統，溫度的精準度低。3、電極數量過多，架設上不方便。4、高溫時流 體(水與 DNA 溶液)會產生氣泡，影響流體操控能力。
在平台改進上，可以設計溫度感測器並連接回饋系統，並省去不要用的電極，增加 晶片平坦度。以及對流體除氣或改散溫度量測精準度。
介電層 白金/鈦 玻璃基板 Teflon 電極與電極間的落差
(高溫產生區)
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