整合熱電阻與介電質加熱法於介電濕潤數位微流體平台以實現微液滴同時加熱與操控

Abstract

微流體加熱平台常應用於生化反應上(如聚合脢聯鎖反應)，其加熱系統需額外設計。如可將之整合於驅動系統上，將可簡化設計而有助於晶片微小化。因此本論文目的為整合加熱與驅動液滴功能於介電溼潤平台上，以熱電阻與介質兩種原理來加熱，並使兩者功能可同時運作。 整合加熱與驅動流體功能方面，熱電阻式主要利用導體阻抗來加熱，故將傳統下板電極修改成曲繞形，增加其電阻以提高加熱能力。當給予電極兩端直流電時，液滴會被加熱；給予等電位時則與傳統介電溼潤電極一樣而可驅動液滴。微液滴溫度與直流電功率、電極電阻成正比關係，功率於450 mW時，3.6 □L去離子水溫度可達~93 oC。介質式方面利用電容損耗能量以熱能形態消逝來加熱，於平行板測試中發現，1 kHz頻率可驅動但無法加熱去離子水，100 kHz以上卻可加熱之，因此介質式主要以改變電壓與頻率來驅動或加熱微液滴。其溫度隨電壓增加而上升並與頻率成正比關係。3.6 □L去離子水溫度可達~80 oC(300 kHz、120 Vrm、兩板間距0.5 mm)。 加熱與驅動同時運作方面，熱電阻式透過電路接法來達成；給予下板曲繞形電極直流電，並施加上板大於之的交流電位時，上板因與下板電極兩端均有電位差，而有介電溼潤效應可來驅動流體，下板電極又因電極兩端有直電流流過而可產生熱阻加熱。介質式透過兩種訊號，一為1 kHz與某加熱頻率(如100 kHz)的混合交流電，二為與前者同加熱頻率的交流電。以前者來操控與加熱流體，並利用後者來增加加熱面積使液滴溫度更為穩定。以上為本論文主要概念。

Microfluidic chips with a heating capability have been widely applied to biochemistry but transportation and heating of microfluidis were handled separately. To simplify chip design and miniaturize chip size, it is necessary to integrate heaters into a transporting system. In this thesis, based on the thermoresistive and dielectric heating, we successfully demonstrated droplets moved and heated simultaneously by the same electrode on a EWOD-based parallel-plate device. The meander-line electrode was designed for the thermoresistive heating the bottom plate. The meander-line electrode is regarded as a heater when a DC power was applied at the two ends and as a traditional EWOD electrode when an AC signal was applied between it and th top plate. The droplet temperature was proportional to the supplied power. A 3.6 □L droplet could be heated to about 93oC when the applied power was 450 mW. For the dielectric heating, the droplet manipulated in the parallel plates was moved when the frequency of the applied voltage was at 1 kHz and heated at 100 to 300 kHz. A 3.6 □L droplet was heated to about 80oC when the applied signal was 300 kHz and 120 Vrms. In addition, the droplet was moved and heated at same time by the signal mixed with a 1 kHz signal and a signal of the frequency heating the droplets.