樣本置放於一個鋁製反應槽，此反應槽固定於線性馬達的移動平台上，而在系統建立三個固定的溫度區，樣本的升降溫則藉由線性馬達的往復式移動，使反應物在一個直線通道上，接觸不同的三個溫度區，達到聚合酶連鎖反應（Polymerase Chain Reaction，PCR）的三個反應溫度和反應時間。反應槽往復式移動過程中，與加熱鋁塊保持些微距離以能順利移動，但也因此增加了彼此間的接觸熱阻，並影響熱傳效能。

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利用商用軟體CFD-ACE+TM模擬在不同接觸熱阻邊界條件及反應槽移動速度時反應槽內溫度之變化。結果顯示，反應槽中心溫度的模擬與實驗曲線非常接近，並以此往復式熱循環器成功完成潮黴素B的核酸複製。

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This work illustrates an application of a technique for predicting the thermal characteristics of a bidirectional thermocycling device for polymerase chain reaction (PCR).

 

The micro-milling chamber is oscillated by a servo motor and contacted with different isothermal heating blocks to amplify the DNA templates successfully. Because a comprehensive database of contact resistance factors does not exist, it causes researchers not to consider thermal contact resistance at all.

 

We are motivated to accurately determine the thermal characteristics of the reaction chamber with thermal contact effects between the heater surface and the chamber surface. Numerical results show that the thermal contact effects between the heating blocks and the reaction chamber dominate the temperature variations and the ramping rates inside the PCR chamber. However, the influences of various temperatures of the ambient conditions on the sample temperature during three PCR steps can be negligible.

 

The experimental temperature profiles are compared well with the numerical simulations by considering the thermal contact conductance coefficient, which is empirically based on the experimental fitting. To evaluate thermal contact conductance coefficients in the thermal simulation, it is recommended that a reasonable temperature profile of the reaction chamber be predicted during various thermal cycling processes.

Finally, the PCR experiments present that Hygromycin B DNA templates are amplified successfully. Furthermore, our group is the first to introduce the thermal contact effect into a theoretical study that has been applied to the design of a PCR device and to perform the PCR process in a bidirectional thermocycler.