聚合脢鏈鎖反應(PCR)是一種被廣泛應用於大量增殖某一種特定去氧核糖核酸(DNA)序列的標準技術。此技術因具備快速、材料便宜、可用極少量DNA樣本大量增殖可供進一步分析的DNA分子⋯等特性，遂成為分子生物學實驗室不可或缺的要角，具有大量的市場需求。而PCR的技術原理是以少量耐熱性的DNA於高溫循環作用中經由變性、黏合及延伸的程序將其大量增殖。由於在增殖過程中，溫度循環控制的速度及準確度是非常重要的因素，然而傳統比例積分微分(PID)控制在溫度昇降速度與超越量間存在衝突。因此，本論文著手研究PCR儀的設計，其目的在改善目前PCR儀的溫度控制系統之性能。改善的方式是於控制架構上利用熱流迴授取代傳統PID控制中的溫度微分項部分，亦即是比例積分熱流(PIT)控制器，可避免PID控制放大雜訊，使得PCR溫度循環控制系統有效達成PCR儀所需要的精確溫度；於理論上以李亞普諾夫(Lyapunov)穩定定理決定PIT與PID控制法則的穩定條件。其次利用PCR儀的實例模擬以驗證PIT控制器能有效維持期望的溫度循環與其強健性。最後，藉由Elettrronica Veneta公司的溫控箱實驗証實本論文所提出PIT控制器的有效性。

PCR(Polymerase Chain Reaction) represents a standard technology which is widely used to amplify a great deal of some special array of DNA (Deoxyribonucleic Nucleic Acid). This technology possesses some characteristics, for example, the fast duplicate process, the cheap material, using only a small amount of DNA sample to produce a large amount of DNA for further analyzing, …etc. It has become an indispensable role in the molecular biology laboratory. Hence, PCR has a large amount of market demanding. The technologic principle of PCR is that the fewer template DNAs with heat endurance through the process of denature, annealing and extension in the high-temperature circulation are amplified to achieve the DNA duplication. In the course of duplicating DNA, both the speed and the accuracy of the controlled temperature circulation are very important factors. However the traditional Proportional-Integral-Derivative (PID) control exists a conflict between the speed of temperature rising and descending and the overshoot of temperature. Therefore, this paper studies the PCR instruments design, whose purpose is to improve the temperature control system of PCR instruments. In the control structure, we utilize a thermal flow as the feedback signal to replace the temperature differential term in the traditional PID control, namely a Proportional-Integral-Thermal (PIT) control is set up. Then, the ability of the noise immunity of the control system can be enhanced. In the control theory, the aim of this paper is to determine the stability conditions of the PIT and PID control rules by Lyapunov stability theorem. Finally, the experimental results demonstrate the effectiveness of the proposed controller.