樹脂轉注成型(Resin Transfer Molding, RTM)是一種常用來製造高分子複合材料(polymer composites)的技術，在RTM製程中，纖維預織物的滲透率與孔隙率的比值是影響流動的關鍵因素，其隨著纖維預織物的不均勻編織或是不整齊的堆疊而有差異，此參數也決定了樹脂流動的特性，繼而影響最終產品的品質。量測滲透率的方法已經發展成許多不同的量測系統，其中較大部分採用高速攝影機記錄流體流動的波前，然而文獻所提出方法，需能辨識流體與纖維預織物的顏色差異，當纖維預織物放置於一個非透明的模具抑或是流體的顏色跟纖維預織物相仿，此方法便難以辨別，為了克此方法所遇到的問題，本研究採用了平行板電容器的方法偵測流體波前，藉由在RTM製程中所使用的模具外加裝銅條，偵測其模具內灌注的電容變化從而根據推測波前，由於本研究的電容條不須直接碰到需要量測的纖維，所以可以使用於碳纖維等導電纖維，其原理是透過系統中的混合介電常數(dielectric constant)隨樹脂灌入而變動，導致電容值不斷增加，再根據電容定義可推得一移階函數(shifting-order)，合併達西定律，聯立求解後能獲得電容與時間的關係式，根據此關係式從而推得纖維滲透率。

Resin transfer molding (RTM) is a widely adopted technique to produce polymer composites. In RTM, Darcy’s law is commonly used to describe the flow pattern during the resin infusion, where the permeability of fiber reinforcement is a crucial parameter greatly influencing the flow and eventually influencing the final product quality. In the existing literature, various methods have been proposed for estimating the permeability of fiber sheets. In these methods, flow fronts are usually recorded by visual systems, e.g. cameras. Therefore, transparent molds and dyed resins are often required, which are impractical in industrial applications. In this study, a permeability measurement system is proposed, which applies a parallel-plane capacitor for flow front detection. The capacitance changes as long as the resin flow front moves forward. By placing copper strips outside the mold, the measurement system does not affect the flow pattern inside the mold. In addition, owing to this feature, this system cannot only be applied to glass fibers but also on carbon fibers which are conductive.

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