以丙烯酸酯聚合物為基底之直流驅動振盪器及其應用

導電高分子材料之正溫度係數(Positive temperature coefficient, PTC)現象已被廣泛認同與高分子材料結晶度有關。非晶質(Amorphous)高分子材受熱時由於體積熱膨脹過小以致於無法產生龐大正溫度係數現象。其材料包含絕緣高分子基材與導電粒子，在特定溫度區間材料阻值有數個數量級距變化。本研究將丙烯酸丁酯與丙烯酸十八酯照光合成丙烯酸酯聚合物並混合石墨球導電粒子。將此材料導入微機電製程所形成超高敏度溫度感測器，結合微型加熱器提出一全新電熱式振盪器，透過溫度感測器自行切換微型加熱器之直流電源供應，產生穩定溫度振盪現象。本研究之元件具有製程容易、運作原理單純、與簡單系統架構等優勢。本研究同時提出利用電熱式振盪器穩定溫度振盪現象結合PDMS翻模氣泡薄膜與 Nozzle-Diffuser流道形成熱氣動式無閥擴散幫浦之應用。於系統直流電源供應8V電壓於微型加熱器，6V電壓於溫度感測器成功產生振幅為56.5℃，週期為20.3秒穩定週期振盪。利用Labview人機介面同步儀器量測四項參數。透過訊號擷取卡(DAQ)監測PTC材料兩端電壓變化推算電阻變化，利用K-Type熱電偶量測加熱器與感測器溫度，同步記錄電源供應器電電壓與電流值分析系統特性。探討振盪系統失效原因並提出壓克力與不鏽鋼材料夾具改良元件。透過不同材料夾具與加熱器電壓供給，可使振盪器擁有不同振盪週期與溫度振盪區間。於微型幫浦流量量測利用數位攝影機監測流體於出口端管內流動位移。成功於直流電熱式振盪器產生溫度振盪振幅8˚C，振盪頻率0.05Hz下使管內流體10秒內前進1.54mm，換算流量為1.813μL/min。

關鍵字

正溫度係數；電熱式振盪器；丙烯酸酯聚合物；熱氣動式無閥擴散幫浦

並列摘要

In this work, we present a novel electrothermal oscillator by employing ultra-sensitive temperature sensor for self-switching on/off a microheater with a DC power supply that produces stable temperature oscillating phenomenon. The fabricated device features advantages such as simple fabrication process, easy operating method, and simple system architecture. The periodic electric current switching for activating a nozzle-diffuser valveless thermopneumatic pump with the electrothermal oscillator was demonstrated by supplying a constant DC voltage. The voltages applied to the micro heater and the PTC copolymer sensor are 8 V and 6 V that had successfully produced stable oscillating phenomenon with the amplitude of the oscillation is 56.5 ℃ and the period of oscillation is 20.3 s. A data acquisition (DAQ) card was employed to measure the resistance of the PTC copolymer sensor. A K-type thermocouple was used to measure the temperature near the microheater and sensor. In addition, the cause of oscillating failure was studied and discussed, and can be improved by fixing the PTC copolymer with acrylic and stainless steel plates. For the flow rate measurement of the micropump, the fluid meniscus displacement in the tube connected to the outlet is recorded by a digital video camera. The amplitude of the oscillation is about 8˚C. The frequency of oscillation is about 0.05Hz. The flow rate is estimated about 1.813μL/min.

並列關鍵字

Positive temperature coefficient ； Electrothermal oscillator ； Acrylate copolymer ； Nozzle-diffuser valveless thermopneumatic pump

參考文獻

[19] 張繼升, “可撓式正溫度係數高分子電阻薄膜之研究,” 化學工程研究所, 國立清華大學, 2006.

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以丙烯酸酯聚合物為基底之直流驅動振盪器及其應用

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