Since polydimethylsiloxane (PDMS) is notorious for its severe sorption to biological compounds and even nanoparticles, thermoplastics become a promising substrate for microdevices. Although CO2 laser engraving is an efficient method for thermoplastic device fabrication, it accompanies with poor bonding issues due to severe bulging and large feature size determined by the diameter of laser beam. In this study, a low-cost microfabrication method is proposed by reversibly sealing a 1 mm thick polymethylmethacrylate (PMMA) over an engraving substrate to reduce channel feature size and minimize bulges of laser engraved channels. PMMA, polycarbonate (PC), polystyrene (PS), perfluoroalkoxy alkane (PFA), cyclo-olefin polymers (COP) and polylactic acid (PLA) were found compatible with this sacrificial layer assisted laser engraving technique. Microchannel width as small as ~ 40 µm was attainable by a laser beam that was 5 times larger in diameter. Bulging height was significantly reduced to less 5 µm for most substrates, which facilitated leak proof device bonding without channel deformation. Microdevices with high aspect ratio channels were prepared to demonstrate the applicability of this microfabrication method. We believe this fast and low-cost fabrication approach for thermoplastics will be of interest to researchers who have encountered problem with polydimethylsiloxane based microdevices in their applications.

由於聚二甲基矽氧烷（PDMS）會嚴重吸附生物小分子甚至是納米粒子， 熱塑性塑膠逐漸成為製作微流控晶片的理想材料。二氧化碳鐳射雕刻技術是製 作熱塑性材料晶片的有效方法，但是由於嚴重的軌道邊緣凸起所導致的糟糕的 晶片粘合品質和由於鐳射聚焦斑點大小的限制所導致的較大的軌道尺寸都是該 方法存在的問題。 目的：在本次研究中，提出了一種快捷且廉價的微加工方法，即利用犧牲 層輔助鐳射雕刻技術以減小軌道尺寸和軌道邊緣凸起。並且篩選出更多能夠應 用於二氧化碳鐳射雕刻的熱塑性塑膠。 方法：利用 1 毫米厚的聚甲基丙烯酸甲酯（PMMA）作為犧牲層，通過熱 粘合法，使用到的溫度略低於底物與犧牲層兩種材料中玻璃轉化溫度較低的材 料所對應的溫度。使得犧牲層與雕刻底物之間產生緊密且可逆性的貼合。並且 在雕刻任務完成後，將底物與犧牲層分離，從而在底物上得到具有小尺寸軌道 和微小邊緣凸起的微流控晶片。 結果：實驗成功的篩選出 PMMA，聚碳酸酯（PC），聚苯乙烯（PS）， 全氟烷氧基烷烴（PFA），環烯烴聚合物（COP）和聚乳酸（PLA）六種熱塑 性塑膠，確定其適用於二氧化碳鐳射雕刻。通過使用犧牲層輔助鐳射雕刻，當 最小的鐳射聚焦斑點約為 200 微米的情況下，我們可以在底物 PMMA 上製作得 到最小寬度為 40 微米的晶片軌道。大多數材料上軌道邊緣凸起的高度都減小至 5 微米以下。微小的邊緣凸起可以有效的防止軌道的變形或是阻塞，並且實現 軌道的完全密封。兩個實際應用，微腔中形成微渦旋和利用二氧化碳鐳射雕刻 技術製作濾網分離三種不同的生物樣品，證明此方法的可行性和製作所的晶片 的實用性。 結論：PMMA，PC，PS，PFA，COP，PLA 六種熱塑性塑膠確定為適用於 二氧化碳鐳射雕刻。通過使用犧牲層輔助鐳射雕刻能夠有效減小軌道尺寸與軌 道邊緣凸起。