使用超音波駐波技術進行非接觸式微粒的操控

Abstract

本研究旨在建構一套簡易型於顯微鏡下自由大量操控生物高分子或細胞的音波駐波操控系統，其組成包括市售音波產生器、可直接觀察微流道結構與可調控入射角導波塊，以及CCD光學顯微鏡。 微流道結構製作以長15cm的方型毛細管做為微流道，以及將鋁片裁成長100mm、寬80mm、厚1mm以及長80mm、寬20mm、厚1mm的兩片鋁片，方型毛細管夾於兩片鋁片之間，並在上方放置一載玻片做為傳導音波元件，最後以紫外光固定膠將此四個元件相互黏著固定。音波傳導元件則是將直徑24mm的鋁管以51度角切割成長約37mm的楔型導波塊。載玻片與導波塊間使用超音波傳導膠作為傳遞。 利用半徑25mm × 厚度1.22mm 的壓電晶片，施予24伏特的交流電壓，使其產生1.75MHz的音波，經由觀察發現音波傳導元件將音波傳遞至微流道，而不影響顯微鏡系統觀測路徑的形式較佳，並利用此系統產生音波駐波場操控直徑分別為1、2、3、4、6、7、8、9、10、12、14、16、18、20μm等14種顆粒大小不同的聚苯乙烯微粒(Polystyrene particles )，除了1μm微粒經過文獻的證實，並透過實驗測試，其顆粒大小不適用於音波操控，而其餘微粒將成功地聚集排列於流道之中。

A particle manipulation system using ultrasonic standing wave has been constructed for manipulating micro particles under microscopy. The system consists of a piezoelectric transducer with an angle-variable ultrasonic guiding block, rectangle micro-channel, and an optical microscope with a CCD video recorder. A micro-channel in this system is constructed with a rectangle capillary (0.70*0.7 mm) about 15 mm in length lodged in a flat piece of aluminum (120mm×80mm×1mm). A glass slide was placed upon the flat piece of aluminum with a micro-channel to be an ultrasound transmission element. UV light curing adhesive was then utilized to solidify above three components. The guiding block made of an aluminum cylinder wedge was attached with the glass slide with various angles to the surface normal by ultrasonic conductive gel. The 1.75 MHz of ultrasound transducer was powered with AC 24V to induce a standing wave in the flow channel. The micro-channel chip was obliquely coupled an ultrasonic transducer consisting of a piezoelectric transducer attached by ultrasonic conductive gel to an aluminum wedge with an angle, θof 51° relative to its surface normal, in order to efficiently drive a ultrasonic standing wave into the fluid channel via wave refraction. Micro particles of polystyrene (1~20 μm) were effectively aligned to the center line of a micro-channel by radiation force of the ultrasonic standing wave.