這份研究探討了在低遲滯的奈米材質表面上產生楔形梯度，而使不同體積的水液滴瞬時以及快速的移動實驗以及模型。利用0.014M甲基三氯矽烷的無水甲苯溶液與玻璃底材反應兩小時後，因相分離所產生的奈米纖維來形成超疏水性的奈米材質表面，其靜接觸角與遲滯分別為168度與6度。奈米纖維的直徑與厚度分別為34.5±9.6 nm與320.65 nm。水液滴在接觸利用化學方法產生楔形梯度圖案的奈米材質表面時，會產生瞬時自我導向移動。此表面具有兩種不同的濕潤性質以及低遲滯性。液滴的形狀與移動速度與液滴的位置及梯度的角度psi相關。此方法可傳輸的液滴體積範圍相當地廣泛，且傳送速度最快可達0.5 m/s。根據動量守恆定律所預測的液滴速度與實驗量測結果相當吻合。此研究也展示了在psi=8時，液滴在不同傾斜角的表面都會向上移動以及小於奈升液滴的移動。總結以上結果，液滴的運動主要是由表面梯度與奈米尺度的濕潤驅動的結合所產生的。這個發現可做為在藥物研發、DNA與蛋白質陣列以及單一細胞研究時，相當有用的微流體工具。為了展現其做為生物鑑定研究時的自我導向微液滴平台的成效，梯度圖案也重新安排成循環地楔形梯度陣列。最後，一個俱聲波微混合能力的完整自導向微液珠產生平台設計被提出並被成功地展現。

This work reports on the modeling of, and experiments on, wedge-shape gradients to facilitate spontaneous and fast motions for a wide range of water droplet volume on low hysteresis nanotextured surfaces. The nanotextured surfaces were prepared by phase separation of methyltrichlorosilane in anhydrous toluene at 0.014M and reacted with the glass substrates for 2 hr to produce the quasi-network nanofibers that provide the superhydrophobicity with a static CA and hysteresis of about 168o and 6o, respectively. The typical diameter and thickness of these nanofibers were 34.5±9.6 nm and 320.65 nm, respectively. Water droplets underwent spontaneous self-directed motion upon contact with a chemically patterned nanotextured surface with wedge-shape gradient. The surface exhibited two distinct wetting properties and low hysteresis. The droplet profile and velocity were related to the droplet position and the gradient angle psi. A wide range of droplet volume could be transported and a droplet velocity as high as 0.5 m/s was achieved herein. Ascension of water droplets with all-round acclivity when□psi = 8 and a subnanoliter droplet movement were also demonstrated. Based on the principle of conservation of momentum, the predicted velocity evolutions are fairly consistent with the experimental data numerically. We conclude that it is the combination of surface tension gradient and nano-wetting actuation that governs the droplet motion. The finding could provide a valuable microfluidics tool in drug discovery, DNA and protein microarray, and single cell study. For demonstration, the gradient patterns were rearranged into an array of circulating wedge-shape gradients to act as a self-directed microdroplet platform for colorimetric study. Finally, a complete self-directed microdroplet manipulation platform with acoustic micromixing capability was also proposed and successfully demonstrated.

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