具有載物功能之微型液晶彈性體爬行機器人

Abstract

本研究受蛇直線爬行運動所啟發，開發具載物功能之光熱驅動液晶彈性體微形仿生軟性爬行機器人。爬行機器人由一對向外張開的後腳、一對具有爪狀的前腳以及內凹狀載物平台所構成。元件透過由微影製程所製作的之模具翻印而成，利用單軸配向定型，並在上方選擇性塗布光熱薄膜。外張的後腳在致動時，將推動身體前進。而特殊爪狀的前腳設計，有助於元件在回復時提供摩擦各向異性，順勢將後腳拉回。內凹狀的載物平台，提供元件致動時穩定的運輸能力。當受到近紅外光的照射加熱下，塗布光熱薄膜的區域將會產生宏觀上形變。搭配前後腳尺寸上的差異及前腳爪狀的設計，提供元件致動過程中前後不對等的摩擦力，使其往向前爬行，模擬蛇之直線爬行時之鱗片運動。 實驗結果顯示，光熱薄膜能有效提供光轉熱之能力，能在小於1秒內提升到液晶彈性體的相變溫度。液態金屬的加入能夠提升元件傳遞與散發熱能，使加熱及冷卻響應時間減少50%。元件在無負載的情況下，速度達每分鐘1.96身長。元件在負載情況下仍然擁有良好的速度，負載在7mg下仍保有每分鐘0.89身長的速度。此外，元件在多次驅動之下，依然保持記憶效應，擁有良好的重複性。在未來的研究中，亦可將透過不同設計的爬行機器人，應用在環境探勘等領域中。

This work presents a light-driven miniaturized soft robot with the ability of transporting cargo. The proposed device comprises four legs and a concave cargo platform, and is made of liquid crystal elastomer (LCE). The device is fabricated using a simple lithography-based molding process with SU-8 photoresist. A photothermal thin film, which is composed of liquid metal and acrylic copolymer, is selectively coated on the LCE structure for effectively converting light energy into heat for actuation. The locomotion of the actuator is inspired by the rectilinear movement of snakes. While heated by near-infrared illumination, the LCE structure deforms due to the LC-to-isotropic phase transition phenomenon. The special asymmetric design of the front and rear legs results in asymmetric friction, and thus induces the forward crawling motion. The rear legs are round-shaped and larger than the front legs to provide greater friction force while actuating and push the device forward. The claw-like front legs are inspired by snake scales to fix on the ground while the rear legs recovering. Experimental results demonstrate that under conditions of no cargo load, the robot achieves a speed of 1.96 body length (BL) per minute. While carrying a cargo of 7 mg, the actuator maintains a speed of 0.89 BL/min. In addition, the effect of the length of the rear legs was systematically investigated. The measurement results indicate that the devices with longer rear legs crawl faster while maintaining the maximum device inclined angle to be less than 20 degree.