以植物表皮細胞製作人工肌肉暨觸覺感測器

Abstract

在本論文中，我們提出了一種由洋蔥表皮細胞來製作成電驅動的致動器和電容式的觸覺感測器。致動器是一種通過能量轉換成系統動態的機制，如電能轉變為機械變形。大多數的致動器，可以有彎曲與收縮/伸長的功能，如人工肌肉。但是，目前還沒有任何一種致動器可以同時完成彎曲並且收縮/伸長的功能。在這個研究中，我們成功將這樣的新型致動器研發完成。我們發現洋蔥表皮細胞的天然微結構在當作致動器使用時，可以同時有彎曲並且收縮/伸長的功能。在通過電壓大小的調變，就可以使致動器產生致動方向的偏轉和收縮/伸長。 當所施加的電壓在0-50 V時，洋蔥致動器會伸長並且向下彎曲-30 μm；而當所施加的電壓在50-1000 V時，洋蔥致動器會收縮並且向上彎曲1.0 mm。該致動器的應變速率在10-5 s-1到10-3 s-1之間，並且電壓變化速率在每秒50 V超過200個循環周期以上的測試底下，應變率皆沒有任何明顯的改變。電壓變化速率遠遠超過每秒1 V。該致動器在1000 V的驅動電壓下連續6小時，其位移變化亦非常穩定。而在1000 V驅動電壓下最大輸出力為20 μN。最後我們展示了利用兩個洋蔥致動器所組合而成的鑷子，成功的夾取起一個約0.1 mg的小棉球。 而在本文中我們還提出了利用柔軟的洋蔥表皮細胞的天然微結構，來取代傳統的平行板電容式觸覺感測器。洋蔥的表皮細胞可以有效的降低電容式觸覺感測器的複雜結構，而減少的更多的製造流程。單層的洋蔥表皮細胞有良好的機械彈性和高透明度，並且成本低廉方便製作出大面積的觸覺感測器。我們製作了一個5 × 5的觸覺感測器陣列，總面積大小為22 × 22 mm2。單一個觸覺感測器在未施加任何壓力時的初始電容為3 pF。洋蔥觸覺感測器的量測範圍在0-1.8 N (200 kPa)，靈敏度為0.02 kPa-1。最後由實驗結果顯示出洋蔥觸覺感測器有著良好的靈敏度與線性度。 本研究中我們成功的利用一種從未使用過的材料，洋蔥表皮細胞來製作新型的致動器與觸覺感測器。洋蔥表皮細胞的天然微結構有著結構簡單，可撓性和環保等優點。所製作出的致動器和觸覺感測器更有著成本低的優勢。因此是非常有潛力可應用於機械人的電子皮膚與人工肌肉等生物醫學裝置之上。

In this dissertation, an onion actuator and tactile sensor was proposed. Actuators functionalize dynamics of mechanisms or systems via an energy conversion, such as the transformation of electricity into mechanical deformation. Most motor-driven actuators and engineered artificial muscles are very capable at either bending or contraction/elongation. However, there are currently no actuators that can accomplish these actions simultaneously. Here we show the successful development of such a device. We found that the simple latticed microstructure of onion epidermal cells allowed itself to simultaneously stretch and bend. By modulating the magnitude of the voltage, the actuator made of onion epidermal cells would deflect in opposing directions while either contracting or elongating. At voltages of 0 - 50 V, the actuator elongated and had a maximum deflection of -30 μm at voltages of 50 - 1000 V, the actuator contracted and deflected 1.0 mm. The strain rate ranges from 10-5 s-1 to 10-3 s-1 and underwent up to 200 actuation cycles at 50 V/s without any strain degradation. The strain changes were observed in our onion artificial muscle after acid pretreatment at different sweep rates, even much greater than 1 V/s. The artificial muscle has also been statically driven at 1000 V for continuous 6 hours, and the displacement shift was negligible. The maximum force response is 20 μN at 1000 V. We demonstrated the combination of two onion cell actuators to act as tweezers and gripping a small cotton ball of around 0.1 mg in weight. The results show how an artificial muscle can be produced from never used materials. And in this dissertation we also presents and demonstrates the development of flexible tactile sensor utilizing the microstructures of onion epidermal cells, which replace the intermediate dielectric layer in a typical parallel-plate capacitive sensor. The onion epidermal cells can effectively reduce the complexity of the sensor structure and thus simplifies the device fabrication process. The single layer of the onion epidermal cells is robust for high tactile sensitivity, mechanical flexibility and optical transmittance with potentially low-cost sensor manufacturing in a large area. The 5 × 5 tactile sensor array with the total area of 22 × 22 mm2 is demonstrated. A single tactile sensor has the initial capacitance of 3 pF without applying external pressure. The force ranging from 0 N-1.8 N (200 kPa) is applied for sensor characterization. The sensitivity of the sensor is 0.02 kPa-1. The fabricated sensor shows high sensitivity and linearity. We show how a new type of actuator and tactile sensor can be produced from a never used material―onion epidermal cell, in the hope of initiating a new field of fusing plant and mechatronics for the benefits of inducing large deflection measurements in both transverse and longitudinal directions in a ubiquitous and low-cost manner. And the proposed sensor array will be applied in robotic electronic skin and biomedical devices in the future.