微機電技術應用於可撓性觸覺感測器陣列之研製

Development of Flexible Tactile Sensing Array Using MEMS-Based Technologies

鄭茗元(Ming-Yuan Cheng)

指導教授 ： 楊燿州

國立臺灣大學/工學院/機械工程學研究所/博士(2009年)

https://doi.org/10.6342/NTU.2009.01757

摘要

本研究係運用以微機電技術，發展不同形式之觸覺感測器陣列，將做為於仿生機器人之人工皮膚。研究中，分別發展導電橡膠與電容式感測技術。為了使感測陣列能覆蓋於複雜的曲面，其感測元件以聚亞醯胺(Polyimide, PI)與聚二甲基矽氧烷(Polydimethylsiloxane, PDMS)構成其可撓性基材與主要結構材質。以導電橡膠為感測機制的研究中，分別利用自動點膠製程或黏貼方法，將導電橡膠個別的固定於感測電極上做為觸覺感測單元。此種製造程序，能有效的降低感測單元彼此之間的交互干擾。對於溫度感測，則是利用溫度感測晶片做為感測單元。經由微細加工技術所製做的可撓曲性基材，可輕易的將觸覺與溫度感測器陣列進行整合。觸覺感測單元之間的交互干擾抑制與量化的驗證均有詳細的討論。另外，觸覺感測單元的機械與電學性質也有進行量測與討論。為了能正確的讀取感測器陣列數值變化，觸覺感測陣列與溫度感測陣列的掃瞄電路亦進行開發與應用。最後，不同圖形的溫度與壓力分佈，均可以利用8×8感測陣列或更大面積的32×32感測陣列成功的進行辨識。本研究亦提出螺旋式電極，所具備的高度伸展性與撓曲性，將可提升軟性基材上之導體在大幅度扭曲變形下的可靠度。所製做出的感測器陣列能承受高於70度扭轉變形，而不會導致裝置在結構上或功能性的損害。
在電容式感測機制的研究中，本研究提出創新性電容感測器結構。此種設計不但可簡化製造程序，更具有高可靠度的特性。本研究之電容式觸覺感測陣列採用微機電製程及軟性電路板技術製作而成。電容式觸覺感測陣列則是由兩層PDMS結構與一層軟性電路板所構成。每一電容式觸覺感測單元則是由一個浮動電極搭配兩個感測電極所構成。浮動電極使用微機電製程所製造。感測電極與導線則利用軟性電路板技術製作完成。此設計概念能有效降低感測結構的複雜性，與改善導線與電極容易破裂缺點，進而提升感測器陣列的穩健性。另外，本研究製作出不同尺寸的感測器單元分別進行量測與討論。相對應的電容式觸覺感測掃描電路亦進行開發與應用。並成功利用8×8電容感測器陣列，擷取到不同形狀之壓克力模塊壓印圖形。

關鍵字

人工皮膚 ； 軟性電子 ； 微細加工 ； 觸覺感測陣列 ； 溫度感測陣列 ； 螺旋電極 ； 導電橡膠 ； 浮動電極 ； 電容感測

並列摘要

This dissertation presents the developments of various types of tactile sensor arrays which will be used as the artificial skins for robot applications. Conductive-polymer-based mechanism and the capacitive mechanism are employed as the sensing techniques. Polyimide (PI) as well as polydimethylsiloxane (PDMS) are used as the substrate materials. For the conductive-polymer-based approach, the tactile sensing elements are formed by dispensing or attaching conductive polymer bumps on the pre-defined electrodes. This novel fabrication method can effectively reduce the crosstalk between each sensing element. Discrete temperature sensor chips are employed as the temperature sensing cells. Also, the temperature and tactile sensing elements are heterogeneously integrated on a flexible substrate using micromachining techniques. Scanning circuits are implemented. Finally, measured temperature and tactile images have been successfully obtained by using the integrated 8×8 and 32×32 sensing arrays. Extendable spiral electrodes, which are highly stretchable and durable, are also designed and fabricated as the row and column interconnects for tactile sensing arrays. The fabricated sensor array can conform to complex surfaces The device can be twisted up to 70 degree without any damage in structure or functionality.
For the approach using the capacitive sensing mechanism, tactile sensing arrays are realized by using MEMS fabrication techniques and flexible printed circuit board (FPCB) technologies. The sensing array consists of two micromachined PDMS structures and a flexible FPCB. Each capacitive sensing element comprises two sensing electrodes and a common floating electrode. The sensing electrodes as well as the metal interconnects for signal scanning are implemented on the FPCB, while the floating electrode is patterned on one of the PDMS structures. This special design can effectively reduce the complexity of device structure and thus makes the device highly manufacturable and robust. The characteristics of the devices with different dimensions are measured and discussed. The corresponding scanning circuit is also designed and implemented. The tactile images induced by the PMMA stamps of different shapes are also successfully captured by a fabricated 8×8 array.

並列關鍵字

artificial skin ； flexible electronics ； micromachining ； tactile sensing array ； temperature sensing array ； spiral electrode ； conductive polymer ； floating electrode ； capacitive sensing

參考文獻

[1] K. Suzuki, K. Najafi, and K. D. Wise, “A 1024-element high-performance silicon tactile imager,” IEEE Transactions on Electron Devices, vol. 37, no. 8, pp. 1852-1860, 1990.

[2] B. J. Kane, M. R. Cutkosky, and G. T. A. Kovacs, “A traction stress sensor array for use in high-resolution robotic tactile imaging,” Journal of Microelectromechanical Systems, vol. 9, no. 4, pp. 425-434, 2000.

[3] L. Wang and D. J. Beebe, “A silicon-based shear force sensor: development and characterization,” Sensors and Actuators A-Physical, vol. 84, pp. 33-44, 2000.

[4] C. C. Wen and W. Fang, “Tuning the sensing range and sensitivity of three axes tactile sensors using the polymer composite membrane,” Sensors and Actuators A-Physical, vol. 145, pp. 14-22, 2008.

[5] L. Beccai, S. Roccella, A. Arena, F. Valvo, P. Valdastri, A. Menciassi, M. C. Carrozza, and P. Dario, “Design and fabrication of a hybrid silicon three-axial force sensor for biomechanical applications,” Sensors and Actuators A-Physical, vol. 120, pp. 370-382, 2005.