In this work, we presents the development of a capacitive tactile and shear-stress sensing array which can be easily and reliably fabricated by using MEMS techniques and flexible printed circuit board (FPCB) technologies. The sensing array consists of two micromachined PDMS structures and an FPCB with sensing electrodes. Each shear sensing element comprises four capacitive sensing element arranged in 2×2 array, and each capacitive sensing element has two sensing electrodes and a common floating electrode. The proposed design can effectively reduce the complexity of the capacitor structure without compromise in sensitivity. The sensing electrodes as well as the metal interconnect 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. The characteristics of the devices with different dimensions are measured and discussed. The corresponding scanning circuit are also designed and implemented. The measured capacitance images induced by applied normal and shear forces are also successfully captured by a fabricated 8×8 shear sensing array.
Figure 1. (a) The schematic of the capacitive sensing array proposed in this work. (b) The exploded drawing of the sensing array.
Figure 2. The detailed illustration and dimensions of the proposed tactile sensing element. This figure is not to scale.
Figure 3. (a) The fabricated PDMS bump layer. (b) The fabricated PDMS structure layer. (c) The FPCB layer. (d) The fabricated flexible 8x8 tactile sensing array.
Publications：
1. M.-Y. Cheng, C.-L. Lin and Y.-J. Yang, “Tactile and shear stress sensing array using capacitive mechanisms with floating electrodes,” 23rd IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2010), Hong Kong, 2010. (Oral presentation)
Address :
Department of Mechanical Engineering,
National Taiwan University,
No. 1, Roosevelt Rd., Sec. 4, Taipei, Taiwan (R.O.C)
