We propose a concept of a flexible sensor array using a novel capacitive force sensor not having a vulnerable electrode on the force applied site. It has a polymer domed structure inside which silicone oil is contained. When the force is applied, the oil is pushed into the surrounding thin channels, where the change in capacitance due to the inflowing dielectric oil is measured between two electrodes on the top and bottom surfaces of the channel. Since the channel does not have a directly applied external force to it, the electrodes do not suffer from damage problems. The change in capacitance was simulated using a simplified flow model. The first trial device of the sensing element has been fabricated. A sensitivity of 0.05 pF/gf was achieved.
References
[1]
Lee, H.-K.; Chung, J.; Chang, S.-I.; Yoon, E. Normal and shear force measurement using a flexible polymer tactile sensor with embedded multiple capacitors. IEEE J. Microelectromech. Syst. 2008, 17, 934–942, doi:10.1109/JMEMS.2008.921727.
[2]
Someya, T.; Sekitani, T.; Iba, S.; Kato, Y.; Kawaguchi, H.; Sakurai, T. A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications. Proc. Natl. Acad. Sci. USA 2004, 101, 9966–9970.
[3]
Suzuki, S.; Tuchitani, S.; Sato, K.; Yokota, Y.; Sato, M.; Esashi, M. Semiconductor capacitance-type accelerometer with PWM electrostatic servo technique. Sens. Actuat. A: Phys. 1990, 21–23, 316–319.
[4]
Binh-Khiem, N.; Matsumoto, K.; Shimoyama, I. Polymer thin film deposited on liquid for varifocal encapsulated liquid lenses. Appl. Phys. Lett. 2008, 93, 124101:1–124101:3.
[5]
Petralia, M.T.; Wood, R.J. Fabrication and Analysis of Dielectric-elastomer Minimum-Energy Structures for Highly-deformable Soft Robotic Systems. In Proceedings of the IEEE/RSJ Conference on Intelligent Robots Systems (IROS2010), Taipei, Taiwan, 18–22 October 2010; pp. 2357–2363.
[6]
Maleki, T.; Chitnis, G.; Ziaie, B. A batch-fabricated laser-micromachined PDMS actuator with stamped carbon grease electrodes. J. Micromech. Microeng. 2011, 21.