PVDF Sensors – Research on Foot Pressure Distribution in Dynamic Conditions

Abstract:

The paper presents a dynamic measurement method of the distribution of foot pressure exerted on the ground by a four-point shoe insole, developed by authors, which can be placed in any sport footwear. The value of pressure was measured on the heel, medial midfoot, metatarsal, and great toe by recording values of a generated voltage by sensors which were made of piezoelectric polymer PVDF film 110 µm thick with printed silver electrodes. As confirmed by scanning microscope studies, the foil applied in the sensors is semi-crystalline. The shoe measurement insert consists of two polyester films without piezoelectric properties between them, electroactive polymer sensors were placed. The films were glued together. To match the measuring circuit to the sensors used, two circuits were tested, a voltage measuring circuit with an input resistance of above 10¹² Ω (open circuit), and a charge measuring circuit (shorted circuit). The charge measuring circuits with the RC high-pass filter, which attenuates the slow-changing pyroelectric signal was selected as it ensures the desired measurement accuracy. As presented in the paper, as PVDF sensors are very sensitive to any mechanical deformation, it is important to properly design the shoe insole to ensure its correct use during pressure distribution measurements. The measuring system developed by the authors, allows testing of foot pathology for any length of time in a dynamic way.

• Periodical: Advances in Science and Technology (Volume 79)
• Pages: 94-99
• DOI: https://doi.org/10.4028/www.scientific.net/AST.79.94
• Online since: September 2012
• Authors: Ewa Klimiec, Wiesław Zaraska, Jacek Piekarski, Barbara Jasiewicz
• Keywords: Foot Pressure, Piezoelectric, PVDF Sensor, Pyroelectric, RC Filter

References

[1] A.B. Putti, G.P. Arnold, R.J. Abboud, Foot pressure differences in men and women, Foot and Ankle Surgery 16 (2010) 21–24

DOI: 10.1016/j.fas.2009.03.005

[2] M. Saitoa, K. Nakajimaa, C. Takanoe, Y. Ohtaa, C. Sugimotob, R. Ezoeb, K. Sasakib, H. Hosakab,T. Ifukubec, S. Inof, K. Yamashita, An in-shoe device to measure plantar pressure during daily human activity, Medical Engineering & Physics 33 (2011) 638–645

DOI: 10.1016/j.medengphy.2011.01.001

[3] J. Lorkowski. Methodology of pedobarographic examination –own experiences and review of literature. Przegl. Lek. 63 Suppl 5, (2006) 23-7.

[4] J. Lorkowski, D. Zarzycki, Clinical use of pedobarograhphic examination – own experience and review of literature. Przegl. Lek. 63 Suppl 5, (2006) 28-32.

[5] J. Lorkowski, W. Hładki, D. Galicka-Latała, M. Trybus, L. Brongel, Underfoot pressure distribution of female patients with obesity and planar fasciitis, Przeg. Lek. 66/9 (2009) 513 – 518

[6] Measurment Specialties Inc., Piezo Film Sensors, www.msiusa.com 1-4

[7] T. Tsuey, Production of Piezoelectric PVDF Films, Patent US 4241128 (1980)

[8] K. Tashiro, M. Kobayashi, , H. Tadokoro, Calculation of Piezoelectric Constants of Poly(Vinylidene Fluoride) Form I, Polymer Bulletin 2 (1980) 397-402

DOI: 10.1007/bf01064370