PVDF film micro fabrication for the robotics skin sensor having flexibility and high sensitivity

This paper provide a novel and potential method to realize a flexible and high sensitive, high resolution skin sensor useful for the application of robotic skin. MEMS technology was applied and by etching process 140~300/40- μm of micro structures were realized easily directly on the elongated and polarized polyvinylidene fluoride (β - PVDF) film that will be used as the sensing element in the skin sensor. The effects of PVDF film etching condition, especially the experienced temperature history to the PVDF important sensing parameter of piezoelectric constant was evaluated by experiment. PVDF film etching characteristics were introduced also. N,N´-dimethyl acetamide (DMA, C₄H₉NO) solution was used as the wet etching etchant, and O₂ gas for the RIE dry etching process. Under the temperature of less than 55°C, the PVDF film piezoelectric constant was got almost no change, and at the range over 55°C, the constant start to deteriorate linearly according with the temperature rise about 0.3×10^-12; (C/N)/°C. At about 100°C , there was only 50% of deterioration on the PVDF film piezoelectric constant. Such a strong piezoelectric activity will be useful to the sensitivity of the skin sensor. By photo mask design and control of the process condition, much fine and complex micro structure could be fabricated directly on the PVDF film without noticeable degradation of its piezoelectric constant, and it will be useful to realize the required soft and high sensitive, high-resolution skin sensor.