Film-type single axis tactile sensor with various thicknesses using nitrile butadiene rubber

Recent development in technology has enabled the fabrication of low-cost and high-performance multi-axis thin-film type tactile sensors using polymer materials. Nitrile Butadiene Rubber (NBR) in particular is one of the primary materials used for the sensors, because the dielectric constant of the NBR is about 3 times higher than that of other popular material such as silicone. In case of shear force sensors, the sensitivity is affected by the thickness of the fabricated films. However, the NBR has a critical disadvantage: it tends to generate bubbles during the curing process due to the evaporation of the solvent. This paper presents an analysis on the effect of the bubble in the film-type tactile sensor and proposes a fabrication method that minimizes the bubble forming during the curing process of NBR solutions. Using the proposed NBR molding method, single-axis film-type shear force sensors are fabricated in various thicknesses (1.2 mm-2.8 mm). Experimental results show that they are capable of measuring shear forces up to 12 N.