Carbon Black/PDMS Based Flexible Capacitive Tactile Sensor for Multi-Directional Force Sensing

Abstract

Flexible sensing tends to be widely exploited in the process of human–computer interactions of intelligent robots for its contact compliance and environmental adaptability. A novel flexible capacitive tactile sensor was proposed for multi-directional force sensing, which is based on carbon black/polydimethylsiloxane (PDMS) composite dielectric layer and upper and lower electrodes of carbon nanotubes/polydimethylsiloxane (CNTs/PDMS) composite layer. By changing the ratio of carbon black, the dielectric constant of carbon black/PDMS composite layer increases at 4 wt%, and then decreases, which was explained according to the percolation theory of the conductive particles in the polymer matrix. Mathematical model of force and capacitance variance was established, which can be used to predict the value of the applied force. Then, the prototype with carbon black/PDMS composite dielectric layer was fabricated and characterized. SEM observation was conducted and a ratio was introduced in the composites material design. It was concluded that the dielectric constant of carbon sensor can reach 0.1 N within 50 N in normal direction and 0.2 N in 0–10 N in tangential direction with good stability. Finally, the multi-directional force results were obtained. Compared with the individual directional force results, the output capacitance value of multi-directional force was lower, which indicated the amplitude decrease in capacity change in the normal and tangential direction. This might be caused by the deformation distribution in the normal and tangential direction under multi-directional force.

Elastomer-Based Visuotactile Sensor for Normality of Robotic Manufacturing Systems

“…Silicone-based elastomers are semi-inorganic polymers with a silicon-oxygen chain and two hydrocarbon groups. Polydimethylsiloxane (PDMS) is a popular silicon-based elastomer that is not only used for micro/nanofabrication [ 35 , 36 , 37 ] but also used by several researchers in developing tactile sensors [ 38 , 39 , 40 ]. Other silicon-based elastomers have been recently investigated for the development of tactile sensors.…”

Liquid Metal Patterned Stretchable and Soft Capacitive Sensor with Enhanced Dielectric Property Enabled by Graphite Nanofiber Fillers

“…In this work, by utilizing the unique features of the liquid metal electrode and the dielectric elastomer, we fabricated a soft and stretchable capacitive sensor. Polydimethylsiloxane (PDMS) has been widely used to fabricate dielectric elastomers by adding fillers such as graphene oxide [39], functionalized graphite oxide [40], carbon black [41,42], copper calcium titanate [43], barium titanate [44], and titanium di-oxide [45]. We also utilized PDMS to prepare dielectric elastomers with enhanced dielectric properties by dispersing graphite nanofiber (GNF) in the PDMS matrix.…”

“…Graphene Oxide 3.4-9.6 [39] 0.5 vol % PDA@SiO 2 @GO 1 ~6 [40] 6 wt % SrTiO 3 2 ~14 [76] 30 vol % Carbon Black ~6.5 [42] 4 wt % CCTO 3 6.5 [43] 20 wt % BaTiO 3 4 ~5 [44] 40 wt % TiO 2 5 ~4.5-4.9 [77] 8-10 vol % TiO 2 @SiO 2 6 ~7 [45] 16 vol % Ag@SiO 2 7 6.8 [78] 3 wt % GNF (this work) 6.41 6 wt % 1 Polydopamine modified silicon dioxide@graphite oxide hybrid. 2 Strontium titanate.…”

Batch Fabrication of a Polydimethylsiloxane Based Stretchable Capacitive Strain Gauge Sensor for Orthopedics

“…The different strain microstructures exhibited issues related to stretchability, a complicated manufacturing process, low yields, and high costs. Alternative low cost solutions are (1) doctor blading [22] into pre-structured molds [23,24], (2) injection or cast molding, and (3) spray coating [25]. In the first technique, doctor blades get liquid PDMS into the cavities of a planar, half-open negative mold, to achieve a structured PDMS device after curing and mold release.…”