Investigation of Tactile and Strain Sensing Utilizing Carbon-Fiber Network in Silicone Elastomer Matrix

Abstract As the popularity of immersive and interactive technology continues to grow, there is demand for wearable or conformable tactile and strain sensors for human–computer-interaction. A major challenge in current conformable sensors is durability, tremendously limiting their applications in the market. This study utilizes long carbon-fiber networks in silicone elastomer matrix as electrodes for sensing, which consequently strengthens the sensors. Row and column pattern of long carbon-fiber was used to create projected capacitive touch sensors at every intersection and demonstrate multi-touch and spatial mapping capabilities. Similarly, these intersections were also demonstrated as piezoresistive force sensor where deformation from pressure on the intersection decreases the resistance between the row and column electrodes by altering the electrical network among the carbon-fibers. Lastly, piezoresistive strain sensors were manufactured by impregnating a pre-woven carbon-fiber fabric with silicone. Deformation in the 45-degree angle relative to the fabric caused changes in the electrical interactions between carbon-fibers and therefore the resistance along the sensor as well. These strain sensors showed an interesting behavior of increasing then decreasing resistance as the tensile load shifted from the silicone matrix to the carbon-fibers. The ultimate strength of properly bonded strain sensors using Smooth-On Sil-Poxy was significantly greater than the strength of pure two-part silicone. An intricately designed carbon-fiber network within a silicone matrix could combine these sensing mechanisms to potentially create a durable and compact multifunctional sensor that expands wearable sensing technology to rugged environments.