A Comparison of High Dielectric Fillers for a Stitchable Flexible Capacitive Sensor

Flexible capacitive sensors are pervasive across multiple sectors, from healthcare to robotics. Although they offer better linearity and lower hysteresis, they require a large surface area to provide suitable sensitivity. One way of addressing this is through dielectric fillers. However, finding the right amount and type of filler is a challenge: the same material that improves a sensor's sensitivity can also cause detrimental changes in physical parameters. This paper describes how low-cost, high performing dielectric fillers - strontium titanate and barium titanate - can be introduced into Ecoflex to form a soft, sew-able sensor; and presents the concentrations of dielectric materials which offer both a good dielectric response, and the ability to pour the material and form the device. It highlights the advantages of barium titanate - which shows a better percentage dielectric constant increase - unless applications require the use of fine detail or cross-axis strain. The linearity, hysteresis, sensitivity, and cross-axis sensitivity of the resulting flexible, stitch-able sensor are discussed.