The development of flexible polymer monofilament fiber strain sensors have many applications in both wearable computing (clothing, gloves, etc.) and robotics design (large deformation control). For example, a high-stretch monofilament sensor could be integrated into robotic arm design, easily stretching over joints or along curved surfaces. As a monofilament, the sensor can be woven into or integrated with textiles for position or physiological monitoring, computer interface control, etc. Commercially available conductive polymer monofilament sensors were tested alongside monofilaments produced from carbon black (CB) mixed with a thermo-plastic elastomer (TPE) and extruded in different diameters. It was found that signal strength, drift, and precision characteristics were better with a 0.3 mm diameter CB/TPE monofilament than thick (∼2 mm diameter) based on the same material or commercial monofilaments based on natural rubber or silicone elastomer (SE) matrices.

For the development of piezoresistive sensor fibers compounds based on thermoplastic elastomer (TPE) matrix and electrical conductive carbon black powder was used. In this paper the fabrication of piezoresistive fibers by using thermoplastic extrusion method will be demonstrated. With the thermoplastic processing route (e.g. melt spinning process) smart functional senor fibers with a diameter of 300 µm where produced. Their dynamic and static electrical conductive properties where investigated by using a cycling mechanical tensile test in combination with conductive measurement. Compounds of three different SEBS type TPEs and compounds with different content of carbon black were used to investigate the influence on the drift and shift of the electrical signal during dynamic and static strain exposure. By changing the SEBS-Block copolymer matrix and by increasing the carbon black content above 45 wt% stable electrical signal with low relaxation behavior can be achieved.

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