Spatial resolution coating for sensory yarns with length information
For private consumers, smart textiles have so far mainly been visible in the areas of health and fitness, for example in sportswear for monitoring pulse rate. In order to achieve a higher market penetration of smart textiles, among other things, the product functionalities must be increased and the manufacturing processes must be implemented more cost-effectively.
Currently, sensory yarns can already be functionalized well for various purposes with the aid of wrapping technology. This is done, for example, by helically wrapping a conventional yarn with one or more fine wires. In an IGF research project, wrapping yarns with different capacitive-sensory areas within a yarn were investigated. This means that it is no longer only possible to measure whether the yarn has been touched, but also in which section.
The length-dependent yarn coating required for this was successfully implemented by modifying common application methods. By raising and lowering the yarn using the kiss-roll method, yarn sections were left out during coating. Alternatively, a roller with partial recesses was applied. An automated process for location-dependent coating is available with the aid of digitally controllable nozzles for water-based solutions as well as for thermoplastic materials. This allows yarn lengths to remain uncoated, to receive a low coating or a completely enveloping coating in a very flexible manner. The variability of the capacitive properties on the yarn sections is achieved by conductive additives.
The yarns produced in this way were processed into textile sheet structures, with the textile structure being designed in such a way that several sensor yarns run towards each other and, when touched or loaded, sensor signals can be picked up at the respective crossing points. These signals can then be assigned to a specific area in the textile surface. In this way, the detection of complex contact and load patterns is possible. It has been shown that the capacitive sensitivity of the sequential areas can be adjusted in steps as desired using different coating formulations and varying the number of wraps.
