We are investigating the methods of creating conductive patterns on porous textile materials by different printing techniques. The properties of textiles as a rough, porous polymeric soft substrate makes it very challenging to use as printing media. We have investigated the processing difficulties and solutions to manufacture high-throughput printed electronics devices on textile platform with high resolution.
We have developed methodology for solution-based processes (i.e. direct-jet application) of sol-gels and solid solutions. Printing of conductive colloidal solutions with very different viscosities are studied through direct write printing and inkjet printing techniques. We have redesigned the fluid flow actuation system of a typical DOD spray coating device for the viscous conductive solutions according to the rheological behavior of the fluids. An improvement of 10X increase in process throughput is achieved. This technology is patented by NC State University.
Additionally, we are able to engineer the fiber structure in the textile to create vertically connect conductive via on flexible form. We have fabricated very durable composite conductive structure with very low sheet resistance (9 mΩ/□) by the direct write process. Our developed large area flexible heater (directly printed without interface layer) can generate 400 C heated textile surface over 150 cm2 surface area with 7 V (DC) power supply.