Direct-Write Printing of Conductive Inks Speeds the Production of Wearable Electronics

Achievement date: 
2017
Outcome/accomplishment: 

A scalable printing process for integrating conductive inks onto textiles can reach speeds 16-times faster than earlier “smart-textile” printing, according to tests conducted at the Engineering Research Center (ERC) for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST), based at North Carolina State University and funded by the NSF.

Impact/benefits: 

Integrating electronics into textiles, a key to developing wearable sensors, is labor-intensive and has been limited to embroidery techniques with yarns made to conduct electricity. The new printing process promises to speed the development, and lower the cost, of adding complex interconnect patterns for electronics-infused garments.

Explanation/Background: 

The new printing technology builds on efforts to apply to garments the speed and scalability seen in the electronics industry, which uses conductive inks to create components for printed circuit boards. Conductive yarns were an initial path to creating textile circuitry, but like monograms on clothing, require knitting that can be expensive and relatively slow to produce. Previous printing process included screen-printing that, while providing conductive interconnects, limited their complexity because of low resolutions.

Known as direct-write, the process developed at ASSIST applies backpressure to the conductive material allowing it flow through shear-thinning behavior, in which the viscosity of fluids tend to decrease under strain. As the material flows out the dispense nozzle, a conductive film is formed. The printing process also promises material that is more flexible and easier to wear.