Flexible electronics can revolutionize the applications for new technology, but combining durability and flexibility in a conductive material has been difficult. Researchers at the University of Maryland have developed an inexpensive alternative to current approaches.
As described in a University of Maryland News article, researchers from the Department of Materials Science and Engineering and Fischell Department of Bioengineering teamed up to create a polymer foam of sorts that is highly flexible, cheap to produce and can accommodate conductive media.
The base material, a block copolymer (alternating blocks of styrene and isoprene), is solution blow spun to form a cohesive fibrous mat, joined at fiber intersections during processing. The mat is treated with a silver solution from which silver nanoparticles nucleate onto the fibers. The resulting polymer-
The trouble with other methods of creating flexible conductors is that they must be relatively rigid because of the conductor material’s lack of flexibility or fatigue resistance. The fundamental difference with this new approach is that the fibers condense and touch during stretching, which creates additional pathways for electricity to flow, even if particles on a single fiber lose contact in locations.
What’s even better is the versatility of the process. The polymer mat can be directly applied to a surface rather than being transferred from a separate substrate, and the surface geometry can be non-planar. The versatility and durability of the process and material were demonstrated by applying the polymer material to a standard laboratory glove, which was then worn while measuring the resistance in various hand positions.
The measurements were achieved by selectively running conductive paths down each finger allowing for individual strain measurements to be isolated. These strain measurements not only emphasize the versatility of the process, but also indicate some of the many uses for flexible electronics which also include transistors, solar cells, antennas and wearable electronics (including epidermal electronics).
Simple and effective. While the technique and material is still in its infancy, it is already showing promise to extend the usefulness of flexible conductors and reduce their cost. And that’s no stretch.
The science behind the material is discussed in the ACS Nano article, Sprayable Elastic Conductors Based on Block Copolymer Silver Nanoparticle Composites.
Images: University of Maryland