Stretchable electronics have the potential to enable a wide variety of emerging applications including sensors or electronic device integration into textiles, conformable power, enhanced robotic mobility and manipulation, energy harvesting, fieldable biosensing, chemical sensing technology, as well as exoskeletons and multifunctional conforming suits. But such applications are still largely out of reach. Methods to make stretchable electronics, and their reason for failure are listed below:
|Use of inherently conductive polymers with conjugated backbones||Extremely brittle, prone to fracture and small strains; very high melting points|
|Incorporated conductive fillers||The most promising – carbon nanotubes (CNT’s) – have poor uniformity, high cost, and are not stretchable|
|Deposition of conductive materials on a flexible substrate||Are not stretchable; require intricate production methods|
To address the above, Army researchers have developed deformable polymer composites with controlled electrical performance during deformation through tailored strain-dependent conductive filler contact. The Army material is a deformable elastomeric conductor and includes an elastomeric polymer matrix and a conductive filler material of metal-coated carbon fibers (and related materials) uniformly dispersed in the elastomeric polymer matrix. The conductive filler material comprises non-entangled particles having an aspect ratio sufficiently large to enable the particles to remain in contact with adjacent particles so as to maintain conductive pathways in the material when the material is subjected to deformation and strain.
This technology yields a stretchable multi-conductor cable with control over geometry, stiffness, impedance, and percolation threshold. Compatible with communications protocols such as USB, Ethernet, and many other differential signaling protocols used in aviation, military, industrial, and commercial environments. Manufactured using roll-to-roll and melt processes.
- This technology does not use a conventional metal conductor, but instead uses elastomeric materials having conductive additive materials, which readily permits elastic deformation and maintains conductive properties of the materials when deformed
- Over a transmission distance of an electrical signal through the conductor, the transmission does not suffer greater than about 3 dB of signal attenuation when subjected to the deformation
- Viable polymeric materials may include polystyrene, natural rubber, silicone elastomer, epoxy elastomer, PDMS, neoprene nylon, polyurethane, Teflon and PTFE
- Material properties can be tailored for decreasing, increasing or constant conductivity without geometric patterning
- US patents 9,748,015 and 10,032,538 are available for license
- Potential for collaboration with Army scientists and engineers