New nano-scale processing technology paves the road for using carbon nanotubes in flexible and stretchable electronics

Research scientists at Department of Microtechnology and Nanosciences, Chalmers University of Technology have recently developed a new large scale method to functionalize carbon nanotubes (CNTs). This makes it potentially possible for utilizing CNTs as interconnect material for flexible and stretchable electronics products.
Flexible and stretchable electronics are considered as one of the most interesting high growth industries. With successful implementation of the developed technology, many new applications such as portable and wearable smart systems, paper based displays, smart clothing, and bendable biomedical sensors, for instance, can become a reality.
However, most of these dreams still remain as research topics at current stage. Low reliability and poor electrical properties of interconnects under high and complex mechanical loading are, among other things, significant bottlenecks which limit performance of flexible and stretchable electronics.
Professor Johan Liu and his research team developed a new surface treatment process for synthesizing intrinsically flexible multi-functionalized CNT based hybrid nanowires. The key benefit of the hybrid nanowire lies in their high electrical conductivity and flexible structures to maintain stable electrical and mechanical performances under significant deformation. The multi-functionalized CNT based hybrid nanowires are synthesized with different functional materials on the surface of CNTs to produce a metal nanoparticle coating layer and form uniform dispersions whilst possessing the CNT’s original structural integrity and high flexibility. Using this unique concept, they are able to show that the flexible and stretchable circuits (FSCs) made by the CNT based hybrid nanowires can have a relatively low and stable electrical resistivity about 1×10-5 ohm·centimeter (Ω·cm) under different bending and stretching states. This value is orders of magnitude lower than pure CNTs (1 Ω·cm) and also competitive with that of pure copper (1.7×10-6 Ω·cm).
The CNT based hybrid nanowires have a high reliability as well as stable electro-mechanical properties under repeated bending, which is superior than many of metal based systems.
In addition, the CNT based hybrid nanowires are able to be dispersed in various solvents and form homogenous suspensions that facilitate making uniform and fine structures with existing patterning and printing techniques.
The work is carried out in collaboration with SHT Smart High Tech AB, Sweden and Shanghai University, China.
For further information, please contact:
Professor Johan Liu, email:
For further reading:
Figure 1. Fabricated high-resolution flexible and stretchable electronic circuit with a minimum width of 40 micrometer.
Figure 2. Flexible and stretchable electronics using Light Emitting Diodes. The LEDs show no almost degradation in performance under bending and stretching conditions.

Figure 3. Synthesis and processing steps for formation of CNT based hybrid nanowires.

Published: Mon 08 Jun 2015.