The days of flexible ebooks and wearable computers may have moved a step closer, with the development of a net-shaped nanostructure that improves the ‘stretchability’ and resilience to fracture strain of polymers (Nature Communications, doi: 10.1038/ncomms1929).
By combining the polymer nanostructure with metal alloys, a team of Korean and US scientists has demonstrated stretchable connections with good electrical performances even after repeatedly applying large strains.
‘Our work is the first demonstration that over a large area, a patterned 3D nanostructure can change and extend the intrinsic material property: stretchablility,’ says Seokwoo Jeon of the Korean Advanced Institute of Science and Technology.
The researchers employed a special optical technique to produce the polymer nanostructure and then used this as a template to create a 3D nanoporous silicone sponge. ‘We used controlled 3D structural shapes to engineer desired mechanical properties into the system,’ says co-author John A. Rogers from the University of Illinois at Urbana-Champaign, US. The 3D silicone nano sponge was then filled in with a liquid metal – a Ga:In alloy – thus creating a composite material that serves as a stretchable conductor capable of joining various electronic components, such as light emitting diodes.
Stretchable electrical connections are expected to pave the way for flexible devices such as displays and biomedical sensors. ‘This is a very interesting work, which will have high impact in the field of “epidermal” electronics’ that can be embedded on human skin,’ says Sanjay Banerjee, nanoelectronics scientist at the University of Texas in Austin, US.
Such devices could be used to monitor body functions such as blood pressure, sugar level or temperature around the clock and to supply drugs to patients as and when needed.
‘By incorporating conductive polymers as stretchable interconnects, they have made them much more mechanically rugged and opened up the range of potential applications of this class of electronic devices.’
Jeon believes the technique can be applied not only to stretchable electronics, but to a wide range of fields requiring artificial 3D nano-networks that give rise to remarkable mechanical, optical and electronic properties not possible with natural materials.
‘The efficiency and cheap cost of the technique suggests great promise for realising applications based on 3D nano-networks,’ Jeon says.