When current is fed through the thermoplastic – off-the-shelf graphene polyactide composite – it heats and expands causing the paper to bend or fold – an process which reverses when the current is stopped.
“We are reinventing this really old material,” said Lining Yao, a researcher at the University’s Human-Computer Interaction Institute. “Actuation turns paper into another medium, one that has both artistic and practical uses.”
Members of the Lab designed different actuators, including some using origami and kirigami forms. “These enable the creation of structures that can turn themselves into balls or cylinders, or, they can be used to construct more elaborate objects, such as a lamp shade that changes its shape and the amount of light it emits, or an artificial mimosa plant with leaf petals that sequentially open when one is touched,” said the University.
On normal copy paper, the printing needs to be around 0.5mm thick, printed by simple melted filament (FDM) printing.
To form the default shape, the printed paper is heated, bent and folded into the desired shape, then allowed to cool.
Electrical heating of the pattern causes the thermoplastic to expand – straightening the paper.
Printed touch sensors, finger sliding sensors and bending angle detectors have also been made.
Future work includes speeding actuation using papers that are more heat conductive and different printable plastics, as well as trying plastics and fabrics instead of paper.
The printed paper actuators will be exhibited at the Ars Electronica Festival in Linz, Austria (6-10 Sep), Bozar Centre for the Fine Arts in Brussels (13-30 Sep); and at Hyundai Motorstudio in Beijing (Oc-Mar).
There is a charming video.