Paper – one of the oldest materials known to humans – can bend and fold and even flatten itself due to recent innovative, simple and low-cost technology.
This amazing technology was developed by researchers at Carnegie Mellon University’s Human-Computer Interaction Institute.
Researchers have applied a thin layer of conducting thermoplastic, to common paper with an inexpensive 3D printer or even painted by hand that serves as a low-cost, reversible actuator.
Then when electricity is applied by researchers, the thermoplastic heats and expands, causing the paper to bend or fold; when the current is removed, the paper returns to a pre-determined shape.
“We are reinventing this really old material,” said Lining Yao, assistant professor in the HCII and director of the Morphing Matter Lab, who developed the method with her team. “Actuation truly turns paper into another medium, one that has both artistic and practical uses.”
Basic types of actuators that enable the creation of structures that can turn themselves into balls or cylinders, have been already designed. 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.
“… A new electrical and reversible paper actuator printed by a FDM 3D printer is composed of inexpensive materials, such as common paper and off-the-shelf thermoplastic printing filaments. The fabrication process is fast and straightforward, which requires a single layer printing with a desktop FDM printer,” researchers say.
Such paper actuator can be easily embedded into everyday objects to enable new types of paper-based shape-changing interfaces that exhibit motion, transformation, and rich interactivities such as pop-up books, toys, origami robots, and lampshades….”
Recently for example, the paper actuation technology to create elaborate pop-up books, including interpretations of famous artworks, such as Van Gogh’s Starry Night and Sunflowers, was used by students in a workshop at Zhejiang University in Hangzhou, China.
“Most robots — even those that are made of paper — require an external motor,” said Guanyun Wang, a CMU Manufacturing Futures Initiative fellow.
“Ours do not, which creates new opportunities, not just for robotics, but for interactive art, entertainment and home applications.”
The thermoplastic actuator is printed on plain copy paper in a thin layer, just half a millimeter thick. The actuator is then heated in an oven or with a heat gun and the paper is bent or folded into a desired shape and allowed to cool. This will be the default shape of the paper. Electrical leads can then be attached to the actuator; applying electrical current heats the actuator, causing the thermoplastic to expand and thus straighten the paper. When the current is removed, the paper automatically returns to its default shape.
Yao said the researchers are refining this method, changing the printing speed or the width of the line of thermoplastic to achieve different folding or bending effects. They have also developed methods for printing touch sensors, finger sliding sensors and bending angle detectors that can control the paper actuators. The team will also use papers that are more heat conductive and developing printing filaments that are customized for use in actuators.
The same actuation used for paper might also be used for plastics and fabrics.