The age of 3D printing is upon us, and many individuals and companies alike have leveraged the power of 3D printing for everything from the manufacturing of parts to creating fully functioning prosthetic limbs. Now, researchers at Northwestern University and the University of Illinois at Urbana-Champaign have developed a new fabrication technique that is simple and will create beautiful and complex 3D micro- and nanonstructures.
This new technique mimics the action of the classic children's pop-up book. The structure begins as a flat 2D structure that will then pop up to form a much more complex 3D structure. Using multiple materials including silicon, researchers have created more than 40 different geometric designs and even complex shapes such as: shapes resembling a peacock, flower, starburst, basket and starfish.
"In just one shot you get your structure," co-author of the new study from Northwestern University, Yonggang Huang says. "We first fabricate a two-dimensional structure on a stretched elastic material. Then we release the tension, and up pops a 3-D structure. The 2-D structure must have some place to go, so it pops up."
This new technique offers many advantages over traditional 3D printing, including the ability to use a variety of materials, which is something that is quite difficult for traditional 3D printing. This technique is also much more inexpensive when compared to 3D printing, and it can be used to create many different structures all at once.
Complex, 3D structures are common in biology with many parts of the body such as bones, neural circuits and even veins, containing many more twists, turns and curves than more traditional geometric based shapes. Current 3D printing technology is limited and simply cannot reproduce these shapes. This new fabrication method, however, can do it with relative ease, and quite quickly as well.
"The pop-up technique will expand what is possible," Huang says. "3-D fabrication lets you use the space to gain more function in a structure."
Another of the three co-authors on the study, Yihui Zhang, who is an assistant professor of civil and environmental engineering at Northwestern University and who originally came up with the initial idea, says, "we know how to design a 2-D structure so that it pops up into the 3-D structure we desire."
Zhang worked together with the research group of John A. Rogers, the paper's third co-author, in developing the structural designs of the 2D structures, to form the various classes of 3D objects.
"A key, unique feature of these approaches to 3-D microarchitectures is that they work equally well with a very wide variety of materials, including the highest performance semiconductors, such as device-grade silicon, and fully formed, state-of-the-art planar devices and systems," Rogers says. "We believe, as a result, that these ideas have relevance to nearly every class of microsystem technology-from electronics to photonics, optoelectronics, microelectromechanical structures and others."
Everything is created and fabricated in two dimensions, then assembled to form the more complex 3D objects. The keys to the technique are both strong and weak points of adhesion between the 2D structure and the elastomer it is placed on. When it is released, the strong adhesion points remain, while the weak points break away, allowing for a pop-up effect to occur forming the three-dimensional object.
