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US researchers have developed a technique for generating 3D circuits that could underpin new medical implants, solar cells and other electronics.
The team at the University of Illinois at Urbana-Champaign devised a process for transforming 2D micro- and nano-structures into 3D, using concepts they described as similar to those used to create children’s 3D pop-up books.
The process could allow complex 3D structures to be built using materials only a few microns thick. Because the process can be used to create silicon structures, it could be used to help make circuitry for range of electronic devices – from battery anodes, to solar cells, and biomedical devices. Researchers hope the structures will have a use in microelectromechanical components, photonics and optoelectronics and metamaterials.
The team at Illinois claim this method bypasses some of the constraints on existing methods for building 3D structures at this scale, which limits the classes of materials that can be used and the complexity of the geometries that can be built.
u201cConventional 3D printing technologies are fantastic, but none offers the ability to build microstructures that embed high performance semiconductors, such as silicon,u201d said John Rogers, a Swanlund Chair and professor of materials science and engineering at Illinois.
u201cWe have presented a remarkably simple route to 3D that starts with planar precursor structures formed in nearly any type of material, including the most advanced ones used in photonics and electronics.u201d
The technique, called compressive buckling, works by printing a 2D structure onto a layer of material that has been compressed. The 2D printed structure is bound to the compressed substrate at several points and when the substrate is released and expands back into its original shape, the 2D structure sat on top rises up into a 3D form.
Because the technique could be combined with other fabrication methods, such as photolithography, and processing techniques used in the semiconductor and photonics industries it could be used to create 3D electronic, optoelectronic and electromagnetic equipment.
An array of shapes
Initial experiments have created more than 40 distinct shapes, ranging from single and multiple helices, toroids and conical spirals, to structures that resemble spherical baskets, cuboid cages, starbursts, flowers, scaffolds and fences.
u201dWe’re now exploiting these ideas in the construction of high performance electronic scaffolds for actively guiding and monitoring growth of tissue cultures, and networks for 3D electronic systems that can bend and shape themselves to the organs of the human body. We’re very enthusiastic about the possibilities,u201d Rogers said.
An example of the complexity of the 3D structures that can be created.
Here you can see the fine detail that can be replicated throughout a structure.