Researchers at Delft University in the Netherlands have developed an alternative method to 3D printing, giving the products more functionalities than those produced by standard 3D printers. The final product can be used in medical implantations, flexible electronic devices and other sensitive applications.
The method is inspired by the Japanese paper folding art called origami. The research team, led by Professor Amir Zadpoor, developed the method by looking into the process of manufacturing lattice structures that are used to develop metamaterials. These are materials built to achieve unusual physical, biological or mechanical properties, such as ultra-thin energy absorption and ultra-stiffness, among others. The new properties are not dependent on the base material but from the geometry of their lattice structure.
Nowadays, these lattice structures can only be made using 3D-printing techniques; once the 3D structure is made, functionalities can be added to the surface of the final product by using fabrication techniques such as electron beam nanolithography and others. The big problem encountered nowadays is the limited access to the internal surfaces of the 3D-printed lattice structures.
To incorporate advanced functionalities into the metamaterials, the surfaces of the lattice structures need to be ornamented with special features. The alternative approach used by the researchers is to start with a flat surface, incorporate the needed functionalities, and then fold the device into a 3D structure.
“Combining free-form surface ornaments with lattice forms seemed therefore impossible. But, inspired by the Japanese art of paper folding (origami), we have found a way that does allow for that combination. We have proposed the unusual approach of ‘folding’ lattice structures from initially flat states. That approach provides us with full access to the entire surface of what will eventually become our lattice structure. We could then use the currently available techniques to ornament the surface. We have categorized lattices into three basic categories and, for each of those, have proposed a folding strategy. Self-folding mechanisms have been also incorporated into the flat material to allow for self-folding into the final lattice shape,” says Zadpoor. The folding mechanism is activated (for instance by a change in temperature) to enable folding of the flat sheet and the formation of complex 3D structures. The lattice structures could bear arbitrarily complex surface ornaments at different scales. “We show how free-form 3D ornaments could be applied on the surface of flat sheets with a resolution of a few nanometers.”
This simple technique can revolutionize the manufacturing of 3D devices without 3D printing methods. Professor Zadpoor say: “There are several areas where the proposed approach could be used for creating metamaterials with advanced functionalities. One specific area is the development of meta-biomaterials that stimulate tissue regeneration. Another example of the potential areas of application is integration of flexible electronics (for example, sensors and actuators) in the design of metamaterials.”
The result of the research was published in Science Advances on November 29; an abstract can be found here.