Researchers from Massachusetts Institute of Technology (MIT) devised a new approach to fabricate nano-scale 3D objects of different shapes
A team of researchers from MIT developed an approach to fabricate nano-scale 3D objects of different sizes. According to the researchers, the new technique can be used to create any desirable shape and structure by patterning a polymer scaffold with a laser. The team attaches other useful materials to the scaffold and reduced its size to one thousandth the volume of the original. The microstructures can be used in various fields ranging from optics to medicine to robotics. The research was published in the journal Science on December 14, 2018.
The team used a technique, known as expansion microscopy, which involves embedding tissue into a hydrogel. The tissue was later expanded to allow high resolution imaging with a regular microscope. The team reversed the process and found that it is possible to create large-scale objects that are embedded in expanded hydrogels and the size of the objects can be reduced to the nano-scale. The new approach was dubbed as ‘implosion fabrication.’ The team used a very absorbent material made of polyacrylate as the scaffold for their nanofabrication process. The scaffold is immersed in a solution containing molecules of fluorescein that attach to the scaffold as they are activated by laser light. The team used two-photon microscopy to attach fluorescein molecules to specific locations within the gel. The fluorescein molecules play major role in binding to other types of molecules added by the researchers.
The team reduces the size of the entire structure by adding an acid when the desired molecules are attached in the right locations. The acid blocks the negative charges in the polyacrylate gel to avoid repelling each other, which in turn causes the gel to contract. According to the researchers, the technique can be used to reduce size of objects to 10-fold in each dimension. The ability to reduce size of objects facilitates increased resolution and makes it possible to assemble materials in a low-density scaffold. In the current research, the team was successful in creating objects that were around 1 cubic millimeter and patterned with a resolution of 50 nanometers.