Researchers are pushing the capabilities of 3D printing, using soft materials for medical applications such as drug delivery systems, cartilage replacement, retinal implants, and much more. Researchers at the National Institute of Standards and Technology (NIST) have developed a 3D printing technology to fabricate gels using beams of electrons or X-rays. Employing these types of radiation solves a problem faced by more conventional 3D printing processes that use ultraviolet or visible laser light.

The problem with using ultraviolet and laser light to create gel scaffolding is that their relatively low energy and longer wavelengths cannot be focused enough to produce the fine structures desired. X-ray and electron microscopes emit shorter wavelengths with more energy for finer detail and more robust structures. However, X-rays and electrons also present a major challenge; the liquid in the polymer soup used to construct the gel structures evaporates in the vacuum normally required by the energy sources. The NIST researcher’s breakthrough is the workaround that makes using the higher energy radiation sources possible.

 NIST researcher Andrei Kolmakov and other scientists at NIST and the Elettra Sincrotrone Trieste in Italy devised and demonstrated a process that places an ultrathin sheet of silicon nitride between the vacuum and the liquid polymer chamber. With this process, the radiation can penetrate the liquid, but the barrier prevents evaporation. The team used the technology to create 3D-printed soft gel structures as thin as 100 nanometers (nm): about 1/1000th the thickness of a human hair.

According to Kolmakov, the NIST plans to refine the technology to print virus-size gels as small as 50nm. With the technology to print using electron beams and X-rays in liquids, the team envisions the process that could create injectable electrodes, biosensors, and soft robotics. The NIST team described their advance in 3D printing in ACS Nano.