3D Printing Silica Aerogels for Small Scale Applications

International researchers working with the Swiss Federal Laboratories for Materials Science and Technology (EMPA), led by Shanyu Zhao, Gilberto Siqueira, Wim Malfait and Matthias Koebel, are exploring new ways to use aerogels on the micro scale for additive manufacturing, detailing their study in the recently published “Additive manufacturing of silica aerogels.” Currently used in a variety of applications where thermal conductivity is required, silica aerogels may be found in optics, particle capture, physics, and more. Most commonly though, these materials are used for thermal insulation—especially for constricted spaces that may require buffering.

Historically, silica aerogels have been known as difficult to manipulate because of their brittleness (often resulting in the need for additives, which may be even further limiting in terms of miniaturization), leading the researchers to develop a new, patent-pending technique for making micro-structures through direct ink writing (DIW).

Using a silica aerogel powder slurry, the authors reported improvements such as shear-thinning, leading to better flow—and higher viscosity after printing, leading to more stable 3D printed objects made of pure silica. The goal of the researchers overall was to refine aerogels for better use on the smaller scale—here, measuring as thin as one-tenth of a millimeter.

The thermal conductivity of a silica aerogel is not substantial, but the materials possess good mechanical properties. The authors report that the 3D printed aerogels can be “drilled and milled,’ leaving the potential for post-processing with moldings. 3D printed samples in the form of leaves and a lotus flower were produced during the study, demonstrating not only the ability to design overhanging structures but also to print complex geometries with multiple materials. Because of the small size, these materials can also be used to insulate electronics thermally, preventing them from affecting each other while in close proximity, and effectively managing conductive hot spots.

The researchers also created a thermos-molecular gas pump (or a Knudsen pump) from aerogel material, fortified on one side with black manganese oxide nanoparticles. Upon exposure to light, the material then warms up on the dark side and pumps gas or releases solvent vapors.

To demonstrate that fine aerogel structures can be produced in 3D printing, the researchers printed a lotus flower made of aerogel (Image: Courtesy of EMPA)

Such progress also lends potential for the use of aerosols in medical implants, protecting body tissue from heat over 37 degrees. Currently, the EMPA researchers seek partners interested in using the novel 3D printed aerogels for industrial applications. Check out some of their previous research studies too as they have developed other types of 3D printing inks made with cellulose, as well as unique molds used in the development of sensors.

(Image: Courtesy of EMPA)