Creation of Materials Through Light

By Hari Nanthakumar

In the common and just slightly overused film representation of cavemen, our ancestors gaze at the bright, fluttering, and stupidly majestic light of fire with expressions of varying combinations of amazement, fear, and confusion, and all with an infinite curiosity that often leads to Hollywood’s idea of a well-thought-out joke—charred hair and soot-covered skin. Having higher intelligence and sophistication (or so we think), we might laugh at our foolish predecessors, who were amazed and befuddled by something as ordinary and simple as light. The closest we seem to get to that same feeling of awe in the face of light nowadays is staring at the bright lights of Butler Library late at night with sleep-drunk and beautifully clueless minds.

However, a change is brewing. Recent developments in the use of light to revolutionize materials and products are beginning to bring out that same feeling of exhilaration and awe that our ancestors felt so many years ago.

Just last year, Adidas, together with the startup Carbon, released the Futurecraft 4D, a sneaker manufactured through Digital Light Synthesis (DLS). It seems a little wild, but this essentially means that the sneaker was carved out by light. In DLS, an ultraviolet light is used to harden a photocurable polymer resin, a liquid solution that is reactive to light, within minutes. By projecting an image of the shoe onto the mixture, thereby controlling which parts of the resin harden, the light very quickly chisels out the structure of the shoe, leaving its structure surrounded by a solution of uncured resin. The structure is then baked, leaving the fully-functional prototype of a shoe.

This is the first time that such a method has been used to manufacture shoes. Previously, three-dimensional printing had been used to create certain components of footwear, but the finished product still required more traditional methods such as molding, which can take as long as a month. The necessary additional processes severely extended the time needed to advance new innovations and versions.

DLS changes this. Digital light allows the creation of several new, specially tailored versions within a single day, advancing the landscape of the footwear manufacturing process for years to come. The incredible flexibility in changing the projections of light that can be produced gives manufacturers the unique ability to easily influence the architecture of the shoe. It opens up a future in which shoes are made to beautifully and perfectly fit everyone’s feet and to suit their specific tasks—from running to daily life—with the entire process of design-to-product lasting a matter of minutes. And as the process becomes more common and more cost-efficient, footwear made out of light will be everywhere.

This is not the first revolutionary product to come out of simple light.

In 2015, Boeing, in partnership with HRL Laboratories, revealed the lightest metal in the world, created using a similar light-based manufacturing process. Using a UV light array projecting ordered rays into a polymer resin, Boeing and HRL created a micro-lattice structure that was electroplated with nickel. The polymer was then dissolved away with acid, revealing an ultralight, hollow metallic microlattice that was 99.99% air, lightweight enough to sit comfortably on a dandelion. However, this metal is not just any weak gimp. The lattice structure maintains the metal’s strength, allowing it strong elasticity and energy-absorption properties. Because of its ultralight and strong nature, the nickel micro-lattice can be incorporated in next-generation aircraft, making components that create the potential for large bounds in the search for fuel and waste efficiency.

The uses of the metal do not simply stop at creating ultralight and strong structural components. Applications by HRL of the micro-lattice’s energy absorption have been extended to use in football helmets for energy dissipation in collisions, providing progress on the issue of concussions, which have been threatening the game of football since people have become increasingly wary of the dangers of chronic traumatic encephalopathy (CTE).

Enough? No, the uses of these light-based structures have been further squeezed for even more applications. J. Bauer’s study of glassy carbon nanolattices demonstrated that pyrolysis can burn these structures into nanolattices that approach strengths that haven’t been seen before.
Using light-based methods to create these wonderful, little structures opens up the unimaginable ability to influence the structure’s architecture and nature for specific and tailored purposes. Creation through light will soon influence the development of aircraft, football helmets, and shoes with the possibilities being open to much, much more. It is just beginning. We will look aghast, amazed, confused, and a little overjoyed at the transformations caused by light-based manufacturing processes. Through it all, we will let our inner cavemen out, and be proud of it as we gaze at the true magnificence of light.

Hari Nanthakumar is a freshman in SEAS hoping to study materials science & engineering. A staff journalist for CSR, he enjoys spending his time watching random Netflix shows and occasionally venturing out into NYC.