Researchers develop world's first chip-based 3D printer

Such a device could revolutionise fields ranging from medical engineering to on-site prototyping. Researchers from MIT and the University of Texas at Austin have taken a significant step towards this vision by demonstrating the first chip-based 3D printer.

The proof-of-concept device comprises a single millimetre-scale photonic chip that emits reconfigurable beams of light into a well of resin, which solidifies upon exposure to the light. The prototype chip, devoid of moving parts, utilises an array of tiny optical antennas to steer a beam of light. This beam projects into a specially designed liquid resin that rapidly cures when hit by the light's wavelength.

By combining silicon photonics and photochemistry, the interdisciplinary research team demonstrated a chip capable of steering light beams to 3D print arbitrary two-dimensional patterns, including the letters M-I-T. Shapes can be fully formed in mere seconds.

In the long term, the researchers envisage a system where a photonic chip sits at the bottom of a resin well and emits a 3D hologram of visible light, rapidly curing an entire object in one step. This portable 3D printer could have numerous applications, such as enabling clinicians to create tailor-made medical device components or allowing engineers to make rapid prototypes at job sites.

Jelena Notaros, the Robert J. Shillman Career Development Professor in Electrical Engineering and Computer Science (EECS) and a member of the Research Laboratory of Electronics, commented: “This system is completely rethinking what a 3D printer is. It is no longer a big box sitting on a bench in a lab creating objects, but something that is handheld and portable. It is exciting to think about the new applications that could come out of this and how the field of 3D printing could change.”

Joining Notaros on the paper were Sabrina Corsetti, lead author and EECS graduate student; Milica Notaros, PhD ’23; Tal Sneh, an EECS graduate student; Alex Safford, a recent graduate of the University of Texas at Austin; and Zak Page, an assistant professor in the Department of Chemical Engineering at UT Austin. The research was published in Nature Light Science and Applications.

Printing with a chip

The Notaros group, experts in silicon photonics, previously developed integrated optical-phased-array systems that steer beams of light using microscale antennas fabricated on a chip with semiconductor manufacturing processes. By adjusting the optical signal speed on either side of the antenna array, they can direct the emitted light beam.

Such systems are crucial for lidar sensors, which map surroundings by emitting infrared light beams that reflect off nearby objects. Recently, the group focused on systems emitting and steering visible light for augmented-reality applications, pondering if such a device could be adapted for a chip-based 3D printer.

At around the same time, the Page Group at UT Austin demonstrated specialised resins that rapidly cure using visible light wavelengths. This breakthrough enabled the chip-based 3D printer to become a reality. Sabrina Corsetti noted: “With photocurable resins, it is very hard to get them to cure all the way up at infrared wavelengths, which is where integrated optical-phased-array systems were operating in the past for lidar. Here, we are meeting in the middle between standard photochemistry and silicon photonics by using visible-light-curable resins and visible-light-emitting chips to create this chip-based 3D printer. You have this merging of two technologies into a completely new idea.”

Their prototype chip contains an array of 160-nanometre-thick optical antennas. When powered by an off-chip laser, these antennas emit a steerable beam of visible light into a resin well. The chip sits below a clear slide, similar to those used in microscopes, which holds the resin. Researchers use electrical signals to non-mechanically steer the light beam, causing the resin to solidify upon contact.

A collaborative approach

Modulating visible-wavelength light, which involves modifying its amplitude and phase, presents challenges. Heating the chip is a common but inefficient method requiring substantial physical space. Instead, researchers used liquid crystal to create compact modulators integrated onto the chip. This material's unique optical properties allowed for efficient modulators only about 20 microns in length.

A single waveguide on the chip channels the light from the off-chip laser, with tiny taps directing light to each antenna. Researchers tune the modulators using an electric field to precisely control the light’s amplitude and phase routed to the antennas.

Forming and steering the beam was only half the challenge. Interfacing with a novel photocurable resin required collaboration between the Page Group at UT Austin and the Notaros Group at MIT. They fine-tuned the chemical combinations to achieve a long shelf-life and rapid curing.

Using their prototype, the team successfully 3D printed arbitrary two-dimensional shapes within seconds. Building on this, they aim to develop a system where a chip emits a hologram of visible light in a resin well, enabling volumetric 3D printing in a single step. Jelena Notaros stated: “To be able to do that, we need a completely new silicon-photonics chip design. We already laid out a lot of what that final system would look like in this paper. And now, we are excited to continue working towards this ultimate demonstration.”