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Researchers from MIT and the University of Texas at Austin have taken a significant step toward the vision of a portable 3D printer by demonstrating the first chip-based 3D printer. This innovative device consists of a millimetre-scale photonic chip that emits reconfigurable beams of light into a resin, curing it into a solid shape upon contact.
The prototype chip relies on an array of tiny optical antennas to steer a beam of light, projecting it into a specially designed liquid resin that cures quickly when exposed to visible light. This groundbreaking combination of silicon photonics and photochemistry allows the chip to steer light beams to 3D print complex two-dimensional patterns, including intricate designs like the letters M-I-T, within seconds.
“This system completely rethinks what a 3D printer is. It’s no longer a big box in a lab but something handheld and portable. The potential new applications and the transformative impact on 3D printing are exciting,” said Jelena Notaros, Robert J Shillman, Career Development Professor in Electrical Engineering and Computer Science (EECS) and an MIT Research Laboratory of Electronics member.
The merger of standard photochemistry with silicon photonics using visible-light-curable resins and visible-light-emitting chips creates this chip-based 3D printer. “With photocurable resins, it’s tough to get them to cure at infrared wavelengths, which is where integrated optical-phased-array systems previously operated for lidar,” explains Sabrina Corsetti, lead author and EECS graduate student.
Their prototype comprises a single photonic chip with 160-nanometer-thick optical antennas fitting onto a U.S. quarter. When powered by an off-chip laser, the antennas emit a steerable beam of visible light into a well of photocurable resin. Like those used in microscopes, the chip sits below a clear slide, containing a shallow indentation that holds the resin. Electrical signals nonmechanically steer the light beam, solidifying the resin wherever the beam strikes.
Modulating visible-wavelength light, which involves adjusting its amplitude and phase, is particularly challenging. One common method requires heating the chip, which could be more efficient and space-consuming. Instead, the researchers used liquid crystals to create compact modulators integrated into the chip. The material’s unique optical properties enable these modulators to be extremely efficient and only about 20 microns long.
A single waveguide on the chip channels the light from the off-chip laser. Tiny taps along the waveguide divert a bit of light to each antenna. The researchers use an electric field to tune the modulators, reorienting the liquid crystal molecules to precisely control the light’s amplitude and phase.
Forming and steering the beam was only part of the challenge. Interfacing with a novel photocurable resin posed additional hurdles. The Page Group at UT Austin worked closely with the Notaros Group at MIT, fine-tuning the chemical combinations and concentrations to achieve a formula with a long shelf-life and rapid curing.
The group used their prototype to 3D print complex two-dimensional shapes within seconds. They aim to develop a system where a chip emits a hologram of visible light in a resin well for volumetric 3D printing in a single step.
“To achieve that, we need a new silicon-photonics chip design. In this paper, we’ve outlined much of what that final system would look like. We are excited to continue working toward this ultimate demonstration,” says Jelena.
Looking ahead, the researchers envision a system where a photonic chip sits at the bottom of a resin well, emitting a 3D hologram of visible light to cure an entire object in a single step. Such a portable 3D printer could revolutionise various fields, enabling clinicians to create tailor-made medical device components on-site or allowing engineers to make rapid prototypes at job sites.
