Fast and affordable printing of polymeric nanostructures via superluminescent light projection

Abstract

The ability to additively manufacture polymeric nanostructures is highly desirable, but existing light-based techniques are challenging to scale up due to the need to engineer optical nonlinearity into the process. This nonlinearity enables overcoming the optical diffraction limit so that nanoscale features that are smaller than the focused light spot can be printed. However, achieving optical nonlinearity requires either expensive high-intensity femtosecond lasers to activate multi-photon absorption or novel custom-designed photoresists to activate multi-step absorption. Here, we present the superluminescent light projection (SLP) technique as an alternative approach that does not require one to engineer optical nonlinearity into the process, yet it is still capable of sub-diffraction printing. We achieved this by digitally patterning a low-intensity light beam generated from a low-cost superluminescent diode and projecting the patterned beam into a UV-curable photoresist. SLP can print features as small as 325 nm with 405 nm light and at an intensity of 36 W/cm², which is more than 25 billion times lower than that required for multi-photon 3D printing. Furthermore, it enables rapid printing of 3D structures through its layer-by-layer writing mechanism at a voxel generation rate of up to 2.3 × 10⁵ voxels/s using a system which is 35 times less expensive than multi-photon printers. Thus, SLP can significantly advance the affordability of rapid nanoscale 3D printing for a variety of applications.