The broader impact of this Small Business Innovation Research (SBIR) Phase I project will be the development of a new strategy for patterning polymers on the microscale. Specifically, this project will develop a high-resolution volumetric 3D printer. This printer will generate objects in high performance materials that feature no accompanying support structures, and minimal artifacts such as layering from the printing process. This project will achieve printing at the focal point of a laser beam. Because this process has substantially reduced power requirements, printing can be achieved much faster and a a significantly reduced cost. This technology will support rapid prototyping of ultrahigh resolution parts or creation of microelectromechanical systems and will enable widespread use. This project will build a volumetric 3D printer based on photon upconversion nanocapsules. These nanocapsules contain a liquid core of molecules that undergo triplet-triplet annihilation to convert red photons to blue photons with a quadratic power dependence. When paired with an appropriate photopolymerization scheme that is activated by blue light but transparent to red light, these nanocapsules can be used to drive polymerization exclusively at the focal point of a red laser. The development of larger anti-stokes shifts for the upconversion process, and the enhancement of the upconversion efficiency will allow for rapid printing. Work optimizing upconversion wavelengths and efficiencies will be achieved using photoluminescence spectroscopy. The development of multiplexed optical schemes will further enhance the printing speed. Beam profiling will be performed to determine the success of light-shaping approaches. Functionalization of the nanocapsules will allow them to be made compatible with a broad range of 3D printing resins. Development of resins especially suited for this style of 3D printing will further differentiate this technology from existing approaches to 3D printing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
