Real 3D Writing by Two Photon Induced Polymerization

摘要

Photo induced polymerization is utilized in stereolithography and rapid prototyping to provide 3D structures with greatly improved resolution in comparison to melt based 3D printing. Traditional stereolithography tends to be limited, however, to the diffraction limit of the light used. Achieving even smaller features is possible, and two-photon induced photopolymerization (TPIP) is one of the more promising top-down approaches for doing this [1-3]. As the name implies, TPIP requires the absorption of two photons for an initiating molecule to be activated to induce polymerization. This necessitates an extremely high flux of light provided by a femtosecond- pulsed NIR laser. Since polymerization can occur only within the focus of the laser beam, resolution is about one order of magnitude better (line widths of about 100 nm) than μ- stereolithography. Fundamentally, the biggest advantage is that this level of control is afforded not just in the x-y plane but also along the z-axis, thus “real” 3D writing can be performed within a suitable matrix to provide cured 3D structures [4]. Interestingly, since water and hydrocarbons are virtually transparent in the NIR, it is possible to write through living tissue without causing damage [5]. The capabilities of TPIP are likely still not fully realized but already provide great promise in diverse fields such as microelectronics, μTAS, optical communications, and regenerative medicine [6,7].