By Cnr Ifn
Direct laser writing with ultrashort laser pulses is a promising three-dimensional microfabrication method that has recently attracted considerable attention. When focused into the volume of a photosensitive material (or photoresist), the ultrashort pulses initiate a multi-photon absorption process that leads to a very localized polymerization. After illumination of the desired structures inside the photoresist volume and subsequent development — e.g., washing out the non-illuminated regions — the polymerized material remains in the prescribed 3-D form. This allows fabrication of any computer-generated 3-D structure by direct laser writing into the volume of a photosensitive material. Because of the threshold behavior and nonlinear nature of the process, a resolution beyond the diffraction limit can be achieved by tailoring the irradiation conditions. At IFN-CNR we have a long tradition in direct laser writing, with two homebuild setups targeting several applications. Current trends include the development of 3D scaffolds for cell proliferation and differentiation, the fabrication of lab-on-chip with engineered constrictions for cell motility studies and the realization of microlenses with arbitrary profile.
