Title: Laser Microfabrication and Nanofabrication of Medical Devices Speaker: Professor Roger Narayan, Ph.D., School of Engineering, North Carolina State University Date/Time: Monday, April 12, 2010, 10:00 am Location: CSRI Building/Room 279 (NM) & the 940 Auditorium in SNL/CA Brief Abstract: Most current medical applications of lasers involve use of the laser as an “optical scalpel” in minimally invasive surgery techniques that involve little blood loss, little or no laser-tissue contact, accurate removal of unwanted tissue, and shorter operating times. Lasers have recently found greater use in processing cells and materials. Laser direct writing, two photon induced polymerization, and other laser-based processes may be used to process cells and materials with unique structures and added functionalities for next generation medical and dental prostheses. We have demonstrated a novel approach for layer-by-layer growth of tissue engineered materials using a laser direct writing process known as matrix assisted pulsed laser evaporation- direct write (MAPLE-DW). In MAPLE-DW, a biomaterial is solvated in a transparent matrix and spin-coated onto a quartz disk. The biomaterial-seeded quartz disk is then placed in a position such that the biomaterial-coated side faces the substrate. A low-energy argon fluoride laser pulse propels the material from the biomaterial-seeded ribbon to the underlying substrate. Laser-based processing provides several advantages over conventional tissue engineering techniques. These include: (1) enhanced biomaterial-substrate adhesion, (2) deposition can be performed under ambient conditions, (3) the amount and location of transferred material can be quantitatively determined, and (4) multilayered structures can be prepared using multiple quartz disks or segmented targets. Three-dimensional patterning of cells and fabrication of differentially adherent surfaces have recently been demonstrated using MAPLE-DW. We have also recently demonstrated direct writing of three-dimensional medical device nanostructures by two photon polymerization of inorganic-organic hybrid materials. This technique involves the application of light to induce several chemical reactions between starter molecules and monomers in a transparent resin. Femtosecond laser pulses from a titanium:sapphire laser are tightly focused by a high numerical-aperture objective lens into a focal volume within the photosensitive resin. Within the vicinity of the focal volume, nonlinear absorption of the laser pulses breaks chemical bonds on starter photoinitiator molecules. Structures are fabricated by moving the laser focus in three dimensions. The quadratic character of the two photon absorption probability and the well-defined polymerization threshold allow structures with sub-micrometer features to be prepared. Two-photon polymerization has recently been used to prepare microneedles, ossicular replacement prostheses, and other medical devices. CSRI POC: Elebeoba May, (505) 844-9933 |