Laser-induced forward transfer of pre-machined donor films
Micro-pellets of ZnO with a diameter of 5-10 μm and extremely smooth edges have been printed using laser-induced forward transfer from 1 μm thick films, that had been prepatterned using focussed ion beam (FIB) machining.
Study on metal microparticle content of the material transferred with Absorbing Film Assisted Laser Induced Forward Transfer when using silver absorbing layer
Abstract Absorbing Film Assisted Laser Induced Forward Transfer (AFA-LIFT) is a modified LIFT method where a high absorption coefficient thin film coating of a transparent substrate is used to transform the laser energy into kinetic in order to transfer the “target” material spread on it. This method can be used for the transfer of biomaterials and living cells, which could be damaged by direct irradiation of the laser beam. In previous experiments, ∼50–100 nm thick metal films have been used as absorbing layer. The transferred material can also contain metal microparticles originating from the absorbing thin film and acting as non-desired impurities in some cases. The aim of our work was to study how the properties (number, size and covered area) of metal particles transferred during the AFA-LIFT process depend on film thickness and the applied fluence. Silver thin films with different thickness (50–400 nm) were used as absorbing layers and real experimental conditions were modeled by a 100 μm thick water layer. The particles transferred without the use of water layer were also studied. The threshold laser fluence for the complete removal of the absorber from the irradiated area was found to strongly increase with increasing film thickness. The deposited micrometer and submicrometer particles were observed with optical microscope and atomic force microscope. Their size ranged from 100 nm to 20 μm and depended on the laser fluence. The increase in fluence resulted in an increasing number of particles of smaller average size.
The deposition, structure, pattern deposition, and activity of biomaterial thin-films by matrix-assisted pulsed-laser evaporation (MAPLE) and MAPLE direct write
Two techniques, Matrix-Assisted Pulsed-Laser Evaporation (MAPLE) and MAPLE Direct Write (MDW) were developed to deposit biomaterial thin-films. MAPLE involves dissolving or suspending the biomaterial in a volatile solvent, freezing the mixture to create a solid target, and using a low fluence pulsed laser to evaporate the target for deposition of the solute inside a vacuum system. Using simple shadow masks, i.e. lines, dots and arrays, pattern features with length scales as small as 20 μm can be deposited using multiple materials on different types of substrates. MDW uses pulsed laser to directly transfer material from a ribbon to a substrate. Patterns with a spatial resolution of ∼10 μm can be written directly. Biomaterials ranging from polyethylene glycol to eukaryotic cells, i.e. Chinese hamster ovaries, were deposited with no measurable damage to their structures or genotype. Deposits of immobilized horseradish peroxidase, an enzyme, in the form of a polymer composite with a protective coating, i.e. polyurethane, retained their enzymatic functions. A dopamine electrochemical sensor was fabricated by MDW using a natural tissues/graphite composite. These examples and the unique features of MAPLE and MDW for biosensor fabrication have been discussed.