The survival, proliferation, and differentiation of freshly isolated and cultured cells were studied after absorbing film-assisted laser-induced forward transfer. Rat Schwann and astroglial cells and pig lens epithelial cells were used for transfer and the cells were cultured for 2 weeks after laser-pulsed transfer. All three cell types survived, proliferated, and differentiated under cell culture conditions and regained their original phenotype a few days after cell transfer. Time resolution studies have shown that the time required to accelerate the jets and droplets containing the cells was less than 1 micros and that the estimated minimum average acceleration of those ejected cells that reached a constant velocity was approximately 10(7) x g. This suggests that the majority of studied cells tolerated the extremely high acceleration at the beginning of the ejection and the deceleration during impact on the acceptor plate without significant damage to the original phenotype. These results suggest that the absorbing film-assisted laser-induced forward transfer technique appears to be suitable for several potential applications in tissue engineering and the biomedical tissue repair technologies.

We present an investigation on absorbing film assisted laser induced forward transfer (AFA-LIFT) of fungus (Trichoderma) conidia. A KrF excimer laser beam [λ=248nm,FWHM=30ns (FWHM, full width at half maximum)] was directed through a quartz plate and focused onto its silver coated surface where conidia of the Trichoderma strain were uniformly spread. The laser fluence was varied in the range of 0–2600mJ∕cm2 and each laser pulse transferred a pixel of target material. The average irradiated area was 8×10−2mm2. After the transfer procedure, the yeast extract medium covered glass slide and the transferred conidia patterns were incubated for 20 h and then observed using an optical microscope. The transferred conidia pixels were germinated and the areas of the culture medium surfaces covered by the pixels were evaluated as a function of laser fluence. As the laser fluence was increased from 0 to 355mJ∕cm2 the transferred and germinated pixel area increased from 0 to 0.25mm2. Further increase in fluence resulted in a drastic decrease down to an approximately constant value of 0.06mm2. The yield of successful transfer by AFA-LIFT and germination was as much as 75% at 355mJ∕cm2. The results prove that AFA-LIFT can successfully be applied for the controlled transfer of biological objects.

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Polytetrafluoroethylene (PTFE) thin films were prepared from pressed powder pellets via pulsed laser deposition by using ArF (193 nm) excimer laser. The applied laser fluences were in the 1.6-10 J cm-2 range, the substrate temperature was varied between 27°C and 250°C and post-annealing of the films was carried out in air at temperatures between 320°C and 500°C. Films deposited at 250°C substrate temperature were found to be stoichiometric while those prepared at lower temperatures were fluorine deficient. Morphological analyses proved that the film thickness did not significantly depend on the substrate temperature and the post annealing at 500°C resulted in a thickness reduction of approximately 50%. It was demonstrated that the films prepared at 8.2 J cm-2 fluence and annealed at 500°C followed by cooling at 1°C min-1 rate were compact, pinhole-free layers. The adherence of films to the substrates was determined by tensile strength measurements. Tensile strength values up to 2.4 MPa were obtained. These properties are of great significance when PTFE films are fabricated for the purpose of protecting coatings.

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