Absorbing film assisted laser induced forward transfer of fungi (Trichoderma conidia)

We present an investigation on absorbing film assisted laser induced forward transfer (AFA-LIFT) of fungus (Trichoderma) conidia. A KrF excimer laser beam [lambda=248 nm,FWHM=30 ns (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 0-2600 mJ/cm(2) and each laser pulse transferred a pixel of target material. The average irradiated area was 8x10(-2) mm(2). 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 355 mJ/cm(2) the transferred and germinated pixel area increased from 0 to 0.25 mm(2). Further increase in fluence resulted in a drastic decrease down to an approximately constant value of 0.06 mm(2). The yield of successful transfer by AFA-LIFT and germination was as much as 75% at 355 mJ/cm(2). The results prove that AFA-LIFT can successfully be applied for the controlled transfer of biological objects. (C) 2004 American Institute of Physics.