Time resolved schlieren study of sub-pecosecond and nanosecond laser transfer of biomaterials

A comparative study of the effect of ultrashort (0.5 ps) and short (15 ns) pulses on the laser forward transfer of DNA molecules is presented in this paper. We use femtosecond laser pulses to directly print a wide range of biomaterials, in complicated patterns and structures. The ultrashort laser pulses reduce the thermal effects, thus allowing the effective deposition of sensitive biomaterials at high spatial resolution for micro-fabricating patterns. This direct laser printing process enables gentle and spatially selective transfer of biomaterials and facilitates application possibilities for the fabrication of biosensors and arrays for multi-analyte assays. Here, we present the direct micro-printing of biomaterials such as enzyme patterns by laser-induced forward transfer method using 500 fs laser pulses emitted at 248 nm. Furthermore, the dynamics of the process was investigated by stroboscopic schlieren imaging for time delays up to 3 ms following the laser irradiation pulse. # 2005 Published by Elsevier B.V.