Direct laser printing of biotin microarrays on low temperature oxide on Si substrates

Laser Induced Forward Transfer (LIFT) technique is a direct-write method allowing the effective deposition of a wide range of materials with high spatial resolution. In this work, we present the direct printing of microarrays from a biotin solution by using a Nd:YAG laser (266nm wavelength, 4ns pulse duration). Standard materials of microelectronics such as Si and Low Temperature Oxide on Si (LTO/Si) were used as receiving substrates. For the LTO substrate, a detailed study for the optimum surface functionalization was carried out as it is a common passivation layer for biosensors. The laser beam parameters, such as the energy density and the beam size, were systematically varied in order to evaluate the effect on the transferred droplets. Furthermore, the energy density threshold for the ejection of the droplets was defined. Finally, the viability of the deposited droplets was demonstrated through the biotin-streptavidin reaction on silane coated LTO/Si substrates. This reaction was confirmed by fluorescence microscopy. These results have shown that the LIFT process can be used for biosensors and possibly for label-free detection by the combination of the method with capacitive sensors, sensors based on cantilevers or other sensors with electrical output. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim