Droplet release in a highly parallel, pressure driven nanoliter dispenser

For the first time we report about the correlation between satellite free droplet release and liquid viscosity in a highly parallel, pressure driven nanoliter dispenser. In extensive studies we found that for liquids of different viscosities the length of the pressure pulse is the predominant effect compared to pressure amplitude. This result is of essential importance when actuation parameters have to be adopted for different media like oligonucleotide, DNA or protein solutions as it is the case for the non-contact high-throughput fabrication of microarrays. For each used printing buffer we found the CV to be better than 1 % within one single dispensing channel and 1.5 % within all 24 channels at a pitch of 500 /spl mu/m.