TOPSPOT-a new method for the fabrication of microarrays

This article outlines the new non-contact TOPSPOT method for printing microarrays in a highly parallelized fashion. It is based on a micromachined print head incorporating a central microarray of presently up to 96 vertical nozzles on the output side. Droplets featuring volumes down to 1nl aligned in a 500 μm grid are simultaneously ejected by applying a steep air pressure ramp to the open upper side of the liquid. Each of these nozzles is connected to a distinct fluidic reservoir constituting the interface to the macro world. To allow an automated replenishing of the chip, the alignment of the reservoirs is amenable for liquid handling via standard pipetting robots. Depending on the design of the print head, a maximum of 20 μl can be stored thus allowing one to dispend about 20.000 droplets of equal quality in a row. Besides its suitability for a robust biochip manufacturing facility in the laboratory, the print head is also well-integrable in a high-throughput production plant. These versions are scheduled to become commercially available in 2000