Types of printing
pins
(A)Tweezers or split-pin designs
transfer low nanoliter (10-9 liter) amounts of DNA to the array by capillary action as the tip strikes the solid surface.
(B)TeleChemTM tips and pins apply small droplets by contact between the pin and
substrate.
(C)Pin-and-loop design picks up the
DNA in a small loop, and a
pin stamps solution on a slide at a uniform density.
(D)Ink jets spray picoliter (10-12
liter) droplets of liquid under pressure.
The spacing between spot centers is specified form 120-250 μm according to the density required. The entire microarray usually covers an area 2.5x5.0 cm, though shorter grids can be printed when fewer clones are to be represented.