Microarray printhead

A microarray printhead has been developed with a plurality of glass or quartz spotting capillaries disposed in a support that maintains a fixed spacing between the spotting capillaries, and that permits the spotting capillaries to move in a direction parallel to the long axis of the capillaries (82). 

Inkjet printing techniques can be used that forcibly eject fluid droplets from a printhead structure. The ejected droplets fly through the air and land on the substrate. The methods of traditional inkjet printers cannot be directly translated to microarray applications. 

For example, the TopSpot technology [3, 4] has been developed for the fast mass production of low- and medium-density microarrays. The system enables highly parallel non-contact printing of different media like oligonucleotides, DNA or protein solutions. It is based on a micromachined printhead which is driven by a separate actuation unit. The printhead formats allow the simultaneous application of 24, 96 and even 384 different reagents in one step. A 24-channel TopSpot printhead and the corresponding working principle are displayed in Fig. 2. 

In recent years, advances in microelectronic fabrication technology have led to many vapor-bubble actuators, such as thermal inkjet printheads, vapor-bubble micropumps, vapor-bubble perturbators and DNA microarrayers. In all of these microelectromechanical devices, microbubble(s) are generated on a microheater under pulse heating with pulse widths ranging from microseconds to milliseconds. 

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