Non-contact printing

The microarray manufacturing method that enables microarray printing without direct contact to the surface is termed non-contact printing. Piezoelectric, bubble-generated, and microsolenoid driven pipettes as shown in Fig. 3 work with the same physical principle as ink-jet printers and are capa-... 

Fig. 3 Spotting tools for non-contact printing a Bubble ink-jet A heating coil locally heats the loaded sample, resulting in a changed viscosity and expansion of fluids. The generated droplet can be easily expelled from delivery nozzles, b Microsolenoid A microsolenoid valve, fitted with the ink-jet nozzle is actuated by an electric pulse transiently opening the channel and dispenses a defined volume of the pressurized sample, c Piezo ink-jet A piezoelectric transducer that is fitted around a flexible capillary confers the piezoelectric effect based on deformation of a ceramic crystal by an electric pulse. An electric pulse to the transducer generates a transient pressure wave inside the capillary, resulting in expulsion of a small volume of sample...

Non-contact printing — Since inkjet does not use contact between the substrate and the printing head, it is relatively free from the main disadvantages of contact printing, namely degradation of the print quality over time due to abrasion of the print form, and also )deld loss due to particles. 

Non-contact printing—there is neither direct nor indirect contact (e.g. offset processes). Examples ink jet and laser printing. 

Packard Bioscience SpotArray Bio Chip Arrayer Non-contact printing with a piezo-electric printhead. Spot size of 75 to 200 p dependent upon the pin type. www.packardbioscience.com... 

For the production of different types of microarrays, a wide variety of microarray production techniques and specialized microarrayers are available. This entiy will focus on the three basic techniques commOTily used on-chip synthesis, contact printing techniques, and non-contact printing techniques. In the following, currently available microarray production methods are presented, but the discussicm does not claim to be exhaustive. 

In addition to on-chip approaches and contact and non-contact printing of agents onto microarrays, there are further methods for microarray fabrication. Two examples are the protein profiling chips offered by the company Zyomyx and the electronic microarrays offered by the company NanoGen. 

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. 

Ink-jet printing- Non-contact printing that uses electrostatic acceleration and deflection of ink particles released by small nozzles to form the pattern. 

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. 

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