ABSTRACT
Miniaturization is one of the key forces driving down the cost of modern drug discovery research. In addition to reducing the volume of reagents used in expensive screening assays, miniaturization also allows a substantial increase in the number of data points in each experiment. The best example of this is in the area of DNA microarrays, where a single experiment can probe the function of thousands of genes. The cost-effective use of DNA microarrays is a direct result of improvements in the ability of scientists to dispense nanoliter to picoliter volumes of liquids to a solid support. Contact liquid dispensing with pin tools and non-contact liquid dispensing based on inkjet technologies are two approaches that provide a means to rapidly generate DNA microarrays. Contact liquid dispensing technology is more mature than non-contacting liquid dispensing technology, and is the dominant platform for generating DNA microarrays. Contact liquid dispensing benefits from technically simple pin tools that provide reliable performance and accuracy in both the volume and position of spots on solid supports. While more technically challenging, non-contact liquid dispensing provides a means to dispense samples to a greater variety of substrates and it has the potential of very high throughput based on techniques such as dispense-on-the-fly. The major difference between contact and noncontact liquid dispensing is the influence the substrate has on dispensing parameters. Contact liquid dispensing relies on the interaction between the substrate, liquid sample, and the pin tool to determine the volume of the dispensed liquid. The volume of liquid dispensed by non-contact methods is influenced only by conditions within the dispensing tip. The unique capabilities of non-contact liquid dispensing suggest that this approach will eventually surpass the popularity of contact liquid dispensing techniques for generating microarrays. In this chapter, we will explore the technical aspects of noncontact liquid dispensing technologies and show how microarray applications in life science research benefit from this approach.
