Nano- and pico-dispensing of fluids on planar substrates using SAW

The increasing interest in miniaturization of biological and chemical experiments or assays demands precise metering of the smallest amounts of reagents, e.g., on a planar substrate. Very sophisticated spotting systems can nowadays produce arrays of many thousands of different substances on an area of a few square inches. Such micro arrays and the technology behind them have become an important tool in genomic expression assays, proteomic applications, and even in the field of combinatoric chemistry. We present a technique to dispense the smallest amounts of fluids in the form of either simple spots or more complicated microarrays, where we use surface acoustic waves in combination with a predetermined surface chemistry. In addition to a detailed description of the technique, several examples of applications are presented.