High density oligonucleotide expression arrays are a widely used tool for the measurement of gene expression on a large scale. Affymetrix GeneChip arrays appear to dominate this market. These arrays use short oligonucleotides to probe for genes in an RNA sample. Due to optical noise, non-specific hybridization, probe-specific effects and measurement error, ad-hoc measures of expression, that summarize probe intensities, can lead to imprecise & inaccurate results. Various researchers have demonstrated that expression measures based on simple statistical models can provide great improvements over the ad-hoc procedure offered by Affymetrix. Recently, physical models based on molecular hybridization theory, have been proposed as useful tools for prediction of, for example, non-specific hybridization. These physical models show great potential in terms of improving existing expression measures.

Carbohydrate microarrays have been used in glycomics research to examine the interactions of carbohydrates with other molecules. The chip-based format of microarrays offers important advantages over common screening techniques, such as enzyme-linked immunosorbent assays (ELISAs), because several thousand binding events can be screened on a single glass slide & only minuscule amounts of analyte and ligand are required. Assay miniaturization is particularly suitable for glycomics, because access to pure oligosaccharides is the limiting factor. The first carbohydrate microarrays relied on isolated saccharides that were non-covalently attached to membranes. Current screening efforts rely on carbohydrate arrays in which chemically or enzymatically synthesized & isolated oligosaccharides with a linker on the reducing terminus are covalently attached to glass slides. Standard DNA printing and scanning equipment is used to produce & analyse the carbohydrate microarrays Carbohydrate microarrays can be used to address the interactions of sugars with other types of molecules, as well as entire cells. Carbohydrate-RNA interactions were screened by incubating labelled RNA with aminoglycoside microarrrays. Mechanisms responsible for antibiotic resistance were studied using these arrays together with resistance-causing enzymes.