Development of multianalyte sensor arrays composed of chemically derivatized polymeric microspheres localized in micromachined cavities

The development of a chip-based sensor array composed of individually addre ssable polystyrene-poly(ethylene glycol) and agarose microspheres has been demonstrated. The microspheres are selectively arranged in micromachined ca vities localized on silicon wafers. These cavities are created with an anis otropic etch and serve as miniaturized reaction vessels and analysis chambe rs. A single drop of fluid provides sufficient analysis media to complete s imilar to 100 assays in these microetch pits. The cavities possess pyramida l pit shapes with trans-wafer openings that allows for both fluid flow thro ugh the microreactors/analysis chambers and optical access to the chemicall y sensitive microspheres. Identification and quantitation of analytes occur s via colorimetric and fluorescence changes to receptor and indicator molec ules that are covalently attached to termination sites on the polymeric mic rospheres. Spectral data are extracted from the array efficiently using a c harge-coupled device allowing for the near-real-time digital analysis of co mplex fluids. The power and utility of this new microbead array detection m ethodology is demonstrated here for the analysis of complex fluids containi ng a variety of important classes of analytes including acids, bases, metal cations, metabolic cofactors, and antibody reagents.