Opto-electronic immunosensors: a review of optical immunoassay at continuous surfaces

Optical techniques for monitoring immunological reactions on continuous surfaces are reviewed. Initially Langmuir-Blodgett film techniques and ellipsometry are discussed, followed by internal reflection spectroscopy (IRS) systems. The latter includes attenuated total reflection (ATR) and total internal reflection fluorescence (TIRF). Finally, light scattering and surface plasmon resonance methods are presented. Overall, it was considered that the IRS systems and ellipsometric approaches offered the most promise for the design of a specific immunosensor device. Of these two, the ellipsometric methods are the most sensitive but also the most vulnerable to non-specific signal interference. Although lacking in extreme sensitivity, the IRS approaches reviewed were more specific in signal generation and were considered to have considerable potential for the future.