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High-sensitivity integrated optical fluoroimmunassay array chip

An integrated optical chip is being developed by the ORC, which will allow 32 simultaneous fluorescence-based immunoassays to be conducted with high sensitivity in a compact instrument. Optical wave guides are defined at the surface of a glass “chip” using the fabrication techniques familiar from microelectronics. These wave guides conduct light around the surface of the chip, in an integrated optical circuit, to the 32 sites where the surface is chemically modified for specificity to a particular analyte. Light is introduced from a semiconductor laser diode and wave guides are optimised at the sensing sites to yield efficient excitation of surface fluorescence using the evanescent fields. The final chip size is approximately 15mmx68mm, and the fluorescent patch sizes are approximately 0.2mmx1.5mm. Prototype chips have been fabricated and are presently being tested without permanently attached fibre pigtails.

Applications of this result will be in environmental monitoring, medical diagnostics and biotechnology. The applications are not for screening very large numbers of compounds in high concentrations, but fairly low numbers of compounds in very low concentrations. End-users will include instrument manufacturers and scientific researchers who wish to analyse small volumes of analyte for multiple compounds with good stability and repeatability and low detection limit.

The main innovative features are the wave guide design leading to high sensitivity, the massfabrication technology employed for the chips, which will help keep unit costs down, and the robust connection to instrumentation which is expected to lead to greater reliability and ease of use and to reduced detection limit through improved stability. These chips are being developed for fluorescence-based measurements but may be applied to other surface scattering or luminescence techniques, such as Raman spectroscopy.

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Reported by

Eberhard-Karls-University of Tuebingen
Auf der Morgenstelle 8
72076 Tubingen
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