ORC Seminar Series

Pre Viva Talk


"Integrated Optical Fluorescence Multi-Sensor System"

Speaker: Ping Hua

Date: 3 June 2009

Venue: B53 Seminar Room


Research on fluorescence-based integrated optical immunoassay multisensing systems has gained growing interest in the last ten years.  This is because the systems have the potential to simultaneously detect multiple analytes in a single measurement, and the techniques involved are fast, robust and cost-effective.  Therefore they have the potential to replace conventional chromatographic techniques, as the monitoring systems for the rapid assessment of water or food samples.  Other areas, such as clinical diagnostics or forensic science also have a demand for highly multiplexed analytical systems.   

This talk will present a novel 32-analyte integrated optical fluorescence-based multisensor, and its integration to an automated multi-bio-sensing system.  This system is primarily used for detecting organic pollutants in river water.

A fibre-pigtailed sensor chip consists of a channel waveguide circuit which distributes evanescent excitation light to 32 separate sensing patches on the chip surface is realised.   Bio/immunochemistry may be used to sensitise each of the 32 patches to a specific analyte and a microfluidic system is used to automatically handle the sample injection over the sensor surface, enabling rapid, simultaneous and high-sensitivity fluorescence detection of up to 32 pollutants.  A fibre coupled photodiode detection array monitors the 32 separate fluorescence signals, and software controls the laser, fluidics, data acquisition and processing of the fluorescence signals and records the laser power and ambient and chip temperature.

The surface immunochemistry used in this research was based on binding inhibition tests that require antibodies directed against specific analytes and analyte derivatives that can be covalently bound to a transducer surface.  The sensing system was characterised for a single analyte, estrone, and a limit of detection (LOD) below 1 ngL-1 was achieved.  The sensing system was then applied against up to six organic pollutants (propanil, atrazine, isoproturon, sulphamethizole, bisphenol A and estrone) and the LODs below 0.020 µgL-1 were achieved for all six analytes.

In addition, this talk will present the outcome of study in a CCD detector system, used to replace the fibre collection and photodiode array system and allow straight forward extension to more than 32 analytes.  A direct comparison between these two systems will be also presented.

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