Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Proof of concept instrument

The University of Manchester's responsibility was to design an overall instrument platform to enable detection of the effects of oxygen quenching on fluorophores and enzymes incorporated into an ORMOCER film.

UoM designed and built a a prototype for use by the other partners to allow them to evaluate the biosensor coatings developed. The prototype was built so that as well as being a development tool, it will form the basis of a field trial unit when the other partners have completed the development of the sensitive ORMOCER films incorporating Ruthenium complex and enzymes.

The detection method was lifetime changes due to oxygen quenching due to immunity to coupling and ageing effects within the optical engineering pathway. A Photomultiplier tube (PMT) is used for detection together with ratiometric photon counting.

Excitation light at 470 nm is delivered to the sensitive film supported on a glass substrate by a fibre bundle. Fluorescent light centred on 590 nm is collected from the film and returned to the instrument housing where it is amplified by the Photomultiplier tube to produce discrete pulses corresponding to collection of individual photons. These pulses are counted electronically and measure the fluorescent intensity decay at precise points in time. The ratiometric method assumes the lifetime decay to be amplitude independent and only depends on exponential decay processes characterised by decay constants (lifetimes). By measuring the light intensity at two contiguous points within a few microsecond after the cessation of the excitation and forming a ratio from these two intensities then a value is produced which is a function of - and is single valued for any value of the decay lifetime. This functional dependance of the ratio is used together with a pre-calibrated lookup table to measure the value of the oxygen at the fluorophore sites.

The above technology has been incorporated into an industrial housing suitable for field trials.

Reported by

UNIVERSITY OF MANCHESTER Address: Centre for Instrumentation and Analytical Science (CIAS) School of Chemical Engineering and Analytical Science Sackville Street P.O.Box 88 M60 1QD Manchester UNITED KINGDOM
United Kingdom
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