Anti-biofouling coatings for optical fiber sensors

Abstract

One of the most relevant problems of using optical fiber sensors in real-world environments is surface fouling, that is the cumulative build-up of undesirable material on the working surface of the sensor.

One of the scopes of the Brite-EuRam Project 'BOSS' was the development of non-toxic, optically-transparent and biologically-inert materials, suitable to inhibiting or reducing bio-fouling, to be used as coatings for optical and optical fiber sensors.

The present paper presents the results of tests of anti-biofouling coated fiber optic probes for reflectance spectroscopy in blood-simulating 'foul' media, that are Bovine Serum Albumin (BSA), Fibrinogen and Platelet Enriched plasma (PEP). The anti-biofouling coating, a proprietary invention of Biocompatibles Ltd., was a cross-linkable polymer with silane functionality to improve adhesion to silica-containing substrates.

Two identical fiber optic probes for reflectance spectroscopy were considered, one of which was coated by means of PC-1036 layer. Both probes were optically excited and the signals were continuously detected while immersing the probes in a by-pass flow cell used as dynamic test environment. After 24-hour testing, a visual check of both probes was carried out by means of optical microscopy.

All tests in BSA, Fibrinogen and PEP showed that PC-1036 coating was suitable to avoid build-up of biological material. In fact optical signal variations of non-coated probes showed fluctuations in the 6-20% range, while coated probes exhibited a nearly-stable optical signal. These results were confirmed also by microscopic check, which showed adhesions of biological material on non-coated probes.

The figure below shows the end surfaces of two optical fiber couples after 24-hour testing in BSA. Fibers at the left were anti-biofouling coated and appeared perfectly clean: only the shadow of the coating was visible. Fibers at the right were un-coated and showed a relevant adhesion of biological material. Similar images were obtained by testings in Fibrinogen and PEP.

Photos: 1506_BSA

Acknowledgements
This work was funded by Brite-EuRam EU Project 'BOSS', contract # BRPR-CT97-0485.

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