Pesky protein and microorganism buildup can foul up fiber optic oxygen sensors during long-term, continuous immersion in aqueous media, leading to drift and sensor failure. But researchers have discovered that polymer coatings containing phosphorylcholine-substituted methacrylate can substantially reduce this problem with little or no effect on the performance of the sensor.The coated oxygen-sensitive layers, which the researchers say are mechanically stable for up to a year, were developed by a team from Universidad Complutense de Madrid in Spain, in conjunction with Biocompatibles Ltd. in Farnham, UK, and the Institute for Bioprocessing and Analytical Measurement Techniques in Rosenhof, Germany.During testing, nanometer-size coatings reduced buildup of marine bacteria by more than 70 percent and thrombocytes by more than 90 percent on doped silicone, compared with samples with no coatings. The research group reported its results in the Nov. 1 issue of Analytical Chemistry.The researchers from Universidad Complutense de Madrid have also begun using Biocompatibles' coatings to protect sensors that measure environmental and physiological pH through intensity- and lifetime-based luminescence optosensing.