A biosensor based on high spatial resolution imaging ellipsometry has been studied to examine its role in the rapid detection and analysis of the tropomyosin allergen existing in crustaceans. This methodology has been established for detection of the tropomyosin allergen and includes ligand screening, the determination of sensitivity, and a comparison with traditional detection methods. Three kinds of monoclonal antibodies (2F9, 4C7, and 2H6) known to have a high bioactivity against the tropomyosin allergen were screened and separately immobilized as ligands on a silicon wafer surface, thus allowing them to capture the tropomyosin allergen. Resulting changes on the wafer surface were visualized in gray scale variation on an ellipsometry image. Images showed that these antibodies are able to recognize the presence of the tropomyosin allergen in shrimp and crab with sensitivity of 1 mg L(-1), and at a detecting time of approximately 30 min for an extracted sample. This preliminary study has shown that the detection of the tropomyosin allergen is rapid and specific when using this type of assay on products containing shrimp and crab. When compared with the enzyme-linked immunosorbent assay, the biosensor based on imaging ellipsometry is able to perform a fast label-free analysis.