**4.8. Surround, optical fiber immunoassay (SOFIA)**

A billion times more sensitive and dynamic technique than conventional diagnostic methods is "surround, optical fiber immunoassay (SOFIA)" for in vitro diagnostics, in which surround optic fiber assembly is used to capture the fluorescence from the sample. SOFIA's sensitivity is up to attograms level, that is, (10−18 g). SOFIA has a power to differentiate the analyte over 10 orders of magnitude. This technique is used for *ante mortem* screening test for, Scrapie, BSE, vCJD, CWD, Alzheimer's, Parkinson's disease and transmissible spongiform encephalopathies [53].
