Immunosensor based on optical heterodyne phase detection

An immunosensor based on optical heterodyne phase detection was developed. A transverse Zeeman laser was employed as the light source in this sensor, which includes a p-polarized light and an s-polarized light, as the light s ource. For phase detection, the measurement accuracy is improved by replaci ng de detection of luminous intensity with ac detection to avoid the impact of shift in the case of de detection. Theoretical analysis indicates that phase change relies strongly on the thickness of the sensing membrane and t he material and thickness of the metallic membrane. An experimental apparat us was constructed with optimized design parameters, and a research was con ducted on the dynamics of interaction between ricin and its antibody. Exper imental results show that the sensor has good performance in sensitivity, s tability and reliability. (C) 2001 Elsevier Science B.V. All rights reserve d.