<title>Integrated optic biosensor</title>

Abstract

A micro-sized biosensor is formed using integrated-optic channel waveguides in a Mach- Zehnder interferometer configuration. The device measures refractive index changes on the waveguide surface, so it is called a biorefractometer. With an appropriate overlay or selective coating, the sensor can monitor proteins in blood or pollutants and bio-warfare agents in water. The waveguides are fabricated in a glass substrate using potassium ion exchange. A patterned glass buffer layer defines the interferometer's sensing and reference arms. A silicone-rubber cell arrangement brings sample analytes into contact with proteins immobilized on the integrated-optical waveguide surface. Data obtained for antigen-antibody binding of the proteins human Immunoglobulin-G and staph enterotoxin-B indicate that a 50 - 100 ng/ml concentration levels can be measured in less than ten minutes.