Feasibility of evanescent wave interferometer immunosensors for pesticide detection: chemical aspects

A waveguide Mach-Zehnder Interferometer (MZI) immunosensor has been developed which can detect, in a direct way, a minimum average layer growth thickness of the analyte of 2X 10e3 nm (bound mass, I’=lX low4 fig cm-“). The design and fabrication of the sensor and the experimental set-up are aimed at decreasing the detection limit. A flow cell has been designed and incorporated into the set-up to allow a high mass-transport rate of the analyte molecules to the sensor surface, in this way decreasing the net response time. Results for the immunosystem cr-hSA/hSA are presented. All improvements have been done as a first step towards the use of the MZI immunosensor in the direct detection of low coverages of pesticides with an expected layer growth of 2 x 10e4 nm. Keywo&.~: Evanescent wave interferometer: Immunnsensors; Pesticide detection