ABSTRACT
The combination of an integrated Mach-Zehnder-interferometer (iMZI) at the bottom of a fluidic microchannel system with supramolecular interfacial binding layers optimized for biosensing purposes is described. The model system used is based on the highly specific interaction of streptavidin to its 'ligand' biotin: a single monolayer of a correspondingly derivatized silane-compound is formed by a self-assembly procedure on top of the channel rib guiding the light through the channels. Injection of a streptavidin solution which leads to the formation of a protein monolayer of d = 2.8 nm in effective thickness results in a phase shift of the sample light relative to the reference channel of delta phi = 6 pi, in good agreement with the theoretical sensitivity of delta phi/delta df = 2.9 pi/nm for a protein layer (n = 1.45) calculated for the device.
Subject(s)
Biosensing Techniques , Interferometry , Biotin , Miniaturization , Refractometry , Sensitivity and Specificity , Silicon , StreptavidinABSTRACT
Microsystems are set to contribute much to the medical device market. New microfabrication processes allow the mass production of microcomponents in a variety of materials. These processes are described together with examples of miniaturized medical devices and components that are now possible.
