Optimal hybridization efficiency upon immobilization of oligonucleotide double helices.

For the first time, the covalent immobilization of oligonucleotides double helices onto surfaces prior to sequential denaturation and rehybridization is proven to lead to optimal hybridization efficiency. Two indirect methods were used for monitoring these reactions in situ: the quartz crystal microbalance with dissipation monitoring (QCM-D) and the wavelength interrogated optical sensor (WIOS, Bright Reader). Both techniques led to the result that with this immobilization approach one could reach nearly 100% hybridization efficiency.

Wavelength-interrogated optical sensor for biochemical applications.

A novel miniature integrated-optical sensor for versatile multichannel applications is described. Wavelength-modulation techniques using laser diodes (vertical-cavity surface-emitting lasers) are used to interrogate multiple-waveguide sensing regions on a single integrated-optical chip for accurate measurement of effective refractive-index changes at a high data rate. With the experimental miniature sensor system, a resolution of DN(PP) = 10(-7) (short term, peak to peak) of the effective refractive index was demonstrated.

Compact integrated optical sensor system.

A compact integrated optical sensor system for a large variety of different (bio-) chemical applications using replicated sensor chips is described. Features of the refractometric system to be emphasized for practical applications include a high-resolution window that can be positioned within a wide measuring range, an in situ chip testing and characterization procedure, and on-chip referencing. As an application example, experimental results on refractometric measurements as well as on the suppression of non-specific binding are given.

Novel integrated optical sensor based on a grating coupler triplet.

A novel approach for accomplishing robust integrated optical biosensors is presented. The principle is based on a symmetric grating coupler structure with the inherent feature of compensating disturbances originating from different kinds of mechanical instabilities. The complete sensor system has no moving parts and provides the high sensitivities typical for integrated optical sensors based on grating couplers.