Integrated optical sensor micro-systems based on disposable transducers

In this work novel concepts for the realization of miniature integrated optical sensor systems are presented. An important aspect for all realized approaches was their suitability for the use of disposable sensor chips. This is essential, especially for applications in the medical, food and environmental field. A robust sensor system with the inherent feature to compensate for disturbances originating from different kinds of mechanical instabilities is presented. It is based on a symmetric grating coupler structure, does not require any moving parts and provides the high sensitivity typical for integrated optical sensors based on grating couplers. The feasibility of this approach is demonstrated by determining the refractive index of liquids as well as by measuring the specific binding of bio-molecules (anti-chicken IgG) to immobilized chicken IgG on the sensor chip surface. A further approach for the realization of a refractometric integrated optical sensor system is presented featuring a high-resolution window which can be positioned within a wide measuring range. It also includes an in-situ verification procedure for disposable sensor chips. This realized sensor platform is suited for a large variety of current and future (bio-) chemical applications. As application examples, experimental results on refractometric measurements as well as on the suppression of non-specific binding are given. The realization of a hand-held, miniature integrated optical sensor system for versatile multi-channel applications is also described. Wavelength modulation techniques using vertical cavity surface emitting lasers (VCSELs) are used to interrogate multiple waveguide sensing regions on a single integrated optical chip for accurately measuring effective refractive index changes at a high data rate. With the experimental miniature compact dual-channel sensor module, a resolution of ΔNPP = 10-7 (short-term, peak-peak) for the effective refractive index was demonstrated. In terms of surface mass coverage, this resolution corresponds to ΔΓPP = 130 fg / mm2.