A chip-based PCR device is presented that is capable of rapid temperature ramping and handling sample volumes in the microliter range. The PCR chip comprises a microchannel thermally connected to three temperature zones. Inside this microchannel, the PCR sample plug is driven and precisely positioned by a ferrofluidic actuator for more than 40 cycles within 5 min. Computer simulations predict that the sample plugs are thermally equilibrated on a time scale of some 10 ms when transported to a different temperature zone. Hence, the thermal limitations on the cycle speed of the system are considerably reduced compared with conventional cyclers. The system was developed on a modular platform suitable for handling further microfluidic tasks such as DNA extraction and preparation of the PCR mix. Thus, the aspired chip-based platform represents not only a PCR system but a complete analysis system, from the injection of a patient's blood sample to its final appraisal.

Plastic optical fibres (POF) continuously gained its importance during the last decade, since they are widely used in automotive applications for optical data communications (for e.g. MOST). The application of POF for in-flightentertainment (IFE) optical networks in civil aircraft cabin areas is currently under investigation. Since it is expected that the optical networks will develop from a point-to-point network architecture to more complicated structures there will be a need for optical couplers distributing the signals to different suppliers. Typical applications would be for e.g. the distribution of optical data to IFE implemented within single seats of a seat row of an airplane. Within this work the fabrication of an optical 1x2 POF coupler by the Laser-LIGA technique is demonstrated. The Laser-LIGA technique compared to standard X-ray lithography is simpler and more cost effective. Moreover, the Laser ablation technique also allows rapid prototyping of the same structures. The POF couplers fabricated by this technology show insertion loss values down to about 5.6 dB, depending on the waveguide core material and exhibit good uniformity values in the order of 0.1 dB.

Micro-lenses, including Fresnel-Lenses, were fabricated by excimer laser ablation of polymers by means of lasergenerated grey-tone-masks. The smallest reproducible holes that could be fabricated by excimer laser ablation (193 nm, 1 J/cm²) of chromium-on-quartz (thickness 50-100 nm) were around 3 µm, the pitch of which should be at least at the same value to ensure a reproducibility of hole-arrays. To achieve acceptable ablation times during the fabrication of the grey-tone-masks, on-the-fly ablation instead of step-and-repeat technique was used, operating the laser at a constant pulse repetition rate <30 Hz with a continuously moving quartz-substrate. In this way and using different encoding techniques it was possible to generate at least 11 different grey-tones. The available grey-tones were used to generate grey-tone-masks for ablation of Polymethylmethacrylate (PMMA) and Polycarbonate (PC). For that, fluences in the range of 0.07-0.14 J/cm² could be applied, corresponding to a value of 1.25 J/cm² on the workpiece without grey-tonemask and a value lying well below the damage threshold of the chromium mask. Refractive micro-lenses fabricated in this way did not show a good imaging quality, since 11 grey-tones is less than required to generate a continuous surface profile over the full diameter of the lens during ablation and the achievable aspect ratio is limited with the small fluences. However, flat diffractive micro-lenses of the Fresenel type with a quasi-continuously surface profile could be fabricated in a sufficient manner. This can be attributed to the fact that each segment of the Fresenel-lenses can be encoded by 11 grey-tones, leading to much smoother surface reliefs and to a sufficient imaging quality.