We have fabricated microthruster chip pairs - one chip with microthruster structures such as injection capillaries,
combustion chamber and nozzle, the other chip with platinum thin film devices such as resistance temperature
detectors (RTDs) and a heater. The platinum thin film was sputtered on thermally oxidized silicon wafers
WITHOUT adhesion layer. The effects of anneal up to 1050°C on the surface morphology of platinum thin films
with varied geometry as well as with / without PECVD-SiO2 coating were investigated in air and N2 and results
will also be presented. Electrical characterization of sensors was carried out in a furnace tube in which the
sensors' temperature was varied between room temperature and 1000°C with a ramp of ±5Kmin-1 in air and N2.
The experiments showed that the temperature-resistance characteristics of sensors had stabilized after the first
heating up to 1000°C in N2. After stabilization the sensors underwent further 8 temperature cycles which
correspond to over 28h of operation time between 800 - 1000°C. To reduce the loss of combustion heat, chip
material around the microthruster structures was partially removed. The effects of thermal insulation were
investigated with microthruster chip pairs which were clamped together mechanically. The heater power was
varied up to 20W and the temperature distribution in the chip pairs with / without thermal insulation was
monitored with 7 integrated thin film sensors.
The quality and safety of drinking water is of major importance for human life. Current analytical methods recognizing
viable bacteria in potable water are time consuming due to a required cultivation step. Fast and automated detection of
water borne pathogenic microorganisms with high sensitivity and selectivity is still a challenging task. We report on a
novel biosensor system using micromechanical filters with nano sized pores to capture and enrich bacteria on the filter
surface. Thus the accumulated organisms are accessible to different detection methods using fluorescent probes.
Depending on the kind of detection - specific (identification of a certain species) or unspecific (total amount of cells) -
different assays are applied. For non-specific detection we use fluorescent dyes that bind to or intercalate in the DNA
molecules of the bacteria. Upon binding, the fluorescent signal of the dyes increases by a factor of 1000 or more.
Additionally, we use enzyme substrates for the detection of active cells. The whole detection process is automated by
integrating the microsieves into a fluidic system together with a high performance fluorescence detector. To ensure
realistic conditions, real potable water, i.e. including particles, has been spiked with defined amounts of microorganisms.
Thus, sampling, enriching and detection of microorganisms - all with a single micromechanical filter - is not only
possible with ideal media, e.g. laboratory buffer solutions, but also with tap water. These results show the potential of
microfilters for several applications in fast pathogen detection.
We have designed and built integrated, movable micromirrors for on-chip alignment in silicon- optical-bench technology. The mirrors are fabricated using surface micromachining with three polysilicon layers. A polysilicon-hinge technology was used to achieve the required vertical dimensions and functionality for alignment in hybrid photonic integrated circuits. The positioning accuracy of the mirrors is measured to be on the order of 0.2 micrometers . This precision is shown theoretically and experimentally to be sufficient for laser-to-fiber coupling. In the experimental verification, we used external actuators to position the micromirror and obtained 45% coupling efficiency from a semiconductor laser (operating at 1.3 micrometers ) to a standard single-mode optical fiber. The stability and robustness of the micromirrors were demonstrated in shock and vibration tests that showed that the micromirrors will withstand normal handling and operation without the need for welding or gluing. This micromirror technology combines the low-cost advantage of passive alignment and the accuracy of active alignment. In addition to optoelectronic packaging, the micromirrors can be expected to find applications in grating-tuned external-cavity lasers, scanning lasers, and interferometers.
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