G. A. Urban

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To study the spread of excitation in ventricular heart preparations we have designed a fast, high-resolution recording and mapping system. Papillary muscles were dissected from the isolated guinea pig hearts. The preparation was fixed in a tissue bath and superfused with Tyrode solution. Linear and two-dimensional arrays of Ag/AgCl electrodes were made on(More)
Foreign body responses and bio-fouling caused by the physiological environment impair sensor performance due to alteration of the sensor/tissue interface. For in vivo applications longterm stability is a critical prerequisite and often affected due to host response towards the implant. In order to assess tissue response towards implants, we propose(More)
An enhanced flow sensor is under development at IMTEK to enable simultaneous measurement of thermal properties of a fluid and its flow velocity. Simultaneous measurement of these properties is necessary to measure flow rates accurately by thermal means in cases where fluid properties fluctuate in time. Here, we report the design and the fabrication of our(More)
A combined-application nanocalorimeter is being developed at IMTEK in order to sense both flow and thermal properties of the flowing medium at the same time. It is designed to measure flow velocity, direction, thermal conductivity of the fluid, and its specific heat by application of a sinusoidal heating. In this report, we present the effects of design(More)
For the first time, we present a simple and robust optical concept to enable precise and sensitive read-out of colorimetric assays in flat lab-on-a-chip devices. The optical guidance of the probe beam through an incorporated measurement chamber to the detector is based on the total internal reflection at V-grooves in the polymer chip. This way, the optical(More)
This paper presents an optical concept for the read-out of a parallel, bead-based fluorescence immunoassay conducted on a lab-on-a-disk platform. The reusable part of the modular setup comprises a detection unit featuring a single LED as light source, two emission-filters, and a color CCD-camera as standard components together with a spinning drive as(More)
We introduce a microsensor implant (MSI) comprising microsensors for dissolved oxygen, pH and electrical impedance to monitor ingrowth behavior of biomaterial coatings into tissue. The chorioallantoic membrane (CAM) of ex ovo transferred avian embryos served as a physiological tissue environment. Here, different signal progressions during ingrowth could be(More)
The performance of our previously devised thermal multi-parameter wind sensor for gaseous fluids is noticeably influenced by the thermal heat shunt induced by the thin-film membrane where heating and temperature sensing elements are embedded. Consequently, reliable values for the thermal parameters of the thin-film membrane are mandatory for their design(More)
A new capillary pressure technique is developed that supports the controlled handling of liquids in Lab-on-a-Chip systems. Capillary pressure barriers, called phaseguides, are used to enable controlled patterning of gel and sample. In this paper design rules are defined for phaseguide pattering and several applications are discussed.