Bernd Hillerich

Surface-micromachined electrostatic microrelay

Abstract Three variants of electrostatically driven microrelays are reported. These switches have a high off resistance like conventional mechanical relays, but are also characterized by a low power consumption (

Comparison of lateral and vertical switches for application as microrelays

This paper discusses the suitability of lateral and vertical switches for use as micorelays. These two types of switch are fabricated and tested and the advantages and disadvantages are outlined. The lateral motion switch consists of a single-crystalline silicon cantilever beam, which is made by a deep silicon etching process. Therefore the switch provides a high stiffness in the vertical axis, a high degree of design flexibility and a stress free structure, which is a main advantage of this type. The vertical motion switch is a multi-layer cantilever beam, which is distinguished by high isolation resistances and metallic contacts. Both types are candidates for microrelays; however the vertical switch seems more suited.

Micromechanical relay with electrostatic actuation

Three variants of electrostatically driven microrelays are reported. The concepts of these microrelays are a cantilever beam, a fixed-fixed beam and a torsion beam with a double contact configuration. Because of the complete fabrication by surface micromachining technology, there is no need for a chip bonding process. This paper reports on the device concept, fabrication and performance of the microrelay.

Application of finite element method and SPICE simulation for design optimization of oven-controlled crystal oscillators

Thermal finite element method (FEM) calculations and SPICE-based dynamic thermal models are used to simulate and optimize the static and dynamic performance of miniaturized oven-controlled crystal oscillators (OCXOs). FEM can be used to generate the values of the SPICE circuit elements. Good agreement is achieved between simulation and measurement. Several application examples, including directly heated OCXOs, are discussed.

A Silicon-based Microreaction System for Analytical Applications

A silicon microreaction system is presented, which forms a microfluidic concept for well-established detection procedures of indicator-based colorimetric analysis. The system comprises capillary dosing systems for the precise delivery of sample and indicator solution, respectively, a novel active micromixer for a rapid and complete mixing of both components and a microcuvette for the detection of the resulting colorimetric signal. The microfluidic set-up is realized as compact modules to be integrated into a conventional flow injection analysis system for sample preparation and analysis control. The performance of the micromixer and the microreaction system as a whole is demonstrated with a well-established pH- detection method.

Directly heated quartz crystal microbalance with an integrated dielectric sensor

Cross-sensitivity, especially to humidity, is a common problem in the analysis of chemical gas-sensor signals. To identify the contributions of two gas components at least two suitable signals are needed. This article presents a new chemical sensor unit which is a combination of a quartz crystal microbalance and a dielectric sensor. Thus it yields information about both the mass and the dielectricity of the same chemically sensitive film. The differences in absorption isotherms and drift behaviour are discussed. To make this a universal element for gas sensing, a heater and a temperature gauge are also integrated directly on the quartz by thin-film technology. This allows the application of temperature modulation techniques to the quartz microbalance principle.

Efficient design and optimization of MEMS by integrating commercial simulation tools

This article presents a simulation tool for developing and characterizing microelectromechanical systems (MEMS). The advantage of the demonstrated modular concept is due to the flexibility of the program structure and to the reduction of costly software support by integrating commercial simulators. A novel application manager controls the different subprograms by specific drivers and ensures the data management for parametric studies. So complex system behaviour and the interactions of MEMS components can be analysed and optimated during the design process, resulting in shorter manufacturing cycles.