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MEMS Heater Sensor

IP.com Disclosure Number: IPCOM000238372D
Publication Date: 2014-Aug-21
Document File: 5 page(s) / 4M

Publishing Venue

The IP.com Prior Art Database

Abstract

A MEMS temperature sensor (or heat sensor, or calorimeter sensor) device is disclosed in which a sensor region (or sensor platform) is separated from a supporting structure (such as a carrier chip) through two or more beams (cantilevers, linking structures) in such a way that the beams are fabricated from planar (or thin film) segments of which the orientations of the segments (i.e. the surface normal from the planar segment) point in at least two directions. Thereby the overall stiffness (or mechanical resonance frequency) in all special directions is increased by a factor of 10 or more with respect to a conventional structure with only one orientation.

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MEMS Heater Sensor

    Highly sensitive measurements of heat-flux (or thermal conductance) are needed for various technological applications. For example, the detection and photography of infra-red or THz radiation, calorimetry of small samples for analytics in chemistry and life science, materials characterization using thermal analysis including scanning thermal microscopy, and sensors of various kinds measuring, for example, gas pressure or biological activity in living tissue.

    The measurement of heat flux (or thermal conductance) typically involves the measurement of temperatures on either side of a known thermal resistor. The sensitivity attained in such measurements is fundamentally limited by the apparatus of measuring temperature. In electrical temperature measurement, the electrical leads contacting the thermometers carry away significant amount of heat to limit the measurement of microscale samples, for example. Therefore, the better the thermal insulation of the thermometer the better is the measurement sensitivity.

    In typical solutions of this technological problem, the electrical leads leading to the thermometers are fabricated to have a sufficiently small thermal conductance for example by choosing a small cross-section and a large length. Typically, thin membranes formed into beams carry the leads.

     One of the major problems towards application is the result of mechanical force or stress in such planar membrane MEMS devices. This can lead to the deformation of the geometry out of plane, as shown in the following picture. This is not always a desired effect.

    Furthermore, stiction to substrate or a manipulator may occur. Furthermore, the interaction with fluids during processing or operation is an issue.

    To increase mechanical stability by increasing thickness or reducing length of the membrane constrictions is not a desired option, because the thermal conductan...