Micro string resonators as temperature sensors

T. Larsen, S. Schmid, A. Boisen

    Research output: Contribution to journalConference articleResearchpeer-review

    Abstract

    The resonance frequency of strings is highly sensitive to temperature. In this work we have investigated the applicability of micro string resonators as temperature sensors. The resonance frequency of strings is a function of the tensile stress which is coupled to temperature by the thermal expansion of the string and the frame clamping it. The sensitivity improves when the length and pre-stress are reduced and the difference in thermal expansion, Young's modulus and resonant mode are increased. At low tensile stress, the sensitivity becomes highly dependent on temperature. The investigation was done with silicon rich silicon nitride (SiNx), nickel (Ni) and aluminum (Al) micro strings. Aluminum strings show a relative sensitivity of up to 15±1 %/°C, which is more than 100 times higher than values reported by other groups for similar devices. Sub-millisecond time constants can be achieved due to the low thermal mass of the strings. A temperature resolution of 2.5×10-4 °C has been achieved with silicon nitride strings. The theoretical limit for the temperature resolution of 8×10-8 °C has not been reached yet and requires further improvement of the sensor.

    Original languageEnglish
    JournalA I P Conference Proceedings Series
    Volume1552
    Pages (from-to)931-936
    ISSN0094-243X
    Publication statusPublished - 2013
    EventNinth International Temperature Symposium - Disney Resort, Los Angeles, United States
    Duration: 19 Mar 201223 Mar 2012
    Conference number: 9

    Conference

    ConferenceNinth International Temperature Symposium
    Number9
    LocationDisney Resort
    Country/TerritoryUnited States
    CityLos Angeles
    Period19/03/201223/03/2012

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