<?xml version="1.0" encoding="utf-8"?>
<export-example>
  <doc>
    <id>9981</id>
    <completedYear/>
    <publishedYear>2012</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>93</pageFirst>
    <pageLast>96</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName>IEEE</publisherName>
    <publisherPlace>Piscataway, NJ</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2013-11-12</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Wide pressure range operation of air-coupled CMUTs</title>
    <abstract language="eng">We present measurement results of capacitive micromachined ultrasonic transducers (CMUTs)in permanent contact mode over a wide pressure range(1 – 8 atm). The CMUT plates are in contact with the bottom of the cavities due to atmospheric pressure, even without any dc bias voltage. The&#13;
electrical input impedance at various dc bias voltages are measured at elevated pressure to characterize individual devices. The open and short circuit resonant frequencies&#13;
are extracted from the impedance data, and the acoustic performance of pairs of devices is evaluated by performing&#13;
pitch-catch measurements. A frequency matching method is proposed and used to determine the optimal dc bias voltages for the transmitting and receiving CMUTs individually. &#13;
Our electrical impedance results show good agreement with&#13;
the finite element model results (modal and harmonic analysis performed with ANSYS) over the entire pressure range. Moreover, the pitch-catch measurement results validate the proposed frequency matching method for an optimal biasing scheme, and a received signal with good signal-to-noise ratio of 45 dB was observed at a pressure of 7 atm. In conclusion, the behavior of CMUTs in permanent contact mode can be predicted well with our FEA, and they are indeed a promising solution in providing ultrasonic transducers that can operate over a wide pressure range.</abstract>
    <parentTitle language="eng">IEEE International Ultrasonics Symposium, Dresden, Germany, 7 - 10 October 2012</parentTitle>
    <identifier type="doi">10.1109/ULTSYM.2012.0023</identifier>
    <identifier type="isbn">978-1-4673-4561-3</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <author>
      <firstName>Min-Chieh</firstName>
      <lastName>Ho</lastName>
    </author>
    <submitter>
      <firstName>Madlen</firstName>
      <lastName>Herzig</lastName>
    </submitter>
    <author>
      <firstName>Mario</firstName>
      <lastName>Kupnik</lastName>
    </author>
    <author>
      <firstName>Kwan Kyu</firstName>
      <lastName>Park</lastName>
    </author>
    <author>
      <firstName>Kristian</firstName>
      <lastName>Eckhoff</lastName>
    </author>
    <author>
      <firstName>Butrus T.</firstName>
      <lastName>Khuri-Yakub</lastName>
    </author>
    <collection role="old_institute" number="03016">LS Allgemeine Elektrotechnik und Messtechnik</collection>
    <collection role="institutes" number="1101">FG Elektronische Systeme und Sensorik</collection>
  </doc>
</export-example>
