Ultrasonic Transducers

cMUT and pMUT

MUTs transform an electrical signal into an acoustic one, through a mechanical complex movement. Designers make use of several electrical, mechanical and acoustical models, and each of them depends on many physical parameters. Therefore, there is a strong need to compare simulation and in-situ experimental results.

The main vector for this signal transfer is the membrane movement of the MUT. Measurement of its 3D topography time-sequence along the phase of the excitation signal is needed for understanding the energy transfer processes.

 Cross talks and surface waves

Full field measurement enables simultaneous characterization of many MUT membranes. It enables analysis of:

  • cross talk between neighboring membranes
  • surface wave propagation
  • statistical distribution of membranes characteristics
  • the quality of the device
cMUT @ 8MHz : Time-sequence of topographies. Courtesy of Fraunhofer IPMS, Dresden, Germany
cMUT @ 8MHz : Amplitude vibration map
cMUT @ 8MHz : Phase vibration map

Membrane topography – collapse voltages

The topography of each membrane is measured over its complete surface with high lateral resolution, enabling:

  • measurement of the 3D temporal evolution of any membrane point along its excitation cycle with high temporal resolution
  • determination of collapse voltage

Characterization of cMUT by Dynamic Holography Microscopy – IEEE Conference Publication

Profile of a non-collapsed MUT membrane @ 200kHz. Courtesy of team n°5, INSERM U930, Université de Tours (France)

Measure in burst mode

Lyncée  Tec stroboscopic module enables short burst mode excitation, commonly used for medical imaging modes.

Record echo in immersion

The DHM® unique optical configuration enables measurement of the deformation of immersed membranes resulting from both the transmitted wave and the receiving acoustic echo.

Acoustic wave echo recorded in Immersion. Red curve : burst excitation signal. Black curve : MUT response. (1) Wave is generated by the MUT, (2) Wave is reflected on the microscope objective, and (3) MUT topography is modified by the echo. Courtesy of Philips, The Netherlands


Characterization of cMUT by Dynamic Holography Microscopy – IEEE Conference Publication

“3D topogaphy time-sequence immersed measurement of MUT response to burst excitation” Y. Emery, C. van Heesch. 14th International Workshop on Micromachined Ultrasonic Transducers MUT 2015