Lab for the characterization of MEMS ultrasonic transducers

Ultrasonic MEMS transducers are used in applications such as medical imaging, environmental monitoring, gesture recognition, and distance measurement. To ensure reliable performance and enable design optimization, precise characterization during development is essential.

The Fraunhofer EMFT Ultrasonic Lab in Munich provides manufacturers with the opportunity to test and characterize MEMS ultrasonic transducers using professional measurement equipment and the expertise of experienced MEMS ultrasound specialists.

Electrical Characterization

Impedance Measurement

Measurement of the electrical impedance of the device under test (DUT) and extraction of a 7-element Butterworth–Van Dyke (BVD) equivalent circuit model. Based on this analysis, key device parameters can be determined, including the electrical capacitance, resonant and anti-resonant frequencies, and the electromechanical coupling coefficient.

Acoustic Characterization

3D Acoustic Field Mapping

Measurement of the peak-to-peak acoustic pressure distribution in the X, Y, and Z directions (DUT used as transmitter).

Center Frequency and Acoustic Bandwidth

Measurement of the acoustic pressure as a function of the actuation frequency at a fixed XYZ position (DUT used as transmitter). This measurement also enables the determination of the DUT’s fractional bandwidth.

Transmit Sensitivity

Measurement of the acoustic transmit sensitivity of the DUT based on the slope of the linear relationship between acoustic pressure and transmit voltage at a fixed XYZ position (DUT used as transmitter). This measurement also enables the determination of the DUT’s maximum peak-to-peak acoustic pressure and second-harmonic distortion.

Receive Sensitivity

Measurement of the acoustic receive sensitivity of the DUT by evaluating the relationship between the acoustic peak pressure at the DUT surface and the resulting electrical output signal at a fixed XYZ position (DUT used as receiver). This measurement also enables the determination of the DUT’s round-trip sensitivity (DUT operating as both transmitter and receiver).

Mechanical Characterization

Destructive Power Test

Measurement of the maximum electrical drive and resulting acoustic output power that the device under test (DUT) can withstand prior to failure or destruction.

Laser Doppler Vibrometry

Laser Doppler vibrometry measurements are available upon request but are not included in the standard measurement portfolio.

DUT Preparation

Prior to acoustic characterization, key information about the DUT is required, including operating conditions such as maximum actuation voltage and frequency, the expected acoustic field, and the intended operating medium.

The DUT must be mounted and wire-bonded to a suitable evaluation board (PCB). For measurements in liquids (e.g., DI water), the device must also be hermetically encapsulated.

Preparation services, including PCB mounting, wire bonding, and encapsulation, can be provided upon request.