MEMS ultrasound transducer

MEMS ultrasound transducers

© Fraunhofer IPMS

Among the sensors, ultrasound transducers are the all-rounders that have established themselves for many tasks of detection in technical applications. The use of sensor systems for information exchange in the near distance and contact area is becoming increasingly important. For example, in gesture recognition or collision warning. Especially in the field of gesture recognition, miniaturized sensors with low energy consumption are increasingly required to be integrated into mobile web-enabled devices.

The novel ultrasound transducers in MEMS technology, which were developed in the business unit Monolithically Integrated Actuator and Sensor Systems of the Fraunhofer IPMS, can close this gap. The technology makes it possible to eliminate the membrane used in conventional ultrasound transducers. Instead, microscopically small bending actuators are used, which are made to deflect by a signal and vibrate in the chip plane. In order to generate sound, these bending actuators are arranged in sound chambers. The resulting sound exits the sound chambers via inlet and outlet slots.

Advantages of MEMS ultrasound transducers

  • Volume utilization → by using the chip volume, sound transducers with very small dimensions can be realized
  • Low control voltages → control voltages of less than 48 V enable the use of the transducers in compliance with the german low-voltage directive.
  • Complete silicon → reliable CMOS-compatible manufacturing processes enable production in almost any clean room. The transducers also comply with the german RoHS directive
  • Frequency range → the frequency of a transducer can be manufactured for a wide range of applications. Frequencies from 20 kHz to 500 kHz are possible
  • Combination → sensor and actuator elements can be integrated directly into a component. This can also be implemented for different frequencies
  • Flexibility → the transducers can be adapted to customer requirements in a variety of ways. These include the form factor, the radiation characteristics and the frequency range.

Status of MEMS ultrasound transducer

With the NED actuators, MEMS ultrasound transducers can be manufactured completely in silicon. The proof of suitability as ultrasonic transducers was done with internal research projects and resulted in a demonstrator. The demonstrator evaluates the running time of a radiated and reflected signal, whereby different gestures and distances can be recognized.