Frequency-tunable ultrasonic device

An ultrasonic device, comprising an ultrasonic transducer comprising:

• a membrane suspended above a cavity arranged on the upper surface side of a substrate;
• a piezoelectric layer attached to a surface of the membrane;
• a first electrode arranged on the lower surface side of the cavity;
• and
• a second electrode arranged on the upper surface side of the cavity, in contact with the piezoelectric layer,
• the device further comprising a control circuit connected to the first electrode and the second electrode and capable of simultaneously applying a first control voltage on the first electrode, and a second control voltage different from the first voltage on the second electrode,
• wherein the control circuit is configured to, during a phase of emission of an ultrasound wave, apply a DC bias voltage on the first electrode, and apply an AC excitation voltage on the second electrode, and
• wherein the control circuit is configured to, during a phase of reception of an ultrasound wave, apply a DC bias voltage on the first electrode, and read an AC voltage generated on the second electrode under the effect of the received ultrasound wave.