Title: SEN0209 for measuring 20–60 kHz surface vibration – mounting and noisy AOUT signal

Hello,

We are testing the SEN0209 Flexible Piezo Film Vibration Sensor to detect ultrasonic vibrations propagating through a metal surface.

Our setup consists of:

A power ultrasonic transducer exciting an aluminium plate in approximately the 20–60 kHz range

The SEN0209 piezo film attached directly to the vibrating surface

The sensor powered with 5 V

The output selector set to AOUT

The Signal and GND pins connected directly to a Tektronix DPO2024 oscilloscope using a 10X probe

Our objective is not to obtain an absolute calibrated displacement value. We want to compare the relative vibration level at different positions and distances from the transducer and identify the dominant frequency components.

However, the AOUT signal is very noisy and unstable. Its amplitude and baseline fluctuate, and we observe many sharp spikes and frequency components, making it difficult to isolate the vibration caused by the transducer.

We initially fixed the piezo film to the plate using paper masking tape, but changing the attachment did not produce a clear improvement.

Could you please advise us on the following?

What is the recommended way to mechanically mount the piezo film for detecting surface vibrations in the 20–60 kHz range?

Should the entire film be firmly bonded to the surface, should only one end be clamped, or should it be installed as a small cantilever?

Is there a recommended adhesive, preload or mounting method that provides better and more repeatable mechanical coupling?

Although the piezo film itself has a very wide stated frequency range, is the SEN0209 converter board and its AOUT circuitry suitable for measurements at 20–60 kHz?

Is any additional amplification, band-pass filtering, shielding or impedance matching recommended when connecting AOUT to an oscilloscope?

Has anyone previously used the SEN0209 for ultrasonic surface-vibration measurements or a similar application?

We have also compared measurements with the ultrasonic transducer switched on and off, but we would like to distinguish genuine mechanical vibration from electrical interference more reliably.

I have attached several oscilloscope screenshots showing the signals we observed. Any advice about the mounting arrangement, measurement circuit or whether this sensor is appropriate for this application would be greatly appreciated.

Thank you.