The wave from the piezoelectric material may be
sine wave (classmate told me )
AC wave (but not sine, I suppose it from the paper)
DC wave (from the oscilloscope it seems like a DC wave, not AC wave)
Red oscilloscope line connects to the red line. Black oscilloscope line connects to the black line. No load (resistor or capacitor), as in the picture shown below
Here are the wave situations, shown in the oscilloscope
- no press: a horizontal wave which has noise
- at the time I press: the horizontal wave goes down
- at the time i release: the horizontal wave goes up
After that, the horizontal wave returns back to the original, and this is the reason: I think the wave produced from the piezoelectric material is a DC wave, because there is no AC wave, only DC. However, I read some papers and articles from the internet, and they all said that the wave from the piezoelectric material is definitely not a DC wave. So, did I miss any steps before I tested the wave with the oscilloscope1?
I saw a waveform from this pdf ( Chinese version), and in Fig 14 & 15 there is a voltage waveform, as shown below.
1I’m using a WaveRunner-8000 oscilloscope.