The detector was made on the base of a 28 μm PVDF film (Precision Acoustics, UK) and operated in the open-circuit regime [41]. A typical pressure of the detected OA signals varied in the range of 102–105 Pa. The detector was calibrated in the frequency range of 0.1–50 MHz, had a smooth spectral transfer function in the range of 0.1–40 MHz and the low frequency sensitivity of 4.5 μV/Pa (see Fig. 2b). The detected OA signals were amplified and digitized by a Tektronix TDS 1012 digital oscilloscope (USA; analog frequency, 100 MHz; sampling rate, 1 GHz) and finally transferred to a PC for further signal processing.
It is important that the detector makes it possible to acquire pressure signals with the minimum amplitude of few tens of Pa without any changes of the front of OA signals for all the test solutions. Similar detectors were used also in our previous WORKS [29] and [42] and showed an extremely high efficiency of their APPLICATION for the wide-band detection.