A new method for characterizing piezoelectric properties of hexagonal boron nitride nanoflakes activated by focused ultrasound

Piezoelectric nanomaterials wirelessly activated by ultrasound have been studied for biomedical applications. However, the quantitative measurement of piezoelectric effects in nanomaterials and the correlation between the ultrasound dose and the piezoelectric amplitude are still explored. We demonstrated the synthesis of boron nitride nanoflakes by mechanochemical exfoliation and employed the electrochemical method to quantitatively evaluate the piezoelectric performance of the nanoflakes under ultrasonic circumstances. The change of voltametric charge, current, and voltage in response to different acoustic pressure was obtained in the electrochemical system. The charge was reached up to 69.29 μC with a net increase of 49.54 μC/mm2 under 2.976 MPa. The output current was measured up to 597 pA/mm2 and positive shift of output voltage shifted from -600 mV to -450 mV. Additionally, the piezoelectric performance linearly increased with acoustic pressure. The proposed method could be a standardized evaluation test bench for characterization of ultrasound-mediated piezoelectric nanomaterials.