Figure 2
From: Wearable piezoelectric mass sensor based on pH sensitive hydrogels for sweat pH monitoring
Resonant behavior studies by LDV. (a) Resonant frequency spectra and (b) LDV recorded frames of unclamped membrane at 90 kHz in one cycle of actuation: first row actuation voltage at different time, second and third row are the 3D and 2D views of the actuated membrane (highlighted by the dashed white line), respectively; (c) Resonant frequency spectra and (d) LDV recorded frames of clamped membrane at 330 kHz in one cycle of actuation: first row actuation voltage at different time, second and third row are the 3D and 2D views of the actuated membrane (highlighted by the dashed white line), respectively.
