3.3. The Acoustic Transmission in T

3.3. The Acoustic Transmission in Theory and Experiment. Then, we study the acoustic properties of the as-preparedsingle-layer bubbles. The experimental setup and the model forcalculations have been shown in Figures 1e and4a, respectively.Namely, a pulse was generated by the piezoelectric transducer inwater, and then propagated through the experimental sample,which consists of a glass cover plate, patterned bubbles in water,and the silicon substrate, finally reaching the hydrophone andbeing recorded. The patterned bubbles trapped by adodecagonal pillar group consisting of 12 pillars (N = 12)were prepared (Figure 4b), and the bubble interval varied from200 to 3600 μm. The effect of the patterned bubbles on theacoustic transmission is first investigated (Figure 4c). It suggeststhat without bubbles in the sample, the sound normallytransmits, and the presence of a single-layer bubbles caneffectively enhance and reduce the transmission of the sound inwater at different frequencies. There is a deeply reducedtransmission with a minimum of 5 × 10−5 at the frequency of692.5 kHz, below which it exhibits an enhanced transmission(601.0 kHz). The experiment results agree well with thecalculation. The comparisons of the calculations (Figure S8) forthe patterned bubbles in water, pure water, and the patternedbubbles in silicon demonstrate that the patterned bubbles inwater contribute the reduced and enhanced transmission. The