With the respective inlet pressure rates, 14 to 164 droplets per second passed the microfluidic channel and we achieve 100% injection (Table ), further supporting the reliability of our acoustoinjection device. In contrast, injection experiments in the MHz frequency domain show no acoustoinjection of passing droplets, which is a finding that perfectly aligns with our proposed mechanism (Section 2.1). Interestingly, because the droplets that we inject are 50-80 µm diameter, they can be excited by their respective eigenfrequency in the ultrasonic frequency range of 1-100 kHz. This finding is supported by the field but has never before been demonstrated, as it is here, within an integrated PDMS based acoustofluidics device. This leads us to emphasize the potential implications of interface stabilizing surfactants on the efficiency of acoustoinjection, as our proposed mechanism of injection is based on interface destabilization.