36 MHz, 1 V p-p 10 kHz, 1 V p-p Temperature (K) 293 323 that a higher input amplitude, 1 vs 3 Vp-p, leads to a slightly higher change in the droplet aspect ratio, suggesting that more fluid is injected. This trend substantiates the values of the LDV mean displacement measurements (Table ), where a higher input amplitude leads to a larger mean displacement, in turn demonstrating that higher input amplitudes lead to stronger droplet destabilization. The difference between individual aspect ratio values can be explained when interrogating brightfield images of the analyzed high-speed-camera videos (Fig. ). These images demonstrate that the volume injected into a droplet depends on the size of the drop formed at the injection nozzle. The formation of this droplet is affected by the Laplace pressure and may be responsible for small variations in the injection volume between individual droplets within the same injected droplet population. For a closer look at the correlation between amplitude and injection pressure rate, we measure the variation of droplet injection as a function of the change in droplet aspect ratio, influence of three input amplitudes, and two different inlet pressure rates for the injection fluid across three different devices (Fig. ) with all droplets initially stabilized by 3 wt% fluorosurfactant in the oil phase. The general trend of increasing droplet aspect ratio with increasing input amplitude is confirmed where a higher pressure at the injection nozzle increases the volume of injected fluid into the passing droplet (Fig. , top panel vs bottom panel). The reproducibility of the change in the droplet aspect ratio between the different devices seems to be more stable for 135 mbar pressure rate at the injection nozzle. Described a different way, the variability in aspect ratio of each droplet in comparison to the population of analyzed droplets for each condition is higher at 120 mbar pressure rate in comparison to 135 mbar. This behavior shows the influence of the pre-drop formation at the injection nozzle as a function of the applied pressure. A higher coefficient of variation, or CV determined as the ratio of the standard deviation to the mean and presented by the diameter of the points in Fig. , indicates a less constant pre-drop formation. The error could be minimized by increasing the pressure at the injection nozzle so that the formation of the pre-drop happens faster or before the pre-drop is cut off by the continuous oil phase. Additionally, the CV could be minimized by a feedback control that adjusts the droplet passing rate at the injection nozzle so that the droplet passing and the formation of the pre-drop is synchronized. A final alternative for minimizing the error in injection is to optimize the design of the injection nozzle, for example by reducing the width of the nozzle. Using the most stable surfactant concentration (3 wt%) as optimized for our acoustoinjection approach, we analyze the injection efficiency of various droplet passing rates.