# Versatile High-Throughput Platform for Focused Ultrasound In Vitro Application
## 3 Results
### Cross-Coupling Between the Wells (HIFU)  
It is also important to consider the effect of sound propagation from the active wells to the adjacent well when using these platforms or similar setups on standard multi-well plates. It is therefore essential to minimize the impact of this cross-talk in order to accurately determine the sound intensity and sound pressure acting on the media within the well. In order to investigate this influence, the HIFU platform was employed. In this configuration, only four rows (32 transducers) were active, while two adjacent rows were not sonicated. The maximum sound pressure was measured in all wells of the 96-well  
Figure 15: Results of hydrophone measurements with the 1 MHz HIFU platform. A correlation between filling volume and measuring position in the well with the HIFU platform (1 MHz) along the z-axis in the 32 wells from the bottom of the well (z = 1 mm) to the maximum filling level at the different filling volumes (200 \(\mu\)L, 300 \(\mu\)L, 350 \(\mu\)L) was analyzed. The step size along the z-axis was 0.1 mm. The influence of filling volume and measuring position on the position of the maximum sound pressure level from measurements was analysed in 32 single wells. (**a**) Data are presented as a scatter plot. (**b**) Data are presented as a bar diagram, including mean value and SD.  
\begin{table}
\begin{tabular}{c c c c c} \hline  & **200 \(\mu\)L** & **300 \(\mu\)L** & **350 \(\mu\)L** & **No Well** \\ \hline mean p\({}_{\text{max}}\) [kPa] & 197.66 & 219.82 & 238.19 & 255.07 \\ SD p\({}_{\text{max}}\) [kPa] & 40.60 & 45.14 & 54.70 & 47.81 \\ mean z\({}_{\text{pos}}\) [mm] & 2.36 & 2.25 & 2.12 & 2.14 \\ SD z\({}_{\text{pos}}\) [mm] & 0.80 & 0.35 & 0.40 & 0.38 \\ \hline \end{tabular} \(\overline{\text{p}_{\text{max}}}\) = maximum pressure, z\({}_{\text{pos}}\) = z-position of maximum pressure, SD = standard deviation.  
\end{table}
Table 3: Maximum sound pressure levels in the 32 wells at different filling volumes and positions within the wells.  
plate, and the cross-talk to inactive wells was determined using a hydrophone positioned within each individual well. The acoustic pressure values along the z-axis in each well (96) were recorded with a step size of 0.1 mm, from the bottom of the well (z = 1 mm) to the maximum filling height of 10 mm at a filling volume of 350 \(\upmu\)L. The platform was operated with an excitation voltage of V\({}_{\text{peak}}\) 20 V.  
The maximum sound pressure levels were observed to range between 204 kPa (SD 17 kPa) and 290 kPa (SD 22 kPa) in the activated transducer positioned beneath the wells of rows 2, 5, 8, and 11. In the non-sonicated wells, the maximum sound pressure levels were observed to be between 19 kPa (SD 4.8 kPa) and 31 kPa (SD 4.8 kPa) (Figure 16).  
The measured values demonstrated that the cross-coupling in this HIFU platform did not exceed 13% of the mean sound pressure. Consequently, a sound pressure that was attenuated only by a maximum of \(-\)18 dB was applied to the surrounding wells. The values of these measurements can be employed to calculate the precise applied sound pressure per well when utilizing such a platform.