Given that the effect of acoustic streaming cannot be neglected in BAW systems for manipulating bacteria, we considered this by refining our mesh at the water-silicon interfaces and, by that, account for the viscous boundary layer (Fig. ). Subsequently, a study in the frequency domain was performed with excitation J o u r n a l N a me , [ y e a r ] , [ v o l . ] , frequencies ranging from 1.6 to 2 MHz, as for this spectrum, the strongest particle attractions had been suggested in preliminary experimental investigations. As a measure for the device efficiency, we chose the average acoustic energy density, i.e. acoustic energy density (Eq. 4) integrated over the cross-section of the liquid channel and divided by its area. Similarly, we computed the average wall displacement. Simulation results show a global maximum in the average acoustic energy density and the average wall displacement at 1801 kHz with additional minor resonances being visible at slightly higher and lower frequencies (Fig. ). The subsequent detailed experimental analysis confirmed the initial observations as well as the results of the numerical simulation by demonstrating strong particle attraction in the investigated frequency range. However, we were unable to experimentally reproduce the exact relative strength of the resonances, which might be caused by the idealized material parameters used as inputs for our 2D simulations.