In this work, we presented a new acoustofluidic device design with a novel trapping principle that outperforms similar approaches in terms of throughput and particle size. The device's capabilities were then successfully demonstrated by semicontinuous medium exchange for the model bacterial workhorse E. coli from growth medium to ultrapure water. As an example of successful medium exchange, we electroporated the cells prepared with our acoustic device and showed successful transformation with plasmid DNA. In contrast to centrifugation, our device works well for microliter volumes and can easily be automated and integrated into microfluidic systems. It presents a crucial step towards automating transformation. Furthermore, we carried out numerical studies to get an insight into the physical phenomena that lead to particle trapping at the thin vibrating silicon wall. The simulations revealed that at a frequency close to the experimental resonance frequency, the thin silicon wall located between the water and the air channel has its maximal displacement, while the liquid channel exhibits a maximum in average acoustic energy density. A Gor'kov Potential minimum forms at half of the wall's height, leading to strong particle attraction towards this point. Additionally, counter-rotating streaming vortices are generated, which limit the movement of particles close to the wall. Both effects lead to trapping of particles even in the range of the critical particle radius. In contrast to other designs, we can utilize straight channel walls for the particle trapping, thus preventing contamination with bubbles.