In the field of tissue engineering 3D bioprinting methods are used to manufacture spatially complex, cell-loaded constructs that mature into mimetic tissue replacement in a subsequent cell culture process. In the bioprinting techniques currently available, nozzles are used for printing the cells embedded in hydrogels as carrier fluids. The nozzles are a limiting factor because they limit the print resolution to a few hundred microns. If the nozzle diameter is too small, clogging of the nozzle will occur. In addition, the shear stress on the cells increases significantly with reduction of the nozzle diameter. At a critical shear stress, the printed cells are mechanically irreversibly damaged.

In this research project funded by the German Research Foundation (DFG), the Acoustic Droplet Ejection (ADE) method, which has so far only been used in the technical field, is to be made usable for 3D bioprinting. With this technology, droplet sizes can be variably generated over more than three size scales from the millimeter range down to the small two-digit micrometer range. By varying the size of the droplets, larger cell aggregates as well as single cells can be printed precisely in three dimensions across scales. The acoustic method does not require a nozzle. This is of crucial advantage for the cells to be dispensed, since the high shear stresses can be avoided by using the acoustic method. The mechanisms relevant to bioprinting in ADE technology are to be investigated in the research project step by step. By modulating the frequency and amplitude and the corresponding signal duration, it is possible to influence the drop accuracy, which is determined by a camera system. Cell-loaded hydrogels are printed. Different cell lines and primary cells are used to understand the cell biological behavior in the ADE process in detail. The hypothesis is that cells can be applied three-dimensionally with sound-induced bioprinting in a much gentler way than with the established nozzle-based bioprinting processes.