Acoustic Levitation assisted Contactless Printing of Microdroplets for Biomedical Applications

The artificial cell is a biomimetic microcapsule system wherein biological materials are encapsulated by a thin membrane, which provides valuable information on the metabolism, morphology, development, and signal transduction pathways of the studied cell. However, it is extremely difficult to manufacture such systems. Mostly vesicles such as liposomes, polymersomes, and microcapsules are first produced by a high-pressure homogenizer and microfluidizer as an emulsion and then encapsulated microcapsules by the drop or emulsion method. Currently, acoustic levitation opens up entirely new possibilities for creating artificial cells because of its ability to suspend tiny droplets in an anti-gravity and non-contact manner. Herein, we propose a contactless printing of single-core or multi-core artificial cells based on acoustic levitation. First, the oscillation mode and microscopic morphology of the droplets under different ultrasonic vibration frequencies are shown by simulation, and the curing characteristics of the shell structure under different ultraviolet illumination conditions are quantitatively measured. The feasibility of manufacturing multi-core artificial cells and manufacturing sub-millimeter-scale particles based on oil trapping is extensively studied. To explore the morphological adaptability of artificial cells, ferromagnetic Fe3O4 nanoparticles are used to give cells magnetic responsive properties and the microscopic deformation and motion in microfluidic channels under the magnetic field are characterized. Finally, the proposed printing method proves the versatility of in-space contactless printing of complex 3D beam structures and provides a powerful platform for developing biomedical devices and microrobots and studying morphogenesis and synthetic biological systems