Acoustic Bioprinting: Liquid-Bridge-Based Efficient Single-Cell Encapsulation Using Gigahertz Bulk Acoustic Waves

Single cell encapsulation techniques are essential for biological analysis, regenerative therapy, and drug screening. However, current methods still suffer from issues such as insufficient spatial resolution, complex operation, and poor biocompatibility. Furthermore, the low encapsulation efficiency has resulted in significant waste of biological samples. In this study, we propose an acoustic-based bioprinting method to address these challenges in single cell encapsulation. Unlike most bioprinting approaches, the proposed method transfers cells via a liquid bridge, providing an error correction channel for cell encapsulation. Combined with an optical feedback system, almost 100% single cell encapsulation efficiency can be achieved. Benefiting from the ultrahigh resonant frequency and small footprint of the device, the encapsulation resolution can be further improved (<100 μm). We also demonstrate the combined encapsulation of single cells and particles. This liquid-bridge-based bioprinting technology exhibits high encapsulation efficiency, versatility toward different micro-objects, and good biocompatibility for handling viable samples, allowing its potential application in cell assembly, chemical analysis, and biofabrication.