Abstract
Picolitre monodisperse droplet printing technology has important applications in biochemistry, such as accounting for quantitative analysis and single-cell analysis, and can be used for parallel high-throughput analysis of biomarkers and chemicals. However, commonly used droplet generation devices require complex control systems or customised microfluidic chips, making them costly and difficult for researchers to operate. Additionally, generating picolitre monodisperse droplets with microfluidic devices necessitates the introduction of an oil phase to block and separate the liquid. This requirement can reduce the throughput of the target droplets and cause cell contamination, hindering the adoption of this technology. By employing a common 1-mm-diameter capillary in the laboratory in combination with a piezoelectric transducer, we have achieved on-demand picolitre droplet printing of less than 100 pL in an oil-free environment. The device was found to be biocompatible with K562 cells. This approach is less costly, offers greater operational freedom, and is easier to integrate with other downstream assay modules or even handheld cell-printing devices. This study holds great potential for application in areas such as single-cell analysis, cell sampling, and pharmaceutical analysis.