A simple and low-cost approach for irreversible bonding of polymethylmethacrylate and polydimethylsiloxane at room temperature for high-pressure hybrid microfluidics

Microfluidic devices have been used progressively in biomedical research due to the advantages they offer, such as relatively low-cost, rapid and precise processing, and an ability to support highly automated analyses. Polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA) are both biocompatible materials widely used in microfluidics due to their desirable characteristics. It is recognized that combining these two particular materials in a single microfluidic device would enable the development of an increasingly in-demand array of new applications, including those requiring high flow rates and elevated pressures. Whereas complicated and time-consuming efforts have been reported for bonding these two materials, the robust adhesion of PDMS and PMMA has not yet been accomplished, and remains a challenge. In this study, a new, simple, efficient, and low-cost method has been developed to mediate a strong bond between PMMA and PDMS layers at room temperature in less than 5 min using biocompatible adhesive tape and oxygen plasma treatment. The PDMS–PMMA bond was hydrolytically stable, and could tolerate a high influx of fluid without any leakage. This study addresses the limitations of existing approaches to bond these materials, and will enable the development of highly sought high-pressure and high-throughput biomedical applications.

One cell, one drop, one click: hybrid microfluidic mammalian single-cell isolation

The process of generating a stable knockout cell line is a complex process that can take several months to complete. In this work, we introduce a microfluidic method that is capable of isolating single cells, selecting successful edited clones, and expansion of these isoclones. Using a hybrid microfluidics method, droplets in channels can be individually addressed using a co-planar electrode system. In our hybrid microfluidic device, we show that we can trap single cells and subsequently encapsulate them on demand into pL-sized droplets. Furthermore, individual cells inside the droplet can be released from the traps or merged with other droplets by simply applying an electric potential to the electrodes that is actuated through a user interface. We use this high precision control to sort and to recover single isoclones to establish monoclonal cell lines, which is demonstrated with a heterozygous NCI-H1299 lung squamous cell population resulting from loss-of-function eGFP and RAF1 gene knock-out transfections.