A magnetically controlled microfluidic device for concentration dependent in vitro testing of anticancer drug

A system for fluid pumping by liquid metal multi-droplets

The transportation and control of microfluidics have an important influence on the fields of biology, chemistry, and medicine. Pump systems based on the electrocapillary effect and room-temperature liquid metal droplets have attracted extensive attention. Flow rate is an important parameter that reflects the delivery performance of the pump systems. In the systems of previous studies, cylindrical structures are mostly used to constrain the droplet. The analysis and quantitative description of the influence of voltage frequency, alternating voltage, direct current voltage bias, and solution concentration on the flow rate are not yet comprehensive. Furthermore, the systems are driven by only one droplet, which limits the increase in flow rate. Therefore, a pump with a cuboid structure is designed and the droplet is bound by pillars, and the flow rate of the pump is increased by more than 200% compared with the cylindrical pump. For this structure, the mechanism of various factors on the flow rate is analyzed. To further enhance the flow rate, a pump system with multi-droplets is proposed. Moreover, the expression of flow velocity of the solution on the surface of each droplet and the relationship between the flow rate, alternating voltage, and the number of droplets are deduced. Finally, the potential of applying the multi-droplet cuboid pump system in drug delivery and analytical chemistry is demonstrated. Additionally, the core of the pump, the droplet area, is modularized, which breaks the overall structural limitations of the liquid metal pump and provides ideas for pump design.

Rapid-release reversible bonding of PMMA-based microfluidic devices with PBMA coating

PMMA-based microfluidics have been widely used in various applications in biological and chemical fields. In the fabrication process of PMMA-based microfluidics, the substrate and cover plate usually need to be bonded to enclose the microchannel. The bonding process could be permanent or reversible. In some application scenarios, reversible bonding is needed to retrieve the samples inside the channel or reuse the chip. Current reversible bonding methods for PMMA-based microfluidics usually have drawbacks on bonding strength and contaminations from the adhesives used in the bonding process. In this study, a new approach is proposed for the reversible bonding of PMMA-based microfluidics, a layer of PBMA (with a very similar structure to PMMA) was coated on the surface of PMMA and then use the thermal fusion method to achieve the bonding with a high bonding strength, a tensile bonding strength of around 0.8 MPa was achieved. For debond process, a rapid temperature drop will trigger the immediate release of the bonding within several seconds. Detailed bonding strength measurement and biocompatibility tests were also conducted in this study. The proposed bonding method could have wide application potential in the fabrication of PMMA-based microfluidics.