A flexible and cost-effective manual droplet operation platform for miniaturized cell assays and single cell analysis.

Herein, we developed a flexible and cost-effective manual droplet operation system (MDOS) for performing miniaturized cell assays as well as single cell analysis. The MDOS consists of a manual x-y-z translation stage for liquid transferring and switching, a high-precision syringe pump for liquid driving and metering, a tapered capillary probe for droplet manipulation, a droplet array chip for droplet loading and reaction, sample/reagent reservoirs for storage, and a microscope for droplet observation, with a total expense of only $4,000. By using the flexible combination of three elementary operations of the x-y-z stage's moving and the pump's aspirating and depositing, the MDOS can manually achieve multiple droplet handling operations in the nanoliter to picoliter range, including droplet generation, assembling, fusion, diluting, and splitting.

A Microfluidic Droplet Array System for Cell-Based Drug Combination Screening.

In the last few decades, drug combination therapy has been widely applied in oncology and in other complex diseases. Due to its potential advantage of lower drug toxicity and higher therapeutic efficacy, drug combination treatment has been more and more studied in fundamental labs and pharmacy companies. In this chapter, we report cell-based drug combination screening using a microfluidic droplet system based on a sequential operation droplet array (SODA) technique.

Cell-based drug combination screening with a microfluidic droplet array system.

We performed cell-based drug combination screening using an integrated droplet-based microfluidic system based on the sequential operation droplet array (SODA) technique. In the system, a tapered capillary connected with a syringe pump was used for multistep droplet manipulations. An oil-covered two-dimensional droplet array chip fixed in an x-y-z translation stage was used as the platform for cell culture and analysis.

Microfluidic cytometer based on dual photodiode detection for cell size and deformability analysis.

Cellular mechanical properties play an important role in disease diagnosis. Distinguishing cells based on their mechanical properties provides a potential method for label-free diagnosis. In this work, a convenient and low-cost microfluidic cytometer was developed to study cell mechanical properties and cell size based on the change of transmission intensity, using a low-cost commercial laser as a light source and two photodiodes as detectors.

Microfluidic droplet-array liquid-liquid chromatography based on droplet trapping technique.

We describe the first realization of liquid chromatographic separation in a droplet-based microfluidic system and develop a novel mode for microchip-based chromatography named as droplet-array liquid-liquid chromatography. In this system, two arrays of picoliter-scale droplets immobilized on both sidewalls of a microchannel with droplet trapping technique served as the stationary phase in chromatographic separation, while the other immiscible phase flowing in the microchannel served as the mobile phase. The chromatographic separation was achieved on the basis of multiple extraction and elution of analytes between the droplet array stationary phase and the mobile phase.

Droplet-based microfluidic flow injection system with large-scale concentration gradient by a single nanoliter-scale injection for enzyme inhibition assay.

We described a microfluidic chip-based system capable of generating droplet array with a large scale concentration gradient by coupling flow injection gradient technique with droplet-based microfluidics. Multiple modules including sample injection, sample dispersion, gradient generation, droplet formation, mixing of sample and reagents, and online reaction within the droplets were integrated into the microchip. In the system, nanoliter-scale sample solution was automatically injected into the chip under valveless flow injection analysis mode.