Droplet microfluidics is an extremely useful and powerful tool for industrial, environmental, and biotechnological applications, due to advantages such as the small volume of reagents required, ultrahigh-throughput, precise control, and independent manipulations of each droplet. For the generation of monodisperse water-in-oil droplets, usually T-junction and flow-focusing microfluidic devices connected to syringe pumps or pressure controllers are used. Here, we investigated droplet-generation regimes in a flow-focusing microfluidic device induced by the negative pressure in the outlet reservoir, generated by a low-cost mini diaphragm vacuum pump. During the study, we compared two ways of adjusting the negative pressure using a compact electro-pneumatic regulator and a manual airflow control valve. The results showed that both types of regulators are suitable for the stable generation of monodisperse droplets for at least 4 h, with variations in diameter less than 1 µm. Droplet diameters at high levels of negative pressure were mainly determined by the hydrodynamic resistances of the inlet microchannels, although the absolute pressure value defined the generation frequency; however, the electro-pneumatic regulator is preferable and convenient for the accurate control of the pressure by an external electric signal, providing more stable pressure, and a wide range of droplet diameters and generation frequencies. The method of droplet generation suggested here is a simple, stable, reliable, and portable way of high-throughput production of relatively large volumes of monodisperse emulsions for biomedical applications.

Microfluidics is a rapidly growing area that provides innovations in biotechnology, medical diagnostics, and life science. Along with the commercial solutions, there are open-source projects aimed to make such technologies more affordable and flexible for end users. In this article, we developed an open-source, low-cost, and easy-to-use microfluidic pressure controller with a modular design based on electropneumatic regulators to introduce liquids into microfluidic devices under constant pressures. For implementation of complex experimental protocols, the controller contains a vacuum pump, relay outputs, analog inputs, and digital inputs/outputs to connect external equipment. It can be operated using five displays and an encoder or from a personal computer in a manual or automatic regime through the custom open-source software. In this study, we applied this pressure controller for the generation of water-in-oil droplets in microfluidic flow-focusing droplet generators. Droplets’ diameters linearly depended on the dispersed and continuous phases’ ratio in the range 5– $65 \mu \text{m}$ . In all the cases, the generation regimes were stable for at least 4 h. Direct comparison of the droplet generation obtained with the developed pressure controller and precise syringe pumps showed that it will suit the needs of the microfluidic community for different flow-based lab-on-a-chip applications, as a more affordable and flexible solution for introducing liquids and controlling flow sensors, heaters, valves, light sources, and so on during experiments.

Advantages of devices on a microchip platform are discussed in comparison with traditional systems. Stages and processes of creation of microfluidic chips are considered. The basic technologies of formation micro- and nanostructures on a substrate from various materials and techniques for microchip sealing are introduced. Special attention is given to microfluidic chips for separation and analysis of nucleic acids and proteins, as well as to microchips for PCR. Examples of integrated systems on the basis of microfluidic technique are considered. Data on the commercialization of devices based on microfluidic chips are presented.

Loop-mediated isothermal amplification (LAMP) is widely used as a fast and sensitive diagnostic method and is most promising for analysis in conditions of limited time and resources, for example, in places of care. The paper discusses the basic principles of LAMP technique, methods for detecting reaction products, as well as some microfluidic devices and analytical systems based on LAMP, including those developed for express diagnostics in the context of the COVID-19 pandemic.

The rapid detection of pollutants in water can be performed with enzymatic probes, the catalytic light-emitting activity of which decreases in the presence of many types of pollutants. Herein, we present a microfluidic system for continuous chemoenzymatic biosensing that generates emulsion droplets containing two enzymes of the bacterial bioluminescent system (luciferase and NAD(P)H:FMN–oxidoreductase) with substrates required for the reaction. The developed chip generates “water-in-oil” emulsion droplets with a volume of 0.1 $\mathsf{\mu }$L and a frequency of up to 12 drops per minute as well as provides the efficient mixing of reagents in droplets and their distancing. The bioluminescent signal from each individual droplet was measured by a photomultiplier tube with a signal-to-noise ratio of up to 3000/1. The intensity of the luminescence depended on the concentration of the copper sulfate with the limit of its detection of 5 $\mathsf{\mu }$M. It was shown that bioluminescent enzymatic reactions could be carried out in droplet reactors in dispersed streams. The parameters and limitations required for the bioluminescent reaction to proceed were also studied. Hereby, chemoenzymatic sensing capabilities powered by a droplet microfluidics manipulation technique may serve as the basis for early-warning online water pollution systems.

The results on making a microfluidic chip for in vitromicroscopic investigations of single cells are presented. Numerical simulation of the motion trajectories of microparticles makes it possible to...