PROTECTIVE FILTERS AGAINST DUST AND DIRT PARTICLES FOR DROPLET MICROFLUIDICS APPLICATIONS

Currently, droplet microfluidics technologies are actively studied and implemented to solve various biological problems: screening of new drugs, molecular diagnostics, chemical synthesis, etc. However, most of the proposed devices are suitable only for laboratory use due to problems with reliability and reproducibility of results. One of the key problems arising when using microfluidic chips is clogging and blocking of microchannels with dust and dirt particles. Various designs of filter elements placed near the input interfaces of the microfluidic chip are proposed in the literature. However, many of them are not suitable for working with microdroplets of aqueous emulsions, since the filter structure can lead to disruptions of the original emulsion (separation or merging of droplets). In this paper, we studied 17 filter designs integrated into microfluidic chips that retain dust microparticles and pass water-in-oil emulsion microdroplets through themselves. The study determined the efficiency of filtration of microparticles from a model solution of dust in water and fluorocarbon oil. The overall range of dust microparticle filtration efficiency was within 88–99% for all the studied filter designs. The best 4 designs with a filtration efficiency of over 98% were used to study the transport of water-in-oil emulsion microdroplets. Based on the study results, the optimal design of the filter element was determined that retains dust microparticles with an efficiency of 99% and increases the variation coefficient of the diameter of monodisperse water-in-oil emulsion microdroplets by no more than 2 times from 6% to 12%.