Recent advances in magnetic digital microfluidic platforms

Abstract

Magnetic Digital microfluidics (DMF), which enables the manipulation of droplets containing different types of samples and reagents by permanent magnets or electromagnet arrays, has been used as a promising platform technology for bioanalytical and preparative assays. This is due to its unique advantages such as simple and “power free” operation, easy assembly, great compatibility with auto control systems, and dual functionality of magnetic particles (actuation and target attachment). Over the past decades, magnetic DMF technique has gained a widespread attention in many fields such as sample‐to‐answer molecular diagnostics, immunoassays, cell assays, on‐demand chemical synthesis, and single‐cell manipulation. In the first part of this review, we summarised features of magnetic DMF. Then, we introduced the actuation mechanisms and fabrication of magnetic DMF. Furthermore, we discussed five main applications of magnetic DMF, namely drug screening, protein assays, polymerase chain reaction (PCR), cell manipulation, and chemical analysis and synthesis. In the last part of the review, current challenges and limitations with magnetic DMF technique were discussed, such as biocompatibility, automation of microdroplet control systems, and microdroplet evaporation, with an eye on towards future development.

Merging microfluidics with luminescence immunoassays for urgent point-of-care diagnostics of COVID-19

“…Droplet formation includes active and passive ways. The active approach applies an external force to microfluidics, including opto-electrowetting [ [250] , [251] , [252] ], magnetism [ [253] , [254] , [255] ], thermocapillary forces [ 256 , 257 ], surface acoustic waves [ [258] , [259] , [260] ], dielectrophoresis (DEP) [ [261] , [262] , [263] ], electrowetting-on-dielectric (EWOD) [ [264] , [265] , [266] ], etc. However, these methods are suitable for manipulating droplets but not for massive droplet generation to meet digital immunoassays.…”

Digital microfluidics for biological analysis and applications

“…With the ability to precisely manipulate discrete droplets in an integrated microfluidic device, DMF allows the addressable picoliter-to-microliter-sized droplets to be dispensed, moved, merged and split according to a preset path programmatically. 1,2 The actuation mechanism of DMF includes electrowetting on dielectric (EWOD), [3][4][5] magnetic, 6,7 and surface acoustic waves. [8][9][10][11] Among them, although EWOD-based force requires relatively more complicated fabrication of multiple layers of structures and has less tolerance to different types of liquid, 6 it is currently the most popular technology due to its fast response, simple system and high precision, which is the focus in this review.…”

Development of a Microfluidic Chip Powered by EWOD for <em>In Vitro</em> Manipulation of Bovine Embryos

“…The technology employs applied electric fields [44] to manipulate pico-to micro-liter (10 -12 -10 -6 L) droplets in a rapid manner on an array of insulated electrodes on the chip [45][46][47]. Plentiful examples of EWOD based microdevices created for chemistry and life sciences exist [48][49][50][51][52][53][54]. A novel direction for EWOD in ARTs was proposed recently, allowing for the analysis of spent culture medium from a single human embryo with no interference to the culture protocol, which is unachievable using standard techniques [55].…”