Magnetic digital microfluidics on a bioinspired surface for point‐of‐care diagnostics of infectious disease

Abstract

Magnetic digital microfluidics uses magnetic force to manipulate droplets on a Teflon‐coated substrate through the added magnetic particles. To achieve a wide range of droplet manipulation, hydrophilic patterns, known as surface energy traps, are introduced onto the Teflon‐coated hydrophobic substrate. However, the Teflon‐coated substrate is difficult to modify because it is nonwettable, and existing techniques for patterning surface energy traps have many limitations. Inspired by the mussel adhesion mechanism, we use polydopamine, a bioinspired substance that adheres strongly to almost any materials, to pattern surface energy traps on the Teflon‐coated substrate with a great ease. We have optimized the polydopamine coating protocol and characterized the surface properties of the polydopamine surface energy traps. Droplet operations including particle extraction, liquid dispensing, liquid shaping, and cross‐platform transfer have been demonstrated on the polydopamine surface energy trap‐enabled magnetic digital microfluidic platform in both single‐plate and two‐plate configurations. Furthermore, the detection of hepatitis B surface antigen using ELISA has been demonstrated on the new magnetic dgitial microfluidic platform. This new bioinspired magnetic digital microfluidic platform is easy to fabricate and operate, showing a great potential for point‐of‐care applications.

A 3D-printed magnetic digital microfluidic diagnostic platform for rapid colorimetric sensing of carbapenemase-producing Enterobacteriaceae

“…The droplet manipulator is translucent so that the location of the droplets can be observed through the droplet manipulator. The semicircular droplet holders on the droplet manipulator are rendered hydrophilic by a polydopamine coating 27,40 .…”

“…4avi, bvi, and cvi). The droplet holders at the observation windows are coated with polydopamine 27,40 , which makes them hydrophilic and capable of holding the droplets in position while the magnetic particles are extracted from the droplets. Finally, the droplets are incubated at room temperature in a humid chamber.…”

“…We explore modifications to the Carba NP test that allow miniaturization and parallel testing of CPE by introducing magnetic digital microfluidics (MDM) technology [26][27][28] . By digitalizing liquids into discrete droplets, MDM accomplishes a full range of fluidic operations, such as liquid merging, mixing, dispensing, and serial dilution, upon the application of magnetic force through added magnetic particles [29][30][31][32][33] .…”

“…Compared with conventional continuous-flow microfluidics for Carba NP 34 , MDM obviates the need for valving and pumping systems, thereby offering an easy way of handling small amounts of fluids in bioanalytical assays and a potential solution for simple automation. The use of MDM was previously demonstrated for sample-to-answer molecular testing 32,33,[35][36][37] , immunotesting 27,30 , and broth microdilution-based antimicrobial susceptibility testing 31 . Compared with digital microfluidics based on electrowetting on dielectrics (EWOD), the droplet manipulation and system automation of MDM are less efficient, but MDM is more suitable for conducting biochemical reactions, particularly point-of-care (POC) diagnostics, due to its simple fluidic manipulation and the dual functions of magnetic particles.…”

Magnetic Particles for Advanced Molecular Diagnosis

“…There have been several studies in the literature reporting the use of magnetic particles for the detection of viruses. Specifically, hepatitis A virus and hepatitis B virus were captured and detected using carboxyl-derivatized magnetic beads [110] and magnetic digital microfluidic systems [111], respectively, with improved specificity and virus liberation from the matrix. Furthermore, one study reported targeting and isolation of the influenza virus using erythrocyte-membrane-cloaked nanoparticles modified with magnetic functionalities by encapsulating superparamagnetic iron oxide nanoparticles.…”