Development of a Droplet Microfluidics Device Based on Integrated Soft Magnets and Fluidic Capacitor for Passive Extraction and Redispersion of Functionalized Magnetic Particles

Abstract

Based on a recent droplet microfluidic device for target molecules' extraction, purification, and redispersion, here an original fluidic control system is proposed to improve the device versatility and usability. This approach relies on the coupling of functionalized magnetic particles handling by integrated soft magnets and a passive droplet splitting control at a channel junction. To reach the high standards required for bioassays' implementation, this device integrates a pressure‐driven variable volume component, acting as a fluidic capacitor, which allows a passive and controlled self‐triggered droplet fingering in a dead‐end channel. The working principle is described, and the modeling of the induced fingering phenomenon by an electric analogy is presented. Then, the achieved finger length is characterized as a function of geometrical and material properties of the fluidic capacitor. The complete device configuration guarantees extraction and purification efficiencies higher than 97% and 95%, respectively, showing high‐throughput particles handling between droplets with a passive droplet splitting control. Finally, this technology is successfully applied to gene expression study for cancer diagnosis by performing magnetic particle–based messenger RNA (mRNA) extraction followed by reverse transcription (RT) and quantitative polymerase chain reaction (RT‐qPCR) analysis.

Experimental Investigation of Air Compliance Effect on Measurement of Mechanical Properties of Blood Sample Flowing in Microfluidic Channels

“…However, during the process of supplying a blood sample into a microfluidic device, the syringe pump causes fluidic instability at low flow rates [22]. To stabilize unstable flows resulting from the syringe pump, several techniques including air cavity in a driving syringe [23] or microfluidic channel [24,25], portable air cavity unit [22,26], and flexible compliance unit [27][28][29][30][31][32], were demonstrated in microfluidic systems. These methods act on the compliance element in the fluidic circuit model.…”

Magnetic Polymers for Magnetophoretic Separation in Microfluidic Devices

“…Composite PDMS structures were also recently implemented on the channel wall for droplet microfluidic. Serra et al reported a device for the extraction, purification, and redispersion of target molecules by coupling soft composite magnets and passive fluidics [65]. Composite blocks were obtained by mixing iron particles (1 to 6 µm) with PDMS and pouring the mixture into a CycloOlefin copolymer master.…”

Recent advances in magnetic digital microfluidic platforms

“…Microdroplets containing magnetic particles are always manipulated by permanent magnets or electromagnets on the plates covered by Teflon AF or other hydrophobic materials. Researchers have demonstrated the physical control mode of microdroplet motion and action based on magnetic particles and explored the intervention and extraction process of magnetic particles from microdroplets [33][34][35]. For example, Z.…”