Table 4.

Summary of microfluidic purification techniques for nanoparticles. Adapted with permission from [282] and used under the Creative Commons license permission (CC BY 3.0). Copyright 2017, Royal Society of Chemistry. All rights reserved.

Techniques	Mechanism	Separation Marker	Sizes Separated (nm)	Efficiency (%)	Throughput (mL·min−1)	Pros	Cons
Field flow fractionation	Asymmetrical flow FFF	Size	5–250	87–88	0.4–1.1	Very high throughput with high separation efficiency	Specific sample/solvent systems and compatible membrane
Centrifugal	Centrifugal force	Size, density	50–200	-	0.0075	High throughput, density gradient, and dilution not required	Discontinuous
Optical	Optical force	Size, refractive index, polarizability	70–1000	-	0.010–0.375	High separation efficiency	Heating and photodamage, low throughput
Affinity capture	Surface interactions	Antigenic site, hydrophobicity, charge	100	-	0.010	High capture efficiency and purity	Expensive, multiple preparation steps
Electrophore-sis	Uniform electric field	Size, charge	<50	97	0.0004	Very high separation efficiency and resolution	Flow rate change with chemistry (buffers, wall effects)
Dielectropho-resis	Nonuniform electric field	Polarizability and size	30–60	85–100	0.000009	High throughput and separation efficiency	Requires high voltage, depends on medium conductivity, very low throughput
Magnetopho-resis	Magnetic field	Size, magnetic properties	5–200	90	0.300	Very high throughput, low cost	Long time for magnetic bead antibody labeling
Acoustopho-resis	Ultrasonic sound wave	Size, density, compressibility	<200	>90	0.00043–0.00081	High separation efficiency, controlled cut off separation	Complex fabrication, limited device material to transmit acoustic power efficiently
Ion concentration polarization	Electric field	Size, electrophoretic mobility	100–500	-	0.0005	Low voltage, no need for internal electrode	Low resolution on small size particles, low throughput
Electrohydro-dynamic vortices	Traveling waves, ohmic heating	Size, charge	200	~100	0.000033	High separation efficiency	Complex fabrication of microelectrode, low throughput
Deterministic lateral displacement	Laminar flow stream	Size, deformability	190–2000	~100	0.00001	Controllable cutoff size, simple and efficient, high separation efficiency (20 nm resolution)	Very low throughput, precise fabrication required, pillar clogging is possible
Hydrodyna-mic filtration	Hydrodynamic sieving	Size	100–1000	-	0.001	Simple, high separation efficiency, medium throughput	Prone to clogging
Spiral microfluidics	Dean vortices	Size, shape	590–7320	95	0.010	Very high separation efficiency, simple	Prone to particle-particle interactions and diffusion disruption
Inertial microfluidics	Shear and wall lift	Size, shape	590–1980	-	-	Very high throughput, separation efficiency, simple	Prone to particle–particle interactions and diffusion disruption
Electrostatic sieving	Electric double-layer force	Size, charge	19–50	97	0.0006	Very high separation efficiency, controllable cut-off size	Separation only possible in low ionic strength conditions, low throughput
Bacterial chemotaxis	Chemotaxis, diffusion, and bacterial motility	Selective adhesion on bacteria	320–390	81	0.000013	Simple, low cost	Requires antibody conjugation for selective adhesion to bacteria, very low throughput, and relatively medium separation efficiency