TABLE II.

Inertial microfluidic devices fabricated by different microfabrication techniques.

Method	Mold materials	Channel materials	Channel shape	Cross-section	Dimension error range (DE)/resolution range (RR) (μm)	Processing time/cost	Actual dimensions range (μm)
Photolithography				Rectangular Square	RR: 5
Photolithography	Si wafer	PDMS	Symmetric and asymmetric spirals94,131–133 Straight and/or curve67,134 Serpentine133	Rectangular	…	…	20–300
Xurography				Rectangular Square	RR: 200
Xurography	Adhesive vinyl sheet Epoxy polymer	PDMS	Spiral74	Rectangular	…	…	100–600
Micromachining			Rectangular Square Trapezoidal Triangular complex	RR: 30
Micro-milling	PMMA	PDMS	Spiral45,135,136 Straight26	Trapezoidal45,135,136 Triangular26 Rectangular45,118	…	…	40–300
Micro-milling	Aluminium	PDMS	Spiral42,87,137,138 Straight16	Trapezoidal16,42,87,137,138 Rectangular138 Complex16,137	DE: ∼3–10 μm RR: x–y: 10 μm z: 2 μm	…	30–600
Diamond cutting	Brass	PDMS	Straight94	Triangular	…	…	20–76
Injection molding	Duralumin	Polycarbonate resin	Spiral75	Trapezoidal	…	∼10 min	50–500
Hot embossing				Rectangular Square	RR: 30
Roll-to-roll hot embossing	PMMA	PMMA	Straight35	Trapezoidal	DE: 5–0 μm	…	40–220
Etching				Rectangular Square Trapezoidal Triangular Complex	RR: 2
Deep reactive-ion etching	Si wafer PDMS	PDMS	Spiral136,139	Rectangular	…	…	10–500
Anisotropic wet etching	Si wafer PDMS	Si wafer PDMS	Straight25,37	Parallelogram Rhombus Polygon (3–6) Half circular	…	…	30–116
Embedding microwire			Circular Semi-circular	RR:50
Microwire	Steel microwire Nylon microwire	PDMS	Straight36	Circular	…	…	50–181
Laser cutting				Rectangular Square Trapezoidal Triangular	RR: 50 (CO2 and UV laser ablation) RR: 10–20 (femtosecond laser ablation)
UV laser ablation	…	PVC film	Spiral97,140	Rectangular	DE: 20 μm RR: 50 μm	0.−1–1.5 ¢/chip ∼20 min	50–760
Femtosecond laser ablation	…	Glass wafer Fused silica glass99	Spiral20 Complex straight99	Trapezoidal20 Rectangular99	…	5 €/chip ∼3.5–6.5h	40–600
Foil-assisted CO2 laser ablation or irradiation	PMMA	PDMS	Spiral34	Rectangular	DE: 20–30 μm	…	80–23
3D printing				Rectangular Square Trapezoidal Triangular Circular Semi-circular Complex	RR: 50
DLP/SLA 3D printing	…	SLA/DLP resin19 Photopolymer141 DSM Somos watershed XC11122111 PDMS142	Straight19,141 Spiral19,142 Serpentine19 Curvilinear19,141 Contraction–expansion19 3D helical111	Rectangular19 Trapezoidal19,142 Triangular19,111	RR: x–y: 25–56 z: 5–100	∼2–5h	80–1000
FDM 3D printing	ABS plastics118	PDMS118 ABS141 PLA141	Straight118	Semielliptical118 Triangular118 Circular118 Rectangular118	RR: x–y: 100 z: 100	…	100–1200
Wax 3D printing	Midas castable material	PDMS	Straight Curvilinear Spiral31	Circular Rectangular Triangular Complex	RR: x–y: 24 z: 6	∼6h	50–250
Multijet 3D printing		VisiJet M3 crystal material	Helical30	River meander-like Circular Rectangular Trapezoidal	…	…	300–1500
Inkjet 3D printing	…	UV curable plastic	Straight141 Curved Serpentine	Rectangular