Table 4.

Advantages and limitations of techniques used to fabricate microchannels.

Geometry	Method	Advantages	Limitations	Application	Reference
Rectangular	Soft lithography	Generation of precise, reproducible and versatile microchannels; Precise control of experimental parameters and accurate measurements; Inexpensive, simple and rapid method.	Different geometry from in vivo microvessels; Difficulties in achieving stable cell seeding at the corners of the channel.	Integration of confocal micro-PIV with a PDMS microchannel to obtain blood velocity profiles	[126]
Circular	Wire casting technique	Simple and inexpensive method; Possibility of fabricating microchannels with different diameters; No need for a clean room or specialized equipment.	It is not possible to generate well-defined complex structures, such as bifurcations.	In vitro hemodynamic studies	[127]
	Partially cured PDMS combined with thermal air expansion molding	Inexpensive and simple method; Possibility of fabricating multiple diameters of circular channel from 100 µm to 500 µm and different cross-sections.	It can be hard to fabricate a perfect circular channel.	Evaluate the clotting events in pathological vessels and testing device for antiplatelet and anticoagulant therapeutics	[128]
	Combination of soft lithography with the reflow phenomenon of a positive photoresist	Simple and efficient method; Possibility of fabricating microchannels with multiple diameters (from 100 µm to 400 µm) and various channel designs.	It can be hard to control the thickness of the photoresist, leading to a difficulty in generate perfect circular channels; Bonding the two semi-circular channels perfectly can be challenging.	This method allows endothelial cells culture, making this project suitable for drug screening and chemical/biological diagnostics	[90]
	Reshaping rectangular microchannels through polymerization of the liquid silicone oligomer around a gas steam	Ability of controlling the diameter from 40 µm to 100 µm; Possibility of fabricating constrictions.	Relatively complex and expensive method; Difficulty in controlling the exact diameter of the channel.	Mimic in vivo systems for cell flow studies	[124]