Table 1.

Important parameters of microwells that are effective in the spheroid generation.

Parameter	Properties	Notes	3D printed fabrication	Conventional lithography fabrication
Microwell shape (cross-section)	Square, hexagonal, circular and triangular	Some reports showed that hexagonal and circular shapes are better than others to form founded spheroid6,27,36,37	✓	✓
Microwell diameter	100–800 µm	Some reports evaluate the well diameter on spheroid size27,38–40	Less than 200 µm performed only with a high-resolution 3D printer2–4,41	✓
Microwell depth	100–1000 µm	The appropriate depth for making a spheroid of the desired size is determined based on the diameter24,27,38,39	✓	The difficulty for fabrication depth more than 200 µm7,29
Microwell bottom	V-conical, V-spindle, U-shape	Help to cell aggregation, form a single and rounded spheroid29,30,37,42,43	Only with a high-resolution 3D printer2–4,41	×
	Flat-bottom	Simple fabrication40,44	✓	✓
Microwell type	Decreasing the cross-section with increasing the depth (conical, spindle, reverse pyramidal)	Help to cell aggregation, form a single and rounded spheroid24,28,45,46	Only with a high-resolution 3D printer2–4,41	×
	Fixed cross-section (cylindrical, hexagonal prism, and cubic)	Simple fabrication40,44	✓	✓