Table 1.

Overview of the possible microfluidic cell migration assays approaches.

References	Details	Constriction Characteristics	Schematic
	PDMS—Straight channels array
Rolli et al. [47] 1 Fu et al. [48] 1 Tong et al. [49] 2 Irimia et al. [50] 1 Spuul et al. [51] 1 Zhou et al. [52] 2 Mishra and Vazquez [43]	Chemotaxis analysis, comparison of migration behaviors depending on channels dimensions or chemical stimuli	Constant cross-section. Channels characteristic dimension from 50 to $3\mathsf{\mu }$m
	PDMS—Microchannels with engineered profile
Mak et al. [53] Mak et al. [54] Ma et al. [55] Raman et al. [56] 2 Boneschansker et al. [57]	Study of migration strategies depending on the local 3D channel geometry, such as tapering or height modulation; Integration of cell traps or bendable micropillars as cell force probes	Variable cross-section. Width varying form 50 to $4\mathsf{\mu }$m. Height varying from 15 to $10\mathsf{\mu }$m
	PDMS—Micropillars
Doolin and Stroka [58] 2,3 Davidson et al. [59] 1	Use of pillar arrays as ECM; Analysis of 2D cell motility depending on environment geometry; Study of cell migration through sub-nuclear dimension pores	Variable cross-section and 2D profile. Width varying from 50 to $2\mathsf{\mu }$m
	PDMS—Fluidic Maze
Tweedy et al. [60] Belotti et al. [61]	Study of cell decision making during migration and cellular environment probing capacity (e.g., fluidic resistance or self-induced chemical gradient)	Constant single channel cross-section. Bifurcations, corners and widenings. Channels dimension from 5 to $3\mathsf{\mu }$m
	Hydrogels—Microchannels
Cheng et al. [62] 1 Choi et al. [63] 1 Wang et al. [64]	Chemotaxis analysis, comparison of migration behaviors depending on channels dimensions or chemical stimuli; Possibility to modify mechanical properties of the channels, such as their stiffness	Constant cross-section. Channels dimension from 14 to $3.5\mathsf{\mu }$m
	Hydrogels—Migration matrix
Huang et al. [65] Anguiano et al. [66] Ayuso et al. [67] Truong et al. [68] Trappmann et al. [69] 4	Use of hydrogel matrix as ECM, mimicking biological tissues in terms of porosity and stiffness. Possibility to embed the cells directly inside the matrix	No opened channels, cells migrate through the hydrogel. Possible presence of voids or pores with micrometric dimension. Mechanical stiffness ranges from few tens of Pa to tens of kPa (e.g., 18 kPa)
	FLM—Glass-based devices
Sima et al. [70] 2 Sima et al. [71] 2	Microchannels with arbitrary cross-section realized in the bulk glass substrate.	Variable cross-section. Width varying from 5 to $0.9\mathsf{\mu }$m
	FLM—Two-photon polymerization devices
Tayalia et al. [72] Olsen et al. [73] 2 Ficorella et al. [29] 1,2,3,4 Sala et al. [74] 1,2,3,4	Polymeric 3D structures working as micrometer spatial constrains fabricated inside wider microfluidic channels. Possibility to arbitrary adjust the target geometry, from scaffolds or woodpiles to microchannels with arbitrary cross-section	Scaffold-like structure with porous size from $5\times 5\mathsf{\mu }$m${}^2$ to $15\times 15\mathsf{\mu }$m${}^2$. Channel with variable cross-section, from $20\times 20\mathsf{\mu }$m${}^2$ to $5\times 5\mathsf{\mu }$m${}^2$

Devices coated with: ¹ fibronectin; ² collagen; ³ Pluronic F127; ⁴ poly-d-lysine.