Biomimetic patterned surfaces for controllable friction in micro- and nanoscale devices

Micro and Nano Systems Letters

Table 1 Water contact angle (CA) values, and friction properties of various biomimetic patterned surfaces at nano- and micro-scales

Surface	CA (deg)	Nano-scale friction force (nN)	Micro-scale friction coefficient (μ)	Ref
Silicon flat surface	22	20-28	0.46	[15]
SU-8 thin film	83	-	0.6	[30]
PMMA nano-patterns	99	0.84-1.97	0.33	[13]
DLC nano-dot surfaces	95	0.98-1.63	0.13	[23]
PMMA micro-patterns (Replicated Surfaces)	91-106	-	0.11-0.13	[25, 26]
Silicon micro-pillars	59	-	0.16	[29]
Silicon micro-pillars coated with DLC	145	-	0.12	[29]
Silicon micro-pillars coated with ZDOL	105	-	0.08	[29]
SU-8 micro-patterns	105	-	0.3	[30]
SU-8 micro-patterns coated with PFPE	108	-	0.19	[30]
SU-8 micro-patterns treated with Ar and coated with PFPE	83	-	0.21	[30]
SU-8 micro-patterns treated with O₂ and coated with PFPE	91	-	0.22	[30]

In these works, atomic force microscope and micro-tribotesters were used to measure friction at nano- and micro-scales, respectively.