Microfluidic valves based on superhydrophobic nanostructures and switchable thermosensitive surface for lab-on-a-chip (LOC) systems

Hierarchical micro and nano structured, hydrophilic, superhydrophobic and superoleophobic surfaces incorporated in microfluidics, microarrays and lab on chip microsystems

“…Andersson et al [107] proposed a plasma deposited Teflon hydrophobic valve, while hydrophobic patters where also proposed by Suk et al to control capillary flow [108]. Londe et al [109] one year later proposed a superhydrophobic valve with a thermosensitive behavior (see Fig. 5(iii)), while Washe et al proposed electrochemical actuation of such valves [110] .…”

Nanoscale surface roughness affects low Reynolds number flow: Experiments and modeling

“…These promising developments necessitate a thorough understanding of the flow characteristics of fluids in rough microchannels and has been the focus of recent studies. [5][6][7] The effect of micro-scale surface roughness (c ¼ 1.6%, where c ¼ 100% Â roughness height=D H , and D H is the hydraulic diameter of the channel) was examined 8 experimentally by using micro-PIV and comparing with a smooth computational fluid dynamics (CFD) simulation of a channel of the same geometry. Flow effects in relation to periodic micro-scale obstructions in height have also been investigated using CFD by various authors.…”

Redox control of capillary filling speed in poly(ferrocenylsilane)-modified microfluidic channels for switchable delay valves

“…33 For example, Londe et al described a thermo-actuated capillary valve in microfluidic channels based on the reversible hydrophobic/hydrophilic switching of PNIPAM. 34,35 The system was controlled by the interfacial tension of the liquid-air-solid interface, and not by the swelling and shrinking of PNIPAM as its lower critical solution temperature (LCST) was traversed.…”