Experimental research of electroosmotic flow in rough microchannels based on current-monitoring method

Two kinds of PMMA microfluidic chips were manufactured,and the surface param-eters of the microchannels were tested.A electroosmotic flow (EOF)experimental system with the microfluidic chip was designed based on the current-monitoring method.Firstly,the EOF ve-locity in smooth microchannels was measured,which validated the feasibility of the experimental method.The method can predict the microchannel surface potential.Secondly,the EOF velocity in rough microchannels was measured.Finally,the influence of the electric strength and ionic concentration on the EOF in smooth and rough microchannels was analyzed .The results show that:(1 )The EOF velocity in smooth and rough microchannels is proportional to the electric strength;the EOF velocity decreases with the increase of ionic concentration both in smooth and rough microchannels.(2)The EOF velocity in rough microchannels is significantly decreased. The velocity is decreased by 23%,when the relative roughness is 5%.(3)The gap between the EOF velocities in smooth and rough microchannels increases with the increase of electric strength or solution concentration.The experimental method possesses the advantage of being intuitive, convenient and low cost.