This study investigated the streaming potential and wall slip effects on pressure-driven liquid flow in hydrophobic microchannels.The Poisson-Boltzmann equation for the electrical double layer(EDL)and Navier-Stokes equation for incompressible viscous fluid were established.For those microchannels with high wall zeta potential

the traditional Debye-H點kel linear approximation for solving the potential distributions of EDL would produce big error

therefore

analytical expression for potential distributions and Navier slip boundary condition were introduced to solve the N-S equation analytically

then analytical solution of streaming potential could be obtained by using the electrical current balancing condition.The influences of electrokinetic parameter(K)

wall zeta potential and slip coefficient on streaming potential and velocity distributions were discussed in detail.The results showed that streaming potential decreased with increasing electrokinetic parameter

while increased significantly with increasing slip coefficient.It also tended to reach a maximum value at a certain zeta potential and then decreased rapidly with increasing zeta potential.Streaming potential and wall slip both affected fluid flow in microchannels

the former retained the development of liquid flow

but the latter accelerated flow velocity.Wall slip effect played a major role at lower zeta potentials

that is

flow velocity increased at lower zeta potentials when the combined effects of streaming potential and hydrodynamic slippage appeared in microchannels.Wall slip velocity gradually reduced to zero at higher zeta potential

then wall slip effect on pressure-driven flow in microchannels could be ignored.