A semi-experimental procedure for the estimation of permeability of microfluidic pore network

Abstract

Microfluidic porous media systems are used for various applications ranging from chemical molecule detection to enhanced oil recovery studies. Absolute permeability data of the microfluidic porous media are important for those applications. However, it is a significant challenge to measure the permeability due to the difficulty in accurately measuring the ultra-low pressure drop across the pore network. This article presents a semi-experimental procedure to estimate the permeability of a microfluidic pore network. The total pressure drop across the porous media chip (ΔPchip) at a given flow rate of a single-phase liquid was obtained from the difference in the inlet pressures at the microfluidic pump with and without the pore network chip connected. The pressure drops in the inlet (ΔPinlet channel) and outlet (ΔPoutlet channel) channels of the pore network are estimated using the hydraulic resistance equation for Poiseuille flow in a wide rectangular cross section. Then the pressure drop across the pore network of the chip (ΔPpore network) is obtained by subtracting (ΔPinlet channel + ΔPoutlet channel) from ΔPchip. Subsequently the permeability of the pore network is calculated using the Darcy’s law. • The proposed method is applicable for both homogenous and heterogeneous pore networks. • This method does not require a differential pressure sensor across the microfluidic chip. • This method eliminates the possibility of gas entrapment that can affect the permeability measurement. Method name: Semi-experimental procedure for the estimation of permeability, Keywords: Microfluidics, Permeability, Pressure drop, Hydraulic resistance, Darcy’s law, Kozeny-Carman