Lipid bi-layers are ubiquitous components of biological cells — and are found in variety of cell components ranging from cell membranes to membranes of organelles inside the cells. In biological membranes, lipid bi-layer membranes carry membrane proteins, which serve as single channel nanopores that are used to study transport of proteins and characterize the properties of proteins. However, lipid bi-layers have very short half lives, which are usually less than an hour. The lipid bi-layers are usually obtained by physico-chemical interactions between a lipid containing organic solvent, an aqueous buffer solution and a hydrophobic surface. We have developed a continuous flow through microfluidic device using pressure driven flow (by means of a tandem syringe pump system) for synthesis of lipid bi-layers. The microfluidic device consists of two glass substrates with micro-channels and microchambers microfabricated using photolithography and wet glass etching. The microchannels in each substrate is in the form of “+” shape and form a mirror image of each other. A Teflon sheet (∼200 microns thickness) is sandwiched between the glass substrates with a ∼200 microns diameter hole etched in the center to communicate with the two sets of microchannels. A lipid solution in an organic solvent (Pentane) and KCl buffer solution are alternately flown through the legs of the microchannel. The conductivity of the buffer is monitored using a current amplifier. The formation of the lipid bi-layer is confirmed by monitoring the resistivity and the impedance to high frequency electrical oscillations. The flow rate in the microfluidic device is optimized to obtain the lipid bi-layer.

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