A method of forming a plurality of lipid bilayers over an array of cells in a nanopore based sequencing chip is disclosed. Each of the cells comprises a well. A first salt buffer solution with a first osmolarity is flowed over a cell in the nanopore based sequencing chip to substantially fill a well in the cell with the first salt buffer solution. A lipid and solvent mixture is flowed over the cell to deposit a lipid membrane over the well that encloses the first salt buffer solution in the well. A second salt buffer solution with a second osmolarity is flowed above the well to reduce the thickness of the lipid membrane, wherein the second osmolarity is a lower osmolarity than the first osmolarity such that an osmotic imbalance is created between a first volume inside the well and a second volume outside the well.