An electrophoretic-type display device including an array of microcells, where each microcell is formed by a microwell containing a quantity of ink and a polymer-based membrane connected to upper edges of the microwell. The membrane is formed by curing an aqueous or hydroalcoholic sealing solution that is overcoated on the ink-filled microwells. The ink includes an isoparaffinic-based or oil-based suspension fluid, and the peripheral side walls of the microwell have a surface energy in the range of 20 to 30 mN/m. The microwell material serves two purposes: to prevent displacement (floating) of the relatively light ink solution above the relatively heavy sealing solution, and to facilitate reliable attachment between the polymer membrane and microwell walls during subsequent curing.