A method of patterning interconnect lines on a flexible membrane film of piezoelectric material includes securing the membrane film to a temporary support structure to allow direct patterning of the interconnect lines. A barrier plane is deposited onto the membrane film. A photoresist then coats the barrier plane. In a subsequent step of photolithographically exposing the photoresist, the barrier plane acts as a screen to prevent radiation from reaching the membrane film. The barrier film is also used as a focusing and alignment structure during photolithographic exposure. Optionally, the resulting structure is soaked in chlorobenzene, with the barrier plane functioning to prevent diffusion of the chlorobenzene through the back side of the porous membrane film to form undesired development-retarding regions of the photoresist. Openings are formed in the photoresist during a development step. A metallic interconnect layer is then deposited. A portion of the interconnect layer enters the openings in the photoresist for deposit onto the barrier plane. The barrier plane ensures proper adhesion of the interconnect layer. Lift-off techniques remove the photoresist and unwanted portions of the interconnect layer. The remaining portions of the interconnect layer provide an etch mask for patterning the barrier plane.