The invention is directed towards improved structures for use with micro-machined ultrasonic transducers, and methods for fabricating the improved structures. The battery cell includes a cathode electrode, an anode electrode, and a separator. A lateral notch is disposed in the outer portion of the form at intervals and across a width of the form to divide the form into what will be the sides of the form when assembled. The stop bolts and associated threaded apertures are designed for minimum overhang of the stop bolts to provide more support. A method for manufacturing such a piston stopper is encompassed. The substrate is formed with a recess defined by a bottom and sidewalls substantially perpendicular to the bottom, the recess corresponding to the part of the gate insulating film with the first film thickness.