A file sharing system using working files is implemented in a computer system having a memory system. The conductive pathway enables electrical signals, such as ECG signals produced by a patient’s heart, to pass through the closed-ended tip of the indwelling catheter while still preventing unintended fluid flow. The shutter is mounted for movement with respect to the aperture of the nozzle between an open position permitting flow of the ophthalmic fluid through the aperture of the nozzle and a closed position at least partially covering the aperture. First and second currents are created as the inherent capacitance is charged and discharged. The electrode structure includes a plurality of IDTs arranged in a direction in which a boundary acoustic wave propagates, and reflectors, wherein where in each of the plurality of IDTs, the overlap width of electrode fingers is W and the interval of electrode fingers is P, WP is in a range of about 20 to about 45.