The configuration of an elongate aperture in a membrane draped over a microneedle assembly may be controlled by controlling the manner in which the aperture is formed and/or by controlling the manner in which the membrane is draped. At least a portion of the membrane may be spaced apart from a microneedle so that a gap is defined between the membrane and the microneedle. The gap may be configured for at least partially controlling the formation of the elongate aperture. The shape of the gap may optionally be at least partially defined by a pleat in the membrane. Any pleats may be aligned in a predetermined manner. The elongate aperture may be formed by a piercing member that is passed through a hole in the microneedle assembly prior to piercing the membrane. The piercing member may be a laser beam.