A piezoelectric resonator includes a substrate and a plurality of vibrating portions constructed such that a thin film portion having a piezoelectric thin film of one or more layers is sandwiched by at least a pair of upper electrodes and a lower electrode, which are opposed to each other, on the upper and lower surfaces of the thin film portion. At least one of the crossbar and the two goalposts, and possibly each of the crossbar and the goalposts, has a facet that is oriented partially towards the opening. In non-gusseted bags, the strips are either heat sealed to the bottom seal and adhered to the upper end of the bag or the strips are adhered at both ends to the front or rear surfaces of the bag. Methods for dosing a substance with the dosing device.