A memory device is operable in either a high mode or a low speed mode. The method includes attaching a housing that contains a battery, sensor and other electronic components to a container. In the metal cluster-carrying metal oxide support of the present invention, the cluster 6a of the first metal is held by the oxide of the second metal 8 on the metal oxide support 9. The frequencies of the two signals are measured and then the ratio of the two periods which is the reciprocal of the two frequencies is calculated.