Abstract: A passive memory device includes a plurality of resonant members, e.g. of a cantilever or bridge-type form, that may have different resonant frequencies and that may be held against vibrations by end or side tethers. Data may be recorded in the device by removing various of the tethers, so that, on applying an excitation signal, e.g. from a transmitter, untethered resonant members vibrate strongly in response to their resonant frequencies, and provide a response signal that can be picked up e.g. by a receiver and correlated with the excitation signal frequencies to determine which resonant members have been untethered. The response by an untethered resonant member can correspond to a logical “1”, whilst the lack of a response signal at a known resonant member frequency can correspond to a logical “0”, or vice versa.

Abstract: A passive memory device includes a plurality of resonant members, e.g. of a cantilever or bridge-type form, that may have different resonant frequencies and that may be held against vibrations by end or side tethers. Data may be recorded in the device by removing various of the tethers, so that, on applying an excitation signal, e.g. from a transmitter, untethered resonant members vibrate strongly in response to their resonant frequencies, and provide a response signal that can be picked up e.g. by a receiver and correlated with the excitation signal frequencies to determine which resonant members have been untethered. The response by an untethered resonant member can correspond to a logical “1”, whilst the lack of a response signal at a known resonant member frequency can correspond to a logical “0”, or vice versa.