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 temperature-monitoring device for attachment to an item, e.g. a frozen food or health product, includes a trigger member that is triggered by a set temperature condition to change state and so register exposure to the temperature condition. In one embodiment, the trigger member is biased to disengage a Thermalloy element once the Thermalloy's Curie temperature is exceeded and its magnetic force is weakened. The trigger member moves sufficiently so that it will not re-engage the Thermalloy, even if temperatures recede. Exposure to a high temperature can thus be determined from the trigger member's state, e.g. by detecting an impedance change in an associated circuit, e.g. in an adjacent coil through vibration of the trigger member under an applied signal, or in a circuit due to an open circuit at the trigger member and Thermalloy. The device may be manufactured using MEMS technology. To allow storage above the Curie temperature, a tether may initially hold the trigger member. The device may be activated, e.

Abstract: In a fluid pumping apparatus suitable for use in drop on demand ink jet printing, a resiliently deformable chamber wall is acted upon to create acoustic waves, which in turn cause a fluid flow in a chamber outlet. The resiliently deformable chamber wall preferably includes both rigid and flexible portions. In an alternative arrangement a channel wall is provided with a region moveable in an actuation direction. An electromagnetic actuator operates under the principle of flux modulation. The invention is preferably of planar construction, manufactured using MEMS techniques.