| 摘要 |
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.g. after freezing the item, by removing the tether, e.g. through laser ablation or a fusing current.
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