University researchers have developed a method in which RFID tags are combined with MEMS bi-material cantilevers to provide item-level environmental monitoring. The MEMS cantilevers can be fabricated directly on a flexible printed circuit board for temperature humidity acceleration and orientation sensing. Additionally the cantilever acts as a power switch for a control circuitry of an RFID chip that functions as zero-power memory elements. A specific tag can be interrogated for any past event that a set environmental conditions has been exceeded. This system uses zero power to monitor temperature and zero power to store memory. Power is only used to change the memory element. Tags are applicable to but not limited to biological and medical inventory monitoring and distribution of blood organs and other biologicals. Applications: This invention is applicable to any item level environmental monitoring needs. It is especially useful for transportation of high value items of which the quality is subject to environmental conditions. The sensor enabled RFID tag is first applied to individual items and then activated for monitoring before the shipment. At the recepient\'s end an RFID interrogater device is used to screen individual items. Items that have experienced extensive hostile conditions are reported by the RFID chip and rejected for further usage.
The invention described herein provides an economic solution to monitor environmental history of individual perishable items over a prolonged time during transportation and distribution. Any item experiencing hostile environment for an extensive period of time can be rejected through an RFID screening conducted by the recipients. The identification of usable and unusable items can be done with high accuracy through this method.