Doctor of Philosophy (PhD)
First Advisor's Name
Stavros V. Georgakopoulos
First Advisor's Committee Title
Second Advisor's Name
Second Advisor's Committee Title
Third Advisor's Name
Third Advisor's Committee Title
Fourth Advisor's Name
Fourth Advisor's Committee Title
Fifth Advisor's Name
Fifth Advisor's Committee Title
RFID, Liquid Crystal Elastomers, Temperature Sensing, Antenna Design, RF Circuit Design, Matching Network Design
Date of Defense
When transporting perishable foods in the Cold Supply Chain (CSC), it is essential that they are maintained in a controlled temperature environment (typically from -1° to 10°C) to minimize spoilage. Fresh-food products, such as, meats, fruits, and vegetables, experience discoloration and loss of nutrients when exposed to high-temperatures. Also, medicines, such as, insulin and vaccines, can lose potency if they are not maintained at the appropriate temperatures. Consequently, the CSC is critical to the growth of global trade and to the worldwide availability of food and health supplies; especially, when considering that the retail food market consists mostly (approximately 65%) of fresh-food products.
The current method of temperature monitoring in the CSC is limited to discrete location-based measurements. Subsequently, this data is used to assess the overall quality of transported goods. As a result, this method cannot capture all the common irregularities that can occur during the delivery cycle. Therefore, an effective sensor solution to monitor such items is necessary.
Radio Frequency Identification (RFID) is a pragmatic wireless technology with a standardized communication protocol. Thus far, passive RFID temperature sensors have been investigated. However, each design has a limitation from which a set of design guidelines for an improved sensor solution is developed. That is, the new sensor should: (a) be compact to be applicable on individual products, (b) utilize purely passive technology to ensure longevity and cost-effectiveness, (c) monitor goods in a continuous fashion (e.g., operate through multiple room-to-cold and cold-to-room temperature cycles), and (d) operate in an independent mode, so that no resetting is required.
In this research, antenna systems and RF circuit design techniques are combined with Liquid Crystal Elastomers (LCEs) to develop three novel temperature sensors. LCEs are temperature responsive polymers that are programmable and reversible. Notably, LCEs return to their original state when the stimulus is removed. Also, for the first time, cold-responsive LCEs are incorporated into the designs presented in this research. Two of the developed sensors convey temperature changes through the controlled shift in the operating frequency. The third design conveys temperature threshold crossings by reversibly switching operation between two RFID ICs (or two Electronic Product Codes). Finally, all designs have been fabricated and tested with favorable results in accordance to the above mentioned guidelines.
Previously Published In
 Y. Shafiq, J. Henricks, C. P. Ambulo, T. H. Ware, and S. V. Georgakopoulos, “A Battery-Free Temperature Sensor with Liquid Crystal Elastomer Switching Between RFID Chips,” in IEEE Access [In Review: Submitted Mar. 2020]
 Y. Shafiq, J. Henricks, C. P. Ambulo, T. H. Ware and S. V. Georgakopoulos, "A Passive RFID Temperature Sensing Antenna With Liquid Crystal Elastomer Switching," in IEEE Access, vol. 8, pp. 24443-24456, 2020.
 Y. Shafiq, J. S. Gibson, H. Kim, C. P. Ambulo, T. H. Ware and S. V. Georgakopoulos, "A Reusable Battery-Free RFID Temperature Sensor," in IEEE Transactions on Antennas and Propagation, vol. 67, no. 10, pp. 6612-6626, Oct. 2019.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Shafiq, Yousuf, "Novel Passive RFID Temperature Sensors Using Liquid Crystal Elastomers" (2020). FIU Electronic Theses and Dissertations. 4379.
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FREQUENCY SWITCHING PATCH ANTENNA DESIGN
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