Research Summary:
Our group has extensively pursued RF and microwave sensing related projects that can be applied to food safety, quality control, environmental monitoring, health care, pipe detection, and supply chain management.
Examples of sensor related projects: (A) a meta-material inspired ring resonator microstrip structure used to detect gases by dielectrically loading the structure [4], (B) schematic of a "smart cap" as investigated in [1], (C) photograph of "smart cap" prototype in [1], (D) illustration of measurement setup in [3] where the ability to passively interrogate RF tags on buried objects is studied, and (E) microstrip resonator design used as a microfluidic sensor [5].
Some recent work related to this effort is cited at the bottom of the page and displayed in the image above. Much of our sensor work is similar to the example in (A) and (E) where microstrip resonator structures are used to detect changes in microfluidics or gases based on an observed shift in resonant frequency due to dielectric loading from the fluids or gas molecules. By using meta-material inspired structures we are able to achieve relatively high sensitivities where the sensor shown in (E) could detect as small as a 1% change in the glucose concentration when mixed with DI-water. Glucose detection has significant application in the medical field towards developing better treatment for diabetics. Gas detection, as demonstrated in (A), is very important for safety in laboratory or home settings.
Shown in (B) and (C) is a "smart cap" [1] that can be used for food safety and quality control through a supply chain. The "smart cap" design we proposed is a hybrid sensor which is comprised of a magnetostatic ribbon and an inductor-capacitor (LC) resonator circuit which can be used for characterizing liquid samples based on their physical properties. The magnetostatic ribbon paired with a coil of wire will have a resonant frequency, and any shift in this frequency indicates a change in the viscosity of the liquid sample. The LC resonator has a resonant frequency which will shift due to dielectric loading of the resonator and therefor any shift in its frequency indicates a change in dielectric constant of the liquid sample. We demonstrated this hybrid sensors ability to detect changes in food products (oil, milk, glucose) which can be useful for food safety, adulteration detection, and tracking these products through a supply chain as these properties (dielectric constant and viscosity) can be related to freshness or spoilage in liquid products. Further work is being done on this project and other ways of detecting and tracking food spoilage through a supply chain as well.
Lastly, shown in (D), detection of buried objects such as pipes is very important as more utilities use plastic pipes over metal ones. When metal pipes were predominantly used, detection of pipe location was straightforward as the pipes, if present, would reflect any signal sent to interrogate them. Given the low cost of plastic pipes over metal pipes, their use is now becoming much more common but they are not as straightforward to detect in the ground since plastic will not strongly reflect a signal. Embedding something in the plastics pipes to communicate with workers on the surface that requires the use of batteries is not a good option given the limitations on battery life and the difficultly replacing batteries would present. Another option would be to embed some sort of passive detection mechanism which is what we have proposed with the use of an RF tag coupled with a harmonic resonator [3]. As present in [3], this approach can currently work through a foot of soil and further work is being done to improve the depth performance.
Recent Related Publications:
[1] S. Karuppuswami, H. Arangali, and P. Chahal, “A Hybrid Electrical-Mechanical Wireless Magnetoelastic Sensor for Liquid Sample Measurements,” in IEEE 66th Electronic Components and Technology Conference, 2016, pp. 2535–254.
[2] S. Karuppuswami, A. Kaur, M. Ifwat, M. Ghazali, and P. Chahal, “RFID Compatible Sensor Tags for Remote Liquid Sample Interrogation,” in IEEE 66th Electronic Components and Technology Conference, 2016, pp. 2401–2407.
[3] M. Ifwat, M. Ghazali, S. Karuppuswami, and P. Chahal, “Embedded Passive RF Tags towards Intrinsically Locatable Buried Plastic Materials,” in IEEE 66th Electronic Components and Technology Conference, 2016, pp. 2575–2580.
[4] N. Wiwatcharagoses, K. Y. Park, and P. Chahal, “Metamaterial-inspired Sensor on Porous Substrate for Detection of Volatile Organic Compounds in Air,” in IEEE 66th Electronic Components and Technology Conference, 2016, pp. 1557–1562.
[5] J. A. Byford, K. Y. Park, and P. Chahal, “Metamaterial inspired periodic structure used for microfluidic sensing,” in Electronic Components and Technology Conference (ECTC) , 2015 IEEE 65th, 2015, vol. 2015-July, pp. 1997–2002.