Electrical Engineering Department
BS in Electrical Engineering
This project is part of a Master’s thesis which looks at alternative ways to measure blood glucose. The Master’s thesis uses mid-field signals in order to match impedance and therefore lose less power as they travel through flesh. The goal of this senior project is to build a receiver for those signals and give accurate RSSI (received signal strength indicator) measurements. Mid-fields were originally explored by Stanford professor Dr. Ada Poon  who used the signaling technique to recharge the batteries of deeply implanted devices. Devices implanted near the surface of the skin were able to have their batteries recharged using inductive coupling but when devices were implanted deeper in the body, the drop in energy before the signals reached the devices made wireless recharging impractical. Using inductive coils to transmit energy is a near field application and the near field coupling decays as as from the source . Far field transmission is called radiative mode when it is used for far field power transfer, and the power decays as, which can be used when the implant is much smaller than its distance from the source. Dr. Poon discovered how to match impedances with flesh which allowed signals to travel farther without attenuation. These signals are called mid-field signals and occupy a position between near field and far field signals. Poon et al showed that in the midfield power transfer combines inductive and radiative modes  and shows much less attenuation as it travels through the body. The project described in this report is part of the larger glucose sensor project but because the glucose sensor system may be patented in the future, details of the work will not be described here. The glucose sensor system needs to sense the strength of a 1.6GHz mid-field wave at some point in the system and developing a sensor to receive and measure RSSI is what is described in this project.
Available for download on Sunday, January 17, 2021