Undergraduate Scholarship Recipients

To miniaturize communication systems, great efforts have been spent on developing tunable RF passives. Fully electrically miniaturized tunable RF passives have been implemented with the integration of both ferromagnetic and ferroelectric thin films directly into the individual specific design. A strategy to improve the ferromagnetic resonance frequency (FMR) of Permalloy to over 6GHz and an electrically tuning method of equivalent permeability for Permalloy with DC magnetic field generated by applied DC current have been developed. A novel engineered substrate implemented with embedded multi-layer Permalloy and lead zirconate titonate (PZT) thin film patterns has been recently investigated and proposed, the substrate has high and DC current tunable permeability and DC voltage tunable permittivity. Miniaturized frequency agile arbitrary RF components could be developed with the proposed electrically tunable engineered substrate combined with state-of-the-art RF design techniques. In this research, it is planned to combine the above two techniques to design, fabricate, and test an electrically tunable filter with the goal of optimizing the resonator structure and the engineered substrate to improve tuning range and performance.

High blood pressure (BP) or hypertension (HTN) is a common condition which can lead to serious cardiovascular complications if left uncontrolled. The condition requires continuous monitoring of BP and electrical activity of heart (Electrocardiography- ECG) which the existing bulky instruments fail to provide without hindering the patient’s daily activities. This work proposes a home monitoring cuff-less and hassle-free blood pressure wrist-based device that derives BP from photoplethysmography (PPG) and ECG signals, and uses Bluetooth for real-time wireless communication with a smartphone. A user can wear this device as a watch/wristband/armband and the signals are transmitted to a mobile device or computer, possibly connected to a cloud for further analyses and computing. Development of a customized Bluetooth circuit with a printed 2.4-Ghz antenna is crucial for continuous monitoring. Quarter wave patch antenna will be developed and characterized and later incorporated on a flexible substrate.

Monitoring elbow joint kinematics after a medical procedure is critical for maximizing/accelerating rehabilitation and preventing future injuries. The most common technologies used to date for monitoring elbow joint kinematics include 3D/2D motion computing cameras and goniometers. However, these technologies are not portable—making it hard for them to capture valuable data in a standard individual’s daily environment. The proposed project seeks to resolve these issues through the development of a lightweight, flexible, and low-cost wearable joint sensor that is embroidered into a textile. These wearable sensors will leverage the principles of magnetic flux in order to measure the flexion of the elbow with high-accuracy and reliability. Additionally, novel methods for powering these wearable sensors are being explored as a way to remove the need for bulky batteries.

Accurate calibration of cryogenic noise measurements has been a long standing challenge due to uncertainties associated with thermal gradients along the path between the reference noise source and the device under test (DUT). One approach to address this problem is to perform the measurement using a tunnel junction noise source, which can be operated at the base temperature and whose noise spectrum is well described by basic physical expressions. However, for this technique to work, the insertion loss between the intrinsic tunnel junction and the input of the amplifier must be known. The goal of this research is to develop a methodology for this loss to be systematically determined. A two-tiered VNA calibration procedure will be developed to allow for determination of the gain of each component along the path from the input of the DUT to the input of a spectrum analyzer. As the system is to be operated under vacuum and at cryogenic temperatures, a suite of microwave switches will be employed to make the connections required to perform this two-tiered calibration. Once the gain from the input of the amplifier to the input of the spectrum analyzer is known, it will be compared to the gain determined using the tunnel junction noise source to determine the unknown loss.

The project aims at building a near-field platform for antenna radiation pattern measurement at Terahertz frequency. The effect of the measuring probe will be delineated using probe compensation techniques. Due to the fine resolution of the stepper motors, the system can be used for other frequency range up to 1.1 THz. The system can also be used for THz imaging with high resolution and characterization of THz probes for a THz Mueller imaging system for cancer detection by exploiting polarimetry. A THz probes with ±45o linear and left- and right-handed circular polarizations which are not commercially available will also be designed, fabricated, and tested.