Theses and Dissertations

The electromagnetic properties of a live biological system are extremely important to many medical applications. While information about electromagnetic properties of tissues are available in the literature, little or no data are available for a single cell or subcellular structures. Microwave biological/cell detection has been demonstrated to be useful and promising in many medical applications due to its internal properties such as non-invasive, fast and label-free.

For the first time, the impedance spectrum of live Jurkat T-lymphocytes human cells was characterized in a single sweep spanning six decades of frequency from 9 kHz to 9 GHz. The ultrawide bandwidth bridged the traditional impedance spectroscopy at kilohertz to megahertz frequencies with the recently developed microwave dielectric spectroscopy, which can probe the cell interior without being hindered by the cell membrane.

A closed-loop capacitance sensing and control mix-mode circuit with a dedicated sensor electrode and a proportional-integral controller was designed for MEMS varactors. The control was based on tuning the bias magnitude of the MEMS varactor according to t

For the first time, wafer-scale fabrication of PtSe2 MOSFETs was demonstrated by photolithography. The on PtSe2 is grown by thermally assisted conversion (TAC) of Pt films under Se vapor at 400 °C. Taking advantage of the unique property of PtSe2 to transition from semiconductor to semimetal as its thickness increases beyond a few monolayers, channel recess was adapted for improving gate control while keeping the contact resistance as low as 0.008 Ω∙cm. The wafer-scale fabrication resulted in uniform device characteristics so that average vs. best results were reported, as well as RF vs.

In this work, we systematically studied and introduced both AFM-based and STM-based scanning microwave microscopy. CMOS interconnects, single dried cell and organelles like exosomes have been imaged with scanning microwave microscopy.The scanning microwave microscopy of CMOS interconnect aluminum lines both bare and buried under oxide has been achieved. In both cases, a spatial resolution of 190 +- 70 nm was achieved, which was comparable or better than what had been reported in the literature.

For the last 50 years, Si metal-oxide-semiconductor field-effect transistors (MOSFETs) have undergone tremendous development under the Moore's law. However, it has become more and more difficult to continue the scaling due to the limitation of Si quantum confinement when the gate length is less than 5 nm. Two-dimensional (2D) atomic-layered materials may replace Si in future-generation ultra-thin-body, low-power, and high-performance MOSFETs. However, for any 2D material to replace Si, it must not only have high mobility and sizable bandgap, but also be manufacturable.

Low-dispersion phase shifters are key components for electrically large phased-array radar and communication systems. Unlike true-time-delay phase shifters with linear dispersion, low-dispersion phase shifters can be designed by switching between right-handed (low-pass) and left-handed (high-pass) states to achieve a constant phase shift over a wide bandwidth. However, the implementation of low-dispersion phase shifters with MEMS switches has been challenging. The designs to date suffer from either high insertion loss or high dispersion.

For the first time, single-cell trapping, characterization, electroporation, and de-trapping were demonstrated by conveniently programming the frequency and power of the same ultra-wideband vector network analyzer (VNA) to perform the different functions across its bandwidth of 9 kHz‒9 GHz. On one hand, trapping of a live biological cell was accomplished by applying to a coplanar waveguide (CPW) through the VNA a continuous wave (CW) signal of 3 dBm and 5 MHz, corresponding to attractive dielectrophoresis.