Fundamental Physics

Single-Input Control of Large Microrobot Swarms using Serial Addressing for Microassembly and Biomedical Applications

This collaborative research project will create a practical control scheme for large swarms of microrobots. These robots are typically no more than a few millimeters in length, and rely on an external power source and control signal. Currently, it is possible to steer the swarm as a whole to a single destination (or perhaps, to a desired average location). However, realizing the full potential benefits of microrobot swarms will require the ability to simultaneously send independent commands, either to individual robots or to small subgroups.

Modeling of the Magnetic Particle Imaging Signal Due to Magnetic Nanoparticles

Magnetic Particle Imaging (MPI) is a new tomographic imaging technique that maps the spatial distribution of iron oxide magnetic nanoparticles (MNPs) in real time and with spatial resolution that is on par or better than other biomedical imaging techniques. In this project, we will develop a theoretical foundation relating the properties of MNPs and MPI magnetic field conditions to the MPI signal strength and resolution. These efforts will yield design rules that will guide the rational design of future generations of MNP tracers for MPI. The proposed research will enable development of a novel biomedical imaging technique capable of high resolution real time imaging using nontoxic tracers suitable for a variety of biomedical applications.

Directed Nanoparticle Assembly by Electrophoretic Deposition

This industry-sponsored project is funded by the MIST Center. The specific details of this project are confidential.


The Multi-functional Integrated System Technology (MIST) Center is an NSF Industry/University Cooperative Research Center (I/UCRC) led by the University of Florida and the University of Central Florida. Our mission is to facilitate integration of novel materials, processes, devices, and circuits into multi-functional systems through research partnerships between university, industry, and government stakeholders. With ~30 faculty participants from 6 different departments, the MIST Center serves as an early-stage research sandbox for developing next-generation smart systems in the Internet of Things era.

Tailoring Energy Flow in Magnetic Oscillator Arrays

Despite the fact that nonlinearities are inherent in many natural and engineered systems, it is common for engineers to remove, or attempt to remove, all nonlinearity from their designs. Although this simplifies the performance analyses, it also overlooks a wide array of phenomena that could potentially enable fundamental breakthroughs.

The objective of this project is to derive fundamental insights for complex arrays of nonlinearly coupled oscillators, using structures defined as magneto-mechanical lattices. The magneto-mechanical lattices comprise periodic arrays of dynamically interacting magnets, which can be conceptualized as an array of equivalent springs and masses, or alternatively, as a solid composed of artificial macro-atoms. The nonlinear magnetic coupling is to be theoretically tailored to exploit nonlinear energy transfer behaviors, such as reconfiguring bandgaps, energy localization, internal resonances, etc. These nonlinear phenomena are to be experimentally demonstrated and measured by fabricated magneto-mechanical lattices.

Micromachining of Permanent Magnet Undulator Structures for Compact X-ray Sources

Research Objective

To investigate the use of advanced microfabrication technologies and MEMS-enabled magnetization methods in developing reduced-scale permanent magnet undulator structures (with fine pole pitch ~5 microns) while maintaining reasonable magnetic field strengths as well as efficient generation of brilliant, high energy (>10keV) mono-energetic x-rays from modest electron beam source energies (~200MeV).


An accelerated beam of electrons with relativistic velocities experiences an undulation when passing through a spatially periodic magnetic field. This undulation of the beam trajectory results in the generation of electromagnetic radiation from which intense, tunable x-rays can be produced.

Effect of Mechanical Stress on AlGaN/GaN High Electron Mobility Transistor (HEMT) Device Characteristics and Reliability


AlGaN/GaN HEMTs are regarded as promising candidate for RF and high power electronics applications due to unique material properties of GaN, such as, wide band gap, high breakdown field, high carrier mobility, and large saturation velocity. Other advantageous characteristics, such as, piezoelectricity and spontaneous polarization within AlGaN and GaN layers result in high 2D electron gas densities. However the wide deployment of the AlGaN/GaN HEMT technology is currently hindered due to its limited electrical reliability. Achieving high-level of reliability concurrently with high power operation remains an important challenge for this technology. Improvements in the reliability of these devices require a thorough understanding of the failure mechanisms that degrade the device performance.

Studies show that AlGaN/GaN HEMTs degrade significantly under typical device operation. Degradation in these devices has been hypothesized to occur due to charge trapping, hot electron effects, and crystallographic defect formation due to inverse-piezoelectric effect. GaN HEMTs have high internal stresses resulting from lattice mismatch between GaN and AlGaN layers and generated during device operation due to inverse piezoelectric effect. Mechanical stress impacts the device performance by affecting the carrier mobility, polarization, band-gap, trap energy levels and trap generation and hence influences the reliability of these devices. The goal of this project is to investigate the effect of stress, bias and temperature on device characteristics and understand the fundamental physics governing the device operation; and hence the failure mechanisms that degrade the device performance. Four-point mechanical wafer bending is used to study the effect of stress on AlGaN/GaN HEMT channel resistance and gate current to provide insight on the role of stress in device reliability.

Wingless Electromagnetic Air Vehicle (WEAV)

The WEAV is a vehicle which is propelled by a plasma (ionized gas) discharge, requires no moving parts and provides near-instantaneous response.  The vehicle operates in atmospheric pressure and is capable of 360° maneuverability.  The key to the success of the project is to reduce the ratio of power to vehicle weight while significantly increasing the thrust generation capabilities of the plasma discharge. 

Development of Fully-Integrated Micromagnetic Actuator Technologies

The objective of the effort is to transition high-performance micromagnets into fully-integrated, batch-fabricated micromagnetic actuators for applications such as micro adaptive flow control.


Magnetically-based electromechanical actuation schemes are ubiquitous in macroscale systems such as audio speakers, relays, solenoids, and electrical motors.  However, implementation of these transduction schemes at the microscale is nearly nonexistent because of certain design and fabrication challenges—primarily the inability to integrate high-performance, permanent-magnet (magnetically-hard) films within more complex micromachined structures.  As a result, most microfabricated transducers rely on other transduction mechanisms (e.g. electrostatic, piezoelectric, thermoelastic).  However, these mechanisms limit the actuation force, stroke (displacement), power density, and efficiency necessary for certain applications. 

The proposed actuator uses an adaptable and scalable actuation scheme, in that the device structure can be tailored for a wide range of applications.  Examples include micro pumps/valves for microfluidic (gas or liquid) systems; high power density motors/actuators for microrobotics; or low-profile acoustic radiators for navigations/sensing.  The evolution of fully-integrated micromagnetic transducers will enable performance improvements for existing applications and opportunities to explore new transformative technologies. 


(1) to validate and characterize the integrability (chemical stability, temperature stability, mechanical reliability, magnetization methods etc.) of the permanent magnet materials in complex microfabrication process flows

(2) to model and optimize a multi-magnet out-of-plane microactuation scheme

(3) to fabricate and characterize a fully-integrated out-of-plane piston-type actuator that can be directly implemented as a micro aerodynamic control surface or adapted as a synthetic jet actuator 




Figure 1: CAD drawings of the proposed micro-electrodynamic synthetic jet actuator actuator: (a) Actuator assembly comprising two dies made from silicon substrate, separated by a separator. The top die is covered with a PDMS diaphragm and has a bonded powder magnet in the center. (b) Exploded view of the bottom wafer.


Investigation of Stress Effects on Thin-Film PZT Ferroelectric Capacitors for FRAM Enhancement

The combined application of stress, temperature, and bias has the potential to enhance FRAM (ferroelectric random access memory) performance at the 130-nm technology node and possibly extend the technology to the 90-nm node and beyond.  While temperature and bias have been traditionally used to pole ferroelectric thin-films, applied stress has also been shown to enhance ferroelectric properties. This can lead to an improved FRAM signal margin, which is a key metric for FRAM reliability and performance.  We propose to comprehensively study the effects of stress, temperature, and bias on the ferroelectric properties of fully integrated thin-film PZT ferroelectric capacitors.  These effects will be investigated experimentally.  We will then develop SPICE simulation models and simulate the stress in ferroelectric films based on TI’s 130-nm process. Our goal is to gain a deep understanding of the underlying physics of stress effects at bias and temperature on ferroelectric capacitors, and use this knowledge to develop accurate models that can simulate these effects and be used in FRAM design.  We will then recommend strain-engineering methods for enhancing FRAM performance at the 130-nm node and beyond. 

Advancing FRAM technology beyond the 130-nm node can increase storage density and reduce cost, leading to new potential markets and applications.  However, further scaling of ferroelectric PZT films can diminish FRAM performance.  It has been suggested that scaling beyond the 130-nm technology node will require different FRAM structure and materials, which can lead to increased costs and development time.  We propose that stress engineering may be a solution to enhance current FRAM technology and extend it to the 90-nm node and beyond.