Projects

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Electromagnetics and Photonics

Investigators: Mark Sheplak

The goal of this research is to develop a MEMS-based Five-hole Probe(5HP) that is able to measure the localized velocity vector (both the velocity magnitude and direction) and the static and dynamic pressure, in steady and/or unsteady flow fields. Five optical pressure sensors located on the hemisphere tip of the 5HP provide all information that is needed to resolve the flow. This 5HP is expected to be able to provide high spatial resolution, high frequency response and is compatible with elevated temperature environments. A primary focus of this research is on the microfabrication and micromachining of a die that incorporates five optical transducers and its successive packaging process. The completed sensors will be tested in flow cells and wind tunnels at UF for the final calibration.

Investigators: David Arnold

This goal of this research and development program is to enable revolutionary advances aimed at providing high resolution imaging through even the worst material environments. The proposed effort utilizes standard ELF-VLF signals of opportunity (VLF transmitter signals and lightning-generated sferics) to provide background imaging capabilities and enhances the background 3-D resolution space by simultaneously leveraging the frequency dependent magnetic transparency properties of highly conducting media. The IMG-related portion of the effort focuses on creating efficient rotating magnets, used to create oscillating static magnetic fields that scatter from conducting media only when the frequency of oscillation is above a corner frequency set by the electrical properties and the thickness of the conductor. The overall effect is a frequency selective transparency that enables imagers to better discern between two adjacent conducting bodies of different thicknesses.

Investigators: Mark Sheplak, Alexandra Garraud

The primary objective of this research is to develop a high-bandwidth pressure sensor to provide benchmark, time-resolved, dynamic pressure data in high-temperature combustion environments. Specifically, these sensors will be designed to be embedded within a system and provide remote interrogation which will enable pressure to be measured in situ and on line under extreme conditions. Ultimately, this sensing technology will lead to better understanding and increased efficiency of complex power generation systems. In order to achieve this objective, research in sapphire laser micromachining and thermocompression bonding via spark plasma sintering technology will be conducted to enable fabrication of a fiber optic lever pressure sensor that uses a sapphire optical fiber for transduction of the pressure-induced diaphragm deflection. The proposed project will result in instrumentation-grade, high-temperature sensors that enable flush mounted measurements without sensor cooling. Furthermore, the use of optical techniques enables “passive” device operation, with electronics located remotely from the sensor. After fabrication and packaging, the pressure sensor will be rigorously characterized in acoustic plane wave tubes under both ambient and high-temperature conditions to determine its performance as a quantitative measurement device.

Investigators: David Arnold

As predicted by Moore's "law", the past few decades have seen massive reductions in the size of integrated circuits, enabling the portable, handheld devices now in everyday use. However, the components that power these devices have not experienced a similar size reduction. For example, the power adapter of a laptop computer is only modestly smaller than that two decades ago, and the printed circuit board inside a smart phone must dedicate between 20% and 40% of the board area for power conversion and management. To date, efforts towards miniaturization have been limited by both materials and manufacturing challenges. To address this gap, this research will study nanomanufacturing processes to facilitate the scalable synthesis of high quality magnetic nanoparticles and nanocomposite core materials and the fabrication of compact power inductors and transformers through assembly of these nanomaterials in a manner that is compatible with current manufacturing processes, such as silicon wafer or printed circuit board fabrication. This compatibility will enable fully integrated and compact system-on-chip or system-in-package power solutions. This research will be accomplished by fostering collaboration among disciplines including materials science, chemical engineering and electrical engineering. It will foster diversity in the profession by involving high school and undergraduate students in research activities and by broadening participation through the inclusion and engagement of women and underrepresented groups.

The overarching goal of this Scalable Nanomanufacutring project is to study synthetic and nanomanufacturing processes that overcome existing integration challenges while affording breakthrough, high-frequency magnetic performance. An aim is to research materials that exhibit high magnetic saturation and low loss. This will be accomplished by leveraging the unique properties of magnetic materials at the nanoscale through a combination of nanomanufacturing approaches spanning bottom-up synthesis to directed assembly and nanocomposite formation. The specific objectives are to: (i) scale-up synthesis of high quality magnetic nanoparticles via thermal decomposition routes by elucidating the underlying correlations between synthesis parameters and nanoparticle properties, leveraging recent developments in the reproducible synthesis of near defect-free nanocrystals with magnetic properties approaching those of the bulk; (ii) study methods for large-scale directed assembly of magnetic nanoparticles via dielectrophoresis into compact power inductors/transformers; and (iii) demonstrate the formation of bi-phasic nanocomposite cores through large-scale electro-infiltration of an additional ferromagnetic material. An expected outcome of this project is to demonstrate scalability through the full-wafer batch-fabrication of microinductor devices using the developed methods on a silicon wafer. From a commercial standpoint, nanomanufacturing technologies providing process-integrable, high-performance magnetic components for power application have the potential to impact a nearly $12B/year market.

Investigators: David Arnold, Y.K. Yoon

This project is under DARPA's Magnetic Miniaturized and Monolithically Integrated Components (M3IC) program in the DARPA Microsystems Technology Office.

The objective of this effort is to develop thick-film magnetic materials that can be fabricated on semiconductor integrated circuits to enable highly miniaturized microwave components such as circulators and isolators operating in the 10 to 110 GHz frequency regime. These nonlinear, non-reciprocal components are critical for next generation radios, radar, and sensing systems for defense, consumer, automotive, and healthcare applications.

Specific efforts include: (1) self-biased microwave magnetic thick-films on semiconductor substrates, (2) integration of permanent magnet bias magnets on semiconductor substrates, and (3) integrated microwave magnetic components on semiconductor substrates.

Investigators: Y.K. Yoon

This project studies on wave propagation in waveguide with periodical boundaries, in such a case, a new kind of resonance occurs. This new kind of resonance is very different from the traditional Bragg resonance.

In Non-Bragg resonance, the resonance frequency and bandwidth strongly depends on the geometric configuration of the waveguide, and, the resonance is tunable. Theoretical and experimental results show good agreements.

Investigators: Huikai Xie

The goal of this project is to develop micro-LiDAR with small size and low power consumption for flapping-wing micro-aerial vehicles. The micro-LiDAR will be based on electrothermally-actuated scanning micromirrors. 

Investigators: Alexandra Garraud, Mark Sheplak

We are developing time-resolved dynamic pressure sensing technology for high-temperature (> 1000 °C) applications in the aerospace, energy, and automotive sectors and for chemical environment sensors for biotechnology companies.

Almost all of the existing pressure sensing systems are not capable of operation in environments in excess of 1000 °C. Those systems that can survive the extreme temperatures suffer from reduced performance and induced bias errors arising from temperature mitigation efforts. We will investigate wireless, electromagnetic wave-guide and sapphire-based fiber optical based transduction technology combined with laser micromachining of sapphire and platinum film deposition to dynamic pressure sensors capable of continuous operation at 1000 °C. These technologies eliminate the need for close proximity electronics and will be fabricated from high-temperature capable materials that possess nearly identical thermal coefficients of expansion to minimize thermal drift.

Investigators: Y.K. Yoon

A Folded Patch antenna is investigated both theoretically and experimentally. The proposed antenna is very compact, and can be matched to desired impedance without any external matching circuitry.  The proposed antenna also offers EM shielding to the internal PCB. Further, omni directional radiation pattern is obtained which is not feasible on traditional patch antennas.

Investigators: David Arnold

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. Device designs have previously been explored that respond to different command amplitudes, however this approach quickly becomes impractical as the number of independently addressable robots grows. This scalability problem can be overcome using serial addressing schemes. Here, there are only a few distinct values for the control signal. Each independently addressable subset of robots is associated with a unique sequence of signal values, and will change its behavior only if the control signal contains that specific sequence. This project considers two fundamental issues that arise in implementing such a scheme. First is the need for on-board computation and memory allowing the robots to recognize the unique sequence and to change the robots state based on the detection of such sequence. Second is the need for a propulsive mechanism that couples to the robot state to allow differential guidance towards a target configuration. This project will advance two innovative engineering platforms that meet both needs. The first is electrostatically actuated, operates on a planar substrate, and is suitable for structured tasks such as microassembly. The second is magnetically actuated, operates in a liquid volume, and is suitable for biomedical applications such as drug delivery. The technical aspects of the project are complimented by outreach activities, including an annual microrobotics mobility competition to be held at the IEEE International Conference on Robotics and Automation -- a premier robotics conference for academia and industry. The results from this project will enhance the national health, by enabling new diagnostic and therapeutic uses for microrobot swarms. They will also promote the national prosperity, by enabling new classes of microassembly robots.

This project aims to develop a practical control scheme to simultaneously control large numbers of microrobots. This will be achieved by using microelectromechanical systems (MEMS) to electromechanically and magnetically decode a sequence embedded in the single global control signal, and couple the reconfiguration of such sequence to the modification of the individual microrobot trajectories. This on-board sequence decoding will be accomplished through sets of on-board physics-based finite state machines (PFSM) that can accept a control sequence embedded in the control signal and change the behavior of the microrobots accordingly. The project will use both electrostatic and magnetic approaches to implement PFSMs, and to couple their "accept" state to the propulsion mechanism to modulate individual trajectories. Sets of stress-engineered electrostatic switches, which will latch in response to a pre-programmed control voltage sequence, will be used to implement PFSM on the electrostatic platform. Electro-permanent magnetic circuits, which change their magnetic moment in response to a sequence of global magnetic field, will be used to implement PFSM on the magnetic platform. The project will develop the theory for PFSM-based multi-microrobot control, construct both electrostatic and magnetic microrobotic PFSM platforms, and validate the concept by implementing the PFSM-based control on swarms of electrostatically and magnetically powered microrobots. The developed theory and approach will pave way for control of large microrobot swarms for numerous biomedical and microassembly applications.

Investigators: David Arnold

We seek to develop a platform that allows magnetic field sensing using a small footprint, in the absence of an external power supply. Our approach uses magnetoelectric nanofibers to create a zero-power magnetic field sensor. The challenge is to develop methods to assemble these materials into devices that leverage their unique anisotropic properties.

The figure of merit for magnetoelectric materials is the magnetoelectric coefficient, a measure of the amount of voltage generated with respect to the magnitude of the applied magnetic field. Bulk magnetoelectrics and thin films are limited by defects and substrate clamping respectively.  To overcome the limitations of thin-film based composite magnetoelectrics we have developed magnetoelectric bilayer structures on a single nanofiber, i.e., 1D magnetoelectrics. These materials are theoretically predicted to have magnetoelectric coupling coefficients that are orders of magnitude greater than their thin film counterparts. 

Magnetoelectric materials can be employed in a wide variety of applications including magnetic field sensors and tunable resonance energy harvesters.  By optimizing for material system and architecture, drastic increases in magnitude of voltage generated with decreased size can be achieved. This could allow for more sensitive magnetic field sensors appropriate for a wider array of applications and decreased size to allow for easier integration into ICs.
 

Materials, Manufacturing, and Modeling

Investigators: Mark Sheplak

The goal of this research is to develop a MEMS-based Five-hole Probe(5HP) that is able to measure the localized velocity vector (both the velocity magnitude and direction) and the static and dynamic pressure, in steady and/or unsteady flow fields. Five optical pressure sensors located on the hemisphere tip of the 5HP provide all information that is needed to resolve the flow. This 5HP is expected to be able to provide high spatial resolution, high frequency response and is compatible with elevated temperature environments. A primary focus of this research is on the microfabrication and micromachining of a die that incorporates five optical transducers and its successive packaging process. The completed sensors will be tested in flow cells and wind tunnels at UF for the final calibration.

Investigators: Mark Sheplak

This project focuses on the development of a non-intrusive, direct, time-resolved wall shear stress sensor system for low-speed applications. The goals of the project include the fabrication and packaging of a 2-D wall-shear stress sensor with backside wire bond contacts to ensure hydraulic smoothness in flow environments. A differential capacitance transduction scheme is utilized with interdigitated comb fingers on each side of a suspended floating element, allowing for measurements to be made in both the positive and negative x- and y-directions.  A synchronous modulation-demodulation circuit is employed to simultaneously capture both mean and fluctuating shear content. Both AC and DC calibrations are performed to determine sensor sensitivity in both directions of transduction. This is the most successful effort of shear sensor development in published literature. 

Investigators: Y.K. Yoon

The Electrospinning and Stamp-thru-mold (ESTM) technique, an integrated fabrication process which incorporates the versatility of the electrospinning process for nanofiber fabrication with
the non-lithographic patterning ability of the stamp-thru-mold process is introduced. In-situ multilayer stacking of orthogonally aligned nanofibers, ultimately resulting in a nanoporous membrane, has been demonstrated using orthogonally placed collector electrode pairs and an alternating bias scheme. The pore size of the nanoporousmembrane can be controlled by the number of layers and the deposition time of each layer. Non-lithographic patterning of the fabricated nanoporousmembrane is then performed by mechanical shearing using a pair of pre-fabricated micromolds. This patterning process is contamination free compared to other photo lithographical patterning approaches. The ability to pattern on different substrates has been tested with and without oxygen plasma surface treatment. In vitro tests of ESTM poly-lactic-coglycolic acid (PLGA) nanofibers verify the biocompatibility of this process. Simulation by the COMSOL Multiphysics tool has been conducted for the analysis of electrospun nanofiber alignment.

Investigators: Mark Sheplak, Alexandra Garraud

The primary objective of this research is to develop a high-bandwidth pressure sensor to provide benchmark, time-resolved, dynamic pressure data in high-temperature combustion environments. Specifically, these sensors will be designed to be embedded within a system and provide remote interrogation which will enable pressure to be measured in situ and on line under extreme conditions. Ultimately, this sensing technology will lead to better understanding and increased efficiency of complex power generation systems. In order to achieve this objective, research in sapphire laser micromachining and thermocompression bonding via spark plasma sintering technology will be conducted to enable fabrication of a fiber optic lever pressure sensor that uses a sapphire optical fiber for transduction of the pressure-induced diaphragm deflection. The proposed project will result in instrumentation-grade, high-temperature sensors that enable flush mounted measurements without sensor cooling. Furthermore, the use of optical techniques enables “passive” device operation, with electronics located remotely from the sensor. After fabrication and packaging, the pressure sensor will be rigorously characterized in acoustic plane wave tubes under both ambient and high-temperature conditions to determine its performance as a quantitative measurement device.

Investigators: Toshikazu Nishida

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.

Investigators: David Arnold

As predicted by Moore's "law", the past few decades have seen massive reductions in the size of integrated circuits, enabling the portable, handheld devices now in everyday use. However, the components that power these devices have not experienced a similar size reduction. For example, the power adapter of a laptop computer is only modestly smaller than that two decades ago, and the printed circuit board inside a smart phone must dedicate between 20% and 40% of the board area for power conversion and management. To date, efforts towards miniaturization have been limited by both materials and manufacturing challenges. To address this gap, this research will study nanomanufacturing processes to facilitate the scalable synthesis of high quality magnetic nanoparticles and nanocomposite core materials and the fabrication of compact power inductors and transformers through assembly of these nanomaterials in a manner that is compatible with current manufacturing processes, such as silicon wafer or printed circuit board fabrication. This compatibility will enable fully integrated and compact system-on-chip or system-in-package power solutions. This research will be accomplished by fostering collaboration among disciplines including materials science, chemical engineering and electrical engineering. It will foster diversity in the profession by involving high school and undergraduate students in research activities and by broadening participation through the inclusion and engagement of women and underrepresented groups.

The overarching goal of this Scalable Nanomanufacutring project is to study synthetic and nanomanufacturing processes that overcome existing integration challenges while affording breakthrough, high-frequency magnetic performance. An aim is to research materials that exhibit high magnetic saturation and low loss. This will be accomplished by leveraging the unique properties of magnetic materials at the nanoscale through a combination of nanomanufacturing approaches spanning bottom-up synthesis to directed assembly and nanocomposite formation. The specific objectives are to: (i) scale-up synthesis of high quality magnetic nanoparticles via thermal decomposition routes by elucidating the underlying correlations between synthesis parameters and nanoparticle properties, leveraging recent developments in the reproducible synthesis of near defect-free nanocrystals with magnetic properties approaching those of the bulk; (ii) study methods for large-scale directed assembly of magnetic nanoparticles via dielectrophoresis into compact power inductors/transformers; and (iii) demonstrate the formation of bi-phasic nanocomposite cores through large-scale electro-infiltration of an additional ferromagnetic material. An expected outcome of this project is to demonstrate scalability through the full-wafer batch-fabrication of microinductor devices using the developed methods on a silicon wafer. From a commercial standpoint, nanomanufacturing technologies providing process-integrable, high-performance magnetic components for power application have the potential to impact a nearly $12B/year market.

Investigators: David Arnold, Y.K. Yoon

This project is under DARPA's Magnetic Miniaturized and Monolithically Integrated Components (M3IC) program in the DARPA Microsystems Technology Office.

The objective of this effort is to develop thick-film magnetic materials that can be fabricated on semiconductor integrated circuits to enable highly miniaturized microwave components such as circulators and isolators operating in the 10 to 110 GHz frequency regime. These nonlinear, non-reciprocal components are critical for next generation radios, radar, and sensing systems for defense, consumer, automotive, and healthcare applications.

Specific efforts include: (1) self-biased microwave magnetic thick-films on semiconductor substrates, (2) integration of permanent magnet bias magnets on semiconductor substrates, and (3) integrated microwave magnetic components on semiconductor substrates.

Investigators: Alexandra Garraud, Mark Sheplak

We are developing time-resolved dynamic pressure sensing technology for high-temperature (> 1000 °C) applications in the aerospace, energy, and automotive sectors and for chemical environment sensors for biotechnology companies.

Almost all of the existing pressure sensing systems are not capable of operation in environments in excess of 1000 °C. Those systems that can survive the extreme temperatures suffer from reduced performance and induced bias errors arising from temperature mitigation efforts. We will investigate wireless, electromagnetic wave-guide and sapphire-based fiber optical based transduction technology combined with laser micromachining of sapphire and platinum film deposition to dynamic pressure sensors capable of continuous operation at 1000 °C. These technologies eliminate the need for close proximity electronics and will be fabricated from high-temperature capable materials that possess nearly identical thermal coefficients of expansion to minimize thermal drift.

Investigators: Saeed Moghaddam

The aim of this project is to utilize the controllable nature of Graphene Oxide as an ultrathin separation membrane in biological applications, specifically targetting removal of uremic toxins. 

Investigators: David Arnold

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. Device designs have previously been explored that respond to different command amplitudes, however this approach quickly becomes impractical as the number of independently addressable robots grows. This scalability problem can be overcome using serial addressing schemes. Here, there are only a few distinct values for the control signal. Each independently addressable subset of robots is associated with a unique sequence of signal values, and will change its behavior only if the control signal contains that specific sequence. This project considers two fundamental issues that arise in implementing such a scheme. First is the need for on-board computation and memory allowing the robots to recognize the unique sequence and to change the robots state based on the detection of such sequence. Second is the need for a propulsive mechanism that couples to the robot state to allow differential guidance towards a target configuration. This project will advance two innovative engineering platforms that meet both needs. The first is electrostatically actuated, operates on a planar substrate, and is suitable for structured tasks such as microassembly. The second is magnetically actuated, operates in a liquid volume, and is suitable for biomedical applications such as drug delivery. The technical aspects of the project are complimented by outreach activities, including an annual microrobotics mobility competition to be held at the IEEE International Conference on Robotics and Automation -- a premier robotics conference for academia and industry. The results from this project will enhance the national health, by enabling new diagnostic and therapeutic uses for microrobot swarms. They will also promote the national prosperity, by enabling new classes of microassembly robots.

This project aims to develop a practical control scheme to simultaneously control large numbers of microrobots. This will be achieved by using microelectromechanical systems (MEMS) to electromechanically and magnetically decode a sequence embedded in the single global control signal, and couple the reconfiguration of such sequence to the modification of the individual microrobot trajectories. This on-board sequence decoding will be accomplished through sets of on-board physics-based finite state machines (PFSM) that can accept a control sequence embedded in the control signal and change the behavior of the microrobots accordingly. The project will use both electrostatic and magnetic approaches to implement PFSMs, and to couple their "accept" state to the propulsion mechanism to modulate individual trajectories. Sets of stress-engineered electrostatic switches, which will latch in response to a pre-programmed control voltage sequence, will be used to implement PFSM on the electrostatic platform. Electro-permanent magnetic circuits, which change their magnetic moment in response to a sequence of global magnetic field, will be used to implement PFSM on the magnetic platform. The project will develop the theory for PFSM-based multi-microrobot control, construct both electrostatic and magnetic microrobotic PFSM platforms, and validate the concept by implementing the PFSM-based control on swarms of electrostatically and magnetically powered microrobots. The developed theory and approach will pave way for control of large microrobot swarms for numerous biomedical and microassembly applications.

Investigators: Y.K. Yoon

The direction of cell growth is associated with chemical, structural and/or mechanical properties of the substrate. Structurally, electrospun nanofibers provide a suitable environment for cell attachment and proliferation due to their similar physical dimension to that of the extracellular matrix. Furthermore, by modulating the topographical features of nanofibers, which include fiber diameter and orientation, cell growth and its related functions can be modified. Here, we demonstrate a solid gradient scaffold for directional growth of spiral ganglion neurons (SGNs). Spatial nanofiber alignment is controlled using a custom directional electrospinning setup. The electric field to spatially control the confinement of nanofibers was simulated with COMSOL Multiphysics simulation tool and experimentally verified. To promote neurite outgrowth and impart directionality to SGN cells, a spatial gradient of neurotrophin (NT) is introduced. By sequentially electrospinning solutions of increasing concentrations of NT in the biodegradable polymer and collecting sections of these aligned fibers along a uniaxial direction, we achieved uniform sectional nanofibers of increasing gradient concentrations. Initial tests with SGNs show improved cell adhesion and decreased morbidity to microfabricated PLGA scaffolds. Our solid gradient nanofiber membrane is versatile, obviates the need for the complex microfluidic mixer system to generate an NT gradient, is potentially implantable, and can be used in other nerve regeneration studies in peripheral nerve system and central nerve system.

Investigators: David Arnold

We seek to develop a platform that allows magnetic field sensing using a small footprint, in the absence of an external power supply. Our approach uses magnetoelectric nanofibers to create a zero-power magnetic field sensor. The challenge is to develop methods to assemble these materials into devices that leverage their unique anisotropic properties.

The figure of merit for magnetoelectric materials is the magnetoelectric coefficient, a measure of the amount of voltage generated with respect to the magnitude of the applied magnetic field. Bulk magnetoelectrics and thin films are limited by defects and substrate clamping respectively.  To overcome the limitations of thin-film based composite magnetoelectrics we have developed magnetoelectric bilayer structures on a single nanofiber, i.e., 1D magnetoelectrics. These materials are theoretically predicted to have magnetoelectric coupling coefficients that are orders of magnitude greater than their thin film counterparts. 

Magnetoelectric materials can be employed in a wide variety of applications including magnetic field sensors and tunable resonance energy harvesters.  By optimizing for material system and architecture, drastic increases in magnitude of voltage generated with decreased size can be achieved. This could allow for more sensitive magnetic field sensors appropriate for a wider array of applications and decreased size to allow for easier integration into ICs.
 

Acoustics and Fluid Mechanics

Investigators: Mark Sheplak

The goal of this research is to develop a MEMS-based Five-hole Probe(5HP) that is able to measure the localized velocity vector (both the velocity magnitude and direction) and the static and dynamic pressure, in steady and/or unsteady flow fields. Five optical pressure sensors located on the hemisphere tip of the 5HP provide all information that is needed to resolve the flow. This 5HP is expected to be able to provide high spatial resolution, high frequency response and is compatible with elevated temperature environments. A primary focus of this research is on the microfabrication and micromachining of a die that incorporates five optical transducers and its successive packaging process. The completed sensors will be tested in flow cells and wind tunnels at UF for the final calibration.

Investigators: Mark Sheplak

This project focuses on the development of a non-intrusive, direct, time-resolved wall shear stress sensor system for low-speed applications. The goals of the project include the fabrication and packaging of a 2-D wall-shear stress sensor with backside wire bond contacts to ensure hydraulic smoothness in flow environments. A differential capacitance transduction scheme is utilized with interdigitated comb fingers on each side of a suspended floating element, allowing for measurements to be made in both the positive and negative x- and y-directions.  A synchronous modulation-demodulation circuit is employed to simultaneously capture both mean and fluctuating shear content. Both AC and DC calibrations are performed to determine sensor sensitivity in both directions of transduction. This is the most successful effort of shear sensor development in published literature. 

Investigators: Mark Sheplak, Alexandra Garraud

The primary objective of this research is to develop a high-bandwidth pressure sensor to provide benchmark, time-resolved, dynamic pressure data in high-temperature combustion environments. Specifically, these sensors will be designed to be embedded within a system and provide remote interrogation which will enable pressure to be measured in situ and on line under extreme conditions. Ultimately, this sensing technology will lead to better understanding and increased efficiency of complex power generation systems. In order to achieve this objective, research in sapphire laser micromachining and thermocompression bonding via spark plasma sintering technology will be conducted to enable fabrication of a fiber optic lever pressure sensor that uses a sapphire optical fiber for transduction of the pressure-induced diaphragm deflection. The proposed project will result in instrumentation-grade, high-temperature sensors that enable flush mounted measurements without sensor cooling. Furthermore, the use of optical techniques enables “passive” device operation, with electronics located remotely from the sensor. After fabrication and packaging, the pressure sensor will be rigorously characterized in acoustic plane wave tubes under both ambient and high-temperature conditions to determine its performance as a quantitative measurement device.

Investigators: Alexandra Garraud, Mark Sheplak

We are developing time-resolved dynamic pressure sensing technology for high-temperature (> 1000 °C) applications in the aerospace, energy, and automotive sectors and for chemical environment sensors for biotechnology companies.

Almost all of the existing pressure sensing systems are not capable of operation in environments in excess of 1000 °C. Those systems that can survive the extreme temperatures suffer from reduced performance and induced bias errors arising from temperature mitigation efforts. We will investigate wireless, electromagnetic wave-guide and sapphire-based fiber optical based transduction technology combined with laser micromachining of sapphire and platinum film deposition to dynamic pressure sensors capable of continuous operation at 1000 °C. These technologies eliminate the need for close proximity electronics and will be fabricated from high-temperature capable materials that possess nearly identical thermal coefficients of expansion to minimize thermal drift.

Chemical and Biomedical Systems

Investigators: Y.K. Yoon

The Electrospinning and Stamp-thru-mold (ESTM) technique, an integrated fabrication process which incorporates the versatility of the electrospinning process for nanofiber fabrication with
the non-lithographic patterning ability of the stamp-thru-mold process is introduced. In-situ multilayer stacking of orthogonally aligned nanofibers, ultimately resulting in a nanoporous membrane, has been demonstrated using orthogonally placed collector electrode pairs and an alternating bias scheme. The pore size of the nanoporousmembrane can be controlled by the number of layers and the deposition time of each layer. Non-lithographic patterning of the fabricated nanoporousmembrane is then performed by mechanical shearing using a pair of pre-fabricated micromolds. This patterning process is contamination free compared to other photo lithographical patterning approaches. The ability to pattern on different substrates has been tested with and without oxygen plasma surface treatment. In vitro tests of ESTM poly-lactic-coglycolic acid (PLGA) nanofibers verify the biocompatibility of this process. Simulation by the COMSOL Multiphysics tool has been conducted for the analysis of electrospun nanofiber alignment.

Investigators: Huikai Xie

The goal of this project is to develop a miniature two-photon microscopy probe with light weight and use it on freely behaving mice for in vivo 3D neural imaging. Both 2-axis MEMS scanning mirror and z-axis tunable microlens will be developed. Double-cladding photonic crystal fibers will be used to accommodate the excitation laser and the frequency-doubled two-photon signals. 

Investigators: Huikai Xie

The goal of this project is to develop an OCT system with a miniature imaging probe that can utilize birefringence for enhanced contrast as well as provide vascular distribution information.

Investigators: Saeed Moghaddam

The aim of this project is to utilize the controllable nature of Graphene Oxide as an ultrathin separation membrane in biological applications, specifically targetting removal of uremic toxins. 

Investigators: Y.K. Yoon

The direction of cell growth is associated with chemical, structural and/or mechanical properties of the substrate. Structurally, electrospun nanofibers provide a suitable environment for cell attachment and proliferation due to their similar physical dimension to that of the extracellular matrix. Furthermore, by modulating the topographical features of nanofibers, which include fiber diameter and orientation, cell growth and its related functions can be modified. Here, we demonstrate a solid gradient scaffold for directional growth of spiral ganglion neurons (SGNs). Spatial nanofiber alignment is controlled using a custom directional electrospinning setup. The electric field to spatially control the confinement of nanofibers was simulated with COMSOL Multiphysics simulation tool and experimentally verified. To promote neurite outgrowth and impart directionality to SGN cells, a spatial gradient of neurotrophin (NT) is introduced. By sequentially electrospinning solutions of increasing concentrations of NT in the biodegradable polymer and collecting sections of these aligned fibers along a uniaxial direction, we achieved uniform sectional nanofibers of increasing gradient concentrations. Initial tests with SGNs show improved cell adhesion and decreased morbidity to microfabricated PLGA scaffolds. Our solid gradient nanofiber membrane is versatile, obviates the need for the complex microfluidic mixer system to generate an NT gradient, is potentially implantable, and can be used in other nerve regeneration studies in peripheral nerve system and central nerve system.

Investigators: Jack Judy

A Tissue Engineered Electronic Nerve Interface (TEENI) combines research areas including flexbile MEMS device fabrication, Hydrogels, Magnetic Microparticle Templating, Tissue Scaffolding, and Nerve Regeneration to develop a highly compliant and versatile interface for stimulating and recording the peripheral nerve with the potential for electrode density to scale in a truly 3-Dimensionsal fashion.

Power and Energy Systems

Investigators: David Arnold

As predicted by Moore's "law", the past few decades have seen massive reductions in the size of integrated circuits, enabling the portable, handheld devices now in everyday use. However, the components that power these devices have not experienced a similar size reduction. For example, the power adapter of a laptop computer is only modestly smaller than that two decades ago, and the printed circuit board inside a smart phone must dedicate between 20% and 40% of the board area for power conversion and management. To date, efforts towards miniaturization have been limited by both materials and manufacturing challenges. To address this gap, this research will study nanomanufacturing processes to facilitate the scalable synthesis of high quality magnetic nanoparticles and nanocomposite core materials and the fabrication of compact power inductors and transformers through assembly of these nanomaterials in a manner that is compatible with current manufacturing processes, such as silicon wafer or printed circuit board fabrication. This compatibility will enable fully integrated and compact system-on-chip or system-in-package power solutions. This research will be accomplished by fostering collaboration among disciplines including materials science, chemical engineering and electrical engineering. It will foster diversity in the profession by involving high school and undergraduate students in research activities and by broadening participation through the inclusion and engagement of women and underrepresented groups.

The overarching goal of this Scalable Nanomanufacutring project is to study synthetic and nanomanufacturing processes that overcome existing integration challenges while affording breakthrough, high-frequency magnetic performance. An aim is to research materials that exhibit high magnetic saturation and low loss. This will be accomplished by leveraging the unique properties of magnetic materials at the nanoscale through a combination of nanomanufacturing approaches spanning bottom-up synthesis to directed assembly and nanocomposite formation. The specific objectives are to: (i) scale-up synthesis of high quality magnetic nanoparticles via thermal decomposition routes by elucidating the underlying correlations between synthesis parameters and nanoparticle properties, leveraging recent developments in the reproducible synthesis of near defect-free nanocrystals with magnetic properties approaching those of the bulk; (ii) study methods for large-scale directed assembly of magnetic nanoparticles via dielectrophoresis into compact power inductors/transformers; and (iii) demonstrate the formation of bi-phasic nanocomposite cores through large-scale electro-infiltration of an additional ferromagnetic material. An expected outcome of this project is to demonstrate scalability through the full-wafer batch-fabrication of microinductor devices using the developed methods on a silicon wafer. From a commercial standpoint, nanomanufacturing technologies providing process-integrable, high-performance magnetic components for power application have the potential to impact a nearly $12B/year market.