Advanced Materials and manufacturing (AMM) Research
Past & Current 

Interfacial Polarization in Multilayered Dielectric Films and Polymer Nanodielectrics
The research objectives of the project aim to 1) obtain fundamental understanding of the mechanism and property of interfacial polarization in multicomponent multilayer polymer films and polymer nanocomposite dielectrics (or nanodielectrics), 2) understand the role of interfacial polarization in trapping space charges and thus enhancing the dielectric breakdown strength, and 3) provide fundamental guidance for better design principles of polymer multilayer films and nanodielectrics. In this project, we like to explore the most power laser spectroscopic techniques of confocal Raman, second harmonic generation (SHG) and electric field induced second harmonic (EFISH) generation. These techniques are very sensitive to molecular dipole orientation, polarization, and capable of 3-dimensional electrical field mapping at a nanometer scale or diffraction limited resolution. Also, by taking the full advantage of static and time-resolved SHG and EFISH laser spectroscopy, it is possible to study dipole rotation/reorientation, electric field-induced ion diffusion, relaxation, electric field change and distribution in real time and space. Examples of published work: ACS Appl. Mater. Interfaces, 7, 19894-19905 (2015); Polymer 55, 8-14 (2014); and Appl Phys Lett 103, 072901-072901 (2013).

Exploring the Extremes of Mechanical and Thermal Properties of Electrospun Nanofibers
The objective of the research project is based on very recent work by others and us indicates that polymer fibers can have surprisingly good thermal and mechanical properties. It HIGHLY depends on manufacturing processes. The realization of the extremes of mechanical and thermal properties of electrospun polymeric nanofibers will lead unprecedented technical breakthrough and bring significant impact to many significant applications. Polymer and its composites have already being used in literally everywhere. Perhaps, it is the Thermal, Mechanical and Electrical properties are the bottlenecks limited their crucial and critical applications, including Defense. The main aim of the project is to take relatively simple approach to identify the correlating among the manufacturing process conditions, the corresponding structures, and mechanical and thermal properties of electrospun polymer nanofibers. It is expected that electrospun nanofibers typically exhibit significant molecular orientation, which may dramatically alter their mechanical and thermal properties. Our preliminary results also indicate drastic increase in thermal and mechanical properties. In view of this, we propose to conduct systematic research through rational control of the electrospinning process, thorough microstructural characterization, mechanical and thermal property measurements, and theoretical analysis to achieve in-depth understanding of electrospun polymeric nanofibers. Examples of published work: Nanoscale 7, 16899-16908 (2015), Soft Matter, 14, 9534-41, (2019).

Smart Separators with Imbedded Sensors and Superior Thermal Conductivity
The separator is a critical, multi-functional component in lithium ion (Li-ion) battery that can play a key role in the performance and safety of energy conversion and storage processes. Managing and monitoring both the production and transport of heat at the separator is very important for minimizing cell temperature and avoiding dangerous thermal runaway. This requires a fundamental understanding of heat generation and distribution (mapping) within the battery cell on both a local and global scale to address battery safety and prevent battery failure, including melting of the separator. Measuring both the heat capacity of the separator and the heat conduction in plane or perpendicular to the separator plane can provide essential guidance to address battery safety issues. The overall goal of this project is to improve fault-tolerance and prevent rupture of lithium ion batteries (LIB). It is crucial to provide early warning via real-time temperature and pressure monitoring. In addition, through development of new processing technology, it will be possible to increase the thermal conductivity to prevent localized hot spots, leading to new innovation in battery technology. Examples of published work: Biosens Bioelectron Open Acc: BBOA-111. DOI: 10.29011/BBOA-111. 100011 (2018)

Development of Surface Plasmon Assisted ZnO/Metal Oxides Core-Shell Nanowire Structures for Optical Nanoemitters and Biochemical Nanoprobes
Zinc oxide has emerged as a promising optoelectronic material due to its direct bandgap of 3.37 eV and large exciton binding energy (60 meV). A wide range of devices, including nanolasers and sensors, have been developed in which the band-edge exciton emission from ZnO nanowires is controlled by growth, annealing, and doping conditions. In addition, both in thin films and nanowires the band-edge emission can be enhanced by placing metal nanoparticles in close proximity to the ZnO emitter. Recently, we have shown that the ultraviolet band-edge emission can be enhanced by coating ZnO nanowires with a layer of MgO, due to optical cavity effects. Moreover, we show that emission from the ZnO-MgO core-shell nanowires is further enhanced by decorating them with Ag nanoparticles, especially at larger MgO shell thicknesses. COMSOL Multiphysics is used to compute the cavity modes for specific shell thicknesses and elucidate the mechanisms underlying increased enhancement of the radiative emission rate for the higher-order modes. Simulations show that the cavity modes include a strongly confined Fabry-Perot resonance as the lowest-order mode and higher-order whispering-gallery modes that lead to an enhanced field intensity near the surface of the core-shell nanowire. The Objectives of the project is to develop surface plasmon assisted ZnO structure-by-design nanostructures for high efficiency light emitters, lasers, and surface enhanced Raman nanoprobes. Examples of published work: Small, 10 (21), 4304-09, (2014); Thin Solid Films 553, 132-137 (2014). ChemNanoMat, 4(3) 291-300 (2018), Nanoscale Advances, 3, 407–417 (2021).

Multifunctional Nanomaterials for Air and Liquid Protection
Multifunctional Nanomaterials for Air and Liquid Protection - This is a proof-of-concept research project to create a new type of dynamic, biofunctionalized nanomaterial to provide real time protection and detection of specific biological and chemical agents through the fusion of multiple, co-located sensing modalities. We will stratify potential targets in the sensing environments by size, using fine control over multiple properties of a piezoelectric fiber to create filters of controlled and well-defined pore sizes ranging from microns to tens of nanometers. Nanofibers (NFs) will be decorated with a 'smart' coating for specific capture of target biological and chemical agents in a size range corresponding to the filter pore size. This approach improves sensing specificity by excluding large agents, such as bacteria, from the sensing fibers for small agents such as viruses and chemicals. Examples of published work: J Poly. Sci Appl. 2, 1000109 (2018)

Ferro-, Magneto-, and Opto- electronic Nanostructures and Devices
The general scope of the materials research addresses cutting-edge challenges in materials science to develop new flexible sensor technology. In the process, we like to 1) establish materials synthesis design rules to optimize functionality of ferroelectric polymeric materials and develop scalable manufacturing through fundamental understanding of the basic science and physical materials processing, 2) integrate the polymeric materials with deformable 2D materials through interface engineering and modeling of heterostructures to achieve nanosystems and nanodevices whose properties and functionality are far beyond that of the single materials alone, and 3) develop integrated devices and discover new functionalities of 2D materials through device fabrication and machine learning.

Advanced and Highly Functional Biomaterials for Biomedical, Food Science and BioAgricultural Applications
The main materials fabrication strategy is based on electrohydrodynamic processing to synthesize sophisticated structured materials with biocompatible and environmentally friendly properties. The structure will be tailored to be able to attack the specific targeted surface and conduct the controlled time and concentration release for biomedical applications. They can also be prepared to have capability in enhancing food's quality, safety, and shelf-life. Examples of functionalized materials may be 1) nano- and micro-particles, core/shell, and opal structures (particles and fibers) that are encapsulated with bioactive compounds for active packaging applications. Examples include: Comprehensive Reviews in Food Science and Food Safety, 1–30 (2021), Polymers 14 (13), 2702 (2022).

Moving Target Defense
Moving Target Defense (MTD) has emerged as a game changing capability to protect distributed computing systems by enabling defenders to change system/network behaviors, policies, or configurations automatically such that potential attack surfaces are moved in an unpredictable manner. With funding from DOD Cyber security Center of Excellence, we are working on MTD based research efforts to protect cloud data centers. Specifically, we are developing approaches to perform Virtual Machine (VM) migration to avoid attacks. We have developed a network cost and security risk aware approach to migrating VMs. Both works provide insight on the cost of MTD based VM migration on cloud data centers. We are also working on MTD-based network diversity models to evaluate the robustness of cloud data centers against potential zero-day attacks.


Resilient Cyber-Insurance Market
A consistent, rational, and universally-applicable framework for risk management, risk sharing, and making business decisions regarding investment in infrastructure protection and resilience cannot be achieved without a stable, competitive, and properly functioning insurance market. A properly functioning insurance market plays a critical role in providing the metrics needed to make risk management decisions and serves as the vehicle for sector-wide risk sharing. With funding from DHS Critical Infrastructure Resilience Institute, we will study the evolution of the emerging cyber insurance market to gain an understanding of how this market can be expanded and improved so that cyber insurance will become widely available. Through economic modeling combined with cybersecurity risk assessment based on analysis of cyberattack data, we will provide the input needed for actuarial analysis. We will quantify the impact of attack due to loss of data or lack of access to critical system resources. We will develop a cyber security risk assessment tool to provide real-time analytics, analyze historical datasets and ability to predict future risks.


Cyber Resilient Smart Grid
The Cyber Resilient Energy Delivery Consortium (CREDC) founded in 2015 focuses on improving resilience and security of cyber networks for Energy Delivery Systems (EDS). The focus of CREDC is to develop approaches to ensure EDS is resilient to accidental or malicious cyber-anomalies. Cyber networks responsible for communication between smart meter and utility, controlling flow of oil or gas in a pipeline. Over 245 reported cyber incidents in EDS occurred in 2014. Research activities will involve security risk assessment, software-defined networking and robust networked control systems. We will develop a security quantification model to quantify impact of DoS attacks in smart grid. We will map security requirements of smart grid network to corresponding cyber network requirements for informed security risk assessment model and attack. We will implement security score model within a OpenFlow controller in a Software Defined Network. We will develop resilient control algorithm that maintains acceptable performance of EDS under cyber attacks.


Interfacial Polarization in Multilayered Dielectric Films and Polymer Nanodielectrics
The research objectives of the project aim to 1) obtain fundamental understanding of the mechanism and property of interfacial polarization in multicomponent multilayer polymer films and polymer nanocomposite dielectrics (or nanodielectrics), 2) understand the role of interfacial polarization in trapping space charges and thus enhancing the dielectric breakdown strength, and 3) provide fundamental guidance for better design principles of polymer multilayer films and nanodielectrics. In this project, we like to explore the most power laser spectroscopic techniques of confocal Raman, second harmonic generation (SHG) and electric field induced second harmonic (EFISH) generation. These techniques are very sensitive to molecular dipole orientation, polarization, and capable of 3-dimensional electrical field mapping at a nanometer scale or diffraction limited resolution. Also, by taking the full advantage of static and time-resolved SHG and EFISH laser spectroscopy, it is possible to study dipole rotation/reorientation, electric field-induced ion diffusion, relaxation, electric field change and distribution in real time and space. Published work: ACS Appl. Mater. Interfaces, 7, 19894-19905 (2015); Polymer 55, 8-14 (2014); and Appl Phys Lett 103, 072901-072901 (2013).


Exploring the Extremes of Mechanical and Thermal Properties of Electrospun Nanofibers
The objective of the research project is based on very recent work by others and us indicates that polymer fibers can have surprisingly good thermal and mechanical properties. It HIGHLY depends on manufacturing processes. The realization of the extremes of mechanical and thermal properties of electrospun polymeric nanofibers will lead unprecedented technical breakthrough and bring significant impact to many significant applications. Polymer and its composites have already being used in literally everywhere. Perhaps, it is the Thermal, Mechanical and Electrical properties are the bottlenecks limited their crucial and critical applications, including Defense. The main aim of the project is to take relatively simple approach to identify the correlating among the manufacturing process conditions, the corresponding structures, and mechanical and thermal properties of electrospun polymer nanofibers. It is expected that electrospun nanofibers typically exhibit significant molecular orientation, which may dramatically alter their mechanical and thermal properties. Our preliminary results also indicate drastic increase in thermal and mechanical properties. In view of this, we propose to conduct systematic research through rational control of the electrospinning process, thorough microstructural characterization, mechanical and thermal property measurements, and theoretical analysis to achieve in-depth understanding of electrospun polymeric nanofibers. Published Work: Nanoscale 7, 16899-16908 (2015)


Smart Separators with Imbedded Sensors and Superior Thermal Conductivity
The separator is a critical, multi-functional component in lithium ion (Li-ion) battery that can play a key role in the performance and safety of energy conversion and storage processes. Managing and monitoring both the production and transport of heat at the separator is very important for minimizing cell temperature and avoiding dangerous thermal runaway. This requires a fundamental understanding of heat generation and distribution (mapping) within the battery cell on both a local and global scale to address battery safety and prevent battery failure, including melting of the separator. Measuring both the heat capacity of the separator and the heat conduction in plane or perpendicular to the separator plane can provide essential guidance to address battery safety issues. The overall goal of this project is to improve fault-tolerance and prevent rupture of lithium ion batteries (LIB). It is crucial to provide early warning via real-time temperature and pressure monitoring. In addition, through development of new processing technology, it will be possible to increase the thermal conductivity to prevent localized hot spots, leading to new innovation in battery technology.


Development of Surface Plasmon Assisted ZnO/Metal Oxides Core-Shell Nanowire Structures for Optical Nanoemitters and Biochemical Nanoprobes
Zinc oxide has emerged as a promising optoelectronic material due to its direct bandgap of 3.37 eV and large exciton binding energy (60 meV). A wide range of devices, including nanolasers and sensors, have been developed in which the band-edge exciton emission from ZnO nanowires is controlled by growth, annealing, and doping conditions. In addition, both in thin films and nanowires the band-edge emission can be enhanced by placing metal nanoparticles in close proximity to the ZnO emitter. Recently, we have shown that the ultraviolet band-edge emission can be enhanced by coating ZnO nanowires with a layer of MgO, due to optical cavity effects. Moreover, we show that emission from the ZnO-MgO core-shell nanowires is further enhanced by decorating them with Ag nanoparticles, especially at larger MgO shell thicknesses. COMSOL Multiphysics is used to compute the cavity modes for specific shell thicknesses and elucidate the mechanisms underlying increased enhancement of the radiative emission rate for the higher-order modes. Simulations show that the cavity modes include a strongly confined Fabry-Perot resonance as the lowest-order mode and higher-order whispering-gallery modes that lead to an enhanced field intensity near the surface of the core-shell nanowire. The Objectives of the project is to develop surface plasmon assisted ZnO structure-by-design nanostructures for high efficiency light emitters, lasers, and surface enhanced Raman nanoprobes. Published Work: Small, 10 (21), 4304-09, (2014); Thin Solid Films 553, 132-137 (2014).


Multifunctional Nanomaterials for Air and Liquid Protection
Multifunctional Nanomaterials for Air and Liquid Protection - This is a proof-of-concept research project to create a new type of dynamic, biofunctionalized nanomaterial to provide real time protection and detection of specific biological and chemical agents through the fusion of multiple, co-located sensing modalities. We will stratify potential targets in the sensing environments by size, using fine control over multiple properties of a piezoelectric fiber to create filters of controlled and well defined pore sizes ranging from microns to tens of nanometers. Nanofibers (NFs) will be decorated with a 'smart' coating for specific capture of target biological and chemical agents in a size range corresponding to the filter pore size. This approach improves sensing specificity by excluding large agents, such as bacteria, from the sensing fibers for small agents such as viruses and chemicals