Susan E. Trolier-McKinstry, Ph.D. - US grants

9308332 Trolier-McKinstry This is a Research Planning Grant (RPG) proposal submitted to the Research Opportunity for Women (ROW) Program. The proposed work uses the spectroscopic ellipsometry (SE) as a nondestructive characterization tool for thin film and graded refractive index transparent materials. The limits of sensitivity of the measuring techniques will be investigated. The absolute accuracy of the measured film refractive index will be calculated as a function of the measured film thickness and the refractive index contrast between the coating and the substrate. Quantitative correlations between film deposition conditions and the film qualities will be made. It can have the effect of facilitating the production of homogeneous and high-quality films. %%% This proposed work uses the spectroscopic ellipsometry (SE) as a nondestructive characterization tool for thin film and graded refractive index transparent materials. It plans to examine the limits of sensitivity of the measurements, and it seeks to separate the effect of microstructural inhomogeneities in the films from the actual optical properties of the material. Transparent films are important in this age of optical communications. This study provides quantitative measures in how to improve the qualities of the films. Its' potentials to improve the optical communication application are very great. ***

9502431 Trolier-McKinstry This research addresses unresolved fundamental issues in the behavior of ferroic films, including the manner in which domain walls contribute to film properties, correlation between microstructure and electromechanical anisotropy, the role of thin film stress states, and the reliability of actuator devices. Laser ablation will be utilized to prepare modified lead zirconate and lead titanium zirconate films in the range of 0.1 - 10 micrometer thickness. Initial emphasis will be placed on developing deposition conditions for thick films on planar and non-planar substrates. Of especial interest in the research is the development of understanding how film microstructure and stress distribution modulate the electromechanical anisotropy of ferroelectric films. The influence on the material properties of temperature, bias electric field, film stress, and stress in the underlying electrode material will be evaluated and utilized to develop a model for the way in which ferroelastic domains interact with two-dimensional stresses. These studies will be coupled with a determination of the principal degradation and failure mechanisms in thin and thick film actuators. Special emphasis will be placed on determining the role of device geometry in stress concentration and crack generation. Finite element modeling will be used to calculate the stresses present in several different actuator structures. Guidelines for acceptable stress concentrations in film-based actuators will be developed. As a subsidiary component of this research, functionally graded films will be investigated. %%% The understanding of fundamental features of thin film ferroelectric materials will be of scientific and technological significance. Additionally, there is a strong educational segment to this project which stresses development of new courses and a focus on mentoring graduate, undergraduate, and pre-college students. The principal investigator will develop two new courses in ''Optical Propert ies and Optical Characterization of Materials" and ''Properties of Electronic and Photonic Materials." The cornerstone of the proposed mentoring program for undergraduate and pre-college students is integration of participants into ongoing research projects. The educational activities planned also include course materials development for faculty at four year colleges currently without materials science courses. ***

EEC-9526808 Dougherty This award is to establish a cooperative/collaborative research program between The Pennsylvania State University Center for Dielectric Studies Industry/University Cooperative Research Center and the University of California at Berkeley Sensor and Actuator Industry/University Cooperative Research Center in the area of lead zirconate titanate dielectrics for microelectromechanical devices. The center at the University of California is working on surface micromachined devices and the design of microsystems and components. The center at The Pennsylvania State University is working on the physics of thin-film dielectric, piezoelectric and ferroelectric materials. In this program the institutions are sharing expertise and facilities with the goal of improving the performance of piezoelectrically-activated microdevices through the implementation of highly active piezoelectric films in microelectromechanical devices.

Engineering - Materials Science (57)
The goal of this project is to develop multimedia courseware for upper level undergraduate students in materials science and engineering and related disciplines. The courseware is cutting across boundaries of the sub-disciplines of materials science and engineering and includes simulations, animations, and virtual instruments. Courseware is being developed through the collaborative efforts of faculty specializing in ceramics, electronic and photonic materials, metals, polymers, and engineering science. The majority of the courseware emphasizes active learning, requiring students to interact with the software as well as each other; and requires them to work with the information they gather from the computer to complete assignments. The courseware is initially being tested at The Pennsylvania State University, both in classes populated primarily by students in Materials Science and Engineering as well as in classes taken by students in various branches of engineering, chemistry, forestry, and food science. After initial testing and formative assessment, course materials are being disseminated to faculty at other institutions for further site testing. Commercial publication of the software and an instructional manual are being investigated.

0103354
Schlom

The technical objective of our NIRT is to understand the fundamental science underlying the structural, dielectric, and optical response of artificially-engineered nanoscale ferroelectrics, which can be drastically different from that of conventional homogeneous ferroelectrics. Using "first-principles effective Hamiltonian" approaches (based on lattice Wannier functions) and Landau-Ginzburg-type phenomenological methods, we will predict the effect of one-dimensional composition and strain gradients, and mechanical and electrical boundary conditions on the appearance and stability of the spontaneous polarization in these systems and on the modifications of ferroelectric domain structures. These predictions will be compared against observations on corresponding nanostructures (made by reactive MBE) of perovskite ferroelectrics in which composition and strain are varied in one direction. The resulting films will be characterized via a combination of TEM, x-ray diffraction (including synchrotron studies), Raman spectroscopy, second harmonic generation, dielectric property measurements as a function of electric field and temperature, and piezoelectric and pyroelectric techniques and compared with corresponding theoretical predictions in order to refine our understanding of nanoscale ferroelectrics. Composition and strain gradients in ferroelectric films will be investigated as a means to incorporate new functionalities: enhanced dielectric and pyroelectric responses, as well as a variety of novel optical properties.
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For over 30 years molecular beam epitaxy (MBE) has been used to build up layered semiconductor nanostructures atom-by-atom to investigate and improve our understanding of semiconductor physics and create new devices. These devices (which include laser diodes, high-performance transistors, and magnetic field sensors) have advanced healthcare, national security, communications, entertainment, and transportation-resulting in significant improvements in the quality of life for all Americans. Recent progress in research has demonstrated that this same atom-by-atom synthesis technique can be used to build up nanostructures of oxides, including ferroelectrics, with comparable nanometer-scale layering control. Since ferroelectric materials exhibit a wide variety of electrical, optical, and electromechanical properties, they are extensively used in healthcare (e.g., medical ultrasound), national defense (e.g., night vision and sonar systems), and communications (e.g., miniature capacitors for cell phones and computers). The ability to customize the layering of ferroelectric materials at the atomic-layer level opens exciting possibilities in terms of creating new functional materials that we believe can be designed (with sufficient understanding) to have exceptional properties. The improved understanding gained via this research will be applied to the development of improved (enhanced performance and smaller size) capacitors, night vision devices, and optical components. This NIRT program will also train and educate future scientists in a highly interdisciplinary research environment in a technologically-significant area of national importance.

This proposal was submitted in response to the solicitation "Nanoscale Science and Engineering" (NSF 00-119). The award is jointly supported through outside sources and the NSF Ceramics and Electronic Materials programs of the Division of Materials Research in MPS with the assistance of the initiative.

Piezoelectric thin films are attractive elements in several MEMS applications due to
the large generated force, high electromechanical coupling coefficients, and
substantial charge output that can be generated. This proposal focuses on two
approaches to increasing the performance in piezoelectric MEMS devices: (i) enhancing
the effective piezoelectric response in thin ferroelectric films utilizing in-plane
poled structures and (ii) developing miniaturized flextensional transducers to amplify
the piezoelectric effect. From the scientific standpoint, the program will determine
how the piezoelectric properties of in-plane polarized lead zirconate titanate films
compare to through-the-thickness polarized transducers, as well as any differences in
the way piezoelectric and dielectric properties age and fatigue relative to
conventionally poled films. A processing scheme to enable production of flextionsional
MEMS transducers will also be developed. In addition, a MEMS switch for RF applications
with large displacement (~2 microns) and high-speed (<1microsecond) will be
demonstrated using the d33 coefficient and a flextensional actuation mechanism. The
educational aspects of this program will concentrate on training graduate as well as
undergraduate researchers.
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Microelectromechanical systems (MEMS) are miniaturized devices produced with the same
techniques developed for integrated circuits, and typically range from several microns
to several millimeters in size. Such devices are now widely used in ink jet printers
and automobile air bag deployment accelerometers. Many fields, including miniaturized
biomedical instrumentation for bedside diagnosis, commercial electronics such as cell
phones, and small sensors to detect phenomena as diverse as toxic gases or the imminent
failure of a piece of industrial equipment would benefit from MEMS devices with higher
sensitivities or with the capability of doing more work. This program is designed to
increase the functionality of MEMS systems by exploring the integration of high
performance ferroelectric thin films with motion amplification. This program will also
train and educate scientists in an interdisciplinary research environment in a
technologically-significant area of national importance.

This Major Research Instrumentation (MRI) award provides funding for an inductively coupled plasma etching system consisting of three process modules: (i) advanced silicon etch module for high etch-rate, high aspect ratio etching of silicon; (ii) oxide etch module for high aspect ratio etching of quartz, silicon dioxide, and other ceramic materials; and (iii) a xenon difluoride vapor phase etching module for isotropic chemical etching of silicon with high selectivity. The instrument will be used by more than 25 research groups in 10 academic departments at Penn State University to conduct research in the areas of microfluidics, biochemical sensors, high-speed switches and nanoscale resonators for radio frequency applications, integration of high-performance piezoelectric and polymeric thin films into silicon microsystems and investigation into fundamental quantum mechanical effects at the nanoscale. It will also be used to develop undergraduate and graduate level laboratory courses in microfabrication techniques as part of a course curriculum in micro and nanosystems technology.

The proposed tool configuration will allow researchers at Penn State to develop novel sensors, actuators, and electronic systems for applications ranging from biomedical technology to homeland security. In addition to fostering interdisciplinary research, the tool will provide hands-on fabrication experience to students and will be instrumental in the creation of a workforce skilled in the areas of micro and nanoscale science and technology. The advanced etching capability with the uniquely developed etching processes will attract new research collaborations with industry and national laboratories to Penn State University. The etch tool will also impact the nano-camp and chip-camp programs currently offered for K-12 students on nanoscience and nanotechnology.

The Instrumentation for Materials Research (IMR) funding provided to this program will be used to purchase a Micromanipulated Cryogenic Probe Station. This instrument will facilitate temperature-dependent characterization of a variety of materials and devices being fabricated in the Penn State Materials Research Science and Engineering Center for Nanoscale Science including ferroelectric thin films and nanotubes, semiconductor and superconductor nanowires, and metal-molecule-metal junctions. These measurements will provide insight into fundamental materials properties such as domain wall motion in scaled ferroelectric thin films and electrical transport in one-dimensional nanostructures. This system offers advantages over conventional cryostats for these samples because it eliminates potentially damaging device packaging (i.e., dicing, mounting, and wire bonding) steps by incorporating six independently controlled micro-manipulated low-noise probes that are used to contact devices across a large sample diameter. In addition, the ability to probe multiple devices in a single cool down will make it easier to collect data on device-to-device variations, which have proven to be significant in many new nanoscale materials such as those described here. The cryogenic probe system will also have broader educational impact in undergraduate research and laboratory-based coursework. Several new laboratory modules will be incorporated into existing undergraduate and graduate physics and electrical engineering courses to provide instruction on temperature-dependent measurement of physical effects in nanoscale materials and devices.


The Instrumentation for Materials Research (IMR) funding provided to this program will be used to purchase a Micromanipulated Cryogenic Probe Station. This instrument incorporates six independently controlled probes that are used to contact individual on-chip devices, which are maintained at temperatures between 4 and 300 K by a continuous flow liquid helium cryostat. The probe station will facilitate temperature-dependent characterization of a variety of new devices being fabricated in the Penn State Materials Research Science and Engineering Center for Nanoscale Science including ferroelectric thin films and nanotubes, semiconductor and superconductor nanowires, and metal-molecule-metal junctions. These measurements will provide insight into fundamental materials properties such as domain wall motion in scaled ferroelectric thin films and electrical transport in one-dimensional nanostructures. The cryogenic probe system will also have broader educational impact in undergraduate research and laboratory-based coursework. Several new laboratory modules will be incorporated into existing undergraduate and graduate physics and electrical engineering courses to provide instruction on temperature-dependent measurement of physical effects in nanoscale materials and devices.

This collaborative program between Penn State University, Argonne National Laboratory and the University of Sheffield (UK) is directed towards understanding tilt transitions in perovskite thin films. These tilt transitions occur due to cooperative motions of the oxygen octahedra framework, and are the most common phase transitions in perovskite structured compounds. Such transitions have a profound impact on the temperature coefficient of resonance frequency and on piezoelectric constants. Despite their importance, the physics of size effects and the effect of mechanical constraint (as in thin films) for these tilt transitions is poorly understood in comparison to displacive/ordering transitions. In this program, we seek to answer the following questions that will allow breakthroughs in our understanding of tilt transitions in constrained systems:
1. How do elastic boundary conditions affect the tilt transitions in perovskites?
2. Are ferroelectric size effects affected by tilt transitions?
3. What are the property consequences of changes in the stability of tilt distortions?
Epitaxial thin films of PbZr1-xTixO3, AgTa1-xNbxO3 and BiScO3-PbTiO3 will be grown with compositions that yield tilt transitions in the bulk. The phase transition sequence as a function of film thickness, in-plane lateral constraint, temperature and composition will be studied via impact on ferroelectric, dielectric, and electromechanical properties, by conventional x-ray scattering, and by synchrotron x-ray scattering at the Advanced Photon Source (APS). In conjunction with Prof. Ian Reaney of the University of Sheffield, films will also be interrogated by transmission electron microscopy and Raman scattering.

NON-TECHNICAL DETAILS: Ferroelectric materials (materials that have a switchable spontaneous polarization) are at the heart of ultrasonic imaging systems for fetal and cardiac monitoring, the multilayer capacitors used in virtually every handheld device and computer, as well as in high precision positioning systems for advanced microscope systems. There are a number of unanswered questions surrounding the properties of the materials under high alternating electric fields; these are becoming increasingly more important as we continue to miniaturize devices. This program attempts to address open questions associated with the field dependence of the properties by investigating the role that defects play in influencing the mobility of ferroelectric domain walls. The insights gained here will be utilized to help design next generation components. The educational outreach program will utilize workshops directed at elementary school students taught by the principal investigators and their graduate students. These will engage ~ 80 students per year in a series of hands-on experimental activities designed to teach fundamentals of materials science. The graduate student will spend time both at Penn State University and at the Center for Nanoscale Materials Science at Oak Ridge National Laboratories.

TECHNICAL DETAILS: Ferroelectric materials are at the heart of ultrasonic imaging systems for fetal and cardiac monitoring, the multilayer capacitors used in virtually every handheld device and computer, as well as in high precision positioning systems. It is known that defects contribute to domain wall pinning in ferroelectric materials, and so influence the dielectric and piezoelectric response. There is a growing need to understand the interplay between domain wall mobility and microstructure as devices continue to scale down in dimensions. Thus, this program is addressing the following fundamental questions:
What is the potential depth associated with any pinning center?
What concentration of defects is required to pin a domain wall?
How do particular defect types influence the volume of material participating in a domain wall cascade?
How do macroscopic nonlinearities develop from local responses?
To address these critical questions, model ferroelectric films with controlled defect concentrations are being grown, including epitaxial ferroelectric films on bicrystal substrates with known twist and tilt angles. Large-grained polycrystalline films allow a wider distribution of grain boundaries to be probed. Point defect concentrations are tailored through aliovalent doping on cation sublattices, or through controlled levels of reduction to create defects on the anion sublattice. The resulting films are being probed by band excitation piezoelectric force microscopy to provide a quantitative measurement of the domain wall mobility at a very fine spatial scale, so that we can understand the relative importance of each type of defect in controlling domain wall mobility.

NON-TECHNICAL: The research in this project opens up new research strategies for sustainable high performance thermoelectrics that could have major societal impacts on energy savings, CO2 reduction and the environment. This investigation explores the interface between two unusual classes of functional materials: ferroelectrics and thermoelectrics, for low cost ¡V high efficiency energy harvesting. There are major economic advantages with a lower cost thermoelectric materials solution for generators; as an example, every automobile, household furnace, and factory exhaust chimney could have heat exchangers equipped with thermoelectric devices and these new enabling thermoelectric materials and strategies.

There is an important educational outreach activity with local schools (Park Forest and Mount Nittany Middle Schools), engaging students in grades 6-8 in material science. Under this project, a materials classification exercise is being designed to test previous perceptions and prejudices of the children towards selecting metals and insulators through ¡§show and touch. The same materials are being introduced to introductory materials classes at Penn State University to see how opinions differ from those of the younger children. The theoretical basis of this concept underpins the technical part of the advances used in transforming ferroelectric materials to thermoelectrics.

Based on preliminary data, the core intellectual property for Penn State University in the ferroelectric-thermoelectrics area has already been protected. Across this project, activities range from local education to global energy-environment-economic benefits in terms of its impact.

TECHNICAL: This investigation explores the interface between two unusual classes of functional materials: ferroelectrics and thermoelectrics. The aim of this work is to provide a broader understanding of highly non-stoichiometric ferroelectric materials near the critical electronic carrier concentration separating semiconducting and metallic conduction, the so-called Mott criterion. Initial observations of thermoelectric properties in non-stoichiometric perovskite BaTiO3-d and <001> tungsten bronze (Sr,Ba)Nb2O6-d ferroelectric materials shows attractive properties, and this project will establish: (1) general structure-thermoelectric property data for various ferroelectric compositions and structures, (2) quantification and modeling of electrical conductivity, Seebeck coefficient, and thermal conductivity, identifying the materials physics controlling the transport, (3) insights into the "best" ferroelectric-thermoelectrics, (4) the relation between the nature of the ferroelectric phase transition behavior and the semiconductor-metallic transition in different materials, and (5) analysis of the optical band edge behavior, quantifying phonon¡Velectron coupling, and structural modifications in the highly non-stoichiometric ferroelectrics across phase transitions. Tetrahertz spectroscopy measurements of the non-stoichiometric ferroelectrics produced under this project are used to establish detailed understanding of the phonon dynamics in the transition region and could open up a new sub-field by challenging the understanding of phase transitions in ferroelectric materials under these unique conditions. The research collaboration with the Czech Institute of Physics will expose the Penn State University students involved in this investigation to the importance of the global network of science and collaboration with groups with unique and world-class facilities and expertise.

Planning Grant for an I/UCRC for Dielectrics and Piezoelectrics (CDP)

1238086 North Carolina State University; Elizabeth Dickey
1238334 Pennsylvania State University; Clive Randall

The proposed Center for Dielectrics and Piezoelectrics (CDP) aims to develop an international leadership position in the fundamental material science and engineering that underpins dielectric and piezoelectric materials. The research efforts will be anchored by North Carolina State University (NCSU) as the lead institution, partnered with the Pennsylvania State University (PSU).

The Center will focus on new functionalities in dielectric and piezoelectric materials that could enable new and potentially disruptive storage and sensing technologies to drive the energy, electronics, medical, and communications sectors of the economy. The proposed I/UCRC will support major industries based on capacitor and piezoelectric materials and devices, through the development of new materials, processing strategies, electrical testing, and nanoscale structural characterization methodologies. The Center will strive to anticipate, define, and address critical material needs for low-power, conformable, mobile devices, as well as for high pulse electrical power. The proposed center also aims to identify and recruit companies across the supply chain, i.e. ones that manufacture dielectric and piezoelectric materials, component manufacturers, and end users, who will provide the technological pull for CDP research activities.

The Center will support training and research in materials development from the atomic to device levels, co-processing of various materials in device integration, and reliability of capacitive devices under high field and cycling conditions. The center will serve as a primary educational resource in these materials from the undergraduate student level through the continuing education of industrial scientists. The CDP will be a resource to other universities, research institutes, national laboratories, and commercial companies engaged in developing and utilizing dielectrics for integration into systems. The center plans to continuously and proactively develop broader participation at both institutions by having guest faculty at center meetings as a means to introduce faculty expertise to the center membership.

The I/UCRC for Dielectrics and Piezoelectrics will engage in the continuous exploration for new functional dielectric and piezoelectric materials and new strategies for integration that expand fundamental understanding, that drive the evolution of existing technologies, and that provide the pathways for disruptive innovation. The CDP?s collective expertise merges conventional dielectrics, organic composites, electrochemistry, thin-film science, and microelectronic materials and methods. The center?s faculty members offer fundamental academic insight and experimental flexibility to generate the science push towards next-generation materials, while industry partners from across the supply chain bring unique insight regarding new product concepts and consumer needs to establish a technology pull for next generation devices.

The I/UCRC for Dielectrics and Piezoelectrics aims to develop a diverse human capital and enhance scientific research, infrastructure, and societal impact through engagement with industry. Through targeted recruiting efforts, the CDP plans to integrate a diverse group of faculty and students in the Center, particularly participants from underrepresented groups (females and minorities) and veterans. In addition, the center intends to develop relationships with strategic international institutions to enhance the research capabilities of the CDP and to provide international research opportunities for graduate students. Center research and human capital development targets impact of our nation?s energy, transportation, security and medical infrastructure by advancing materials that underpin critical technologies for these sectors.

NON-TECHNICAL DESCRIPTION: Ferroelectric materials are used to couple electrical and mechanical energy and store information. Therefore, they are used pervasively as sensors, actuators, and energy and memory storage components in microelectronics, ultrasonic devices, and consumer products. The properties of ferroelectric materials can change significantly as their size is reduced. In ferroelectric thin films, it is now widely recognized that significant size effects are observed at film thicknesses between 10 nm and 1 um. At these thicknesses, the effectiveness of these materials at storing and transducing energy is dramatically reduced - in some cases being suppressed to <20% of the values seen in their larger counterparts. Using state-of-the-art experimental approaches offered by a collaborative team of investigators, this project elucidates the atomistic origins of these size effects in ferroelectric thin films. This understanding enables the design and realization of next-generation devices at substantially smaller length scales with superior performance and functionality. Examples of devices impacted by this research include piezoelectric microelectromechanical systems and scaled capacitors.

TECHNICAL DETAILS: The goal of the project is to develop a universal physical understanding of the fundamental structure-property-processing relationships that govern extrinsic size effects in ferroelectric thin films. The specific objectives include proving the extrinsic mechanism(s) affecting the size effects in ferroelectric thin films, quantifying the relative contributions from intrinsic and extrinsic mechanisms to properties, and establishing new fundamental structure-property-processing relationships. To accomplish these objectives, the Trolier-McKinstry group at Penn State synthesizes high-quality thin films and analyzes property measurements using Rayleigh and Preisach models. The Jones group at North Carolina State University uses in situ X-ray diffraction while applying voltage to quantify the intrinsic and extrinsic contributions under equivalent electrical loading conditions. The integrated results provide a quantitative understanding of contributions of intrinsic and extrinsic effects to the dielectric and piezoelectric coefficients in ferroelectric thin films as a function of film thickness and other key variables. The fundamental nature of the mechanisms and the results in the present work will be applicable to many ferroelectric thin film compositions including those being developed for high-temperature and lead(Pb)-free applications. Graduate students gain additional exposure to facilities and scientists through conducting experiments at the Advanced Photon Source at Argonne National Laboratory. The educational outreach program includes participation by the project participants at workshops and camps directed at elementary, middle school, and high school students. Students from underrepresented groups will be engaged in the project through targeted recruitment and outreach activities.

Scaling the Internet of Things (IoT) to billions and possibly trillions of "things" requires transformative advances in the science, technology, and engineering of cyber-physical systems (CPS), with none more pressing or challenging than the power problem. Consider that if every device in a 1 trillion IoT network had a battery that lasted for a full five years, over 500 million batteries would need to be changed every day. Clearly, a battery-powered IoT is not feasible at this scale due to both human resource logistics and environmental concerns. There is a need for a batteryless approach that dependably meets functionality requirements using energy harvested from the physical world. This project brings together experts in materials, devices, circuits, and systems to pursue a holistic approach to self-powered wireless devices deployed in real-world environments and IoT systems and applications. In addition, educational and outreach activities will help develop the workforce for this relatively new field with the holistic, materials-to-systems perspective that will be necessary to lead innovation in this space.

A critical challenge that this project addresses is that both optimal device operation and energy harvester efficiency are heavily dependent on physical world dynamics, and thus, self-powered devices that are statically configured or that just respond to instantaneous conditions are unlikely to provide the dependability required for many IoT systems and applications. To address this fundamental and critically enabling challenge, data collections will be performed to study the physical world dynamics that impact device operation and harvester efficiency, such as ambient conditions, electromagnetic interference, and human behavior. This scientific study will lead to the development of dynamic models that will, in turn, be used to develop algorithms to dynamically configure devices and harvesters based not only on past and current conditions but also on predictions of future conditions. These algorithms will then be used to dynamically configure technological innovations in ultra-low power device operation and ultra-high efficiency energy harvesting to engineer and operate dependable self-powered things for the IoT.

This IRES program addresses the national priority for research in understanding and imaging brain functionality and in developing engineered materials and mechanisms that provide brain-like processors. PACK fellows have the opportunity to conduct cutting-edge research on magnetic field sensing, biomedical systems and neuromorphic computing with involvement of more than thirty faculty members and over hundred students and postdoctoral fellows at University of Kiel (U Kiel). In order to support this research program, U Kiel is providing dedicated infrastructure with several specialized equipment. This support provides tremendous opportunity for US students and faculty to build a partnership with an excellent cluster of scientists and engineers at UKiel and through them collaborations throughout Europe. Over the course of the program, a substantial number of German students will be visiting US universities, funded through universities in Germany. The US students are drawn from various institutions around the country. The American Ceramic Society (ACerS) is administering the program, managing the student selection process, international network formation and collaboration, and sustainability of the PACK Fellowship. Several student-organized activities are built-into the program, such as retreats, workshops, and lab tours, in order to increase the interactions and provide opportunity for new collaborations. Team of faculty and consultant are providing the support for training PACK fellows on entrepreneurship, social media networking, and career counselling. Sustainability of the peer-to-peer relationships is being ensured through ACerS membership program, participation in annual symposia organized jointly by ACerS and partnering institutions, social media and dedicated PACK webpage, and PACK fellow?s alumni association.

PACK fellows have the opportunity to form an international network in the emerging field of biomagnetic field sensing and its implications towards solving complex human diseases through improved diagnosis and analysis. Different sensor approaches based upon magnetoelectric sensors are being designed and manufactured with the ability to reach a limit of detection suitable for biomagnetism resulting in the development of closed-loop, uncooled, biomagnetic interfaces for diagnostics and immediate treatment. Ongoing programs at U Kiel are providing opportunity to systematically investigate nanocomposite and thin film composite materials that can respond to small magnetic signals emitted from brain and heart, release drugs for treating brain diseases and provide memristive devices for neuronal systems. Extensive research on materials design, nanotechnology and surface sciences is being conducted by PACK fellows. Magnetic measurements promise improved diagnosis, for example in relation to spatial resolution and/or for examinations over a long period of time as a supplement or alternative to the established electrical measurements ? such as the electroencephalography (EEG) or the electrocardiography (ECG). This is rich area for interdisciplinary student training activities covering materials, signal processing, computation and biology. Based upon the understanding of neural functioning, memristive controllers are being designed to provide ultra-low power computation.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

NON-TECHNICAL DESCRIPTION: Ferroelectric materials (which have a spontaneous polarization which can be reoriented by an applied electric field ? the electrical analog of ferromagnetic materials) comprise a multi-billion-dollar industry; in nearly every case, the functional properties depend on the mobility of domain walls (the boundaries between regions with different polarization directions). This project is quantifying the role of realistic microstructure on the mobility of these domain walls, and broadly disseminating these results to the scientific community and industry. At the graduate level, the project is training students who will become next-generation scientific and technology leaders. Graduates typically find employment either at high-tech companies or as university faculty members. In addition, the principal investigator will complete a second edition of the textbook, Materials Engineering: Bonding, Structure, and Structure-Property Relationships.

TECHNICAL DETAILS: The fundamental processes and length scales associated with pinning domain wall and phase boundary motion in ferroelectric materials are at present poorly understood for general cases. This project is using a combination of electrical and electromechanical characterization, transmission X-ray microscopy, nanoprobe X-ray scattering, and piezoresponse force microscopy to develop a quantitative database on the way that different mechanical boundary conditions, including film stress, grain boundary misorientation angle, and interacting crystallographic defects influence correlated motion of domain walls. The interdisciplinary team of researchers from Penn State, Argonne National Laboratories and the Technical University of Denmark are preparing and characterizing model samples with a wide range of different grain boundary angles in order to directly measure the length scales over which correlated motion of domain walls occurs in Pb(Zr,Ti)O3 thin films. The functional properties are being mapped through a combination of Rayleigh and Preisach approaches. Large area measurements are being complemented with local measurements via piezoresponse force microscopy to map the size of the clusters where there is collective motion of domain walls for different strain states and grain boundary misorientations. Samples are being interrogated with nanoprobe diffraction measurements under field excitation. Moreover, the local domain structure in regions identified as strongly or weakly responsive are being interrogated via X-ray dark field microscopy in order to spatially map the defect/domain wall interactions. The ability to localize the major pinning sites and then structurally probe those regions non-destructively while exciting the sample electrically allows the possibility of elucidating the impact of local perturbations on the collective motion of functional domain walls. These results are allowing models of ferroelectric films, ceramics, and single crystals to be developed to capture the fundamental material physics more accurately.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Dynamic mapping of complex brain circuits by monitoring and modulating brain activity can enhance our understanding of brain functions and provide the promise of better treatment and prevention of different neurological disorders. Interfacing with the brain also has the potential to enhance our perceptual, motor, and cognitive capabilities, as well as to restore sensory and motor functions lost through injuries or diseases. The development of closed-loop neural interfaces with high-resolution recording and stimulation capabilities from the distributed neural circuits within the entire brain is still a grand challenge of neuroscience research. Current noninvasive neuromodulation techniques still suffer from poor spatial resolution (> 100-1000’s of mm3), while implantable methods with finer resolution only provide a limited coverage of 100-1000’s of neurons through highly invasive parenchymal implantation. This integrated research and education program enables minimally invasive ultrasound neuromodulation (and neural recording) of the brain with high spatial resolution (< 200 µm) at large scale (over the whole brain). This project will yield a unique building block for a comprehensive set of neural interfaces. It will open new opportunities in neuroscience with significant improvements in spatial resolution and coverage of the brain stimulation in animals. It will also have translational potential for clinical applications in humans, such as the treatment of neurological and psychiatric disorders and brain-machine interfaces. This project also includes an integrated outreach and educational component to impact K-12 teachers and students (particularly from underrepresented groups), minorities, and undergraduate and graduate students, and to develop an interdisciplinary workforce. This project will educate a broad audience (particularly women) in the science and applications of the research components and enhance their research skills through systematic troubleshooting activities. Graduate curriculums across different disciplines will also be transformed with related multidisciplinary projects and guest lectures.<br/><br/>This project includes scientific research to investigate implantable ultrasound stimulation on a flexible platform (placed on the brain surface with no parenchymal penetration) to simultaneously provide high spatial resolution (< 200 µm) and broad coverage (over the whole brain) while dramatically reducing invasiveness. This multidisciplinary project, which brings together expertise in electrical and biomedical engineering as well as material, computer, and neuro science, is transformative in that it is potentially the only method that promises large-scale stimulation across distributed brain regions at different depths with high resolutions of < 200 µm without parenchymal implantation, opening a new venue for understanding neural and cognitive systems at large temporal and spatial scales. The development of this technology builds upon investigators’ strength in circuits, wireless power, flexible technologies, thin-film ultrasound arrays, machine learning, and neural interfaces. The project pushes the limits of ultrasound neuromodulation by investigating a flexible, image-guided (with machine learning models), hybrid electrical-acoustic implantable system with the form factor of a thin flexible sheet (on the brain surface) for ultrasound stimulation (and electrophysiology recording). Three fundamental research gaps will be addressed. 1) For large-scale and high-resolution ultrasound beam focusing and steering, the optimal approach in scaling up the number of ultrasound elements and application-specific integrated circuit (ASIC) channels at high frequencies (e.g., 5 MHz) will be explored. To reduce the complexity, thin-film transistors on a flexible substrate will be leveraged to form a large two-dimensional ultrasound array with selectable one-dimensional arrays (e.g., 256-element) driven by only one ASIC. 2) Selectable thin-film ultrasound arrays with thin-film transistor switches on flexible substrate will be optimized to achieve high efficiency and high pressure output. 3) Imaging and machine learning models based on image sequence analysis will be developed to guide the ultrasound focused beam, considering the device flexibility (ultrasound elements’ orientation) and post-implantation effects. A system-level demonstration in benchtop and in vivo settings will establish the feasibility of this flexible implantable system.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.