Peter M. Hoffmann - US grants

0217789
Hoffmann

Description: This award is for support of a joint research project between Dr. Peter Hoffmann, Department of Physics and Astronomy, Wayne State University, Detroit, Michigan and Dr. Ahmet Oral, Physics Department, Bilkent University, Ankara, Turkey. They plan to study the development of a new high-resolution Atomic Force Microscopy (AFM) technique for biological imaging. Commonly used AFM techniques face fundamental limits to further improvement. These limitations are due to fundamental operating principles of common AFM techniques, which cannot be changed by simple adjustments of parameters. The PIs plan to design and build a prototype of an AFM technique that avoids these limitations and, in principle, should be able to provide non-contact atomic resolution imaging and direct quantitative point-by-point measurements of interactions in situ in liquids. This AFM technique relies on a sub-resonance, ultra-small (< 1A) oscillation of the AFM cantilever. This linearizes the measurement and makes data interpretation straightforward.

Scope: This award will allow a US scientist to collaborate with a Turkish scientist in a research project of high scientific potential. The nanomechanics of biomolecules and the direct imaging of biological structures are of great interest in biochemistry, bioengineering and medicine. The two scientists were directly involved in the development of an ultra-high vacuum (UHV) and a preliminary liquid-based version of the above described AFM technique which proved to be successful in UHV and in liquid. However, the liquid based AFM was very difficult to use and had some fundamental design issues, which will be addressed in this collaboration. The ultimate goal would be the construction of a user-friendly new AFM technique based on a novel operational principle, and the imaging and measurement of actual biological structures. The development of this instrument would enhance current work by the PI, at his university's medical school, on the mechanical behavior of tissues and antibiotic action of native antibiotic agents on certain bacteria, since it would allow for much higher resolution imaging and quantitative measurements of nanomechanical properties. Both investigators are junior scientists, and the project will also support two graduate students from each institution.

Common Atomic Force Microscopy (AFM) Techniques suffer from a number of fundamental difficulties limiting their usefulness in quantifying nanoscale interactions. The goal of this CAREER project at Wayne State University is to apply a novel AFM technique based on fiber interferometry and off-resonance, ultra-small amplitude operation to study important questions of the nanomechanics of individual atoms and molecules on surfaces. This includes the manipulation of single atoms and molecules, atomic scale energy dissipation, atomic bonding as a function of controlled tip and surface chemistry, atomic relaxation, and the relationship between AFM and Scanning Tunneling Microscopy (STM) imaging. These questions, while of a fundamental nature, are crucial for the rational development of future atomic/molecular scale nanosystems. Combined with this study is an integrated outreach program targeting parents of school age children with a series of lectures and demonstrations designed to illustrate the excitement of scientific research and raise awareness of scientific careers as fulfilling career choices for their children. This outreach program will be conducted in collaboration with local schools and two local science museums.

The future of Nanotechnology lies in the controlled manipulation of single atoms and molecules. This lofty goal can only be achieved if we gain solid knowledge of the mechanics of single atoms and molecules. This CAREER project at Wayne State University is designed to use a novel instrument, a "Sub-Angstrom Amplitude Atomic Force Microscope", to measure forces while manipulating single atoms and molecules, and to conduct complementary and important experiments on the 'nanomechanics' of single atoms. These studies will provide crucial knowledge necessary for the design of future nanometer scale devices. Research will involve graduate and undergraduate students at Wayne State University. In addition, the project includes a significant outreach component whereby parents of local school students are provided with an insight into the excitement of scientific research, the stimulating life of a university researcher, and the latest findings in Physics and Nanotechnology. This program, provided through local schools and two local science museums, is designed to raise awareness of scientific careers as fulfilling career choices, and to enlighten the participants about the importance of fundamental and applied science in our society.

A grant has been awarded to Wayne State University under the direction of Dr. Peter Hoffmann to design and construct a new, innovative Atomic Force Microscope (AFM) to study cells and biomolecules. AFM is a technique where a sharp tip mounted on a cantilever spring is scanned across or approached towards a surface in order to image and measure mechanical properties at the nanoscale. The technique has been used for over a decade in measurements of biological structures. However, current AFM's have fundamental design issues that limit their usefulness. These include low sensitivity and inherent non-linearities. As a result, AFM's have not reached their full potential in biological research. The purpose of this grant is to design a radically different AFM system that avoids these limitations from the start and is specifically built to perform unprecedented high-resolution imaging and nano-mechanical measurements of biological samples. The most important features of this new instrument will be the use of a fiber-optic interferometer to measure the deflection of the cantilever (boosting sensitivity by a factor 100), non-contact operation (for non-invasive imaging), and the use of ultra-small amplitudes (< 1 Angstrom = the size of a single hydrogen atom), which will linearize force measurements.

The development of this new instrument will have a tremendous impact on our understanding of cells and cell membranes. Research that will be conducted with this new instrument includes: (1) behavior of transmembrane proteins (proteins that are located in the cell membrane), which play important roles in cell signaling, (2) mechanical properties of fetal membranes, part of a project to address prematurity in humans, and (3) basic research of hydrophobicity and other forces in model systems that mimic cell membranes and their components to gain better understanding of these fundamental building blocks of life.

The instrument will add a significant component to the research infrastructure here at Wayne State University, and is expected to be used for a number of ground-breaking interdisciplinary research projects ranging from biology, medicine, materials science to industrial applications (nanotribology). Results of the work will be communicated to the general public via planned outreach events in Detroit area science museums and schools, part of a currently implemented program consisting of science lectures for the general public.

Our overall objective in this Major Instrumentation proposal is to acquire a unique Scanning Hall Probe Microscope (SHPM). This instrument has exceptional magnetic field imaging and sensing capabilities and has a number of important advantages:
1. It is non-invasive, as the probe itself is non-magnetic.
2. It measures magnetic field directly rather than field derivatives (as in MFM).
3. Its sensitivity at low temperatures is already compatible to the best micro-SQUIDs.
4. It has scanning capabilities and (in contrast to a micro-SQUID) can operate in large external magnetic fields. In collaboration with the Microscope manufacturer, NanoMagnetics Instruments, we will further develop SHPM sensitivity, ultimately allowing single electron spin detection. In particular we propose to do measurements of a single spin in a quantum dot. The implementation of this stage will result in a truly unique instrument with outstanding reaching capabilities.

Broader impact
This work, if successful, will establish the new basis for nanofabrication of unique
nanostructures with potential application in intelligent characterization of molecules and manipulation of single charges. The acquisition and development of SHPM will allow the faculty from several different departments at WSU (Physics, Chemistry, Electrical and Computer Engineering) to integrate the multidisciplinary research and student training. To compliment the research programs the PI and the Co-PIs will use SHPM in the development of a pilot program to introduce a Senior Research Project at WSU as a required part of the curriculum. The instrument will also help broaden the participation of undergraduate in the current NSF- funded IGERT and REU programs and will also be indispensable in the graduate interdisciplinary course, Materials and Characterization Techniques and of a new graduate course "Magnetism, Magnetic Devices and Nanotechnology".

Non-technical:

Moving two solid surfaces with respect to each other is always associated with friction and wear. Lubrication is necessary to reduce damage and to enable reliable operation of any moving part of an engine or machine. Fundamentally, the phenomena of friction, wear and lubrication involve mechanisms occurring on a molecular scale, and a good understanding of lubricant behavior on this scale is thus of primary importance to design more efficient and environment friendly lubricants. The economic value involved is enormous. In developed countries, financial savings resulting from improved attention to friction and wear would, by most estimates, amount to 1-2 percent of gross national product. The research will lead to better understanding of friction by investigating at the molecular level the properties of liquids confined by solid surfaces. It will perform both nanoscale force measurement and time-correlated fluorescence spectroscopy experiments to study the dynamics of nanoscale fluid systems. The force measurements will tell us about how many molecules behave when they act together, while the spectroscopy can track single molecules in the fluid layer. Students and postdoctoral researchers working in this project will learn cutting-edge laser spectroscopy and atomic force microscopy techniques, as well as research skills in areas of materials sciences and nanotechnology, which have huge growth potential. They will be well prepared for future careers in technological fields important for the greater Detroit area, including the auto industry, where questions of lubrication, wear and thin films play a significant role.


Technical:

The goal of this project is to perform direct measurements of molecular relaxation processes within nanometer thick confined fluid films by incorporating single-molecule sensitive fluorescence correlation spectroscopy (FCS) with atomic force microscopy (AFM). The proposed research will identify the relation between single-molecule relaxation processes, such as diffusion, and the mechanical properties measured in AFM experiments, such as stiffnesses and damping coefficients. This will lead to better understanding of the recently observed non-equilibrium behavior of these systems at increased approach speeds and test at the molecular level the hypothesis that the transition from rest (static friction) to sliding (kinetic friction) in thin confined films springs from a phase transition analogous to melting transition of a solid. The research is significant because it bridges the gap between the single-molecule and the ensemble-averaged response of confined fluids. The results will also be relevant to many contemporary ideas of condensed matter physics, such as order of liquids at interfaces, wetting phenomena and systems under extreme conditions, in particular molecular-scale confinement. The progress in this fundamental research can have important consequences for many technological applications. For example, in nano-electromechanical systems, the research may provide insight for the management of frictional dissipation. An improved understanding of the observation that under faster approach rates the system behaves elastically may lead to designs that exploit the confined lubricant as a 'smart liquid' to control approach rates in small devices. The interdisciplinary research program will train students and postdoctoral researchers in cutting-edge laser spectroscopy and atomic force microscopy techniques. They will be well prepared for future careers in technological fields important for the greater Detroit area, including the auto industry, where questions of lubrication, wear and thin films play a significant role.

****NON-TECHNICAL ABSTRACT****
Although water is the most ubiquitous liquid in the environment, its properties are still not well understood. In the context of nanotechnology, the behavior of nanoscale water is a subject of great controversy and great importance. Nanoscale water plays an important role in biology, where it determines the shape of the macromolecules in our cells, and in nanotechnology, where engineers are developing new devices that can analyze ever smaller water samples for medical diagnoses. This award supports a project to study the mechanical properties of water confined between two surfaces that are only 1-20 water molecules apart. When water is confined to such tight places, it behaves quite differently from bulk water. So far, experiments by different research groups have yielded contradictory results. A novel Atomic Force Microscopy (AFM), developed at Wayne State University, will be used to conduct careful measurements under varied conditions, such as changes in ion concentration or different confining surfaces in an attempt to elucidate the properties of water confined to nanoscale spaces. This project is integrated with training opportunities through a new graduate interdisciplinary Materials Science program and undergraduate Biomedical Physics program. Students who will be involved in this research will be trained in instrument development and state-of-the-art nanoscience research. The results of this research will be communicated through ongoing outreach efforts, which have so far reached hundreds of middle and high school students, teachers and parents.

****TECHNICAL ABSTRACT****
The properties of water, as the primary solvent of biological systems, are not fully understood, especially in situations where water is confined to nanoscale spaces. When water is confined to only a few molecular layers, continuum models break down, and oscillatory force profiles are observed. However, experiments to measure the mechanical properties of nanoconfined water have yielded contradictory results. This project will use novel Atomic Force Microscopy (AFM) Techniques, developed at Wayne State University, to study the mechanics and dynamics of nanoconfined water layers. The home-built AFM systems use ultra-small amplitudes of order 0.03 nm to perform linear measurements of the viscoelastic properties of confined water layers. This project will study how the dynamics of water change under various conditions, including changes in dissolved ion concentrations, applied shear, compression speeds, chemistry of confining surfaces, and external DC and RF electromagnetic fields. The latter is intended to elucidate the role of polarity and hydrogen bonding in nanoconfined water on its viscoelastic characteristics. This research is integrated with new educational programs at Wayne State, including a new interdisciplinary Materials Science graduate program and a new undergraduate Biomedical Physics program. Through these programs and this research projects graduate and undergraduate students will be trained in state-of-the-art instrumentation and nanoscience research.

Abstract

This instrument development project by a multi-disciplinary team from Wayne State University creates a Rapid Annealing and Characterization System (RACS) capable of rapidly annealing thin film samples and nanomaterials prepared externally and then characterizing these samples in situ using a variety of non-invasive techniques. With this highly flexible system, the researchers will develop and improve techniques to characterize how a variety of defects modify the materials properties. Defects, including dislocations, grain boundaries, impurity dopants, and vacancies have been found to dramatically alter the magnetic, electrical, and optical properties of materials. These defects are important in establishing the properties of nanomaterials, owing to the much higher surface to volume ratio than in bulk systems. The eventual goal of this study, which will focus on nitrides and superconducting thin films, is to control the type, density, and the distribution of defects to enable the synthesis of materials having specifically tailored properties. The custom designed vacuum chamber with rapid annealing capabilities coupled to a Scanning Electron Microscope with Wave Dispersion Spectrometer (WDS) using a proprietary airlock developed by JEOL will allow researchers to modify the defect structure by thermal annealing in one chamber and then conduct studies on the materials properties and defect structure in the second chamber, all without exposing the samples to ambient conditions. The WDS spectrometer is an important component of this study, as it will allow researchers to determine the concentration of oxygen vacancies, which is exceedingly difficult to determine using other techniques. The unique capabilities of RACS will be utilized to systematically probe the effects of a variety of defects on the fundamental properties of nanoscale systems, leading to a deeper understanding of how to tune the materials properties in nanostructured materials. Establishing the processing parameters for optimizing materials properties using RACS would allow the development of scalable fabrication protocols, which would promote the incorporation of these novel nanostructured materials into commercial devices. The development of this system will provide valuable training for a postdoctoral researcher as well as graduate and undergraduate students, specifically including underrepresented minorities in the Detroit metropolitan area.

This award to Wayne State University is for the acquisition of an integrated fluorescence and atomic force microscope to create a new platform to perform nanoscale measurements of cell-particle interactions. AFM is a force-measuring and surface imaging technique that can provide very high spatial resolution, while fluorescence microscopy provides fast, large scale and specific imaging of cells. By combining the two, (1) single molecule force measurements will be correlated with biological microenvironments or events, (2) simultaneous fluorescence and AFM imaging for a fuller picture of biological systems and their dynamics will be perform, and (3) sophisticated fluorescence techniques, such as Förster resonance energy transfer (FRET), can be correlated with AFM to measure applied forces to changes in structure. The combined instrumental platform will be used for interdisciplinary projects including single molecule interactions on live cells, optimization of DNA release from engineered polymer systems, cell motility studies, interactions of pathogens with cell surfaces, detection of food-borne bacteria, and dynamics and transport of magnetic nanoparticles in live cells.

The new instrumental platform will be a user facility, available to researchers in physics, materials science, biomedical engineering, biology, chemistry, the basic medical sciences, and beyond. The collaborative use of this instrument is expected to foster interactions between different disciplines, and thus create new opportunities and ideas. The proposed research has clear potential to lead to new technologies and benefit human health. The new platform will be integrated into an advanced biophysics lab course, part of the Wayne State University undergraduate Biomedical Physics Program, which impacts a significant number of people from underrepresented groups. As a user facility, this new instrument will help to train and inspire future scientists and engineers.

The objective of this research is acquisition of a dual beam focus ion beam (FIB) system, which will permit synergistic opportunities for nanotechnology, biomedical and energy research at Wayne State University (WSU). The approach is to use the FIB system as a central tool for several current and future projects, which urgently demand the ability to fabricate novel three-dimensional nanostructures and nanodevices in situ. This is a capability uniquely offered by FIB.

Intellect Merit: The sub-100 nm resolution three-dimensional patterning capabilities of FIB through milling/deposition will facilitate many research projects that require custom fabricated complex nanostructures and nanosystems. Consequently, FIB will significantly improve the quality and creativity of research at WSU in a broad range of areas from the development of devices and instrumentation (AFM, NSOM, scanning probe) to biomedical applications (biophysics, DNA sequencing, nanofluidics, single cell analysis, imaging, biosensor) to energy research (characterization of battery materials, catalyst and nanomaterials).

Broader Impact: The success of this proposal will significantly enhance WSU capabilities for nanofabrication and material characterization. FIB will be available to the entire WSU campus, other universities and local industry. Together, we estimate that this proposed FIB will impact more than 100 users from 20 research groups. For local industry, it will serve as a resource for advanced manufacturing, product prototyping and material characterization. This proposal represents a unique opportunity for training under-represented groups, which comprise 41% of WSU?s enrollment. The PIs will integrate FIB in their on-going projects and FIB in training of students.

Wayne State University (WSU) is an urban research-intensive university whose student body reflects the diversity of the metro Detroit area. The primary goal of this project is to support the broad implementation of Evidence-Based Teaching Methods (EBTMs) across the STEM disciplines on campus, and by doing so, to support student persistence within STEM majors, improve the 6-year graduation rate of STEM undergraduates, and enable graduates to be more effective in the 21st century workplace.

Phase 1 of the project involves a critical self-assessment of current teaching practices on campus including STEM faculty attitudes toward and knowledge of EBTMs. Comparisons of self-reported usage of EBTMs to classroom video observations scored using objective measures of classroom activity take place during this phase. In phase 2, the development and implementation of a series of professional development activities aim at broadening the awareness of EBTMs and assisting faculty with their adoption. Additional survey work will assess the impact of the interventions on attitudes and observational work on classroom pedagogy usage. Phase 3 involves the development of an institutional plan for the broad implementation across the 26 foundational courses identified in 4 primary disciplines (Biology, Chemistry, Math and Physics) with an enrollment of approximately 7000 students per semester. Concurrently during the 3-phase plan, metrics for longitudinal tracking of students through the STEM curricula will be developed to: a) understand better how students interface with the degree programs; b) identify critical points within our majors where specific interventions can be developed to improve student outcomes; and c) determine if appropriate developmental curricula are in place and whether the appropriate guidance is provided to students in a timely fashion to maximize student success.

This is an institutional transformation project. It continues work initiated under a planning grant from an earlier NSF program. The project supports a commitment by this university to increasing substantially the use of evidence-based teaching for foundational STEM courses. With this project, the core STEM Departments and the University's administration plan to fully utilize evidence-based teaching methods in lower division courses and study the impact on student achievement. The implementation of this plan allows a test of impact on a student body that is disproportionately non-traditional (50%) and comprised of many underrepresented minority students (25%). Non-traditional and minority students represent an increasing demographic nationwide and their needs must be addressed in order to meet the goal of increasing the number of STEM degree recipients. Heretofore, evidence-based teaching methods have been studied much more extensively on campuses with traditional student populations. The planning grant supported a self-assessment by STEM faculty instructors of their teaching, aided by peer-mentor-led learning communities and departmental conversations on teaching reforms. It initiated a set of pilot interventions in foundational STEM courses in core STEM departments, using professional development workshops to support faculty engagement with the initiative. A recently completed university-wide strategic planning process pinpointed the importance of adopting evidence-based teaching methods to improve student success. This team is well-positioned to move to scale in developing evidenced-based teaching approaches for its STEM courses, with priority given to the 26 foundational classes.

The program supported by this grant will allow departments to compete for course transformation grants. Successful projects will be provided resources in the form of a pedagogical post-doc and faculty professional development stipends to assist them in reformulating the class from a lecture-based curriculum to one dominated by active-engagement methods. Faculty involved in the concurrent projects will comprise a learning community to discuss issues relating to the implementation of evidence-based teaching and their reflections on student learning. Longitudinal tracking will follow students through to graduation, to assess the impact on academic and career trajectories of the students enrolled in the transformed courses. A large part of the present project pertains to data collection and assessment of project efforts. These data will be documented and shared to ensure that other institutions can learn from this institutional transformation effort. Through this program, students will experience engaged learning, and faculty, post-doctoral fellows, and graduate students will be trained in modern evidence-based teaching methods. These students and fellows will be able to bring their training and experiences to other institutions and serve to build a national pool of experienced teachers using engaging and effective teaching methods.

This project focuses on the acquisition and installation of a next generation Superconducting Quantum Interference Device (SQUID) Magnetometer system at Wayne State University, which enables multi-disciplinary research and education efforts in Detroit and Southeastern Michigan. The SQUID magnetometer measures magnetic properties of samples over a wide range of temperatures and magnetic fields. The capability to measure many sample shapes, e.g. films, crystals, and powders, allows researchers from Physics, Chemistry, Engineering, and Physiology to all engage with the new instrument. Undergraduate and graduate students from these departments are individually trained on the SQUID magnetometer. At least 20 graduate research students use the tool regularly, giving students in Detroit and Southeastern Michigan direct experience with a cutting-edge tool in magnetism research. The new SQUID magnetometer is integrated into an existing Materials and Device Characterization course as well as complements a suite of instruments focused on characterizing advanced materials.

The acquisition and installation of a latest-generation SQUID magnetometer system Wayne State University enables researchers in Detroit, southeast Michigan and beyond to engage in advanced magnetic materials and systems research. This magnetic property measurement system is cryogen-free, can operate in a temperature range between 3 and 1000 K, and apply magnetic fields up to 7 Tesla. Using the vibrating scanning magnetometry option, minute magnetic moments can be sensed. The instrument has additional options such as a horizontal rotator and electrical transport probe to study magnetic anisotropies and magneto-transport properties of various samples. The system supports research projects in the areas of antiferromagnetic spintronics, magnetic refrigeration, and the development of new rare-earth free hard magnets. The acquisition of the SQUID magnetometer also enables new collaborative efforts between researchers combining expertise in antiferromagnetism and van der Waals materials. In particular, the investigators use the SQUID magnetometer to work on systems where magnetic anisotropies and interactions are controlled by twist angles between adjacent layers in two-dimensional materials.

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.