Multi-scale Sensors and Systems

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $330,504
• Sponsor: National Science Foundation

Abstract:

Electrophysiological measurement (e.g. ECG, EEG, EMG) is a well-accepted tool and standard for health monitoring and management. A great variety of electrophysiological measurement devices are widely used including clinical equipment, research products, and consumer electronics. However, until now, it is still challenging to secure long-term stable and accurate signal acquisition, especially in wearable condition, not only for medical monitoring such as Holter but in daily well-being management. Motion-induced artifacts widely exist in the electrophysiological recording process regardless of electrodes (wet, dry, or noncontact). These artifacts are one of the major impediments against the acceptance of wearable devices and capacitive electrodes in clinical diagnosis. Also, the development of wearable devices for disease diagnosis and health monitoring is one of the nation's focal points. This project is to provide new strategies to mitigate motion-induced artifacts in wearable electronics for designing accurate wearable electronics for daily monitoring and disease diagnosis. The PIs will disseminate the research products to both students and the research community. New course materials will be developed for undergraduate and graduate education. Undergraduate and graduate students involved in the research program will obtain diverse knowledge in hardware design and data analytics. For K-12 students, the PIs will provide an integrated research and educational experience through unique programs at Michigan Technological University including Engineering Exploration Day for Girls and the Summer Youth Program (SYP). A research demo and hands-on experience for triboelectric generation in textile materials will be developed and provided to K-12 students.

The research goal of this proposal is to understand the fundamental mechanism of motion artifacts in wearable devices and provide synergistic solutions to mitigating the artifacts. Three approaches are proposed to achieve the goal: 1) understanding generation mechanism of triboelectric charge generation in wearable condition; 2) guided by the understanding, developing tribomaterial-based sensors to manipulate triboelectric charges for triboelectric artifact removal; 3) leveraging new tribomaterial-based sensor data statistical data analytics for true electrophysiological signal estimation. If successful, the synergic knowledge of accurate signal acquisition produced by the project will not only enhance the traditional bioinstrumentation in medical society, but also benefit industrial community of consumer wearable electronics.

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $403,000
• Sponsor: American Heart Association

Specific Aims:

Endovascular catheterization is a common approach in minimally invasive diagnostic and therapeutic procedures. The initial step in these procedures is to use an intravascular guidewire, which is a flexible and torquable wire, to navigate into target blood vessels for angiography or for an intervention. Guiding microwires to 4th or 5th order branches in the mesenteric vasculature or in the neurovasculature for the treatment of acute bleeding, vascular malformation, a fistula or a tumor requires significant experience and advanced skills. The tip of these microwires are manually shaped after careful review of the target anatomy evaluating the size, angle and shape of these branches which maybe <1 mm in diameter. At distances >120 cm, trackability or torquability of these wires are significantly impacted leading to numerous trial and error using multiple types of wires with various shapes at their tips to access arterial branches that may be at acute angles. Such challenging vascular anatomy can lead to prolonged procedure times, excessive ·radiation exposure to the patient and the medical staff, fatigue to the operator, high procedure failure rates and extreme costs. The next generation of catheters should be engineered to provide the operator the ability to bend the tip of the catheter in a controllable fashion for in vivo real-time guidance. Such actuation system could replace the current guidewires provided that it has an optimum stiffness, to maintain the trackability of microactuators and, its deformations are elastic, such that only one catheter is used for the case.

The goal of this proposal is to develop a high precision active catheter with tunable and reversible actuation capability. This technological advancement will be clinically transformative in minimally invasive endovascular interventions by reducing procedure time, increasing procedure success rates, reducing costs, reducing radiation exposure and physician fatigue. Our exciting preliminary data using a composite of carbon nanotubes (CNTs) and polymers as electrochemical actuator produced strong electrochemical capacitance and axial strain by applying low potential. We will build upon these preliminary data by first fabrication and characterization of 30 printed nano-bioactuators with higher electrochemical capacitance and better mechanical properties (Aim 1) and their assembly into bending actuators (Aim 2). Then, we will incorporate bending actuators into clinical microcatheters and perform in vitro testing of the active catheter system in blood vessel models (Aim 3).

Innovation:

The innovation of this research is in the design, prototype fabrication, and in vitro testing of safe and easily controllable nanotechnology-enabled active catheters capable of bending 90 degrees. This system will replace the currently used guidewire-catheter systems. There is no heating, encapsulation, strong electrolyte, or complicated control systems required for this design. We will fabricate and test the electrical, mechanical, and electrochemical properties of the fibers. Then, we will incorporate the actuators with clinically used catheters such as 0.018 inch Terumo glidewires and, subsequently, evaluate the actuation performance. We will fabricate artificial blood vessel models and test the system of catheter and actuator in vitro. We believe that the nanotechnology-enabled microwires will reduce procedure failure rates, cut OR time, reduce radiation exposure and lower costs. This platform technology has the potential to be widely disseminated to other devices such as catheters, stents, biopsy needles and tumor ablation needles.

• Co-Investigator: Julia King
• Co-Investigator: Ravindra Pandey
• Co-Investigator: Trisha Sain
• Co-Investigator: Susanta Ghosh
• College/School: College of Engineering
• Department(s): Physics
• Awarded Amount: $14,999,995
• Sponsor: National Aeronautics and Space Administration

Summary:

The Institute for Ultra-Strong Composites by Computational Design (US-COMP) is focused on the modeling-driven design of a new class of ultra-high-strength-lightweight (UHSL) materials for future manned Mars missions. These materials will meet the required mechanical performance goals set forth by NASA and exceed those exhibited by current state-of-the-art carbon-fiber composites. US-COMP's vision is to serve as a focal point for partnerships between NASA, other agencies, industry, and academia to: (1) enable computationally-driven development of carbon nanotube (CNT)-based UHSL structural materials and (2) expand the resource of highly skilled engineers, scientists and technologists in this emerging field to enhance the U.S. leadership in critical lightweight structural materials. This vision will be achieved through the four principle objectives:

• Establish a new Computationally-driven material design paradigm for rapid material development and deployment
• Develop a novel UHSL structural material for use in deep space exploration. The panel-level tests and demonstration of the novel materials will be carried out to move the developed technology to a technical readiness level (TRL) of 4.
• Develop novel modeling, processing, and testing tools and methods for CNT-based composite materials
• Establish a pool of highly skilled engineers and scientists to contribute to the materials development workforce.

An interdisciplinary and diverse team of researchers from academia, industry, and national labs participate in the project. The computational design of the material is be driven by a modeling effort to integrate topological optimization, atomistic modeling, molecular modeling, mesoscale modeling, and continuum-based computational mechanics. Innovations in materials synthesis and manufacturing techniques ensures the performance and scale-up fabrication of aerospace-quality test samples and panels. Multiscale testing and characterization capabilities established and integrated to validate the modeling and manufacturing efforts and to complete the proof-of-concept cycle. Participation of the industrial partners provides and ensures the scalability and aerospace-grade quality of the developed composite material.

The developed materials and materials development methods will have a major impact on the aerospace community. First, UHSL materials will be developed with the rigorous strength, modulus, and fracture toughness properties necessary for manned Mars missions. Second, a new computationally-driven materials design paradigm will be established to develop the UHSL material of interest and for future rapid materials design and development efforts. Third, a fundamental understanding of load transfer and multiscale failure mechanisms of CNT-based composite materials will be established to achieve their theoretical performance. Fourth, a reproducible engineering performance data from aerospace-quality and scale-up panel test results building upon aerospace-grade resin systems and high-quality commercially available CNT materials to ensure scalability to conduct ASTM standard tests.

Another important emphasis of the institute is in workforce development. Students are trained for developing and utilizing advanced computational and experimental approaches for lightweight materials. Funds are reserved for the students to have extended visits to NASA facilities during summer months for direct mentorship by NASA researchers. These activities strengthen the partnerships between the institute members and NASA. With the help of the HBCU participant (Florida A&M University), the institute will establish a diverse group of both researchers and graduate students.

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $163,648
• Sponsor: University of Michigan

Overview:

Periprosthetic infection is challenging complication that may lead to multiple orthopaedic revision surgeries, increased healthcare spending, long-term disability, and increased mortality. The estimated cost for treating total joint (hip and knee) infections is anticipated to rise to 1.62 billion in 2020. The proposed work is intended to speed implant technology to commercialization that reduced the chronic effects of infection and enhances osseointegration and bone bonding.

In vitro work shows nanotexturing titanium implant materials (TiNT) promotes osteoblast differentiation, and upregulated metabolic markers. In vivo studies confirmed increased bone-implate contact and de novo bone formation, higher pull-out forces, and stronger bone bonding. In vitro evidence shows that a nanostructured surface alone has some antibacterial properties, and adding nanosilver shows a very strong antibacterial property. Technology partially supported by prior MTRAC funding to Michigan Tech, uses a benign ammonium fluoride process in contrast to hazardous hydrofluoric acid used elsewhere.

In vitro studies will be conducted to demonstrate the ability to TiNT surfaces to kill bacteria and inhibit adhesion. Clinical isolates of Methicillin-resistant Staphylococcus aureus (MRSA) from joint aspiration of orthopaedic patients with infected total joint replacements presenting at William Beaumont Hospital (Royal Oak, MI) will be used. TiNT surfaces will be tested including nanotubes with diameters 60 nm, 80 nm. And 150 nm. A group consisting of TiNT embedded with nanosilver will be investigated in vitro, all with up to 48 hour time points and informing in vivo studies.

Rabbits will serve as the model for implantation of an intramedullary tibial nail with four groups. Following implantation, in one tibia a human clinical isolate of MRSA will be introduced to the implant. After inoculation of media+/- MRSA, closures will be performed. Osseointegration will be assessed by longitudinal, clinical-resolution CT scanning at 6 and 12 weeks. Harvested tibiae will be subjected to high-resolution micro-computed tomography.

Nanotube surfaces can improve devise function in the spinal market, which in total size is now equivalent to the joint market. Numerous devices could benefit from the nanotube treatment including fusion devised such as rods, plates, and screws used for thoracic, lumbar, and cervical vertebrae, interbody fusion devices, and artificial disks.

• Co-Investigator: Kazuya Tajiri
• Co-Investigator: Ezequiel Medici
• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $650,998
• Sponsor: 3M

lonomer Development and Characterization:

The objective of this task is focused on characterization of novel ionomers as thin film, bulk and electrodes. The Michigan Tech activity will include ex-situ thin film characterization of water transport and swelling, ex-situ bulk characterization of water permeability and oxygen transport of ionomers and electrodes, water imbibition, permeability and wettability of electrodes, and in-cell characterization to extract electrode transport limitation dependency upon ionomer type and content.

NSTF Electrode Development:

The objective of this task is focused on characterization of dispersed NSTF electrodes developed by 3M. The Michigan Tech activity will include ex-situ characterization of water imbibition, permeability and wettability and evaluation of electrode transport limitations using in-cell and ex-situ techniques.

Electrode Integration:

The objective of this task is to integrate best-in-class ionomers with dispersed NSTF catalysts. Task focuses on ionomer characterization and is similar in scope and includes water imbibition, permeability and wettability of the dispersed NSTF electrodes as well as in-cell characterization of electrode transport limitations and is similar in scope to Ionomer Development and Characterization.

Model Development:

The objective of this task is to develop a pore-network architecture for the cathode catalyst layer in order to understand and predict oxygen transport limitations and liquid water transport within the electrodes with the novel ionomers. This task is focused on adaptation of the current GDL pore-network model to the cathode electrode by incorporating the necessary framework to account for ionomer and electrochemical reactions, links the new electrode pore-network model to a continuum model for the membrane and anode, and integrating capillary pressure and transport models into the pore-network architecture. This task will be continuous to coincide data and knowledge gained through ex-situ and in-cell characterization testing.

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $110,000
• Sponsor: Confidential Industrial Sponsor

Objective:

The overall objective of this study is to obtain the in-situ fuel cell performance and pressure drop data to understand the mechanisms of transient phenomena, to provide the data for modeling validation, and to provide the guideline to design better performance fuel cell stacks.

For this overall objective: two separate goals are defined. The first goal is the fundamental understanding of the relation between cell performance and pressure drop using a single-channel fuel cell, and the second goal is more practical study with a multiple, parallel channel segmented fuel cell. In both cases the operation at low current density with low stoichiometric ratio will be focused, because the water drainage is significantly reduced at such operating conditions.

• Co-Investigator: Jeffrey Allen
• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $176,724
• Sponsor: Chung-Ang University

Project Description:

Quenching, rapid cooling, has been used to improve hardness and reduce crystallinity by preventing low temperature processes of phase transformations. So cooling alloys and steels in an extremely rapid manner produces martensitic microstructure in their surfaces. Conventional quenching methods use oil, polymer, air, and water. In this proposal, intensive quenching using high velocity water flows is proposed to improve heat-extraction rate by increasing 3-5 times greater heat fluxes from the heated surface of metals. This method is highly efficient and ecofriendly because it uses water and provides greater heat-extraction rates resulting in greater temperature gradient in the sample. This temperature gradient forms compressive stresses from the surface that mainly eliminates cracking. So the intensive quenching keeps the residual surface stresses compressive, while the conventional quenching normally produces tensile or neutral residual surface stresses. The main goal of this project is to establish fundamental and practical technology on intensive quenching heat treatment.

Michigan Tech will do survey on intensive heat treatment technologies available and/or practical in the world and also do corresponding analytical studies for Year I. For the second year, Michigan Tech will continue doing market survey and analyzing recent research trends for intensive quenching and traditional heat treatment technologies. For Year III, Michigan Tech will provide future market trends and comprehensive technology analysis on heat treatment.

• Co-Investigator: Julia King
• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $101,143
• Sponsor: Colorado Seminary (University of Devner)

This project encompasses three separate projects that are a part of a NSF I/UCRC that is centered at the University of Denver. The three projects are:

• B3: Physical and Chemical Aging of Carbon/Epoxy Composites
• Cl: Development of Advanced Aluminum Alloys for High Conductivity, Elevated Temperature Strength, and Low Galanic Corrosion
• C2: Thermo-Mechanical-Electrical Properties of Carbon Fiber /Nanoparticle/Epoxy Composites

Project Goal of B3:

This project has three objectives:

1. Develop simple and accurate structure­ property relationships relating exposure conditions and nanoparticle content to expected thermo-mechanical performance;
2. Fabricate, characterize, and test polymer and polymer composite materials exposed to long durations of sub-Tg and elevated temperatures, moisture, UV radiation, and oxidative environments; and
3. Use molecular modeling techniques to provide physical insight into observed behavior.

Project Goal of C1:

Potential aluminum alloys will be identified and examined for their conductivity through Vienna Ab-initio-Simulation Package (VASP) Density Functional Theory (DFT). Precipitation kinetics will be simulated with Prisma using the MOBA13 database. Using VASP DFT calculations and ThermoCalc, a computational survey will be utilized to select promising alloy compositions and heat treatments. Once this computational survey has been performed, select alloys will be fabricated and assessed experimentally for conductivity and hardness amongst other properties.

Project Goal of C2:

This project has two objectives:

1. Develop molecular models to efficiently determine nanoparticle/epoxy combinations that enhance stress & heat transfer and
2. Fabricate and test graphite fiber/nanoparticle/epoxy hybrid composite panels for thermal conductivity, impact & compression strength, and electrical conductivity and shielding

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $266,818
• Sponsor: NASA Langley Research Center

Introduction/Synopsis:

Polymer-matrix nanocomposites have the potential to become one of the primary structural materials used in future aircraft and spacecraft. High specific-stiffness and specific-strength properties of these materials can be established by using the right combination of polymer matrices, nanostructured reinforcement, matrix/reinforcement interfacial conditions, reinforcement weight fraction, and reinforcement orientation.

This large combination of nanostructural/microstructural material parameters renders the experimental development of these materials to be expensive and time consuming if a trial-and-error approach is used. Fortunately, multiscale computational modeling can be used to facilitate material development through the prediction of structure-property relationships that are efficient and accurate.

While a significant effort has been put forth by numerous researchers to predict bulk-level mechanical properties of crystalline materials (e.g. metals, ceramics) and other highly-ordered systems (e.g. carbon nanotubes) based on molecular structure, very little attention has been paid to amorphous polymer systems. However, an equivalent-continuum modeling method has been established to predict the macroscopic Young's modulus of polymers and polymer nanocomposites based on polymer type, reinforcement geometry, and polymer/reinforcement conditions using a simple, efficient, and accurate modeling approach. Recently, this approach was improved by placing it within a thermodynamic framework. As a result, the equivalent-continuum modeling method can now predict bulk mechanical properties, such as strength and Young's modulus, of polymer nanocomposites as a function of molecular structure in a manner that is thermodynamically consistent and accurate.

Objectives:

The overall goal of the research is to use multiscale modeling to establish structure-property relationships for polyimide nanocomposites. Molecular- and rnicrostructural characteristics of these materials will be related to tl1e predicted mechanical properties. Specifically, the following nanocomposite materials systems will be studied:

• Polymer matrix materials
  • ULTEM
  • LaRC-8515
• Reinforcement materials
  • SWNTs
  • Graphene oxide sheets

The structure-property relationships will relate the following structures and mechanical properties:

• • Molecular- and micro-structural parameters
  • Polymer matrix material type
  • Reinforcement material type
  • Matrix/reinforcement interface conditions
  • Reinforcement weight fraction
  • Reinforcement orientation
  • Reinforcement size
• Bulk-level mechanical properties
  • Young's modulus
  • Strength (onset of microvoid formation)

The overall objective of establishing the structure-property relationships will be achieved with the following series of tasks:

• Task 1: Establish a series of equilibrated molecular structures for different combinations of matrix and polymer materials and a range of interfacial conditions using MD-based techniques
• Task 2: Predict the molecular-level Young's modulus and the onset of mechanical failure for these materials systems using MD-based techniques
• Task 3: Construct a series of micromechanical models that incorporate the results of Task 2 and predicts the bulk-level stiffness and strength for a range of reinforcement weight fractions, orientations (randomly dispersed, aligned), and size (length, diameter)

• Co-Investigator: Yoke Khin Yap
• Co-Investigator: Stephen Hackney
• Co-Investigator: Claudio Mazzoleni
• College/School: College of Engineering
• Department(s): Physics
• Awarded Amount: $1,736,592
• Sponsor: National Science Foundation

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $109,378
• Sponsor: Pacific Northwest National Laboratory

Scope of Work:

The Environmental Molecular Sciences Laboratory (EMSL), a national US Department of Energy (DOE) User Facility located at the Pacific Northwest National Laboratory (PNNL), requires services to work in collaboration with EMSL staff for the deployment of in-situ TEM and correlative microscopy of biological systems in support of the BER Mesoscale Pilot Project.

The second year of this study will take place from October 1, 2015–September 30, 2016 with potential extension into FY2017. MTU will provide expertise and labor for operating electron and optical based imaging platforms at EMSL, collecting and analyzing data, maintaining scientific records and presenting and publishing research results.

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $445,658
• Sponsor: National Science Foundation

Overview:

Nano-sized transition metal oxides (TMO) are promising materials for lithium-ion batteries. These materials operate through conversion reactions and are associated with much higher energy densities than intercalation reactions. Extensive research is ongoing on the electrochemical characterization of TMO-based electrodes; however, many fundamental questions remained to be addressed. For instance, TMOs exhibit a mysterious extra capacity beyond their theoretical capacity through mechanisms that are still poorly understood. In addition, nano-sized TMOs are highly vulnerable to structural defects produced during synthesis that can alter lithium ion pathways by perturbing the local electronic and lattice strains. No experimental work has been reported to reveal the underlying mechanisms that can correlate structural defects to the electrochemical lithiation in TMOs owing to the difficulty in characterizing structure at the nanoscale, particularly at buried interfaces. This research aims to fill this gap.

The objective is to understand the underlying atomistic mechanisms by which structural defects such as hetrointerfaces, heteroatoms, dislocations, twining, and grain boundaries affect the lithiation behavior of TMOs. In order to meet this objective, single TMO nanowires (NWs) will be subjected to in situ electrochemical lithiation inside high-resolution transmission electron microscope (HRTEM) and aberration-corrected scanning transmission electron microscope (CsSTEM). The in situ electrochemical lithiation will be conducted using state-of-the art scanning tunneling microscope (STM-TEM) and conductive atomic force microscope (cAFM-TEM) holders. This unique combination enables the study of evolution of local lattice strains and electronic perturbations at the vicinity of defects with unprecedented spatial resolutions better than 0.7 A and chemical sensitivity down to 0.35eV.

Intellectual Merit:

The in situ studies will enable research in three poorly understood fields: (I) the effect of structural defects (twins, dislocations, grain boundaries, and hetrointerfaces) on the nucleation of Li₂0 and TM particles due to conversion reactions in TMOs; (II) the pinning/unpinning effect of impurities or dopants during grain boundary movement associated with the nucleation of Li₂0 and TM phases; and (III) the evolution of localized strain and electronic structure at the vicinity of structural defects and their effect on Li-ion pathways The new understanding can facilitate the design of structurally-tailored TMOs for Li-ion battery applications. Furthermore, the experimental methodology and protocols to analyze the in situ data can be extended to other nanomaterials to enable high performance batteries.

• Co-Investigator: Yoke Khin Yap
• College/School: College of Engineering
• Department(s): Physics
• Awarded Amount: $327,763
• Sponsor: National Science Foundation

Abstract:

The research aims to understand the mechanisms by which (1) doping elements and chemistry defects; and (2) structural properties of nanowires (length, diameter, shape, and orientation) affect the piezoelectric-driven electrical output in semiconductor nanowires for energy harvesting systems. This understanding will shed light and provide solid experimental evidence on one of the most important on-going research debates related to the ability to obtain electrical output from semiconducting-piezoelectric nanowires. Currently, the underlying nanoscale mechanisms by which doping elements, defects, and structure affect the piezoelectric-driven electrical output in nanowires are unknown. The electro-mechanical coupling of ZnO nanotubes will be studied by straining the nanotubes specimens using a first of its kind in-situ force and electrical measurement system (AFM/STM) inside the transmission electron microscope {TEM) where the microstructure of ZnO nanowires can be simultaneously imaged in high resolution. The proposed research provides a unique opportunity to advance scientific knowledge on the mechanisms of mechanical energy harvesting in nanowires, and the ability to clear up existing uncertainties in the field.

Intellectual Merit:

The in-situ electrical-mechanical probing of ZnO nanowires inside the TEM will enable research in two unexplored areas: (i) the role of doping elements and defect chemistry; and (ii) the role of structural properties of nanowires (diameter, length, shape, orientation) on the piezoelectric-driven electrical output, for which data is not yet available in the literature. The new understanding on the coupling phenomenon is not limited to ZnO nanotubes, and will pave the roadmap for experimental studies on other semiconductorpiezoelectric nanowires (for instance ZnS, GaN, BaTiQ,, AIN). The PI has several years of research experience in the area of electron microscopy of materials, and the Co-PI is a well-established researcher in the area of nanomaterials synthesis and in particular ZnO nanowires.

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $252,555
• Sponsor: US Department of Defense, Air Force Office of Scientific Research

• Co-Investigator: Julia King
• Co-Investigator: Warren Perger
• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $354,693
• Sponsor: National Aeronautics and Space Administration

Polymer composite materials have become a staple in the design, development, and manufacturing of commercial, military, and research aircraft. Because of their relatively high mechanical properties {per unit mass) they are used as the main structural components in fuselages and control surfaces in many subsonic fixed-wing aircraft. In order to continue to make improvements in aircraft safety, efficiency, and comfort; composites with increased functionality must be developed. Traditionally, a time-consuming trial-and-error approach has been employed 'with the development of polymer composite materials until an acceptable material that meets the design requirements has been found. The development process is further complicated 'with the inclusion of nanoparticles into traditional composite materials {either as a matrix-doping agent or as the primary reinforcement). Because of the small size of nano-reinforcements, the physical basis for observed material behavior cannot always be ascertained through experimental means. Multiscale modeling approaches, which have gained considerable interest in the last decade, can be used to facilitate traditional research by removing these barriers. Thus, coupling multiscale modeling and experiments can increase the rate of materials development and provide physical insight into observed material behavior.

The objective of this research is to develop a multiscale modeling approach to predict the mechanical and acoustic absorption properties of nanocomposite materials as a function of material structure. The model will be validated using experimental tests on the modeled material. The modeled material will be a hybrid composite composed of graphene nanoplatelets, traditional carbon fibers, and a Polyetherimide polymer (ULTEM). The graphene nanoplatelets will be dispersed into the ULTEM polymer to form a nanocomposite material. This nanocomposite will be used as the matrix component of a traditional 'woven fabric composite with curb on fiber. Because graphene has been shown to exhibit sound-absorbing capabilities and improved mechanical properties when used in composite materials, it is anticipated that the hybrid composite will have good overall mechanical and acoustic damping properties. This material could potentially be used in aircraft structures, included the fuselage, for mechanical durability and reduced cabin noise.

The research is broken up into three specific tasks. For the first task, a multiscale modeling technique will be established to predict the bulk-level 1nechanical and acoustic absorption properties of carbon fiber/graphene/ULTEM composites. This modeling strategy will incorporate molecular dynamics simulation, micromechanics analysis, and the Fiber Undulation Model to relate molecular structure to bulk-level properties of the composite. For the second task, composite test specimens will be fabricated and tested to determine the elastic and acoustic absorption properties of the material. This data will be used to validate the modeling strategy. The third task will focus on the development of simple structure-property relationships using the validated modeling approach. The resulting structure-property maps will serve as design guides materials researchers and engineers involved in materials selection.

As a result of this study, an efficient and accurate multiscale modeling approach will be developed 'which can be easily adapted by other researchers to continue the development of materials used for aerospace structures. Also, the model \Viii be experimentally validated and used to establish structure-property relationships for a hybrid carbon fiber/graphene/UL TEM composite which have the potential to improve mechanical properties and noise-reduction capabilities for aerospace structures.

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $637,495
• Sponsor: National Science Foundation

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $305,781
• Sponsor: National Science Foundation

Abstract:

For shear driven flows, a comparison of the traditional boiler and condenser operations with those of the proposed innovative boiler and condenser operations. The innovative devices are introduced for functionality and high heat capability for shear dominated situations that arise in milli-meter scale operations, certain gravity insensitive operations (on aircrafts), and zero-gravity operations. These devices therefore facilitate the development of thermal management applications which employ boilers and condensers under these conditions. The operational methodologies that exploit ways to significantly enhance heat-flux (e.g. > 1 kW/cm2) within the context of the proposed operations are also presented. These benefits are realized at acceptably low mass-fluxes, pressure drops, and inlet temperatures close to saturation temperatures (i.e. without subcooling requirements).

The experimental realizations for innovative devices are reported for flows within horizontal channels. Results for these flows of FC-72 vapor in a horizontal rectangular cross-section duct (2 or 6 mm gap and 15 mm width) of 1 m length. The experiments demonstrate the ability to restrict the boiling and condensing flows to annular flows where a thin film flows (< 0.5 mm) over the entire heat exchange surface of the device.

Introduction and utilization of controlled pulsations (in 5-20 Hz range) in the mass flow rate show an ability to maintain thin film flows with significant additional enhancements ( >300 %) in heat-transfer rates over those obtained in the absence of controlled pulsations. The reported enhancements are associated with asymmetric reduction in the time averaged mean film thickness (associated with high heat-flux values) appears to be related to the larger "dwell" time (relative to the characteristic time period of the pulsation) of wave-troughs when the instantaneous film thicknesses (at the wave troughs) become less than tens of micro-meters. The demands of this "dwelling/sticking" nature of micro-scale flows on top of a wetting heat-exchange surface are believed to be met by interactions with (and destabilization of) the adjacent solid-like adsorbed layer (whose thickness may be <200 nm) on the heat-exchange surface. The presence of adsorbed layer under these conditions (three phases being close to one another) allows for the presence of phenomena that govern film dynamics – e.g. a range of positive to negative disjoining pressures and the ability to withstand shear stresses. In nucleate pool boiling, similar phenomena (very high heat-flux values) under similar conditions are known to be present at the contact line of growing and departing bubbles.

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $356,601
• Sponsor: National Science Foundation

Abstract:

Advancement in electronic-cooling, avionics-cooling, and spaced based operations have posed enormous engineering challenges of low heat removal rates, high pressure drops, and device-and-system level instabilities. The need, to meet these challenges, is innovations for the critically needed shear dominated boiler and condenser operations. This is to allow efficient removal of large amounts of heat. Even large industrial-scale gravity-driven boiler operations need to be innovated for the next generation combined cycle (or related) electric power plant technologies &ndash; towards producing electricity in more efficient and sustainable ways. These innovations need a combined breakthrough in boiler and air-side flow technologies - to meet global energy challenges.

To meet the challenges, on-going research on enabling breakthroughs. These are based on fundamental fluid-physics based experimental discoveries for boiler and condenser operations. For developing scientific knowledge and engineering design tools, these discoveries are also supported by breakthroughs in associated modeling and simulations research.

A key innovative operation procedure introduces passive recirculating vapor flows within the devices. This controls the flows and ensures that very stable boiling and condensing flows occur in a manner where a thin liquid film flow, typically within 0.5 mm thickness, covers the entire heat-exchange surface. A second innovation is introduction of large amplitude waves through controlled resonant pulsations in the liquid film - leading to a 200-1000% enhancement of the heat removal rates. Analysis suggests the underlying physics. As the troughs of the waves on the liquid film approach the wetting heat-exchange surface to within 30-50 &mu;m, the specific location starts exhibiting solid-liquid-vapor interactions phenomena similar to the high heat-flux contact line locations associated with nucleate boiling or drop-wise condensation. Retaining this physics and changing the working fluid to water, ongoing research plans to demonstrate very high heat removal (&gt; 1 kW/cm2) values over the entire length of the innovative devices.

• Co-Investigator: Gregory Odegard
• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $371,802
• Sponsor: National Science Foundation

Abstract:

Cellulose nanocrystals (CNCs) are highly crystalline organic polymers that can be extracted from natural materials. They are stiffer than aluminum and theoretical calculations place their tensile strength at 7500 MPa, higher than glass fibers or steel. Considering that these crystals are biocompatible, lightweight, low cost, and sustainable they offer tremendous potential for applications in biomedical materials, energy technologies, electronics, and microelectromechanical systems (MEMS) devices. However, this potential has not yet been fully realized, primarily because little is known about the parameters that affect the CNC's mechanical properties including: (i) variations between different natural resources of cellulose (e.g. bacteria, plants, and agricultural products), (ii) the size-scale effect, and (iii) crystallographic anisotropy. To date, no experimental tests have been utilized to measure the strength properties of CNCs. In order to evaluate such properties the underlying mechanisms responsible for nanoscale mechanics should be determined. In-situ experiments and multiscale models for deformations in small-scale components could open possibilities for improved design and applications of CNCs. This research aims to fill that gap.

The objectives of this research are (i) to explore the nanoscale mechanics of individual CNCs as a function of the cellulose resource; (ii) to determine the dependency of CNC's mechanical properties to cellulose dimensions; and (iii) to fully characterize the elastic modulus of CNCs as function of their crystallographic orientations. To meet these objectives, nanomechanical properties will be investigated through the use of a novel in-situ characterization technique that enables atomic force microscopy (AFM) experiments inside the chamber of a transmission electron microscope. The in-situ data will then be used to develop and validate the continuum mechanics and molecular dynamics models of CNCs.

These in-situ studies will enable research in two relatively unexplored fields: (i) the effect of cellulose resources on the strength properties of individual CNCs will be directly measured, and (ii) the strength properties of individual CNCs as a function of length-scales, load-modes, and crystallographic orientations. These areas have not been accounted in the literature, but clearly have a large effect on the mechanical properties. The use of AFM allows for the unprecedented material characterization of individual CNCs as compared to other methods that can characterize only aggregate properties.

CNC-based materials are expected to have great impacts on the biomedical field (e.g. as bone scaffolds, hip and cartilage replacements), automotive components (e.g. interior and, potentially, exterior components), and high performance textiles and nonwovens.

• Co-Investigator: Craig Friedrich
• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $252,216
• Sponsor: National Science Foundation

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $640,412
• Sponsor: National Science Foundation

Overview:

Mobility is a key factor to well-being, both emotionally (through increased independence and decreased depression and anxiety) and physically {through reduced disease risk, bone maintenance, muscle strength, and weight control). Over a million US citizens are limb amputees, primarily lower leg amputees. This program will 1) work to improve the mobility of lower extremity amputees through research in design and control of powered ankle-foot prostheses, which mimic the steering mechanism of human gait by having two controllable degrees of freedom (DOF) and 2) integrate research with education and outreach to inspire and equip a diverse next generation of engineers. To work toward these long-term goals, this program will develop &ndash; and use in education and outreach - a lightweight, cable-driven, powered ankle-foot prosthesis capable of steering and traversing slopes by learning from human ankle impedance in the sagittal and frontal planes during gait.

This research is based on the hypothesis that an ankle-foot prosthesis capable of applying torques and impedance modulation in both the sagittal and frontal planes, similar to the human ankle, will improve maneuverability and increase mobility by lowering the metabolic cost of gait - both when walking straight and turning. Advances in powered prostheses have shown the ability to reduce metabolic cost and increase the preferred speed of gait for unilateral transtibial amputees during straight walking by providing sufficient power during push-off. Powered prostheses can also reduce asymmetrical gait patterns and thus may lower risk of secondary complications. However, studies show that turning steps account for 8-50% of steps, depending on activity, and thus may account for 25% of daily steps. Modulation of ankle impedance in the sagittal and frontal planes plays a major role in controlling lateral and propulsive ground reaction forces. While a non-amputee relies on hip movement in the coronal plane and the moment generated in the ankle joint, an amputee using a passive prosthesis uses the hip extension in the sagittal plane as a gait strategy. The hypothesis is supported by preliminary results which show a large inversion of the ankle during the stance period of step turns, indicating a significant deviation of ankle rotations from the straight-step pattern.

Understanding the role of the ankle in locomotion and developing a platform for design and control of new ankle-foot prostheses will allow exploratory research and education. Research includes: Thrust 1: Estimate ankle impedance in the sagittal and frontal planes during the stance period of gait; Thrust 2: Develop a powered ankle-foot prosthesis with two controllable DOF; Thrust 3: Evaluate the design and control of the prosthesis using an evaluation platform and with below-knee amputees through collaboration with Mayo Clinic; and Thrust 4: Education/Outreach: Utilize the steerable ankle-foot prosthesis for education, outreach, and research experiences to impact diverse K-12, community college, undergraduate, and graduate students.

The work is significant in that it will contribute 1) new knowledge about multivariable impedance modulation of the human ankle during the stance period of gait, an area not yet fully explored, and 2) a unique framework for developing and evaluating powered ankle-foot prostheses. The steerable ankle-foot prosthesis is innovative because it will enable amputees to walk with a more natural gait by using the ankle joint, rather than merely the hip and knee. Development of this novel platform will be a substantial step toward the long-term goal of improving design and maneuverability in lower extremity assistive prostheses and robots.

Robotics is a high-impact way to attract the attention of future engineers. Outreach activities are included to that spark and sustain STEM interest in pre-college students, especially underrepresented minorities. Development of an inexpensive powered ankle-foot prosthesis will improve well-being of Wounded Warriors and civilian amputees, while at the same time inspiring and training the future STEM workforce. In addition, a newly developed a low-cost EMG-controlled manipulator will be included as an educational platform that will be used in outreach programs to teach fundamentals of mechatronics, robotics, and biomechanics to K-12, community college, undergraduate, and graduate students.

• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $554,593
• Sponsor: National Science Foundation

Abstract:

Overview: Apoferritin is an organic cage that captures the toxic free ferrous ions and transforms them into a ferrihydrite and iron oxide crystalline nanoparticle through a complex biomineralization process (the resulting structural protein is called ferritin). Any dysfunction of ferritin protein can result in iron toxicity, serious illness, chronic diseases, and especially neurological diseases. Dysfunction in ferritin results in the alterations in the biomineralization of the ferritin cores, and therefore, understanding the process of biomineralization within ferritin, is of great importance in the study of neurodegeneration and other chronic diseases. While these unique proteins have been the subject of intense research in biology and chemistry fields due to their importance in many chronic diseases, little effort has been made to unveil the dynamics of such biomineralization processes in liquid conditions. To the Pl's knowledge, there has been no direct evidence at atomic level on how the biomineralization or demineralization inside a ferritin protein progresses over time. This research aims to fill this gap.

The objective of this project is to investigate the in situ crystallization of ferrous ions into crystalline ferrihydrite and iron oxide nanoparticles as well as the demineralization of crystalline core in healthy and dysfunction ferritins in unprecedented resolutions within liquids. In-situ studies conducted inside an atomic resolution aberration-corrected scanning transmission electron microscope (STEM) enabling imaging at resolutions better than 1A. A miniaturized graphene-based electron transparent bio/nano reactor compatible with the microscope chamber is utilized to preserve the liquid environment inside the electron microscope. In this graphene bio/nano reactor, ferrous ions delivered to apoferritins through break down of liposomes acting as reservoirs of irons to trigger the biomineralization within apoferritins cores.

The research is the first atomic resolution study of protein-mediated biomineralization and demineralization within a liquid media and inside a transmission electron microscope. This CAREER research unfolds: (I) The nucleation and growth mechanisms of mineral core (ferrihydrite and iron oxide crystals), (II) the existence and evolution of atomic defects (vacancy, twinning, misorientation boundaries, amorphous regions, etc) during the crystallization, (Ill) the evolution of chemical gradient from surface to core of crystals during the biomineralization, (IV) the mechanisms of demineralization due to iron release, and (V) The atomic-scale morphological and structural differences between a healthy and dysfunctional ferritins.

This research probes the ground rules for ferritin biomineralization with the goal to unveil the fundamental differences with dysfunctional ferritins responsible for neurological diseases. In addition, a new research field for the utilization of bio/nano reactors to image complex biochemical reactions at atomic resolutions will be developed. The CAREER plan will impact the society by integrating multi-disciplinary research with education at all levels while promoting diversity. Graduate and undergraduate students involved with the project will be trained in cross-cutting areas.

• Co-Investigator: Chang Choi
• College/School: College of Engineering
• Department(s): Mechanical and Aerospace Engineering
• Awarded Amount: $526,784
• Sponsor: National Aeronautics and Space Administration

The research is focused on two of the three key microgravity challenges;

(i) Evaporation and condensation processes and (ii) Efficient use of detailed models to simulate cryogenic propellant behavior.

The research objectives are:

1. Develop a standard method for measuring accommodation coefficients for evaporating hydrogenated cryogenic propellants using neutron imaging. The experiments addressing this objective will utilize the NIST Neutron Imaging Facility (Gaithersburg, MD). The accommodation coefficients for liquid hydrogen and liquid methane will be obtained in both a pure vapor environment and a two-component (vapor and gaseous helium) environment.
2. Develop a numerical simulation of liquid films of hydrogen and methane using a modified version of an evolution equation that couples the vapor phase to the liquid film via a kinetic model for evaporation and condensation.

The research addresses the solicitation goal of supporting future space science and exploration needs of NASA by providing fundamental knowledge on evaporation and condensation of cryogenic propellants. Long-duration, microgravity storage and transfer of cryogenic propellants are mission critical technology. A variety of passive and active technologies have been used to control boil-off, but the current state of understanding of cryogenic evaporation/condensation in microgravity is insufficient and at TRL-1. The proposed effort would increase the state of understanding to TRL-3 through the development of a novel experiment utilizing the Neutron Imaging Facility located at NIST.

The experiments and accompanying modeling will enable determination of the accommodation coefficients necessary for the development of zero boil-off technologies and methodologies. Currently, there are no experimental methods for determining accommodation coefficients for cryogenic propellants. The proposed experiments will enable determination of these coefficients and could become a standard method for measuring accommodation coefficients of hydrogenated cryogenic propellants.

In addition, simulations of evaporation and condensation from liquid films will provide data to address the uncertainty in how kinetic expressions of phase change should be modified in the presence of two-component mixtures in the tank ul1age. The thin film simulations directly address the need for a simplified model to predict instantaneous thermodynamic conditions of cryogenic liquid films in the propellant tank ullage.

The outcomes will be a new standard method for obtaining fundamental data for hydrogenated cryogenic propellants, a more thorough understanding of underlying physics of cryogenic evaporation and condensation, and a foundation for establishing the minimum size of system-level technology demonstrations.