Project descriptions - Summer 2014
Listed below are the project descriptions for the summer 2014 NURF program. To apply:
1) Review the project descriptions (below) and select a project of interest. There are nearly 30 projects to choose from! (Click on research images for larger view.)
Faculty mentors will follow-up with applicants as needed. Fellowship recipients will be notified by NDnano starting the first week of March.
Please note: Students are welcome to apply for more than one project. However, please list and prioritize on your application all the projects to which you have applied. Undergraduate* students from any college or university are welcome to apply.
*For purposes of the NURF program, undergraduates are students who will not yet have completed their undergraduate studies at the start of their summer fellowship.
Thank you for your interest in NDnano!
Project: Nanosensors for micro-RNA profiling: Designing medical devices for personalized medicine
We are designing nanooptical sensors to allow enumeration of single molecules for a large numer of target molecules. One particular application is profiling (quantification) of a panel of regulatory miRNAs for cancer and chronic disease screening. The main technical challenges for such nanosensors are to amplify the optical signals significantly, so that quantification resolution is down to a single molecule, with simple LED light sources and miniature cameras. Such sensitivity enhancement is provided by nanostructures with conic geometries. Conic nanopipettes fabricated with laser-assisted drawing amplifies electric fields by 5 orders of magnitude to assemble a small number of nanoparticles for plasmonic amplification. Optical fiber bundles are wet-etched into nanocone arrays, with each 10-nm cone tip having greatly enhanced scattering and surface energy to attract binding nanoparticles and target molecules. We also design conformation-switching hairpin FRET oligo-probes for the nanoparticles so the entire molecular assay is label free. Such low-cost nanofabrication technologies are integrated to manufacture a medical platform for miRNA profiling that can soon be used in clinics and, at a later stage, at home for personalized disease screening.
Project: Non-Boolean computing using nanodevices
Digital computers are excellent for crunching numbers, but they are not very efficient for many other tasks, such as image recognition and analyzing 'big data'. It is believed that analog, non-Boolean devices could do much better. Our group explores new, 'wave-based' computing paradigms that process information without using logic gates. We design and simulate circuits that are based on novel nano-devices such as spin-torque oscillators, spin-wave devices, analog circuits, and microelectromechanical systems. These devices generate wave-excitations, and the interference of the waves gives the result of the computation. If you join our group for the summer, you may either work on spin-wave devices (such as the one in the figure – this device does a Fourier transform using spin-wave interference) or on the simulation of oscillator-based computing circuits. In either case, you will design non-Boolean computing algorithms based on these devices. This project is suited for all undergraduate levels.
Project: High-speed transistor characterization
GaN-based devices are emerging not only for power applications but also for high-speed, high-performance applications. In this project, aggressively scaled GaN-based devices will be characterized (DC, CV, RF/millimeter-wave) and models developed to describe the observed performance. Physical insights into the internal operation of the devices (e.g., dispersive phenomena) are of particular interest, and the use of the characterization to more fully understand these effects will be a key focus of the project. In addition, equivalent circuit models suitable for circuit design will be extracted and implemented in CAD software. Work will include on-wafer testing of devices (DC measurements, low- and high-frequency CV, and on-wafer RF-millimeterwave (10 MHz-220 GHz) network analysis).
Project: Design and characterization of ultrafast chip-to-chip interconnects
The push to higher and higher frequencies of operation and bandwidth for electronic and optoelectronic systems for communications and sensing places extreme demands on the performance of chip-to-chip interconnects. In this project, high-performance chip-to-chip electrical interconnects for operation at frequencies of over 100 GHz will be designed and characterized. Simulation of the electromagnetic performance of the designed structures, layout and fabrication of test interconnects, and experimental characterization of the achieved performance are included in the project. Development of equivalent circuit models for the interconnects (for inclusion in circuit and system-level designs) will also be performed. The work could potentially include computer simulations, cleanroom fabrication processing, and high-speed electrical testing (at frequencies up to 220 GHz).
Project: DNA origami
Take the genome of m13mp18, a small virus. Add 226 short synthetic strands of DNA, the “staple” strands, and it folds into a flat rectangle as shown in the picture. This is an example of the DNA origami technique. We are looking for a student to explore surface binding interactions of these DNA nanostructures with a range of substrates. In previous studies, we have used mica, silicon, gallium nitride, and even graphene as substrates to bind DNA origami. This summer, we hope to complete a study on the kinetics of surface binding and detachment on chemically modified silicon, and to explore binding interactions with other materials. If you choose to do this project, you will learn how to use and interpret atomic force microscopy and X-ray photoelectron spectroscopy for surface characterization. A student who is very detail oriented, has steady hands, is comfortable with instrumentation, and has taken at least one semester of organic chemistry will be well qualified for this project.
A few lead references:
Project: Synthesis of nanocatalysts
Heterogeneous catalysis is performed on the surface of particles of metal or oxide or composited metal and oxide at the nanoscale. Size is critical as coordination of the environment and electronic structure of atoms on the surface of nanoparticles with different size depends on the size and shape of the catalyst particles. One specific type of nanoparticle catalyst is alloy nanocatalyst. The second metal typically modifies the electronic state of the atoms of the first metal and, therefore, their catalytic performances. In this project, we focus on new synthesis, which can produce new bimetallic nanocatalysts with controllable size and shape. We also measure their catalytic performance (conversion rate and selectivity), therefore building a correlation of structural factors at the nanoscale with catalytic behavior. This correlation is critical for design of new catalysts. More information can be found at http://www.franklin-tao.com/.
Project: Structural evolution of bimetallic nanocluster catalysts at atomic scale
Catalysis is important for energy conversion and chemical transformation. A single event of catalysis is performed on sites of a catalyst surface. A catalytic site typically consists of one or several atoms of the catalyst surface. Formation of a bimetallic surface of a catalyst by alloying the host metal with a guest metal can tune catalytic performance. Under a catalytic condition, atomic arrangement and coordination of the host metal atoms could be largely different from that under an ex situ condition. Thus, an in situ visualization of a catalyst surface at atomic or nanoscale is necessary for building a correlation between the catalyst structure and its catalytic performance toward fundamental understanding of catalysis at atomic and molecular level. A unique in situ ambient-pressure high-temperature scanning tunneling microscope is available in Dr. Tao's group for exploration of structural evolution of bimetallic catalyst under reaction conditions and during catalysis of chemical transformation and energy conversion.
Project: Quantum dot solar cell
In recent years, nanomaterials have emerged as the new building blocks to construct light energy harvesting assemblies. [1,2] Efforts are being made to design organic and inorganic hybrid structures that exhibit improved selectivity and efficiency towards light energy conversion. This project will evaluate the performance of solid state quantum dot solar cells. The summer research involves synthesis of semiconductor quantum dots, assembling them in a solar cell, and evaluation of their photovoltaic properties. Quantum dots (CdSe, Sb2S3, CIS, etc.) are deposited on mesoscopic TiO2 or ZnO film serve as the photoanode. A hole scavenger such as CuSCN, PEDOT, or 2,2´,7,7´-tetrakis-(N,Ndi-p-methoxyphenylamine) 9,9´-spirobifluorene (spiro-OMeTAD) is then deposited onto these photoactive films. A thin layer of metal (e.g., Au or Ag) is deposited on top of the hole transport layer to make the electrical contact. Upon photoexcitation of the semiconductor QDs, the electrons are driven towards the oxide layer and the holes are driven towards the metal contact and thus generate photocurrent. The overall goal is to extend the photorespone into the infrared and overcome the electron recombination at the grain boundaries.
Project: Graphene-based assemblies for the detection and photocatalytic degradation of contaminants
Recent advances in the construction and characterization of graphene-semiconductor/metal nanoparticle composites in our laboratory has allowed us to develop multi-functional materials for energy conversion and storage. These next-generation composite systems may possess the capability to integrate conversion and storage of solar energy, detection and selective destruction of trace environmental contaminants, or achieve single-substrate, multi-step heterogeneous catalysis. This research project will involve synthesis of graphene based assemblies for photocatalytic and photovoltaic conversion of light energy. The graphene oxide-semiconductor assemblies will be characterized by transmission electron microscopy and the excited state processes will be evaluated using time-resolved emission and absorption techniques. The goal is to optimize the performance of graphene based assembly and maximize the photoconversion efficiency.
Project: Nanostructures for ultrasensitive spectro-eletrochemical analysis
The unique properties of nanostructures suggest new routes to ultrasensitive detection and control of chemical reactions involving oxidation and reduction of target molecules. This project seeks to develop a microfluidic device incorporating metallic nanostructures that can push the limits of detection to levels appropriate for trace analysis in biomedical applications. Incorporating metallic wires with nanostructures into a microfluidic platform provides sensors capable to providing chemical identification via spectroscopic methods while simultaneously monitoring the concentration of analyte electrochemically. The design and construction of components are needed to enable this approach to chemical sensing. This project is appropriate for students interested in chemical instrumentation, spectroscopy, and electrochemistry.
Project: On-chip lasers
CPU speeds are currently limited by their power density, and multicore processors need supremely fast buses to each other and to memory. Both of these could be solved by using optical interconnects. But Si doesn't emit light, so we can't make lasers with silicon. On the other hand, germanium is already used in CPUs, and strained Ge will emit light. In this project, the student will implement a straightforward technique for creating tensile strain in Ge films to study the maximum strain available using the stress liner technique and identify future improvements. The optical properties of the strained films will be measured using photoluminescence (PL) and other techniques. The student will be expected to produce research suitable for publication, with assistance from Prof. Wistey and other members of the research group.
Project: Direct bandgap dilute carbides
Molecular beam epitaxy (MBE) can grow new semiconductors that would be impossible under normal thermodynamic limits. It has been shown theoretically that adding dilute amounts of carbon to Ge films can dramatically alter the band structure of the Ge semiconductor, creating a direct bandgap. This could allow efficient lasers and optical transceivers to be grown directly on conventional Si CMOS chips. It may also improve the efficiency of inexpensive Si/Ge solar cells. This project focuses on altering the band structure of Ge using dilute carbide alloys. Students on this project will assist in the fabrication of Ge devices, analyze alloys grown by MBE, and perform optical testing to evaluate the effectiveness of each technique. They will gain a broad knowledge of optoelectronic principles, including the physics of band structure modification, materials science in epitaxial growth, and electrical engineering device design and fabrication. Opportunities for followup research will continue through the following semester and/or school
Project: Plasma jets for nanomaterials synthesis
Plasma jets are an emerging technology that have a wide variety of applications—from killing tumors and healing wounds to cleaning tumors and synthesizing new nanomaterials. This project targets using plasma jets for plasma electrochemistry to synthesize nanoparticles, focusing on how to control the interaction between the plasma jet and a liquid. A NURF student will conduct experiments that look at novel plasma configurations for plasma/liquid interactions and use simple simulations to predict the interaction thermodynamics. The student will work with a team of graduate students studying plasma science, but will have the opportunity to work independently and use their own creativity and imagination. Those who intend to continue the research for credit in the fall semester and have a high interest in going to graduate school will be given preference.
Project: Ultra-low energy computation
Anyone who owns a laptop knows that power dissipation and the associated heat are a problem for the microelectronics industry. As electronic devices scale down in size, they use less power (and hence energy), but is there a lower limit to the energy that must be dissipated by each device? Recent experimental measurements have demonstrated our ability to measure energy dissipation in the range of a ~15 yJ (1 yJ is 10-24 J), and we are building CMOS circuits to operate in this range. Projects in the group of Prof. Gregory Snider will explore the limits of ultra-low power computing, and designing, building and measuring circuits that test these limits, and clock circuits that can recycle the energy used in computation. The projects will include building circuits and amplifiers for energy measurements of the CMOS circuits as well as the actual measurements. A student involved in these projects will gain experience in programming, CMOS design, and device measurement techniques.
Project: Design and evaluation of CNN-based circuits using beyond-CMOS devices
A Cellular Neural Network (CNN) architecture is comprised of cells that are locally connected to just near neighbor cells. The dynamic behavior of this network is governed by a set of non-linear, differential equations. CNN architectures can outperform Boolean equivalents for a variety of important information processing tasks (e.g., in the realm of image processing). However, realizing CNN architectures in hardware is still a challenge for many important image processing applications. Novel beyond-CMOS devices, such as TFET and SymFET, being investigated at the SRC's LEAST Center at Notre Dame, may offer new opportunities to implement CNN architectures. We are looking for students who are interested in the circuit and architecture aspects for novel devices to participate in a project that develops numerical/analytical CNN circuit models, and conducts simulation-based study of how CNN cell functionality is affected when different types of LEAST devices are employed in a CNN cell. Familiarity with Matlab and basic electronic circuits is required.
Project: Stochastic computing and nanomagnet logic (NML)
By placing nano-scale magnets in carefully crafted patterns, logic computation can be performed. Such nanomagnet logic (NML) circuits provide a drastically different way of processing data from traditional CMOS. NML circuits have many desired properties, including lower power, non-volatility, and radiation hardness. Basic structures of NML circuits have been experimentally demonstrated. NML circuits, however, are fundamentally more error prone than charge-based devices. Stochastic computing employs bit streams that encode probability values to represent and process information. If designed properly, a small number of bit flips (regardless of their position) in a long bit stream causes small fluctuation in the value represented by the bit stream. This desirable error tolerance feature is extremely attractive for NML technology. By participating in this project, students will learn fascinating properties of nanomagnets, become proficient with micromagnetic simulation tools, simulate different stochastic NML circuit structures, and investigate the performance and power of these structures. Bolder students will get a chance to try out their own stochastic NML circuit designs.
Project: Nano-optics of electronic molecules
Correlation between particles in finite quantum systems leads to a complex behavior and very unusual new states of matter. One remarkable example of such a correlated system is expected to occur in a dilute electron gas confined in a quantum dot, where the Coulomb interaction between electrons rigidly fixes their relative positions like those of the atoms in a solid, or the nuclei in a molecule. These electron molecules, called Wigner Molecules (WMs), can be accurately controlled experimentally using various combinations of semiconductor materials, numbers of electrons, electrostatic potentials, and magnetic fields. Thus these WMs present a novel and compelling field for fundamental and applied research that could have considerable impact on the electronic and optical devices of the future. Our group at Notre Dame has recently discovered strong emission from such WMs. The student working on this project will be ushered into the infinitesmal world of near-field optical microscopy, where nanostructures are studied that are orders of magnitude smaller than can be seen in a conventional light microscope. Working with the faculty mentor and a physics graduate student, the student will learn to use combined single-electron- and nano-optical control of quantum states in these WMs, which has never been done before. An important result of these experiments may lead to the identification of molecular states that are suitable for quantum computing.
Project: Nanometer-diameter pore-based DNA delivery into single mammalian cells
Transcription factors that dictate cell fate are translated from fewer than a thousand transcripts. However, traditional methods for transfection of a cell, such as electroporation and lipofection, require more than a million copies of an expression vector per cell, thereby being grossly inefficient due to nonspecific and non-uniform delivery. Therefore, a method for precisely conveying a biologically relevant number of distinct molecules into a cell is required to modify its genetic code and create a homogeneous population of a unique phenotype. We have demonstrated that a nanometer-diameter pore in a silicon nitride membrane, namely a nanopore, can be used as a gene delivery tool that offers unprecedented control over transfection—reprogramming single cells with a defined number of nucleic acids—with extremely high efficiency and cellular viability. In this project, undergraduate students will fabricate an array of nanopores to achieve high-throughput transfection. Prior experience in transmission electron microscopy, wet labs, cell culture and MATLAB, C++ and/or Labview coding is preferred.
Project: Artificial tissue formation using laser-based optical tweezers
In vivo tissue is comprised of a heterogeneous, dense population of cells organized hierarchically in three dimensions (3D) with an embedded vasculature. But so far, tissue engineering approaches have failed to recapitulate such a vascular network and a heterogeneous hierarchy of cells. Therefore, thick engineered tissue develops a necrotic core in only a few hours. To resolve this problem, a heterogeneous population of cells need to be hierarchically organized in 3D with microvascular networks. We have demonstrated the capability to precisely assemble and co-culture a hierarchy of cells of human origin to form microvascular networks. In this project, undergraduate students will build structures that resemble a blood capillary and perfuse it with whole blood. Prior experience in optics, wet labs, cell culture and MATLAB, C++ and/or Labview coding is preferred.
Project: Light transmission spectroscopy: A new bio-molecular tool
Nanoparticles are common in nature as well as in many industrial applications. Engineering at the nanoscale is now becoming a part of a wide range of activities including the design of electronics and new materials. Although we may not realize it, we are surrounded by manmade and naturally occurring nanoparticles present in our air, water, food, medicines and even sometimes our cells. As such, nanoparticles have a huge impact, both good (i.e., pharmaceuticals) and bad (i.e., toxic materials, viruses, bacteria), on human and environmental health. Our new platform technology, Light Transmission Spectroscopy (LTS), has the ability to identify and accurately measure in real time the size, shape, and number of nanoparticles ranging in size from 1 to 3000 nm in diameter suspended in fluid. It has an overall performance that far exceeds previous technologies. This general tool for nanoparticle analysis has already spawned a new technique for environmental DNA identification and protein geometrical analysis. Our latest project is using the instrument as a research tool to determine the difference between cancer and normal human cells based on the size distributions sub-cellular particles. LTS represents a true game-changer in medical diagnostics, biological research, and the general advance of human health.
Project: Nanoparticle contrast agents for spectral (color) X-ray imaging
For the last century, X-ray imaging has been the primary means of non-invasive imaging enabling physicians to diagnose and treat disease and injury. Radiography was revolutionized in the 1970s by the advent of computed tomography (CT) which enabled three-dimensional imaging. A similar revolution in X-ray imaging is presently taking shape with the development of spectral (color) CT. In both radiography and CT, image contrast is derived from the differential attenuation of X-rays by different materials or tissues, resulting in ubiquitous grayscale images. However, X-rays exhibit a spectrum just like visible light, but the energy spectrum of X-rays has not been resolved in imaging due to technological limitations. Recent advances in energy-sensitive X-ray detectors have made spectral CT commercially feasible by unmixing the energy-dependent attenuation profile of different materials (see Figure). This transformational technology will enable scientists and physicians to differentiate various materials, tissues, and fluids, where not previously possible by X-ray imaging. Thus, the impact could be far-reaching, affecting any preclinical and clinical X-ray imaging for the study, diagnosis, and treatment of disease and injury. However, spectral differences in physiological fluids and soft tissues are sufficiently small that contrast agents are needed to take full advantage of spectral CT. The most appropriate combinations of contrast agents for spectral CT are not known and unavailable even for preclinical research. Therefore, students on this project will investigate the use of multiple nanoparticle contrast agents for spectral (color) X-ray imaging at concentrations suitable for use in vivo in preclinical animal models for breast cancer. Experience with the synthesis of inorganic nanoparticles from chemical solutions would be ideal for this project but all applicants will be considered.
Project: Nanoparticle contrast agents for detecting damaged cartilage
Post-traumatic osteoarthritis, or arthritis that is initiated by injury to the articulating joint, is a debilitating disease that accounts for an estimated 12% of all cases of osteoarthritis in the lower extremities, affecting more than 5 million people in the United States. Current treatments replace the damaged tissue or even the entire joint, but interventions are under investigation to halt or retard the disease. Many studies have shown that fibrillation, lesions, and disintegration of the tissue at the articular surface occur early in the degenerative process. Techniques to detect these changes could allow clinicians to apply preventative treatments to avoid the pain, deformity, and disability associated with the loss of the damaged articular cartilage. Unfortunately, this is not currently possible due to a lack of suitable in vivo diagnostic imaging techniques. To address this issue, we are currently developing gold nanoparticle contrast agents functionalized to target biomolecules associated with soft tissue degeneration. These contrast agents will enable X-ray imaging of damaged cartilage. Students working on this project will use animal ex vivo models to investigate important practical elements associated with the use of these contrast agents in clinical settings. Students will also gain experience in nanoparticle synthesis and characterization, as well as biological sample collection, preparation and characterization. Experience with synthetic chemistry or materials characterization techniques would be desirable but all candidates with an interest in biomedical engineering will be considered.
Project: Biocomplexity and uncertainty: Science, technology, and ethics in the real-world case of metal nanoparticles in heavy commercial use
The moment is 2014: The National Nanotechnology Initiative is well into its second decade. Thus, large-scale commercial use of the simplest nanomaterials, and development of a multitude of related products, has occurred over a number of years. At the same time, substantial uncertainty remains about the biological impacts, positive and negative, throughout the life cycles (cradle to grave, or conception to disposal/recycling) of novel products and formulations. Meanwhile, there is increased and widespread urgency to offer the next generation of scientists and engineers rigorous and explicit ethics education relevant to responsible practice. These factors will combine in timely NURF research investigating and translating findings and unknowns about metal nanoparticles in heavy commercial use. The goal will be development of a comprehensive real-world, real-time case framed upon the product life cycle, for ethics education. The specific data, as well as the overarching themes of biocomplexity and uncertainty, will be important. This is an ambitious and multi-faceted research project suitable for adaptation into a senior/honors thesis. Student success will depend upon adept navigation, comprehension, and synthesis of published literature from multiple fields as well as creativity and big-picture thinking. This NURF project will allow for undergraduate participation in a collaborative (together with Northeastern University in Boston) research project funded by the National Science Foundation, “Ethics Education in Life Cycle Design, Engineering, and Management.” An abstract of the entire project is available on the NSF website. Over the summer, the selected NURF fellow will work with Dr. Kathleen Eggleson, Notre Dame’s Principal Investigator, on a real-world case module and related one-week workshop for ethics education of science and engineering graduate students.
Project: Restrahlen band optics with surface phonon polaritons
Semiconductor materials are used to generate and control light over a large portion of the electromagnetic spectrum. In the far-infrared, however, light interacts very strongly with vibrations in the semiconductor crystal, making conventional materials and techniques in this so-called “Restrahlen band” ineffective. One possible method of improving access to this portion of the spectrum is to use strongly confined surface waves on polar semiconductors to control and generate light. These surface waves, called surface phonon polaritons, are a combination of light and a crystal vibration. In this project, the student will explore how we can control the optical properties of surface phonon polaritons in the far-infrared. Work will include reflection and transmission spectroscopy in the laboratory and simple modeling. Interested students will also have the opportunity to fabricate samples in the Notre Dame Nanofabrication Facility. This project is appropriate for students with an interest in optics, semiconductors or nanotechnology.
Project: Detection of single nano-objects by optical absorption
Single nanoparticles are usually detected by emission or Rayleigh scattering, and thus are limited to materials with large quantum yields or scattering cross-sections. The goal of this project is to detect single nano particles using optical absorption. This is very challenging, but if successful would greatly expand the range of materials that could be investigated. These experiments will require work in aligning laser systems through microscopes, sample preparation and some programming. Students should have a reasonable knowledge of chemistry and physics. More details about this work can be found at: http://www3.nd.edu/~ghartlan/Site/Hartland_Group.html
Project: Nanoelectronics from two-dimensional materials
Students in this project will build and test electron devices constructed from single-layer materials like graphene. These materials are of wide interest for energy-efficient transistors, ionic switches, memories, solar energy converters, or batteries. A wide range of projects are possible depending on student interest: modeling, fabrication, characterization, and circuit design.
Project: Depositing and characterizing two-dimensional materials for low-voltage memory
The need for low-power electronic devices increases as their size decreases. An example of one specific need is low-voltage flash memory for low-voltage logic devices. We are exploring novel, low-voltage memory concepts that involve the movement of ions within and between two-dimensional (2D) materials. One key issue is learning how to deposit the appropriate 2D material with monolayer precision. The NURF student will explore methods to deposit monolayers of planar molecules on a graphene surface and characterize the surface using atomic force microscopy (AFM). Work will include determining the optimal deposition conditions and annealing temperature to perfect the order of the molecules. The student will prepare and characterize the samples in an inert environment provided by a glovebox, where the oxygen and water concentrations are limited to a few ppm. The student will learn about low-power electronics, the properties of 2D materials, and will gain experience working in a glovebox and operating an AFM.
Project: Engineering multifunctional nanoparticles for targeted drug delivery In cancer
Multiple myeloma (MM), a B-cell malignancy characterized by proliferation of monoclonal plasma cells in the bone marrow (BM), is the second most common type of blood cancer in the U.S. Despite the recent advances in treatment strategies and the emergence of novel therapies, it still remains incurable. A major factor that contributes to development of drug resistance in MM is the interaction of MM cancer cells with the BM microenvironment. It has been demonstrated that the adhesion of MM cells to the BM stroma via a4b1 integrins leads to cell adhesion mediated drug resistance (CAM-DR), which enables MM cells to gain resistance to drugs such as doxorubicin (Dox)—a 1st line chemotherapeutic in the treatment of MM. To overcome this problem, the clinicians apply combination therapy, which is the simultaneous use of two complementary chemotherapeutic agents during treatment. One caveat of this treatment method has been that it is almost impossible to attain the critical stoichiometry at the tumor that is necessary to achieve this synergistic drug effect when conventional methods of chemotherapy is used. Here, we seek to overcome this challenge by using an engineering approach for targeted drug delivery. The overall objective of this proposed project is to engineer “smart” nanoparticles that will deliver and exert the cytotoxic effects of the chemotherapeutic agents on MM cells, and at the same time do it in such a manner to overcome CAM-DR for improved patient outcome. To enable this, we will engineer micellar nanoparticles that will be (i) functionalized with a4b1-antagonist peptides as well as Dox and carfilzomib drug conjugates, and (ii) designed to show the adhesion inhibitory and the cytotoxic effects in a temporal sequence. When the nanoparticles are delivered to the MM cells, as a first step they will interact with the cell surface a4b1 integrins and inhibit MM cell adhesion to the stroma, thereby preventing development of CAM-DR (see figure). In the second step, the chemotherapeutic agents will exert their synergistic cytotoxic effects after cellular uptake, as the nanoparticles will be designed to require a low pH environment such as the endocytic vesicles, to release active drugs. This way, the “smart” nanoparticles will act on the MM cells in a temporal fashion and prevent development of CAM-DR for improved patient outcome.
Project: Approaching real-time photo-induced THz coded aperture imaging using compressed sensing
The submillimeter-wave and terahertz (THz) region in the electromagnetic spectrum has become more and more important to radio astronomy, chemical spectroscopy, bio-sensing, medical imaging, security screening, and defense. In recent years, technologists have intensified their efforts to develop imaging systems operating in the THz region for the above applications. Compared to THz imaging using mechanical scanning and focal-plane arrays, coded aperture imaging (CAI) offers the advantage of both high performance (i.e., high signal-to-noise ratio (SNR) and frame rates approaching video) and the potential for realizing simple and low-cost systems. CAI-based systems are based on spatial encoding and modulation to eliminate the need for detector arrays. In this imaging technique, a single THz detector in combination with a series of N x N coded aperture masks is employed to obtain an image with an N x N resolution. Measurements with N2 masks are taken, and the same number of linear equations are then solved to reconstruct the object image.
In our previous work, we have reported a simple but powerful means to realize THz CAI using photo-induced aperture arrays using an unpatterned silicon wafer illuminated by a digital light processing projector (DLP) [1, 2]. The optical THz modulation described in  was employed to spatially modulate each array pixel with a modulation depth of ~20 dB. Prototype demonstrations of CAI using Hadamard coding at 590 GHz have been performed. Continuous THz imaging with 8 x 8 pixels has also been demonstrated, using a slowly moving metal strip as the target (see figure). To further increase the imaging speed, CAI based on compressed sensing can be employed to significantly reduce the required number of masks. In addition, much faster (e.g., 32 kHz) DMD (digital mirror device) chipsets by Texas Instruments, Inc. and an optimized data acquisition system can be used to realize real-time (>30 frame/second) THz imaging. This project will offer the student an excellent opportunity to work with the state-of-the-art facilities at NDnano, as well as to gain hands-on experiences on solid-state THz sources, detectors, quasi-optical systems, and measurements. Furthermore, we expect that the completion of this work will lead to high-quality journal publications.
2. A. Kannegulla, Z. Jiang, S. Rahman, P. Fay, H. G. Xing, L. Cheng, Lei Liu, “Coded-aperture imaging using photo-induced reconfigurable aperture arrays for mapping terahertz beams,” IEEE Trans. Terahertz Science and Technology, (second round review), 2013.
Project: 2-dimensional semiconductors: New toys for the next nano(opto) electronics era
Two dimensional (2D) materials such as graphene, MoS2, WS2, BN etc. are attracting enormous interests due to their excellent electrical and optical properties. Nanoscale devices based on these 2D materials potentially offer high-performance, large-area and low-cost electronics and optoelectronics. Researchers have recently proposed a variety of applications including low-voltage memory, solar cell, high-speed photodetectors, integrated circuits etc. One representative example of 2D material is graphene, consisting of one layer of carbon atoms. Its unique linear dispersion relation at low energies leads to a broadband optical transparency of ~97% for white light. Initially, the atomically thin 2D materials were obtained by mechanical exfoliation, which, however, can only produce micron-size flakes. To produce large-area films for practical applications, chemical vapor deposition (CVD) growth on metal (Cu or Ni) is well developed in recent years. As one of leading research teams in the field of 2D materials and devices, our group has developed capabilities of CVD-growth, transfer, device fabrication, characterizations of both material properties and device performance for 2D materials. Applications such as THz modulators, transparent electrodes, and tunneling field-effect transistors based on these 2D materials have been actively pursued by our group, with some prototypes being demonstrated recently. For more updated information on the group, please refer to http://www.nd.edu/~hxing and http://www.nd.edu/~djena.An example project on IPE is described in the figure above (click image for larger view), and an appropriate project will be decided based on the student’s interests and background upon joining the group. In the IPE project, we will target for using various 2D materials, not only graphene, but also MoS2, WS2 etc as transparent electrode to enable the observation of hole transitions and the complete determination of band alignment in semiconductor interface. Due to the atomically thin nature of these materials, their optical absorption to the light is significantly lower than the bulk materials. In addition, their excellent conductivities can guarantee that the photo-carriers injected from the emitter material is completely collected. These properties make them as ideal transparent electrodes in internal photoemission (IPE) measurements. A proof of concept trail has been demonstrated in graphene/SiO2/Si and graphene/Al2O3/Si structures by our group. Students that involve in this project will have the opportunities to gain hands-on experience and cutting-edge knowledge of 2D crystal growth, device fabrications, and building optical set-ups; more importantly, why researchers are interested in particular materials for particular applications.