Andrea R. Tao, Ph.D. - US grants

Intellectual Merit: Nanoscale metal tips behave like optical antenna to facilitate near-field amplification of scattered light and are being explored as high-resolution scanning probes for ultrasensitive vibrational spectroscopy. To obtain the highest signal gain from each probe, the metal tip must be designed with highly regulated size and shape. Current fabrication methods produce tips with a range of nanoscopic features that are difficult to characterize and suffer from both mechanical and thermal damage upon use. The research objective of this BRIGE project is to fabricate metal tips by assembling colloidal metal nanocrystals onto an atomic force microscope tip. This proposal will evaluate the optical response of nanocrystal-based tips as a function of nanocrystal shape, size, and assembly geometry. Nanocrystal assemblies will be engineered to achieve specific near-field electromagnetic properties, including tunable plasmon excitation wavelengths, electromagnetic coupling between multiple nanocrystals, and optimal evanescent field decay lengths. Finally, this project will seek to integrate these nanocrystal assemblies with scanning probe instrumentation and to demonstrate tip-enhanced Raman spectroscopy for applications such as chemical identification, detection, and mapping.

Broader Impacts: The proposed research will lead to the development of robust, tailored, and ultrasensitive nanoscale probe tips for tip-enhanced Raman spectroscopy and other near-field optical measurements. An optical technique that is able to pair quantitative chemical analysis with spatial resolution beyond the diffraction limit would have a tremendous impact in a broad range of fields that require surface characterization, including: chemical sensing and molecular identification, heterogeneous catalysis, nanostructure characterization, biomaterials development, and basic life sciences research. This research project will make broad impacts by integrating research with mentoring, education, and social outreach. The research outcomes of this proposal will be introduced to undergraduates within the NanoEngineering curriculum at UC San Diego as an example of how basic research in nanoengineering can drive technological innovation. Work will be conducted with community-based organizations to promote nanoscience education at the precollege level, with particular attention given toward broadening participation through the inclusion of underrepresented minorities and women. In addition, the proposed efforts include the development of online wikis for the dissemination of research results beyond the nanomaterials community. These different educational components will be designed to engage engineers at all levels of education, encouraging open lines of scientific discussion with their peers, mentors, and community.

The research objective of this project is the scalable fabrication of plasmonic nanojunctions, the nanometer-sized gaps created between high-curvature metal surfaces that produce intense electromagnetic ?hot spots.? In this project, metal nanocrystals will be self-organized to form precise nanojunctions by carrying out phase segregation within a nanocrystal-polymer composite. Nanocrystals will be assembled with respect to shape and orientation to create homojunction (similar) and heterojunction (dissimilar) nanocrystal pairs. Molecular simulations will be used to deduce the global phase diagram of the multicomponent nanocrystal-polymer mixtures and to predict the mechanisms and kinetics of large-scale nanocrystal assembly. Guided by simulations, nanocrystals will be chemically modified by polymer grafts with tailored chain lengths, grafting density, and charge. Detailed morphology studies of the resulting nanocomposite will provide insight into how the chemical nature of the nanocrystal surface can be used to tune the key intermolecular interactions that regulate orientation and arrangement of the plasmonic nanojunctions.

The results of this project will facilitate the successful fabrication of large-area, non-close-packed plasmonic nanocrystals arrays that are currently inaccessible by top-down fabrication methods. These nanomaterials will be designed for integration into optical device platforms for applications such as subwavelength focusing, surface-enhanced Raman spectroscopy, and electromagnetic transparency. This work will also provide a fundamental understanding of the general mechanisms governing polymer-directed nanocrystal assembly. By establishing a close collaboration between experiment and theory, this work has the potential for the discovery of novel self-assembly pathways and mechanisms for achieving new and complex nanomaterials architectures. In addition, this research project will contribute to the education of pre-college, undergraduate, and graduate students in the field of nanoengineering. This includes the design of new laboratory modules and research-based coursework for undergraduates as well as outreach activities that will increase the overall diversity of the undergraduate engineering population at UCSD.

The objective of this proposal, NUE: Development of a Computational Curriculum for Undergraduates in NanoTechnology and NanoEngineering (NanoCompute)at the University of California San Diego (UCSD), under the direction of Dr. Andrea Tao, will be to develop a new focus within the nanoengineering curriculum that emphasizes computation, simulation, and modeling. Computation-based learning methods will be integrated into new and existing undergraduate courses in the NanoEngineering (NE) Department, starting with first-year engineering courses and culminating in a two-quarter capstone senior design course. The proposed NanoCompute curriculum is a novel approach to undergraduate education in nanotechnology because it will provide formal hands-on training in computation approaches that is fully integrated with the NE Department's four-year Bachelor of Science curriculum.

The curriculum for NanoCompute is expected to impact all undergraduates majoring in nanoengineering and chemical engineering at UCSD, which is estimated at 1000+ students over the next two years. NanoCompute will be implemented to meet the Engineering Science Program requirements as laid out by the Accreditation Board for Engineering Technology, and this proposal will develop new pedagogy in computational nanoengineering that we expect to impact all future degree programs in this area. There are currently no established criteria for accredited degree programs in nanoengineering or nanotechnology. To enable impact on a national level, the project team will develop a modular course format that is readily implemented by other academic institutions. As part of NanoCompute, there will be a focus on recruiting and retaining undergraduate students in the NE Department from underrepresented and underprivileged groups. The educational efforts of this proposal will seek to develop human resources in advanced technology, which is vital to economic growth in California and the U.S. as a whole.

The Macromolecular, Supramolecular, and Nanochemistry (MSN) Program is funding Andrea R. Tao of the University of California, San Diego for research to develop new methods to prepare semiconductor nanostructures. These structures have a wide variety of applications in optics, such as wireless telecommunication, remote sensing, and bioimaging. The ability to synthesize them with precisely controlled chemical and physical properties is important to understand how light interacts with matter at the nanoscale and to fully exploit their exciting technological applications. To achieve broader impact, this work integrates research with mentoring, education, and outreach. This work promotes nanoscience education at the pre-college level through research internships and short courses in nanoscience for high school educators, with particular attention given to the inclusion of underrepresented minorities and women.

This research aims to discover and develop novel synthetic pathways for achieving new low-dimensional semiconductor nanomaterials with precisely controlled chemical compositions and morphologies. The approach involves the synthesis of metal-organic liquid crystals that are to serve as precursors for the nucleation and growth of copper chalcogenide nanocrystals. These materials are being synthesized for the study of localized surface plasmon resonance in the infrared wavelengths. The carrier density, sizes, and shapes of the resulting nanocrystals are programmed by rationally designing the chemical composition, stoichiometry, molecular structure, and supramolecular order of the liquid crystal precursor. The synthetic techniques developed in this study are also being extended towards the development of an entire toolbox of metal chalcogenide nanomaterials with tailored optical, electronic, and chemical properties.

There is an increasing need for new manufacturing techniques that are capable of organizing nanoscale components. Such techniques would enable the manufacturing of next-generation materials and devices for a diverse range of applications, including energy, medicine, and telecommunication. For example, components can be organized into stacked or layered nano-scale architectures to create three-dimensional composite materials and structures. Nanoscale components can also undergo self-assembly, where they spontaneously organize into precise arrangements. This research will seek to combine these two nanomanufacturing techniques into an integrated fabrication process. The project will involve experiment and modeling to gain new insights into how such a process can be used to engineer and design nanostructured materials. The results of this work will be used in educational activities to show how basic science and engineering research can drive technological innovation. Nanomanufacturing concepts will be introduced to undergraduates, high school students, and K-12 educators through outreach activities that show how basic science and engineering research can drive technological innovation. These activities will be designed to engage underrepresented minorities and women in nanomanufacturing research.

This research aims to combine the capabilities of both layer-by-layer deposition and self-assembly to fabricate stacked nanoparticle architectures with exquisite control over inter-planar as well as intra-planar organization. The underlying theme of this work is to rationally engineer the assembly of nanoparticles (NPs) in the presence of interfaces and to exploit the unique interactions between NPs both within and across layers, which will be achieved through a close-knit collaboration between experiment and modeling. Nanoparticle interactions will be controlled within each layer in a multilayered structure using orthogonal polymer processing to address specific layers within the stack. Inter-planar assembly will be controlled by designing long-range interactions that enable coupled, synergistic assembly between NPs in different layers of a stack.
Quantitative analyses of the assembly process will be carried out and an experiment-guided, predictive model of NP assembly will be developed. Computational modeling will also play an integral role in understanding particle interactions within and across layers, and will provide an opportunity to gain new, fundamental insights into how NPs assemble in quasi-3D geometries and the effect of interfaces on particle diffusion and localization. The results of this work will be used to develop a new fabrication toolbox for device-relevant stacked nanoparticle-polymer architectures.

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Tao at University of California, San Diego, studies and develops new tools for surface analysis. Although surfaces and interfaces play a critical role in dictating key chemical processes, adequate tools for nanoscale surface analysis are lacking. Professor Tao is studying and creating optical probes that are capable of focusing light down to nanoscale volumes (the diameter of a human hair) that could be used in applications such as bioimaging, catalysis, plasmonics, and solid-state surface science. This project provides unique research opportunities for undergraduates, graduates, and high school students to learn about optics and nanomaterials. Professor Tao collaborates with a nanomaterials start-up company, which provides her students with direct and personal insight into the entrepreneur roadmap. Professor Tao is also interested in enhancing the diversity of the engineering community at UC San Diego. This research contributes to chemical industry by ensuring product quality as well as helping to improve synthetic methods by reducing defects.

This project integrates atomic force microscopy (AFM) and tip-enhanced Raman spectroscopy (TERS) for carrying out multi-modal measurement of both the chemical and mechanical properties of surfaces and surface binding events. AFM-TERS carries out point-by-point acquisition of chemical information-rich Raman spectra by using a metallic optical antenna to facilitate near-field amplification of both the incident and Raman-scattered light. This work investigates the chemical and physical properties of colloidal AFM-TERS probes that are fabricated by the assembly of shaped metal nanocrystals onto AFM tips. Silver nanocube probes serve as a model system to understand the light-matter interactions that are critical for achieving large Raman enhancements and low background signals. These studies provide new fundamental insight into how near-field optical probes interact with molecular and surface analytes, clarify how near-field optical confinement is supported at the tip-substrate junction, and investigate how the enhancement of other optical processes (e.g. inelastic scattering, multiphoton absorbance) affect TERS readouts. Both experiments and models are used to identify and develop design rules for nanocrystal optical antennas to maximize Raman sensitivities and imaging resolution. The resulting nanocrystal-based AFM-TERS platform are applied toward the chemical and force imaging of nanomaterials and biological surfaces.

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

Non-technical Description:
The San Diego Nanotechnology Infrastructure (SDNI) is set up as a national nanotechnology research and education infrastructure to serve the country?s needs for advancing research, facilitating technology commercialization, supporting entrepreneurship, developing strong and competitive work force, enhancing K-12, college and graduate education, and promoting diversity and inclusion. By accomplishing its missions, SDNI will become a key contributor to the pursuit of scientific research and the national health, prosperity, and security. SDNI offers unique tool sets, skills, technical support, mentorship, and services to produce a myriad of innovative materials and devices. These unique capabilities will help the nation to gain competitive advantages in areas critical to the nation?s economy and security, including artificial intelligence (AI), advanced manufacturing, quantum information science (QIS), and 5G/6G communications. The SDNI will also play a pivotal role in research pursuits that align with NSF?s 10 Big Ideas for the future, with particular focus on supporting and growing convergent research, enhancing science and engineering through diversity, and seeding innovation. To develop a more diverse and productive scientific workforce, the SDNI is committed to developing a systematic and executable outreach and education program to promote STEM. Built upon a pilot program that has shown feasibility through very positive responses from all stakeholders, including students, teachers, and administrators from school districts with high minority student populations, SDNI?s proposed outreach efforts will bring nanotechnology to the science curriculum of middle and high schools in southern California first and then across the country, through collaborations with other sites in the NNCI network.

Technical Description:
As part of the National Nanotechnology Coordinated Infrastructure (NNCI), the SDNI offers technical strengths in the areas of Nano/Meso/Metamaterials, NanoBioMedicine, NanoPhotonics, and NanoMagnetics. SDNI?s strategic goals are to (1) Provide infrastructure that enables transformative research and education and leverages San Diego?s innovation ecosystem, which includes major research institutes and over 2,000 companies employing more than 60,000 scientists and engineers; (2) Accelerate the translation of discoveries and new nanotechnologies to the marketplace; (3) Become a key contributing member of the NNCI Network to support and advance the nation?s nanotechnology infrastructure, and (4) Collaborate with the California Board of Education and local school districts to develop education and outreach programs to promote STEM efforts in high school and community colleges, especially at schools with high populations of underrepresented minority (URM) students. Because nanotechnology is a foundational technology with applications across disciplines, SDNI will continue to expand its capabilities, optimize its operations, and actively recruit and engage new and nonconventional users to advance discoveries in scientific areas of national priority. In particular, we expect the SDNI will play a crucial role in the advancement of convergent research to help create breakthroughs in areas of human machine interfaces, exploration of the universe, facilitating revolutions based on quantum physics, and enhancing science and technology by broadening participation in STEM. Discoveries made by users of the SDNI will have the potential to create transformative change in fields critical to the future of human society and national interests.

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

The ability to rapidly and accurately detect coronavirus disease 2019 (COVID-19) is imperative in managing the current global outbreak. In response to this critical need, the research groups of Prof. Tao and Prof. Steinmetz at the University of California, San Diego will collaborate to develop sensitive diagnostic tests that are easy to perform at the point-of-care. The project aims to enable 1) direct detection of viral ribonucleic acid (RNA) without the need of RNA amplification; and 2) a sensitive immunoassay at the earlier stages of infection. This project provides interdisciplinary research training opportunities to a postdoctoral researcher, undergraduates, and graduate students. In addition, it promotes teaching and learning by incorporating novel insights from this research into the NanoEngineering undergraduate and graduate curriculum and summarizing the findings in lay terms in videos.

The research team seeks to develop an innovative metasurface-enhanced Raman spectroscopy (mSERS) sensing platform for detecting coronavirus infection. Nanoscale optical cavities are uniquely designed to enhance the sensitivity of optical detection by increasing both the local optical field strengths of hot spots and the hot spot area for sampling a large number of analyte molecules in the cavity. The quantitative readout of Raman scattering intensity for a single vibrational band can be performed using a commercial benchtop spectrometer. Integration of this highly sensitive mSERS optical technique with vertical flow, lateral flow, or dipstick devices enables fast, straightforward sample preparation and easy-to-perform testing. This versatile platform can be used for multiplex detection of nucleic acid (RNA and DNA), antigens/antibodies, or biomarkers.

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

Nontechnical Abstract: The growth, prosperity, security, and quality of life of humans are in large part determined by the materials they use. The mission of the UC San Diego Materials Research Science and Engineering Center (UCSD MRSEC) is to perform innovative, interdisciplinary materials research relevant to societal needs, and to prepare students to become future leaders in materials design and discovery. The research effort of the Center is conducted within two highly interdisciplinary groups. The first group is deploying the most powerful computers available to understand, predict, and ultimately control the properties of materials at microscopic size scales?sizes just larger than molecular dimensions. It is in this size regime where many useful properties of materials emerge. For example, changes in the shape of metal particles at this scale can change their color, their efficiency as a catalyst, or their sensitivity in a medical diagnostic test. The second group is using the tools of the biotechnology revolution?in particular, genetic engineering and synthetic biology?to build new classes of materials that can respond to stimuli from their environment in useful ways. Both groups are targeting fundamental breakthroughs that can impact a number of critically important needs: faster, more accurate sensors for medical diagnostic tests, more efficient decontamination of chemical or biological hazards, better catalysts to reduce the cost of industrial processes, and improved therapeutics for treating diseases. The fundamental research within the two groups is empowered by an integrated educational program to prepare a diverse community of trainees to enhance national proficiencies in the science, technology, engineering, and mathematics fields. Immersive training for scientists across all levels ? novice through established ? develops technical competency in laboratory procedures, advanced instrumentation, and computational methods. Internship and scientist-in-residence programs fuel vital exchange of ideas and leverage partnerships with industry, national laboratories, and other collaborators. Partnership with the Fleet Science Center builds researchers? skills in science communication and connects the UCSD MRSEC with the diverse San Diego community to address community-articulated needs.

Technical Abstract: The UCSD MRSEC addresses two fundamental challenges: (1) How to predict and direct the assembly of materials at the mesoscale, where macroscopic behavior and properties emerge (IRG1: Predictive Assembly); and (2) How to deploy the tools of synthetic biology to build soft materials that meld the characteristics of living systems with the performance requirements of advanced engineered materials (IRG2: Stimuli-Responsive Living Polymeric Materials). IRG1 focuses on the rational design of innovative, functional mesomaterials with programmed plasmonic, catalytic, and structural properties. A computation-driven framework is being created to understand, predict, and design how shaped nanocomponents are used as material building blocks. The models developed bridge length and time scales relevant to mesoscale assembly. IRG2 integrates engineered living matter ? photosynthetic organisms ? into biological composites that respond to stimuli with genetically encoded outputs, such as chemical reagents and polymer feedstocks. The UCSD MRSEC creates unique resources to benefit the broader materials-research community: a MesoMaterials Design Facility ? a virtual, computational facility, and an Engineered Living Materials Foundry, consisting of a bio-synthesis laboratory and soft-matter characterization tools. The Center?s educational goals include preparing the next generation of interdisciplinary materials scientists, and increasing diversity and inclusion in materials research. The Research Immersion in Materials Science and Engineering (RIMSE) Summer Schools provide intensive training in the areas of IRG research. Enabling professional development for Center members in science communication, a partnership with the Fleet Science Center facilitates meaningful engagement with the diverse San Diego community.

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

Energy storage systems for buildings, wind and solar farms, and electric grids are playing an increasingly important role in mitigating the energy, sustainability and climate change challenges. Rechargeable batteries with high safety, low cost, long life and high resilience to environment changes are desired. Today’s lithium-ion batteries (LIBs) can no longer meet these requirements because of the safety issues associated with flammable liquid electrolytes and scaling challenges for critical materials (e.g., cobalt, nickel, lithium) that are typically used for making them. The sodium (Na) all-solid-state battery (NaSSB) is considered a promising alternative technology to LIB for emerging large-scale storage applications. However, solid-state electrolytes (SSEs) used in NaSSB have limited ionic conductivity, air/moisture sensitivity and interface instability with other components in the battery. The major challenges towards the development of efficient and eco-friendly manufacturing process are the achievement of: 1) precision control of the thickness, porosity, and uniformity of electrodes and SSEs; 2) high-speed mixing and rolling with low defects; and 3) high-purity of recycled material with the same level of performance as pristine materials. This Future Manufacturing Research Grant (FMRG) EcoManufacturing project will develop new knowledge to help transform today’s NaSSB battery manufacturing to a closed-loop, eco-friendly, high-precision, and high-yield technology based on a dry fabrication process. It will also make the manufacturing process safer and cheaper because of the increased cell energy density, and the elimination of caustic organic solvents as well as the related safety precautions. Not only limited to solid-state batteries, the new concept and knowledge developed in this project can be leveraged to improve the production efficiency and lower the cost of today’s LIB manufacturing. Therefore, it has the potential to make energy storage more acceptable and affordable, which will help the energy industry to shift towards more renewable sources, leading to a carbon-neutral society. In parallel, new education, training and workforce development programs will be developed to improve equality and opportunities for pre-college, undergraduate and graduate students in the manufacturing industry.

The goal of this project is to develop a paradigm-shift dry fabrication approach to enable eco-friendly manufacturing of NaSSBs for safe, low-cost and resilient large energy storage systems to help the United States meet the sustainable development goal. This project will assemble expertise in chemical engineering, nanoengineering, chemistry, materials science, life-cycle analysis/technoeconomic analysis, machine learning and data science, as well as collaborators in community colleges and industry to develop new fabrication processes, advanced materials and new battery protypes that can potentially be used for a wide range of large-scale storage systems. The research will focus on filling the science and knowledge gaps in NaSSB manufacturing through four highly synergistic thrusts: 1) Dry fabrication processes design for cathode, solid-state electrolytes and anode to enable NaSSB cell architecture with high-capacity loading and long-cycling; 2) Integrated technoeconomic and life-cycle analysis to guide and improve manufacturing steps, materials advancement and recycling process. 3) Multiscale quality control and standardization through materials interfacial engineering and inline analysis for the fabrication process; 4) Design and demonstration of closed-loop and waste-free recycling. The new knowledge and tools created from this research will enable eco-friendly, low-cost and safe energy storage in large scale systems for a sustainable energy infrastructure.

This Future Manufacturing project is jointly funded by the Divisions of Electrical, Communications and Cyber Systems (ECCS), Chemical, Bioengineering, Environmental and Transport Systems (CBET), and Civil, Mechanical and Manufacturing Innovation (CMMI) in the Directorate of Engineering, the Division of Undergraduate Education (DUE) in the Directorate for Education and Human Resources, and the Office of International Science and Engineering (OISE).

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

This Major Research Instrumentation Award is for a 3D Small-Angle and Wide-Angle X-ray Scattering (SAXS/WAXS) instrument, located in a shared nano/microfabrication and materials analysis facility at UC San Diego. As an essential analytical tool, this advanced SAXS/WAXS instrument supports the ongoing research of a broad cross-section of researchers, enabling discoveries in synthetic chemistry, catalysis, inorganic and biological materials, quantum materials, and energy storage/conversion materials. The instrument provides a versatile, state-of-the-art, reliable and local solution to the SAXS needs of the large scientific community in the Southern California region comprising San Diego and Orange Counties. In addition, the SAXS/WAXS instrument is used to enrich the training of both graduate and undergraduate students in the theory, synthesis, and analysis of nano- and microstructured materials. It allows instructors to use modern research data for pedagogical purposes, provides students with hands-on x-ray training to enhance their science, engineering, and technology curriculum, and augments the educational outreach programs at UC San Diego, bringing a significant opportunity to increase participation of underrepresented students in research.

Small-Angle and Wide-Angle X-ray Scattering (SAXS/WAXS) is one of the few experimental techniques that can characterize the nano- and microstructure of soft matter and nanomaterials. It is an essential analytical tool in the characterization of mesoscale and nanoscale features in a wide range of biological and artificial materials. The instrument enables measurement in a dynamic environment (with in-situ control of temperature, humidity, and ambient gas concentration) to provide insights into materials structure-function and structure-response relationships. Unique features of the instrument include automated simultaneous SAXS and WAXS measurements, grazing incidence measurements on liquid interfaces, and low-volume flow-through sampling of biomacromolecules. These features are also appropriate for studies of: (i) short-lived species; (ii) degradation-prone biological samples; (iii) air-, temperature-, or water-sensitive materials; and (iv) materials systems that require frequent or long-timescale x-ray measurements. The instrument also features a doubly focused point source, which allows for collecting scattering data from both isotropic and anisotropic samples because a scattering image can be generated from the entire projected source. The instrument is used to solve transformational materials science problems in the areas of mesomaterials, inorganic, and biological materials, quantum materials, and energy storage/conversion materials.

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