Sungho Jin - US grants

Current focused ion beam techniques are capable of writing nanometer-sized features, but are inherently very slow. The aim of this project is a novel, radically different approach to high-throughput and versatile fabrication of nanometer scale complex patterns over large areas (tens of sq. cm). A broad area collimated beam of ions will be directed at a silicon wafer, and focused as an orderly array of nanometer size spots with the use of sub-micron sized electrostatic lenses. Simulations indicate that regardless of the achievable resolution of current lithography, this method can improve resolution by a factor of up to 100. When the wafer is tilted off normal (with respect to the ion beam axis), the focal point is laterally displaced, allowing the focused beams to be rastered, thus forming any arbitrary pattern. This is the essence of nano-pantography. The desired pattern is replicated simultaneously in billions of spots over tens of sq. cm. The plan is to apply this method to deposit small metal particles that will nucleate the growth of an ordered array of isolated, vertically aligned carbon nanotubes, for field emission applications.

This project aims to provide challenging projects for graduate and undergraduate students, with rich scientific and educational merit, as well as technological advances, not the least of which would be a clear path to large scale manufacturing of nano-devices. It is expected the latter will lead to a high level of interest from, and partnerships with, developing nano-technology companies and consortia. Diversity in undergraduate involvement will be facilitated by several programs at the University of Houston (a designated Minority Status University) and the University of California-San Diego. Outreach activities at the local public schools will help introduce the importance and excitement of nano-science and technology to students at an early age. Besides field emission devices, applications in quantum dot devices and ultra-small transistors will be investigated. The ability to deposit nanoparticles with a variety of size and/or composition could advance combinatorial approaches in fields such as catalysis or sensor development.

Strongly Nonlinear, Highly Tunable Phononic Materials: Processing and Characterization

Principal Investigator: Vitali F. Nesterenko, Professor, MAE Department, UCSD
Co-Principal Investigator: Sungho Jin, Professor, MAE Department, UCSD

Research in linear elastic phononic materials is an active area of basic research with important applications for development of band filters for environmental or industrial noise, delay lines, designing vibration free environment and transducers. They also represent a class of man-designed materials with evolving understanding of their properties and applications. Their properties are different than properties of traditional materials and are based on periodic arrangement of components with elastic contrast unavailable in normal conditions. However, the major part of research is performed with so to speak model structures rather than materials. For example the most favorable configuration for obtaining large acoustic band gaps is a periodic array of water cylinders in mercury. All examples of phononic materials are based on linear wave dynamics in periodic structures. As a result these structures can be tuned only due to an awkward rearrangement in the periodic array of components. Also because sound speed of solid materials is in the range 2 - 10 km/s the tunability of band gaps is limited. It is therefore desirable to design and study new materials, which are capable of significant nonlinear tuning by convenient and viable methods. The objectives of this proposal are therefore to (1) design and process strongly nonlinear tunable phononic crystal (NTPC) materials; (2) characterize their properties and (3) identify areas of their practical applications.
The proposed work has 3 unique aspects. First, unlike other approaches it is based on emerging strongly nonlinear wave dynamics in periodic structures based on solid theoretical, numerical and experimental results. Secondly, the work proposed focuses on processing of clearly identified examples of NTPC materials. Thirdly, the team synergistically combines unique expertise in the nonlinear wave dynamics of "sonic vacuum" and in processing of materials supported by full scale of processing equipment.
The work will prompt theoretical and experimental research in the diverse area of strongly nonlinear wave dynamics creating a broader impact not only in acoustic but in such areas as photonics and electrical transmission lines and signal processing. The design and investigation of unique materials will most likely lead to a discovery of new phenomena (like new type of waves, violations of Snell's law, travelling metal insulator transition induced by small amplitude waves or pressure induced transparency to sound wave) and an establishment of new mechanisms of wave processes.
Potential applications may include (1) design of a sound scrambler/decorder for secure voice communications for military and national security personnel, (2) improved invisibility of submarines to acoustic detection signals, (3) noise and shock wave mitigation for protection of vibration sensitive devices such as head mounted vision devices, (4) drastic compression of acoustic signals into centimeter regime impulses for artificial ear implants, hearing aid and devices for ease of conversion to electronic signals and processing, and acoustic delay lines for communication applications.

The objective of this research is the study of the structure-electrical property correlations in multi-walled carbon nanotube based Y-junctions, for the development of nanoelectronic components such as inverters, logic gates, and frequency mixers. The approach is the sequential: (1) synthesis of Y-junction morphologies through chemical vapor deposition processes, (2) assembly of the junctions into electrical circuits through nano-contacts fabricated by focused ion beam milling and in situ metal evaporation, (3) electrical characterization of nanoscale transport characteristics, (4) structural analysis by transmission electron microscopy, and (5) identification of desirable device characteristics for novel nanoelectronic devices. The carrier delocalization, and the catalyst particles introduced during growth, induces scattering centers at the junction region which can be exploited in Y-junction based electronic devices. In preliminary electrical measurements, both diode like and inverting/switching behavior was observed in three-terminal Y-junctions, up to 50 kHz, which will be investigated.
The broader impact would be: (a) the fabrication of novel and economical devices with advantages of low power consumption, radiation hardness, and reduced heat dissipation over conventional silicon based technologies, relevant to both civilian and military applications, (b) to convey the excitement of nano-science and technology to the wider community through developing new courses, freshman seminars, and outreach activities. By working with Preuss High School on the UCSD campus, a student and teacher exchange program will be developed. The graduate and undergraduate students working on this project will be exposed to cutting edge nanotechnology research, preparing them for careers in academe and industry.

The objective of this research is to provide viable solutions to major bottleneck issues in nano manufacturing, including, i) precise placement of nanomaterials/devices in high enough densities, and ii) convenient high-throughput fabrications. The approach is to introduce new concepts and techniques involving massively parallel, electron-beam-emitting nano probes for large area, simultaneous nano patterning. An array of extremely fine, scanning probe tips with sub-10 nm dimension and identical heights will be fabricated using silicon fabrication, carbon nanotubes, and related materials and processes. The principles and materials behavior involved in the nanofabrication processing steps as well as underlying phenomena during localized electron field emission from extremely small probe tips will be investigated.

The broader impacts of the proposed research on the 10 nm regime nano manufacturing science and technology include scientific understanding and novel conceptual advances. The successful outcome of this research will allow fabrication of a variety of ultra-high-density nanofeatured structures for nanoelectronics, nanophotonics, nanomagnetics, and nano-bio devices. More importantly, high throughput processing of precisely placed, ultra-high-density materials and devices will enable wider use of nanotechnology for electronics and other applications. The ultimate aim is to enable broader industrial utilization in areas such as advanced displays, sensor array technologies, telecommunications systems, information storage memory systems, and medical therapeutics. The research outcome will be leveraged to enhance education in nano-science and technology.

The research objective of this award is to investigate the use of a novel inexpensive printing approach for patterning wafer-level, parallel assemblies of nanoscale electronic materials for biological and chemical sensing from DNA templates. To address features smaller than 20 nm yet still maintain low manufacturing costs, the proposed research will combine a novel soft lithography stamping technique with patterned silicon surfaces to build ordered, spatially defined arrays of DNA and peptide-DNA based scaffolds on flat polydimethylsiloxane. These patterns can then be easily transferred to any receiving flat substrate, such as thermal oxide, metals, or polymers. Limiting the number of nanostructured oxide or silicon substrates needed in the fabrication process will dramatically lower manufacturing costs, while biomolecular scaffolds, such as DNA templates, can address features below 20 nm. The four main research objectives of the proposal are to 1) integrate low-cost, high-throughput inking and stamping methods to generate large area patterned arrays of DNA scaffolds, 2) engineer larger, well-controlled assemblies of DNA scaffolds, 3) incorporate specific molecular recognition motifs to bind nanoscale electronic materials in high yields and with minimal defects, and 4) fabricate fabricating multiplexed parallel, addressable biosensing electrical arrays.

An inexpensive, high throughput method to generate wafer-level arrays of nanoelectronic devices and sensors via benign chemistry and engineering would have an enormous impact on both the electronics and healthcare industries. Despite the wealth of nanoscale materials available, the current limitations of photolithography have prevented the realization of their potential in these applications. The proposed education and research plan will also draw and encourage active participation from teachers and students to help young students learn more about nanoscience and its impact upon society and their everyday lives. In addition, various seminars and interactive demonstrations related to the proposed research will be integrated into existing and new curricula, and open laboratory sessions will be held during university open-house days and on-campus science festivals.

TECHNICAL: Abalone shell is tough and fracture resistant. The structure has a brick-and-mortar organization with calcium carbonate (aragonite) bricks surrounded by the organic mortar. The toughness is attributed to the organized arrangement of the aragonite platelets and nanoscale features present at the mineral/organic interface. These nanoscale features include mineral bridges, nanoasperities on the surface of the aragonite tiles and the viscoelastic/adhesive properties of the organic. The main objectives of this work are to fabricate model ceramic/polymer laminates, identify and quantify the contributions of microstructural features that have been attributed to the toughening of the shell. This work is expected to lead to a new class of bioinspired composite materials that are strong, hard and fracture resistant. Students will be cross-trained in biology, materials science and nanoscience.

NON-TECHNICAL DESCRIPTION: Bioinspired materials are emerging as a new class of synthetic structures. The abalone shell is tough and fracture resistant, despite being built from weak constituents: organic matter and a soft mineral (ceramic). Under magnification, the shell has a "brick-and-mortar" structure of mineral bricks and organic mortar. Bioinspired synthetic layered materials based on this structure are expected to have exceptional toughness and fracture resistance. Fabrication and testing of layered organic (polymer) / ceramic structures that duplicate the structure of the abalone shell is the main focus of research. This work is expected to lead to a new class of composite materials that are strong, hard and fracture resistant. Graduate, undergraduate and high school students will be cross-trained in biology, materials science and nanoscience. New classes will be introduced into the curriculum and outreach to underrepresented student populations is a part of this project.

This award by the Biomaterials program in the Division of Materials Research to University of California-San Diego is to investigate magnetic remote spatio-temporal control of biomaterials and their payloads. Magnetic nanocapsules containing therapeutics could provide a viable means to remotely control the release of therapeutics to cell aggregates, through the blood vessels and blood-brain barrier. The magnetic nanocapsules respond to remotely applied magnetic fields to release drugs on-demand. To experimentally demonstrate the concept of spatio-temporal control of biomaterial response, the investigators will design and construct nanocapsules with innovative on-off switchable drug delivery approaches. The nature and dimension of these capsulated magnetic materials with therapeutics will be varied to understand the effects of these parameters on biomaterial characteristics and their drug release behavior. The anticipated impacts are expected to be significant in the drug delivery area that will benefit clinically challenging central nervous system disorders as well as cancer treatments. Graduate students will be trained with the multidisciplinary facets of this research project, and involves highly interdisciplinary fields such as materials science, biology, bioengineering, chemistry and chemical engineering. The educational outreach plan of this project will involve Annual San Diego Science Festival (Science Week San Diego) and Teacher Training and Professional Development programs that are organized by the BioBridge Science Outreach Initiative, a community based partnership among University of California, San Diego, San Diego School districts and industry.

This research project aims to investigate smart drug release systems based on magnetic nanocapsules containing therapeutic drug payloads. Such a controllable drug delivery techniques could provide viable means to treat Alzheimer's disease and other central nervous system disorders, and various types of cancers using on-demand release of drugs. To experimentally demonstrate the concept of remote spatio-temporal control of biomaterial response, the investigators will design and construct nanocapsules, and the nature and dimension of the capsule materials and magnetic materials will be varied to understand the effects of these parameters on biomaterial characteristics and efficiency of drug release behavior. The new technique can also be applied broadly to many other therapeutic areas to benefit large patient populations, and also provide opportunities for broader economic stimulus. The new approach will also stimulate many scientists and engineers in the materials science and bioengineering field for further innovations and understanding of biomaterials design, behavior and applications. This highly multidisciplinary research project will also emphasize the educational aspects for graduate, undergraduate, and high school students, including under-privileged high school students.