|Speech Date||16/07/13 10:10~10:50||Speech Place||Room 301+302|
|Speaker||John A. Rogers|
|Affiliation||Northwestern University, USA|
|Title||Semiconductor Nanomaterials for 3D Bioresorbable Electronics|
|A remarkable feature of modern integrated circuit technology is its ability to operate in a stable fashion, with almost perfect reliability. Recently developed classes of electronic materials create an opportunity to engineer the opposite outcome, in the form of devices that can dissolve completely in water to yield completely benign end products.1-3 The enabled applications include zero-impact environmental monitors, ‘green’ consumer electronics and bio-resorbable biomedical implants – none of which is possible with technologies that exist today. In this talk, we will describe foundational concepts in materials science and assembly processes for these types of systems, in 1D, 2D and 3D architectures4,5, the latter enabled by approaches that draw inspiration from the ancient arts of kirigami and origami. Bioresorbable, wireless sensors of intracranial temperature, pressure and electrophysiology designed for use in treatment of traumatic brain injury provide application examples.|
|Speech Date||16/07/13 13:30~14:10||Speech Place||Room 301+302|
|Affiliation||Japan Science and Technology Agency|
|Title||Ensuring a Sustainable World: Nanotechnology and Materials for Future Innovation|
|Nanotechnology and materials research has been opening a new horizon of innovations over decades to ensure a sustainable world and enhance national competitiveness. Among the innovative R&D achievements born in Japan are the Li-ion battery, the blue GaN LED, and the IGZO transparent oxide semiconductor. New discoveries of the perovskite solar battery and the Fe-based superconductor are also stimulating world-wide investigation. |
Today, the discussion on national R&D policy is focused on accelerating high impact social and industrial innovations from scientific breakthroughs. To this end, strategic programs such as the advanced low carbon R&D program, the nanoelectronics program, the element strategy initiative program, and the nanomedicine program have been identified from social needs and budgeted with high priority. Speedy proof of concept followed by social implementation is emphasized.
Although R&D on nanotechnology and materials per se is multidisciplinary, further integrated system approach is in progress. It is a reflection of the recent trend of system- and service-oriented manufacturing. Also, new scientific paradigms such as modeling and simulation, data science, and artificial intelligence are aggressively spread in national and industrial programs.
The national science, technology, and innovation system has been reshaped to optimize the nexus of education, research, innovation, and society. Tsukuba Innovation Arena (TIA) has added nanomedicine as a new research domain as it expands public and private partnership. A number of innovation hubs including Center of Innovation (COI) have been launched. The Cross-ministerial Strategic Innovation Promotion Program (SIP) intends to reinforce technology foundation for innovation. Also, R&D platforms for quantum beam measurement, high performance computing, and nanofabrication are actively in service for domestic use and international collaboration. Human capacity development is incorporated in those initiatives.
Japan pursues nanotechnology and materials R&D as a practical science under strong interaction of science and society. It is a long-inherited culture of Japanese academia.
|Speech Date||16/07/13 14:10~14:50||Speech Place||Room 301+302|
|Speaker||Chang Jin Kim|
|Affiliation||University of California, Los Angeles, USA|
|Title||Micro and Nano Technologies for Macro Applications|
|When things are very small – below a millimeter in size, their surface effects (e.g., surface tension) are boosted and inertia effects (e.g., weight) diminished relative to most other effects. In particular, if there exists a liquid-gas interface in a microscale physical system, the interfacial tension would dominate practically all other forces in the system. This dominance poses a unique challenge against developing micromechanical systems, because the existing knowledge of mechanical design does not involve surface tension. How would you exercise mechanical engineering in such a small world? In this talk, I will share how our lab has long been aspiring to perform mechanical engineering based on surface tension, establishing key technologies and design know-hows. While always based on unique mechanical properties in micrometers or below, the applications are in centimeters or above. Presented as examples will be: a high-performance inkjet printing with a surface-tension check valve ; a miniature fuel-cell system complete with on-demand fuel and oxidant supply ; a “mechanical” surface that super-repels all liquids including the most wetting ; a microfluidic platform based on electrowetting-on-dielectric (EWOD) technology ; and a surface that reduces the frictional drag of water flows , e.g., a boat traveling in water. The last example shows micro and nano technologies can lead us to even meter-scale industrial applications.|
|Speech Date||16/07/14 10:40~11:20||Speech Place||Room 301+302|
|Title||Enhancing crucial fluctuations|
|In the study of materials as well as in many other fields of science, computer simulations are pervasively used to solve difficult problems. However, very often the systems complexity makes the application of computer simulations challenging. Many systems of interest exhibit long lived metastable states separated by high barriers. In such cases, only very rarely occurring fluctuations allow the system to cross these barriers. This makes the transitions from one metastable state to another rare events. However, although rare, these events are crucial for a correct description of the system. For instance, phenomena such as nucleation, chemical reactions, and protein folding are a few examples of rare events. Unfortunately, the time scale of standard simulation falls short of what needed and the simulation of rare events is one of the main challenges of present day simulations. Here we present a novel approach to this problem, based on the introduction of a variational principle. We show how this variational principle can be used to study complex problems and calculate transition rates of rare events. We underline that besides offering computational efficiency this new approach provides a qualitative new point of view that will have far reaching consequences in the future.|
|Speech Date||16/07/14 13:30~14:10||Speech Place||Room 301+302|
|Speaker||Nathan S. Lewis|
|Affiliation||California Institute of Technology|
|Title||Sunlight-Driven Hydrogen Formation by Membrane-Supported Photoelectrochemical Water Splitting|
|We are developing a fully integrated and inherently safe artificial photosynthetic system. The system will take sunlight and water as inputs and will employ tandem semiconducting light absorbers to reduce H+ (or H2O) to H2 gas while oxidizing H2O (or OH-) to O2 gas. The photoactive components will be arrays of high-aspect-ratio semiconductor rods, which decouple the light-absorption and carrier-collection distances and provide high surface areas for catalyst loading. The rod arrays will be embedded in a gas-impermeable membrane and supported in a flexible polymer structure, providing a route to an inexpensive, efficient, durable, safe, and scalable artificial photosynthetic system.|
|Speech Date||16/07/14 14:10~14:50||Speech Place||Room 301+302|
|Affiliation||Japan Bioassay Research Center|
|Title||Nanomaterials safety: Predicting their long-term effects by in vivo studies|
|Some multi-wall carbon nanotubes (MWCNT) are similar to asbestos in length distribution and we showed its potential to induce mesothelioma by intraperitoneal injection model using p53 heterozygous mice based on the knowledge of “fiber carcinogenesis” established by asbestos and the alternative fibers. Histologically, non-granulomatous persistent chronic inflammatory microlesions with single fibers were considered to be important for the development of mesothelioma, whereas granulomas formed against aggregates/agglomerates were not directly involved in the process. |
In general, acute toxicity of a biopersistent nanomaterial (NM) is transient and mild, and therefore not considered as a predictor of its chronic toxicity. And when there is no pre-existing knowledge on its toxicity, whole body inhalation toxicity study is a default approach, along with oral and dermal toxicity studies. The most challenging part of the inhalation study is to generate well-dispersed aerosol. Here we report some data using the “Taquann” dispersion method and direct injection system using a MWCNT (Mitsui MWNT-7) as a case study sample.
In addition, using our original and literature data, the nature of the long-term nanomaterial toxicity will be discussed in terms of its shape and size of primary particles, characteristics of secondary particles including the status of agglomeration/aggregation and dispersion, crystalline and amorphous, biopersistency and solublility, and the nature of induced microlesions. (Studies supported by Grants from MHLW, Japan.)
|Speech Date||16/07/15 10:40~11:20||Speech Place||Room 301+302|
|Speaker||Tae Won Noh|
|Affiliation||Seoul National University|
|Title||Flexoelectricity in nano-world|
|Flexoelectricity is an electromechanical effect that refers to a linear coupling between an electrical polarization and a strain gradient in a dielectric medium. Flexoelectricity is ubiquitous in all dielectrics, and most profound at the nanoscale. The theoretical foundation of flexoelectricity is relatively mature and its experimental counterpart is still in its infancy. Although comprehension and control of strain gradient at the nanoscale is nontrivial, over the last decade, a series of discoveries with implication for both fundamental and applied science have been made. I will overview current status of this exciting field, especially related to the nanomaterials.|
|Speech Date||16/07/15 13:30~14:10||Speech Place||Room 301+302|
|Speaker||Catherine J. Murphy|
|Affiliation||University of Illinois at Urbana-Champaign|
|Title||A Golden Age for Colloidal Nanotechnology|
|Colloidal gold nanoparticles have been known in one form or another since ancient times. With the advent of improved methods to control nanoparticle size, shape and surface coating, the application space for these nano materials has expanded to include sensors, photonics, medical diagnostics, photo thermal switches, and therapeutics. In this talk I will present both the promises and the perils of using gold nanoparticles in various applications. Our seed-mediated growth method to control nanoparticle shape and size has been widely adopted, with still some mysteries as to the atomic-level details of facet control. On the biological front, we are finding that nanoparticles can influence living cells at the genetic level, even without intentional targeting; recent results from the lab highlight the complexities of interfacing engineered inorganic materials with living systems.|
|Speech Date||16/07/15 14:10~14:50||Speech Place||Room 301+302|
|Title||Advances in metrology for complex systems embedded in small volumes.|
|Pushing the limits in IC-technology recent evolution towards more confined and even 3D-volumes (like Finfets) has created a demand for metrology suited for very small volumes and more atomic scale observations. Obviously the latter represents a serious metrology challenge (spatial resolution, signal intensity, statistical relevance,..) and seems to make macroscopic concepts like SIMS, RBS, Raman obsolete.|
One obvious solution is to abandon 1D-metrology completely and to focus on metrology such as Atom probe tomography (APT) which is an extremely powerful method providing composition analysis within very small volumes (a few nm3) with high sensitivity and accuracy. Due to its excellent spatial and depth resolution (in many cases with the ability to resolve lattice planes) alloy composition analysis in small trenches, unexpected in diffusion in such volumes, dopant distribution and dopants decorating defects can in principle be identified. Nevertheless the presence of many materials with different evaporation fields does induce severe artefacts and trajectory aberrations which cannot always be corrected, causing severe measurement inaccuracies.
Complementary to the resolving power of APT, is the application of scanning probes (ssrm, c-afm) which enables to grasp the electrical activity of dopants or conduction paths within such volumes. As SPM is inherently a 2D-method, concepts for expanding into the depth dimension are explored cfr Scalpel SPM, ion beam sputtering icw SPM,..).
Despite their unique 3D-resolving power, APT and SSRM suffer from a poor productivity and a lack of statistical averaging over large areas as required in more production oriented metrology. We therefore present the concept of “self focusing SIMS” whereby we demonstrate that it is possible to determine the composition from trenches as small as 20 nm without having an ion beam with nm-resolution. In this case the spatial resolution is provided through the physics of the ion formation process creating a self focusing of the analytical signal to the feature of interest.
Somewhat similar is our approach to probe crystallinity of III-V growth in narrow trenches (< 50 nm) through channeling RBS whereby again we use a large beam but nevertheless probe the information from an array of very fine features. In all these cases, the averaging over a large array provides excellent statistics and improved productivity through the enhanced signal versus the case of a very focused probe beam. The latter is ultimately exemplified in Raman experiments on narrow SiGe-trenches where we demonstrate that the signal from very narrow features (20 nm) is dramatically enhanced (50-100x) as compared to it blanket counterpart enabling to probe composition and structural properties from a small volume.