Daniel Attinger, Sc. D. - US grants

Ink-Jet technology allows the controlled generation and deposition of microdroplets of a wide range of fluids, e.g., organic liquids, polymers, dielectric coolants and liquid metals. Applications include materials processing, microelectronics manufacturing and cooling, as well as surface coatings. A typical droplet diameter of 100 mm implies a very large surface to volume ratio, which drastically enhances transport phenomena between the droplet and its surroundings. However, the temporal and spatial resolutions of current temperature measurement techniques, which are on the order of 1 ms and 1 mm, respectively, are not sufficient to capture the transient transport phenomena occurring during the early stages of the deposition of a microdroplet on a solid surface at a different temperature.
The first objective of the proposed research is to develop a laser-based temperature measurement method with temporal and spatial resolutions on the order of 1 ms and 10 mm, respectively. The second objective is to apply this novel measurement together with an existing finite-element model built particularly for microdroplet impact and an existing high-speed visualization setup: this combined experimental and numerical technique will provide in-depth knowledge on the coupling of the heat flow, fluid flow and phase change during microdroplet deposition. The rapid solidification of a microdroplet on a colder surface and the initiation of boiling of a microdroplet on a hot surface will be investigated, with consideration of the influence of engineered surface roughness and coatings. Predictive and quantitative models for the transient behavior of the interfacial thermal conductance and phase change will be formulated.

ABSTRACT 0449269

Investigation of bubble dynamics in microscale geometries, with applications in bioengineering and microfluidics

Dynamics phenomena involving microbubbles are aesthetic, complex, and important in industrial applications such as bubble-jet printing. If the dynamics of a bubble in an unbounded liquid is well understood, a lot a basic scientific work needs to be done to understand the dynamics of a bubble in contact with a solid surface, in a bounded microscale geometry. This problem of fundamental and practical interest will be addressed through two research initiatives.

The first initiative concerns the dynamic motion of a bubble in a microchannel. The channel geometry, and the dynamic wetting at the gas-liquid-wall interface, control the pressure needed to move the bubble in the channel. This issue is critical in microfluidics devices, where bubbles can clog microchannels with narrow restrictions. This problem will be studied theoretically and experimentally with a MEMS-based setup and high-speed visualization. The second initiative studies how a microbubble attached to a solid surface reacts to ultrasound. Recent investigations have shown that ultrasound drives bubbles oscillations, which produce a tiny, donut-shape vortex in the vicinity of the bubble, a phenomenon called microstreaming. Our theoretical and experimental research will involve simulations of microstreaming in the presence of solid boundaries and Particle-Image-Velocimetry (PIV). This microstreaming field and the associated shear stress will be used to deform biological cells and bring drugs through their membranes, as well as to build a microengine. A general-purpose micro- PIV system will be acquired for this research, with a camera that also allows high-speed imaging.

The intellectual merit is the development of a science base for the dynamic behavior of microbubbles in contact with a solid geometry. This first study on the motion of a bubble in a microchannel will be supported on the theoretical side by a collaboration with Henrik Bruus.s research group in Denmark, and on the experimental side (nanocoatings) with Oleg Gang, from the Center for Functional Nanomaterials at Brookhaven National Laboratory. Significant advances are expected on the understanding of the motion of the wetting angle, its hysteresis and relaxation time scale. Our second study will investigate how microstreaming depends on the bubble wetting angle and the nearby solid surfaces. Theoretical and experimental investigations will be performed, involving (for the theoretical side) coupled solid-fluid interactions acoustic calculations, simulations of acoustic microstreaming in the presence of solid boundaries, and (for the experimental side) high-speed visualization together with micro Particle Image Velocimetry. This second study involve collaboration with Dr. Citovski.s biology group at Stony Brook, as well as Dr. Moraga from the Center for Multiphase Research at Rensselaer Polytechnic Institute.

The broader impact will be the development in collaborations with Seyonic SA and Micronics Inc- of more reliable microfluidic devices, solving the issue of undesired bubbles through self-cleaning channel geometries or bubble traps. Also, novel ways to interact with biological cells through microstreaming will be investigated, with the development of a novel sonoporation device to control drug transfection through cell membranes and manipulate them. The microstreaming flow field will also be used to power a novel type of microengine that fits in a human hair, to be developed in collaboration with Oleg Gang, from the Center for Functional Nanomaterials at Brookhaven National Laboratory. Finally, we are convinced that visualization of bubble-related phenomena provide an attractive path from everyday experience to current scientific challenges involving micro- and nanoscale phenomena. This will be used to interest local high school and elementary school students from the Bronx to engineering, and to generate interest for research in the Stony Brook student community.

0701729
Daniel Attinger, Columbia University
Optofluidics for Next Generation of Laboratory-On-A-Chip


Intellectual Merit: The proposed research will integrate versatile and ultrafast optical sensors with extremely efficient fluid handling techniques into microfluidic chips. These optofluidics chips will perform tasks essential to chemistry and biology, such as mixing, purification, and protein adsorption. These tasks will be executed and monitored at unprecedented frequencies, close to MHz rates. The innovations of the project will be to develop universal integrated sensors with a footprint of a few micrometers, based on state-of-the-art high quality factor optical nanostructured resonators, and to develop fast fluidic mixing based on novel interfacial and segmented flow techniques.

Broader Impact: Remarkable advances in the miniaturization and integration of fluid handling have allowed large-scale integration of thousands of microchannels and valves in so-called microfluidic chips for novel chemical and biological applications, such as particle synthesis and genomic analysis. In current microfluidic chips, the operation frequencies are limited by diffusion-based mixing; also, sensing methods are slow and bulky, many requiring a microscope and visualization setup. The proposed optofluidics chips, integrating high-resolution optical sensors with fast microfluidic capabilities, are expected to contribute significantly to increase the processing power of microfluidic chips, in a similar way that integrated transistors have improved the processing power of microelectronic chips. The educational components of this interdisciplinary research involve theory and numerical design, device micro- and nano-fabrication, as well as fluidic and optical experiments. This program will support two graduate students and summer Research Experience for Undergraduates (REU) activities. It involves cross-boundary topics in Applied Physics, Mechanical, Electrical and Biomedical Engineering. Specific education modules on optofluidics, microfluidics and optical sensors will be developed for K-12 school teachers and presented through two summer workshops for minorities and underrepresented students around the New York metropolitan area, in the Bronx and Harlem.

1025685
Attinger

Intellectual merit

The aim of this project is to prove the concept that microbioreactors with integrated "on-chip" sensing can investigate the process kinetics of microorganisms under a wide array of shear stress and mass transport conditions. This microbioreactor concept will allow the study of low shear stress in combination with fast mass transport, conditions that are not attainable in current larger bench scale reactors.

The target microorganisms investigated in this project are nitrifying bacteria. These bacteria sequentially oxidize ammonia to nitrite and nitrate and thus render it amenable for subsequent reduction to dinitrogen gas. Nitrifying bacteria play an important role in both natural and engineered environments due to their role in the global nitrogen cycle, for instance in relation to waste management.

Microbioreactors have inherent, transformative advantages over currently used benchscale reactors. They feature more homogeneous flow conditions than larger reactors, direct optical access and large surface to volume ratio, for enhanced mass transfer. For instance, permeable membranes are used for gas diffusion, rather than traditional bubbling techniques that come with increases in shear stress. Control and measurement of nitrite concentration and temperature will be implemented using optical and microfabrication techniques.

Broader impact

The PIs will disseminate the results in their graduate course "Microscale Transport Phenomena". Undergraduate and High School students will be involved in this interdisciplinary research, a practice that is customary to the research laboratories of both the PI and co-PI.

This exploratory research will provide a foundation for the submission of a full size proposal to engineer nitrifying bioreactors for wastewater treatment, effectively overcoming currently observed mass-transfer limitations. This research will integrate into synergistic activities of Columbia University with industry (IBM "Smarter Cities") and with the Department of Chemical Engineering to grow this effort into a possible NSF research Center.

Have you ever wondered at the variety of self assembled deposit structures that can be obtained by evaporating liquids containing nanoparticles on top of a solid substrate. Deposit shapes vary from rings around a coffee drop, to hexagonal cells and fractal patterns. An interdisciplinary team of Columbia University scientists will study the related fascinating multiscale physics, using a combination of experimental, theoretical and numerical techniques. The team has the following skills: multiphase flow (Attinger, PI), colloids (Somasundaran), pattern recognition (Chang) and open-source computational fluid dynamics (Spiegelman). The complex self-assembly of nanoparticles will be studied by using first physical principles to explain the resulting selfassembled patterns (what we call a top-down approach), and by identifying features in the patterns that are signs of specific basic laws or transport rules (bottom-up approach).

Intellectual Merit:

Experiments will involve the spotting of microdrops of complex fluids on various substrates, fluorescence microscopy and laser profilometry to scan the three dimensional deposits. The first intellectual merit will be to describe with a phase diagram the self-assembly of nanoparticles during liquid evaporation on a solid substrate. The use of a phase diagram in that context is novel and allows a simple but powerful comparison of the magnitude of competing transport phenomena, such as evaporation at the wetting line, Marangoni recirculation, electrostatic and van der Waals forces, buoyancy, and dielectrophoresis. The phase diagram will provide an insight and an overview of the complex interplay between multiphase processes, influenced by the geometry of the liquid drop or film: fluid mechanics, heat transfer, mass transfer, colloidal interactions. Second, an available proprietary 2D-axisymmetric numerical code with a moving mesh able to very accurately track the free surface will be extended to 3D (see Chandra collaboration letter). This will allow the simulation of a wider ranges of boundary conditions, permitting the consideration of thin films and complex geometries. Explaining the self-assembly of nanoparticles from evaporating drops and liquid films from first principles is a challenging approach, given the multiple transport phenomena and time/length scales. Therefore, we will also develop a bottom-up approach based on pattern recognition of selfassembled features. We will test the hypothesis that the patterns tell us the about the physics that created them.

Broader Impact:

The proposed research will deliver innovative solutions to pattern nanoparticles on solid substrates, with applications in organic electronics and patterning of biomolecules for biosensors. Methods to increase printing resolution by two orders of magnitude (see Sonoplot letter), and to pattern uniform layers of particles will be investigated. The pattern recognition algorithms developed in this proposal will be tested to identify biomolecules (see Zenhausern letter) and enhance the accuracy of bloodstain pattern analysis, in collaboration with forensics expert MacDonell (see collaboration letter). Also, the 3D code developed in this proposal will be distributed freely as an open-source code, allowing every interested scientist to study problems involving drop and film transport phenomena such as drop impact, drop evaporation, film drying. Funding will support one graduate student.

The objective of this program is to examine the integration of optical and fluidic networks into microchips, to sense and manipulate complex fluids for life science applications. The program will examine silicon-based label-free optofluidic chips with enhanced sensing resolution and manipulation capabilities.

The intellectual merit is to create a transformative science base for wavelength-scale integrated optofluidics based on optical resonators, with collaborative efforts with GE Global Research Center. This technology can perform high spatial resolution sensing, while seeking to significantly improve the refractive index measurement sensitivity. Approaches will be pursued for reduced noise and increased specificity. The second thread of this work will advance concepts such as optofluidic multiplexers and demultiplexers in the toolbox of microfluidic chips. Optical waveguide arrays with switchable laser excitation will be examined. A fundamental advantage of our technology over conventional free-space optical trapping is that the resolution can be sub-diffraction with the subwavelength photonic devices.

The broader impacts are the development of high-sensitivity universal integrated optical sensors that will enhance Lab-on-a-Chip functionalities. The proposed silicon-based optofluidic integration is scalable to large arrays for high throughput analysis, and can be manufactured within the vast silicon infrastructure. The proposed optofluidic chips can significantly increase the processing power of microfluidic chips, for industrial applications such as label-free biomolecule sensing, manipulation, and active control. The educational components of this interdisciplinary research include joint PhD student advising, undergraduate internships at GE, outreach to high-school teachers, and a joint annual industrial-university colloquium.

PI: Tony Jun Huang, Pennsylvania State University
Proposal Number: CBET 1160568

The proposed effort seeks NSF funding for student participation grants for the 2011 ASME Society-Wide Micro and Nano Technology Forum to be held during the ASME IMECE 2011 in Denver, Co. The proposed Forum will bring together ASME members and others, with a focus on new developments in the field of micro and nanotechnology. For the past three years the forum has been enthusiastically embraced by ASME IMECE attendees, in particular students; each year, there have been more than 150 poster presentations and about 300 attendees at the forum. The proposed NSF awards will be used to further nurture student development by encouraging participation from a select group of meritorious students working in the general area of micro-/nanoscale engineering by providing them partial travel grants including expenses related to conference registration fees and lodging. The travel awards will be decided by a panel of experts from the Micro and Nano Forum organizing committee, and will be based on the technical quality of the poster abstracts submitted and statement from their research advisors.

In the past, the participating students at the ASME Micro and Nano Forum have greatly valued the opportunity given to them by the Forum to showcase their research, interact with their peers, and meet people outside of their immediate environment. Besides this, the Forum also provides opportunities to increase student exposure to cutting-edge research in the frontiers of micro and nano technologies, and increase student abilities with respect to tools that will make them competitive in a research environment, namely, team work and project management, oral and written technical communication skills, ethics, and overall research acumen. In addition, the students will get an opportunity to attend technical presentations (over 2000 presentations and posters are anticipated to be presented at IMECE 2011) relevant to their current research, and also in other mechanical engineering fields. This will expose them to solutions and challenges that may be relevant to their current projects, while at the same time provide opportunities to discover exciting new research activities to pursue in future. In this regards, the mission of the forum fits well with the mission of NSF (in particular the Engineering Directorate) in attracting young research talents and mentoring them for a career in science and engineering.

Direct exposure of the participating students to leaders in their research fields (technical organizing committee members, judges, etc.) will provide them with a unique opportunity to disseminate their most recent research, and receive first-hand information on available opportunities for postdoctoral positions, as well as faculty positions. ASME traditionally hosts several Grand Challenge sessions where speakers from industry or government identify critical technical challenges facing the nation in various fields. In addition, ASME award lectures by prominent researchers, special sessions on ethics and the next-generation engineering education curriculum, and technical tours to local industry and national laboratories represent other opportunities for student learning and growth. Like in the past, personnel from NSF, DoD agencies, national laboratories, and industry are expected to have a strong presence at the conference. Members from these groups will be involved in providing professional development seminars, workshops, information sessions and recruitment activities, and will provide further new avenues for student development as well. While selecting students for the travel awards, every effort will be made to include and encourage student participation from both minority and traditionally underrepresented student groups in engineering.

CBET-1235867
PIs: Daniel Attinger (Iowa State Univ.) and C. Megaridis (UIC)

This cross-institutional project straddles the areas of thermofluid engineering, materials science and optimization, with main goal to design, fabricate and study novel surfaces that are called ?superbiphilic.? These micro- and nanostructured surfaces juxtapose superhydrophobic areas (with strong affinities for water) with superhydrophobic areas (with strong affinities for water vapor). As such, they show superior performance in pool boiling by controlling the transport of the vapor and liquid phases in a parallel and optimal manner. The study will develop a novel coating-on-metal process, which is scalable and relevant to industrial heat exchangers. The main scientific challenge lies in understanding, controlling and optimizing boiling phenomena on the superbiphilic surfaces. For the first time, biphilic and superbiphilic surfaces will be fabricated on technically relevant, metallic substrates. The technology is based on sprayed-on patternable coatings, an industrial sector where US leadership is challenged from overseas. The research will develop a theoretical science base for boiling enhancement on biphilic and superbiphilic surfaces. The work is challenging because boiling involves multiphase and multiscale transport phenomena (evaporation starts in a sub-micrometer thick film, while detaching bubbles are millimeter-sized) and severely transient processes. To assist with the design and experiments, a modeling effort will be carried through. For simple surface topographies (or patterns of hydrophobic and hydrophilic domains), analytical models will be developed to explain the pool boiling enhancement in a qualitative manner. Computational fluid dynamic simulations will also be performed, to help understand the experimental data, identify the dynamic mechanisms responsible for the boiling enhancement, and evaluate the performance of complex surface topographies. The effort will feature a pattern design optimization approach to determine optimum topographies for boiling performance. The performance of the novel superbiphilic surfaces will be evaluated by a series of experiments, including surface wettability measurements, coating physical characterization, high speed visualization, as well as nucleation and pool boiling curves.

The research, which involves rich fundamental phenomena in a variety of multidisciplinary topics, intends to deliver an innovative solution to transferring heat at superior rates in boiling configurations. The developments from this work will affect -among other technologies- heat exchangers, which are widely used in most energy-intensive industries, which collectively consume over 15 quadrillion Btu/yr in the US alone. Consequently, the non-incremental improvements resulting from this research have the potential to generate tremendous energy savings, and in turn, reduce energy waste and environmental pollution. Two graduate students will be educated in this program, and the team will reach out to underrepresented minorities in the Chicago area.

CBET-1248221
PI: Huang

The travel grant request is for partial travel support for graduate students presenting posters in a Poster Symposium at the ASME Micro-Nano Technology Forum at the ASME IMECE 20112 in Houston, TX. The plan is to support nearly 40 meritorious graduate students from a pool of nearly 150-200 posters that will be presented during this forum. Students selected will be on the basis of merit and diversity.

Professional development of talented, diverse group of scientists in critical emerging areas is an important need for the nation and a priority for NSF. The travel grant is focused on doctoral students preparing for careers in academia and industry and in the vital technological area of nano and micro technology that NSF, CBET and the Thermal Transport program have heavily invested in for over a decade. The ASME IMECE is the premier conference for mechanical engineers and in the nano-technology area, and is therefore a good venue for the proposed poster presentations. The students will be exposed to cutting edge emerging research across the country and world, and those presenting will be able to further develop their professional skills in technical presentations. Beyond that, students attending will have the opportunity to learn from a variety of sources, as approximately 2000 presentations are generally presented at this annual meeting, further facilitating idea development for future careers in research. It is anticipated based on previous year attendance that over 150 presentations will be made, and there will be over 300 attendees.

Nano technology science research is now maturing and leading to transformational technology. Supporting this grant will foster interactions between budding researchers and entrepreneurs and will promote the technology and its transformational aspects.

The conference is expected to help in professional development, and students will be supported with an eye on diversity and encouraging under-represented group participation. Student selection will be done by an expert panel organized by the PIs from the posters submitted to the symposium. Opportunities that exist for postdoctoral positions and faculty as well as opportunities facilitated by other governmental agencies (e.g. DoD) will allow for important career development analyses. By attending, students will also have the option to attend professional development workshops and seminars that go beyond the traditional scientific development into areas important for career success, such as public speaking skills and resume/CV preparation.

Iowa State University (ISU) is organizing a workshop focused on the knowledge, technology, and education needed to engineer agricultural products that are robust under changing climate. The ultimate goal is to develop a research and educational roadmap for engineered crops, of interest to the EPSCoR community because many jurisdictions are rural and have a strong agricultural heritage. The workshop is bringing together plant scientists, with expertise in improving crop performance, and engineers with knowledge of transport phenomena, thermodynamics, and modeling, to unlock the underlying structural and physiological properties of superior plant varieties. Engineering- and physics-based modeling of transport phenomena in plants is still in its infancy, but approximate models have been made and verified experimentally to describe the transport of water and sugar in plants. This workshop provides opportunities for plant scientists and engineers to develop a common language for engineered crops, share ongoing research, form new partnerships, and design the discipline of "plant engineering" - a cyber-enabled framework that will support accelerated crop design with desired optimal performance.

Intellectual Merit

Food security is among the top challenges facing humanity. Environmental stresses due to climate change are accelerating the need for plant modifications, either naturally or through genetic engineering. As a step towards addressing these challenges, ISU's workshop focuses on the emergence of engineering design methods rooted in plant physiology and transport phenomena, to develop improved crops with increased yield and/or better tolerance to abiotic stresses caused by climate change. These technologies have reached a stage where fundamental questions about optimal crop phenotypes can be answered, and the answers efficiently translated into crop improvement. The goal of tailoring crops using engineering know-how coupled with genetic engineering is novel, promising, and challenging. Workshop products include a written roadmap summarizing the necessary education, research and development to advance engineered crops, as well as publications, and a website for displaying outcomes.

Broader Impacts

There is a constant need to improve the efficiency and yield of global agricultural crop production in order to increase food supply. This workshop at ISU will offer opportunities to scientists and engineers from EPSCoR jurisdictions to develop an interdisciplinary approach towards the design and study of engineered crops. Activities in the workshop will highlight the contributions of agricultural businesses and researchers in EPSCoR jurisdictions to the development of engineered plants, and the education of future researchers able to work in this field. Workshop recruitment efforts focus on junior faculty and students from EPSCoR jurisdictions, including from community colleges and schools in the nearby locale that have high underrepresented minority science, technology, engineering, and mathematics enrollments.