Polymer-based wide-angle micro -optic lens system with dynamically variable focal length and field of view

A novel polymer-based integrated wide-angle dynamic micro-optical lens system that can provide variable focal length and field of view (FOV) with large numerical aperture is designed, fabricated, and tested for its optical characteristics. Initial experiments were conducted using static glass lenses to test for configuration of lenses that could provide wide FOV. From these initial experiments, it was found that the higher FOV could be achieved with double concave (DCV) lenses compared to double convex (DCX) lenses of the same focal length. Further, it was observed that increasing the number of DCV lenses increases FOV. Thus, an integrated dynamic polymer microlens system has been fabricated with two or three DCV lenses, which demonstrates a wide range of tunable focal length and FOV. A flexible polydimethylsiloxane (PDMS) polymer membrane is used to form the lens surface. Two such membranes with a fluidic lens chamber are actuated by fluidic pressure to form either a DCX or DCV lens. The curvature of the lens (PDMS membrane) changes because of the fluidic pressure built by a syringe pump and produces the change in the focal length and FOV without any mechanical moving parts. The relationship between the focal length and FOV of the dynamic microlens system with respect to the change in volume of the fluid pumped in or out of the lens chamber has been investigated and reported. Experimental results show that a focal length in the range of several hundred microns to several millimeters and the smallest f-number equal to 0.76, which corresponds to a numerical aperture of 0.55, could be achieved using a single dynamic microlens system. It was observed that the FOV in the range of 0.12 to 61.08 degrees and 7 to 68.22 degrees could be achieved by actuating a single dynamic microlens system, as a DCX and DCV lens. It was also observed that the FOV could be tuned in the range of 8 to 79.65 degrees and 11.49 to 90.44 degrees, by using integrated dynamic microlenses with two or three DCV lenses, respectively. (Abstract shortened by UMI.

Experimental Study of Material Removal at Nanoscale

In order to develop nano-machining into a viable and efficient process, there is a need to achieve a better understand the relation between process parameters (such as feed, speed, and depth of cut) and resulting geometry. In this study, a comprehensive experimental parametric study was conducted to produce a database that is used to select proper machining conditions for guiding the fabrication of precise nano-geometries. The parametric studies conducted using AFM nanosize tips showed the following: normal forces for both nano-indentation and nano-scratching increase as the depth of cut increases. The indentation depth increases with tip speed, but the depth of scratch decrease with increasing tip speed. The width and depth of scratched groove also depend on the scratch angle. The recommended scratch angle is at 90°. The surface roughness increases with step over, especially when the step over is larger than the tip radius. The depth of cut also increases as the step over decreases

V2O5/Graphene Hybrid Supported on Paper Current Collectors for Flexible Ultrahigh-Capacity Electrodes for Lithium-Ion Batteries

An ultrahigh-capacity, flexible electrode made with vanadium pentoxide/graphene (with a specific capacity of 396 mAh/g) supported on paper-based current collectors has been developed. The ultrahigh-capacity graphene-modified vanadium pentoxide is fabricated by incorporating graphene sheets (2 wt %) into the vanadium pentoxide nanorods to improve the specific capacity, cycle life, and rate capability. This active material is then incorporated with the paper-based current collectors [carbon nanotube (CNT)–microfiber paper] to provide flexible electrodes. The flexible current collector has been made by depositing single-wall CNTs over wood microfibers through a layer-by-layer self-assembly process. The CNT mass loading of the fabricated current collectors is limited to 10.1 μg/cm2. The developed electrodes can be used to construct the flexible battery cells, providing a high-capacity/energy and rechargeable energy storage unit for flexible electronic devices

Poly(vinylidene fluoride-hexafluoropropylene) polymer electrolyte for paper-based and flexible battery applications

Paper-based batteries represent a new frontier in battery technology. However, low-flexibility and poor ionic conductivity of solid electrolytes have been major impediments in achieving practical mechanically flexible batteries. This work discuss new highly ionic conductive polymer gel electrolytes for paper-based battery applications. In this paper, we present a poly(vinylidene fluoride-hexafluoropropylene) (PVDH-HFP) porous membrane electrolyte enhanced with lithium bis(trifluoromethane sulphone)imide (LiTFSI) and lithium aluminum titanium phosphate (LATP), with an ionic conductivity of 2.1 × 10−3 S cm−1. Combining ceramic (LATP) with the gel structure of PVDF-HFP and LiTFSI ionic liquid harnesses benefits of ceramic and gel electrolytes in providing flexible electrolytes with a high ionic conductivity. In a flexibility test experiment, bending the polymer electrolyte at 90° for 20 times resulted in 14% decrease in ionic conductivity. Efforts to further improving the flexibility of the presented electrolyte are ongoing. Using this electrolyte, full-cell batteries with lithium titanium oxide (LTO) and lithium cobalt oxide (LCO) electrodes and (i) standard metallic current collectors and (ii) paper-based current collectors were fabricated and tested. The achieved specific capacities were (i) 123 mAh g−1 for standard metallic current collectors and (ii) 99.5 mAh g−1 for paper-based current collectors. Thus, the presented electrolyte has potential to become a viable candidate in paper-based and flexible battery applications. Fabrication methods, experimental procedures, and test results for the polymer gel electrolyte and batteries are presented and discussed

Paper-Based Flexible Lithium-Ion Batteries

Paper-based flexible batteries have a wide range of applications in paper-based platforms, including in paper electronics, packaging, product displays, greeting cards, and sensors. This poster will present lithium-ion batteries using flexible paper-based current collectors. These current collectors were fabricated from wood microfibers that were coated with carbon nanotubes (CNT) through an electrostatic layer-by-layer nanoassembly process. The use of paper-based current collectors provides flexibility and improved electrode adhesion. Electrodes were fabricated by casting thin layers of lithium titanium oxide, lithium cobalt oxide or lithium magnesium oxide on the conductive paper. Half-cell and full-cell devices were fabricated and tested. The results show that the presented batteries use reduced mass loading of carbon nanotubes (10.1 μg/cm2) compared to CNT film based batteries. Experimental capacities of the half-cell devices were measured to be 150 mAh/g for lithium cobalt oxide, 158 mAh/g for lithium titanium oxide, and 130 mAh/g for lithium magnesium oxide. Device designs, fabrication processes of paper-based current collectors, electrodes, and batteries, and further experimental results, including solid electrolytes, will be presented

Learning at the Nano-level: Exploring the unseen and accounting for complexity in how (and why) secondary STEM teachers learn

poster abstractThis study utilizes IUPUI’s Nanotechnology Discovery Academy (INDA) for secondary Science, Technology, Engineering and Math (STEM) teachers (n=13) as its starting point for exploring issues related to teacher learning and professional development (PD). Pilot data was collected as part of an evaluation of INDA during the summer of 2013. Teacher professional learning is often represented as the measurable change (e.g. content knowledge, pedagogical content knowledge, self-efficacy, etc.) that occurs via PD “best practices.” However, following constructivism, the processes of knowledge construction are complex, and what is learned — and, more importantly, how and why it is learned — is itself an assemblage of experiences oftentimes particular to the individual learner. Our preliminary findings suggest that while teacher perceptions of their pedagogical development and confidence may increase, their learning outcomes and subsequent practice take shape in relation to each individual’s teaching/learning history and the political and socioeconomic reality of their school. With teacher PD remaining an important focus of U.S. educational policy, it is important to correctly characterize the emergent outcomes of PD interventions to better understand how teachers learn, what constrains their learning and practice, and how teacher professional learning can, in turn, be mobilized to empower both teachers and their students

Electrospun Nanofibers for Label-Free Sensor Applications

Electrospinning is a simple, low-cost and versatile method for fabricating submicron and nano size fibers. Due to their large surface area, high aspect ratio and porous structure, electrospun nanofibers can be employed in wide range of applications. Biomedical, environmental, protective clothing and sensors are just few. The latter has attracted a great deal of attention, because for biosensor application, nanofibers have several advantages over traditional sensors, including a high surface-to-volume ratio and ease of functionalization. This review provides a short overview of several electrospun nanofibers applications, with an emphasis on biosensor applications. With respect to this area, focus is placed on label-free sensors, pertaining to both recent advances and fundamental research. Here, label-free sensor properties of sensitivity, selectivity, and detection are critically evaluated. Current challenges in this area and prospective future work is also discussed

FABRICATION OF A THIN FILM SOLAR CELLS USING LAYER BY LAYER (LBL) NANOASSEMBLY OF COPPER INDIUM GALLUIM SELENIUM (CIGS) NANOPARTICLES

poster abstractCopper Indium Gallium Selenium (CIGS), a p-type semiconductor material with a tunable band gap, has been broadly studied for high efficiency solar cells as a viable sustainable energy source. Production of CIGS nanoparticles gives the ability of fabricating thin, light, and flexible solar cells. However, the current fabrication technologies of such devices are still very costly. This poster presents the synthesis and functionalization of CIGS nanoparticles and proposes Layer-by-Layer (LbL) nanoassembly process, as a low cost method, to fabricate thin films for solar cell applications. The results show that the synthesized CIGS particles have 1.3 ev band gap and 30 nm diameter in av-erage. These particles were later coated with polymers to provide alternative opposite surface charges suitable for LbL process. Deposition of 20 layers of the particles on indium tinoxide (ITO) coated glass formed a thin film with 220 nm thickness. The measured current voltage (I-V) characteristic of the film gave resistivity of 7.9 MΩ.m in dark and 2.25 MΩ.m under light illumina-tion. A prototype solar cell made out of the film resulted in short circuit cur-rent density (JSC) of 0.3 mA/cm2 and open circuit voltage (VOC) of 0.7 V

SYNTHESIS AND FUNCTIONALIZATION OF CIGS NANOPARTICLES FOR LBL DEPOSITION

poster abstractCopper Indium Gallium Diselenide (CIGS) solar cells have been used widely in thin film solar cells due to their high attainable efficien-cy and tunable band gap. The cost of solar cell manufacturing needs to be further reduced to make CIGS solar cells economically viable. The main objective of this research is to repeatedly and accurately synthe-size CIGS nanoparticles in a desired ratio to allow for an efficient band gap and dispersion in an aqueous solution for Layer-by-Layer (LbL) nanoassembly. CIGS nanoparticles have been synthesized by arrested precipitation in Oleylamine solution. The particles were purified utiliz-ing chloroform, ethanol, and water via centrifugation. The purified na-noparticles were down to a size of 15 nm with average size of 60 nm. A ligand exchange was performed to remove the capping agent, Oleylamine, and replace it with 11-mercaptoundecanoic acid, a thiol ligand. The thiol ligand used had charged functional groups resulting in the functionalized particles with expected high negative zeta potential for stable dispersion. Lastly, the nanoparticles were analyzed through the utilization of X-ray diffractive spectroscopy (XRD), transmittance spectroscopy, energy-dispersive x-ray spectroscopy (EDS) and a scan-ning electron microscope (SEM). Using the oppositely charged disper-sion in aqueous solutions, multiple size-controlled layers of CIGS can be obtained using Layer-by-Layer nanoassembly, creating a solar cell. The synthesis, characterization and functionalization results will be presented in the poster

Preparing ECE Students for Research Career in Nanotechnology via Track Program

Abstract: This paper details the research participation of undergraduate students from the freshman to the senior year. Four courses were designated to prepare students for a nanotechnology research career. New modes of instructions leading to research participation followed in this curriculum have been reported. This covers integration of knowledge, just in time approach, and project portfolio based curriculum. Courses developed in this track emphasize research and applications in health sciences and renewable energy areas. The structure of the track program was presented before with emphasis on the senior level courses of the track. The work in this paper, however, emphasizes research participation in nanotechnology of the junior students within the electrical engineering, computer engineering, and mechanical engineering disciplines. The multidisciplinary components in nanotechnology research topics were attractive to students to work in team. The topics covered in this course included nanotechnology applications in diabetes, cancer research, and neurosciences. Lecture materials were all from up-to-date research papers, and can be altered with the course updates. Students registered for this course were required to emphasize two research topics seven week each, and prepare research posters in a research day where industrial representatives are invited to participate in the discussions with students. Students who completed this course were interested to continue with nanotechnology individual research and get enrolled in upper level courses. The course starts with introducing students to the nanotechnology applications in various fields, including environment, society, consumer electronics, computers, health sciences, optics, electromagnetics, energy, and medical imaging. The course then introduces students to research issues emphasizing health sciences and renewable energy. Students will be required to expand their research to cover in depth one or two research issues that fall within their interests. In the research projects, students work in team, two students/team, and assignment is given to bath to share the contribution of the project. The course was assessed with student satisfaction, and the objectives and the outcomes of the course were met