| 1. |
- Andersson, Henrik, Dr, 1975-, et al.
(author)
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Variable low-density polylactic acid and microsphere composite material for additive manufacturing
- 2021
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In: Additive Manufacturing. - : Elsevier BV. - 2214-8604 .- 2214-7810. ; 40
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Journal article (peer-reviewed)abstract
- Thermally expandable microspheres are extensively used in industry as a lightweight filler for many products. The spheres can expand up to 60 times the initial size and are used for different purposes, including material reduction and surface modification. In fused filament fabrication (FFF), a material is deposited in a layer-by-layer process. Typically, FFF objects need not be solid because such objects are typically used for applications with low mechanical stress. Low material infill percentages are commonly used inside a solid outer shell to reduce material usage, weight, and manufacturing time. This paper proposes a new composite filament for FFF consisting of polylactic acid (PLA) and thermally expandable Expancel microspheres in the form of masterbatch granules. These filaments contain unexpanded microspheres that can be expanded during printing by heating. Two types of filaments containing 2 wt% and 5 wt% of masterbatch granules were manufactured and tested. The filaments were successfully used with a commercial 3D printer to manufacture objects with a density of 45% compared to objects manufactured using standard PLA. The tensile strength of these objects changed linearly with density and was comparable to that of PLA objects of the same density prepared using infill patterns. The composite filaments are advantageous in that they can reduce the amount of material used, as is currently done by using different amounts of infill in a pattern. Further, by varying the nozzle temperature, their density can be adjusted directly during printing as well as during fabrication to produce layers of different densities in the same object.
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| 2. |
- Andres, Britta, 1986-
(author)
-
Low-Cost, Environmentally Friendly Electric Double-Layer Capacitors : Concept, Materials and Production
- 2017
-
Doctoral thesis (other academic/artistic)abstract
- Today’s society is currently performing an exit from fossilfuel energy sources. The change to sustainable alternativesrequires inexpensive and environmentally friendly energy storagedevices. However, most current devices contain expensive,rare or toxic materials. These materials must be replaced bylow-cost, abundant, nontoxic components.In this thesis, I suggest the production of paper-based electricdouble-layer capacitors (EDLCs) to meet the demand oflow-cost energy storage devices that provide high power density.To fulfill the requirements of sustainable and environmentallyfriendly devices, production of EDLCs that consist of paper,graphite and saltwater is proposed. Paper can be used as aseparator between the electrodes and as a substrate for theelectrodes. Graphite is suited for use as an active material in theelectrodes, and saltwater can be employed as an electrolyte.Westudied and developed different methods for the productionof nanographite and graphene from graphite. Composites containingthese materials and similar advanced carbon materialshave been tested as electrode materials in EDLCs. I suggest theuse of cellulose nanofibers (CNFs) or microfibrillated cellulose(MFC) as a binder in the electrodes. In addition to improvedmechanical stability, the nanocellulose improved the stabilityof graphite dispersions and the electrical performance of theelectrodes. The influence of the cellulose quality on the electricalproperties of the electrodes and EDLCs was investigated.The results showed that the finest nanocellulose quality is notthe best choice for EDLC electrodes; MFC is recommended forthis application instead. The results also demonstrated thatthe capacitance of EDLCs can be increased if the electrodemasses are adjusted according to the size of the electrolyte ions.Moreover, we investigated the issue of high contact resistancesat the interface between porous carbon electrodes and metalcurrent collectors. To reduce the contact resistance, graphitefoil can be used as a current collector instead of metal foils.Using the suggested low-cost materials, production methodsand conceptual improvements, it is possible to reduce the material costs by more than 90% in comparison with commercialunits. This confirms that paper-based EDLCs are apromising alternative to conventional EDLCs. Our findings andadditional research can be expected to substantially supportthe design and commercialization of sustainable EDLCs andother green energy technologies.
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| 3. |
- Arshadi Rastabi, Shahrzad, et al.
(author)
-
Metallurgical investigation of aluminum anode behavior in water-in-salt electrolyte for aqueous aluminum batteries
- 2022
-
In: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 523
-
Journal article (peer-reviewed)abstract
- Although ionic liquid electrolytes (ILs) are environmentally unfriendly, they are the most common electrolyte used in aluminum-ion batteries (AIB). Aqueous electrolytes offer a more sustainable alternative, but problem with oxide passivating barrier on Al surface becomes more profound. Recently, a new sub-class of aqueous electrolytes, water-in-salt (WIS) of (AlCl3·6H2O), has been considered, but experimental validation of the behavior of the Al electrode over cycling is required. This work investigates aluminum/graphitic cells using WIS electrolytes with a mass ratio of salt to water of 4, 8, and 12 and finds that they show similar trends in cycling performance. The degradation observed over cycling has been attributed to the formation of a detrimental solid electrolyte interphase (SEI) layer on the Al surface. It was found that WIS 4 increased Al corrosion, resulting in a slightly higher capacity and longer cycling life. Metallurgical observation showed that the Al matrix has a tendency to initiate corrosion around Al3Fe intermetallic phases in both WIS and ILs. This implies that the presence of Al3Fe particles allows the electrolyte to break the oxide barrier and access the bulk Al. These results suggests that metallurgical treatments are important to enhance the electrochemical performance of AIB.
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| 4. |
- Arshadi Rastabi, Shahrzad, et al.
(author)
-
Porous NiMoO4-NrGO as a Battery-Like Electrode Material for Aqueous Hybrid Supercapacitors
- 2023
-
In: Journal of Composites Science. - : MDPI. - 2504-477X. ; 7:6
-
Journal article (peer-reviewed)abstract
- Recently, much research has investigated nanocomposites and their properties for the development of energy storage systems. Supercapacitor performance is usually enhanced by the use of porous electrode structures, which produce a larger surface area for reaction. In this work, a biocompatible polymer of starch medium was used to create the porous nanostructure. Two powders, i.e., Nickel molybdate/reduced graphene oxide (NiMoO4-rGO) and Nickel molybdate/nitrogen-doped reduced graphene oxide (NiMoO4-NrGO), were synthesized using the deposition method in a medium containing starch, nickel nitrate salts, sodium molybdate, and graphene oxide powder. In terms of electrochemical performance, the NiMoO4-NrGO electrode displayed a higher specific capacitance, i.e., 932 Fg−1 (466 Cg−1), than the NiMoO4-rGO electrode, i.e., 884 Fg−1 (442 Cg−1), at a current density of 1 Ag−1. In fact, graphene oxide sheets could lose more oxygen groups in the presence of ammonia, resulting in increased electrical conductivity. For the asymmetric supercapacitor of NiMoO4-NrGO//AC, the specific capacitance at 1 Ag−1, energy density, and power density were 101.2 Fg−1 (111.32 Cg−1), 17 Wh kg−1, and 174.4 kW kg−1, respectively. In addition, this supercapacitor material displayed a good cycling stability of over 82%.
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| 5. |
- Bond, Luke, et al.
(author)
-
Electrically conductive polymer-graphene composite material for selective laser sintering additive manufacturing
- 2024
-
In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE - The International Society for Optics and Photonics. - 9781510670068
-
Conference paper (peer-reviewed)abstract
- Additive manufacturing is rapidly growing, where selective laser sintering technology dominates for industrial use. In the case of polymer selective laser sintering, polyamide is the standard material. However, polyamide is an electrical insulator, and for specific applications, it would be desirable to be able to manufacture polymer-based electrically conductive parts. Electromagnetic Compatibility is one of the most significant targeted applications, where the introduction of electric vehicles raises new electromagnetic compatibility demands. The goal is, therefore, to develop an electrically conductive composite material for selective laser sintering using graphene as the additive. Composites are prepared by mixing polyamide, graphene, and additives with varying graphene/polyamide ratios. The aim of this investigation is the laser-assisted processing of the resulting graphene/polyamide composites with various parameters to sinter the material, forming a solid conductive structure. The structure is characterized using SEM and resistance measurements. Results show sheet resistance values of about 700Ω/sq after laser-assisted processing with good powder flowability.
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| 6. |
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| 7. |
- Ebadi, Seyed Morteza, et al.
(author)
-
A Highly-Efficient and Compact Surface Plasmon Polaritons High-Pass Filter based on MIM waveguides
- 2020
-
In: <em>Frontiers in Optics / Laser Science</em>. - Washington, D.C., United States : Optics Info Base, Optical Society of America. - 9781943580804 ; , s. 1-2
-
Conference paper (peer-reviewed)abstract
- This letter presents design and simulation results of a highly-efficient and compact plasmonic high-pass filter based on a MIM waveguide. Numerical results reveal that by tailoring structural parameters, desired cut-off wavelength can be chosen.
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| 8. |
- Ebadi, Seyed Morteza, et al.
(author)
-
A Multipurpose and Highly-Compact Plasmonic Filter based on Metal-Insulator-Metal Waveguides
- 2020
-
In: IEEE Photonics Journal. - 1943-0655. ; 12:3
-
Journal article (peer-reviewed)abstract
- A multipurpose and ultra-compact nanoplasmonic wavelength filter based on stub structure in a metal-insulator-metal (MIM) waveguide is suggested and numerically investigated. A novel approach of connecting two stepped-like apertures to both input and output ports is applied to form Fabry-Perot (FP) cavities, which enabled the structure to act as a dual band-pass filter at wavelengths 1310 nm and 1550 nm. It is shown that the variation in cavities’ length allows to realize a long-wavelength cutoff filter, and cutoff wavelength can be easily tuned by adjusting the length of the cavities. Furthermore, it is revealed that increasing the gap between the stepped-like apertures and the cavities provides a triple band-pass at telecom wavelengths, e.g. 1267.5nm, 1414.19 nm, and 1644.7 nm. The tunable broadband high-pass wavelength filter is then achieved while the lengths of stepped-like apertures and stub resonators are set to be identical. Finally, a tunable nearly perfect absorber can be obtained by varying the width of stub resonators. Therefore, because of functionality, size, as well as efficiency the proposed plasmonic filter may greatly contribute to miniaturization of next generation of photonic integrated circuits (PICs), and find applications in on-chip integration and wavelength-division multiplexing (WDM) in optical communication systems.
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| 9. |
- Ebadi, Seyed Morteza, et al.
(author)
-
A Reconfigurable and Ultra-Compact Plasmonic Filter based on MIM Waveguides at Optical Channels
- 2020
-
In: <em>OSA Advanced Photonics Congress (AP) 2020</em>. - : Optics Info Base, Optical Society of America. - 9781943580798
-
Conference paper (peer-reviewed)abstract
- This paper reports design and simulation of a tunable highly-efficient reconfigurableplasmonic filter based on MIM waveguides. Simulation results shown that by adjusting structuralparameters, the device can work as a multipurpose optical circuit.
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| 10. |
- Ebadi, Seyed Morteza, et al.
(author)
-
A Tunable and Highly-Efficient Plasmonic Band-Stop Filter at Telecom Wavelengths
- 2021
-
In: 2021 IEEE Research and Applications of Photonics in Defense Conference (RAPID). - Miramar Beach, FL, USA : Institute of Electrical and Electronics Engineers (IEEE). - 9781665446747 - 9781665422239 ; , s. 1-2
-
Conference paper (peer-reviewed)abstract
- This paper reports design and numerical results of an ultra-compact, efficient and tunable plasmonic band-stop filter based on a metal-insulator-metal waveguide at optical channels. Furthermore, a wide-bandgap can be easily achieved by adjusting the width of the of the stub resonator.
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| 11. |
- Ebadi, Seyed Morteza, et al.
(author)
-
A Tunable Plasmonic Wide Flat-Top Band-Pass Filter based on Trapezoid Resonator at Near-Infrared
- 2021
-
In: OSA Advanced Photonics Congress 2021. - : Optics Info Base, Optical Society of America. - 9781943580941 ; , s. 1-2
-
Conference paper (peer-reviewed)abstract
- A miniaturized and efficient tunable wide flat-top band-pass filter at NIR is proposed in a MIM plasmonic waveguide. Furthermore, numerical results illustrate that tunability is readily attained by varying length of right-angle trapezoid resonator.
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| 12. |
- Ebadi, Seyed Morteza, et al.
(author)
-
A Tunable Wide Flat-Top Band-Pass Plasmonic Filter basedon Tilted T-Junction Resonators at Near-Infrared
- 2021
-
In: 2021 IEEE 21st International Conference on Nanotechnology (NANO). - Montreal, QC, Canada : Institute of Electrical and Electronics Engineers (IEEE). - 9781665441575 - 9781665441568 ; , s. 54-55
-
Conference paper (peer-reviewed)abstract
- A highly efficient and compact wide flat-top band-pass filter at NIR is realized in a MIM plasmonic waveguide.Besides, simulation results reveal that through tuning the length of resonators, a broadband band-pass transmission can beeasily achieved.
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| 13. |
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| 14. |
- Ebadi, Seyed Morteza, et al.
(author)
-
An Extremely Miniaturized and Highly-Efficient High-Pass Wavelength Plasmonic Filter at Near-Infrared
- 2020
-
In: <em>Frontiers in Optics / Laser Science</em>. - : Optics Info Base, Optical Society of America. - 9781943580804 ; , s. 1-2
-
Conference paper (peer-reviewed)abstract
- This letter describes design and numerical simulation of an extremely-compact and efficient high-pass plasmonic filter based on MIM waveguides. Numerical results shown that by tuning structural parameters, desired cut-off wavelengths can be chosen.
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| 15. |
|
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| 16. |
- Ebadi, Seyed Morteza, et al.
(author)
-
Chip-Scale and Tunable Flat-Top Surface Plasmon Polaritons Band-pass Filter at Optical Channels
- 2021
-
In: 2021 IEEE Research and Applications of Photonics in Defense Conference (RAPID). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665446747 - 9781665422239 ; , s. 1-2
-
Conference paper (peer-reviewed)abstract
- We present the design and simulation results of a highly-miniaturized and efficient flat-top plasmonic band-pass filter based on a MIM waveguide. In addition to that, it is revealed that by adjusting the length of stub segment, the desired spectral response can be easily realized.
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| 17. |
- Ebadi, Seyed Morteza
(author)
-
Design and Numerical Modelling of Nanoplasmonic Structures at Near-Infrared for Telecom Applications
- 2022
-
Licentiate thesis (other academic/artistic)abstract
- Industrial innovation is mostly driven by miniaturization. As a result of remarkable technological advancements in the fields of equipment, materials and production processes, transistor, the fundamental active component in conventional electronics, has shrunk in size. Semiconductor technology is unique in that all performance metrics are enhanced, while at the same time unit prices are reduced. Moore’s Law, which predicts that the number of components per chip will double every two years, was established in 1965, and the industry has been able to keep up with this prophetic prognosis since. Thermal management, on the other hand, has become a key limiting factor for current electronic circuits and is set to put a stop to Moore’s Law. Given the fact that complementary metal oxide semiconductor (CMOS) scaling is reaching fundamental limits, there are several new alternative processing devices and architectures that have been investigated for both traditional integrated circuit (IC) technologies and novel technologies, including new technologies aimed at contributing to advances in scaling progress and cost reductions in manufacturing operations in the coming decades. These factors will encourage the development of new information processing and memory systems, new technologies for integrating numerous features heterogeneously and new system architectural design layouts, among other things. Energy efficiency is advantageous from a sustainability perspective and for consumer electronics, for which fewer power-hungry components mean longer times between charges and smaller batteries. The creation of novel chip-scale tools that can aid in the transfer of information across optical frequencies and microscale photonics between nanoscale electronic devices is now a possibility. Bridging this technological gap may be achieved by plasmonics. The incorporation of plasmonic, photonic and electrical components on a single chip may lead to a number of innovative breakthroughs. Photonic integrated circuits (PICs) enable the realization of ultra-small, high-efficiency, ultra-responsive and CMOS-compatible devices that can be used in applications ranging from optical wireless communication systems (6G and beyond) and supercomputers to health and energy. This thesis provides a platform from which to design nanoplasmonic devices while facilitating high-transmission and/or absorption efficiency, miniaturized size and the use of near-infrared (NIR) wavelengths for telecom applications. With a significant amount of Internet traffic transmitted optically, communication systems are further tightening the requirements for the development of new optical devices. Several new device structures based on the metal-insulator-metal (MIM) plasmonic waveguide are proposed and investigated using performance metrics. The transmission line theory (TLM) from microwave circuit theory and coupled mode theory (CMT) is studied and employed in the design process of the nanostructures, in particular to address the losses in plasmonic-based devices, which has been the major factor hampering their widespread usage in communication systems. By taking advantage of well-established microwave circuit theory (through new design that paves the way for mitigating these losses and enabling efficient transmission of power flow in the optical devices), we have suggested a number of high-transmission efficiency nanodevices that offer highly competitive performance compared with other platforms. As a result, a promising future for plasmonic technology, which would enable design and fabrication of multipurpose and multifunctional optical devices that are efficient in terms of losses, footprint and capability of integrating active devices, is anticipated.
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| 18. |
- Ebadi, Seyed Morteza, et al.
(author)
-
Design of miniaturized wide band-pass plasmonic filters in MIM waveguides with tailored spectral filtering
- 2024
-
In: Optical and quantum electronics. - : Springer Nature. - 0306-8919 .- 1572-817X. ; 56:5
-
Journal article (peer-reviewed)abstract
- This paper reports the design and numerical results of three new extremely compact and efficient flat-top band-pass plasmonic filters operating in the near-infrared region. The proposed structures are realized in metal–insulator-metal plasmonic waveguides based on stub, tilted T-junction and right-angle trapezoid configurations. A built-in parameterized genetic algorithm is applied to maximize the transmission efficiency, while at the same time contributing to shrinking down the size of the device structures. It is shown that the tunability of the optical filters can be realized by modulating their structural parameters to gain control over the band-pass filtering wavelengths. Numerical calculations are conducted based on the finite element method of CST Microwave Studio and demonstrate that the suggested ultra-compact plasmonic waveguide filters offer wide bandwidths of more than 270 nm, 424 nm, and 289 nm, with transmission efficiencies of higher than 80%, 74.2%, and 74.3%, respectively. The sizes of the proposed wavelength filters are 490 nm × 575 nm, 350 nm × 180 nm, and 420 nm × 150 nm, respectively, which make them attractive candidates for applications in high density photonic integrated circuits (PICs). As a result, because of the promising characteristics of the proposed topologies such as their high efficiency, compact size, tunability, and simple structure they may find applications in on-chip integration, laser technology, and multi-photon fluorescence.
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| 19. |
- Lundberg, Anna, et al.
(author)
-
Aggregation of Color pigments by Surface fixation treatment
- 2011
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In: Journal of Imaging Science and Technology. - 1062-3701 .- 1943-3522. ; 55:5, s. 1-8
-
Journal article (peer-reviewed)abstract
- The quality of a printed image is strongly influenced by the physical and the chemical interactions between the ink and the paper. Print quality can be evaluated either by objective measurements using instruments or by visual assessment studies involving panel of observers judging the final print. In this article, the print quality on commercial papers as well as on non-commercial papers with different amounts of salt for surface fixation has been studied. Perceived detail reproduction depends not only on sharp edge definition but also on the level of color saturation (Chroma). Color saturation and edge definition originate from two different ink and paper interaction processes. Color saturation is heavily dependent on ink penetration while edge definition correlates to ink spreading. In order to gain understanding of the performance of surface treatment by salt, large efforts have been put on splitting up of the increase in color saturation (Chroma) and improved edge definition. The printouts have been made with a desktop printer using pigmented inks. Cross section images have been taken with a light microscope to analyze the ink penetration depth. SEM analysis has been made to analyze the aggregation of the pigments on the surface. The print quality measurements have been both objective measurements such as print density and subjective image evaluation using a test panel of observers in a perceptual study. The perceptual study focused on detail reproduction, and efforts were made to separate the influence of the print density from the edge definition on the detail reproduction. The result from this study shows that an increased level of salt as surface fixation improves the detail reproduction due to aggregation of the pigments on the surface and that the ink penetration depth can be reduced by adding salt as surface fixation resulting in a higher print density.
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| 20. |
- Lundberg, Anna, 1977-, et al.
(author)
-
Improved Print quality by Surface fixation of Pigments
- 2010
-
In: International Conference on Digital Printing Technologies. - : The Society for Imaging Science and Technology. - 9780892082933 ; , s. 251-255
-
Conference paper (peer-reviewed)abstract
- Inkjet printing is a non impact printing method that deposits a limited amount of ink onto the paper surface. To improve runnabillity and printability the demands on papers ability to rapidly absorb the fluid and make the colorants stay on the surface increase. These demands get more pronounced as the technology develops and the print speed significantly increases. The quality of a printed image is strongly influenced by the physical and the chemical interactions between the ink and the paper. Some print quality parameters can be measured objectively by physical measurements using instruments. Subjective print quality evaluation involves human judgments of the final print.In this article, the print quality on commercial papers as well as on trial papers with different amounts of salt for surface fixation has been studied. The printouts have been made with a desktop printer that uses pigmented inks. The print quality measurements have been both objective measurements such as print density and line quality and subjective image evaluation using a test panel in a perceptual study. The perceptual study focused on detail reproduction, and efforts were made to separate the influence of the print density from the edge definition on the detail reproduction. The study confirms the influence of ink and paper interaction on print quality and the relation to different levels of surface fixation.
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| 21. |
- Lundberg, Anna, 1977-, et al.
(author)
-
On the Effect of Variations in paper composition on print quality
- 2009
-
In: International Conference on Digital Printing Technologies 2009. - : The Society for Imaging Science and Technology. - 9780892082872 ; , s. 316-319
-
Conference paper (peer-reviewed)abstract
- During the last few years, digital printing technology has begun to play a significant role in the printing industry due to the quest for short runs and variable data printing. Digital printing using inkjet technology makes heavy demands on the paper's ability to rapidly absorb liquid and thereby increases the need to understand what parameters that affect the dynamics and interactions between paper and ink and how print quality is affected by these parameters. In this paper, the print quality for nine pilot papers with varying composition and eight different commercial papers has been studied. The printouts have been made with two small office/Home office printers; the print quality measurements for this study have been line quality-measurements and color -gamut volume measurements. The line quality and the color gamut volume for the commercial papers and the pilot papers are discussed.
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| 22. |
- Olsen, Martin, 1971-, et al.
(author)
-
Frequency and voltage response of a wind-driven fluttering triboelectric nanogenerator
- 2019
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1
-
Journal article (peer-reviewed)abstract
- Triboelectric nanogenerators (TENG:s) are used as efficient energy transducers in energy harvesting converting mechanical energy into electrical energy. Wind is an abundant source of mechanical energy but how should a good triboelectric wind harvester be designed? We have built and studied a TENG driven by air flow in a table-top sized wind tunnel. Our TENG constitutes of a plastic film of size10 cm × 2 cm which is fluttering between two copper electrodes generating enough power to light up a battery of LED:s. We measured the voltage and frequency of fluttering at different wind speeds from zero up to 8 m/s for three electrode distances 6 mm, 10 mm and 14 mm. We found that the frequency increases linearly with the wind speed with a cutoff at some low speed. Power was generated already at 1.6 m/s. We seem to be able to explain the observed frequency dependence on wind speed by assuming excitation of the film into different harmonics in response to von Kármán vortices. We also find that the voltage increase linearly with frequency. We anticipate that TENG:s of this design could be useful both as generators and speed sensors because they work at low air speeds.
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| 23. |
- Olsen, Martin, 1971-
(author)
-
Nanomechanics – Quantum Size Effects, Contacts, and Triboelectricity
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- Nanomechanics is different from the mechanics that we experience in everyday life. At the nano-scale, typically defined as 1 to 100 nanometers, some phenomena are of crucial importance, while the same phenomena can be completely neglected on a larger scale. For example, the feet of a gekko are covered by nanocontacts that yield such high adhesion forces that the animal can run up on walls and even on the ceiling. At small enough distances, matter and energy become discrete, and the description of the phenomena occurring at this scale requires quantum mechanics. However, at room temperature the transitions between quantized energy levels may be concealed by the thermal vibrations of the system. As two surfaces approach each other and come into contact, electrostatic forces and van der Waals forces may cause redistribution of matter at the nano level. One effect that may occur upon contact between two surfaces is the triboelectric effect, in which charge is transferred from one surface to the other.This effect can be used to generate electricity in triboelectric nanogenerators (TENGs), where two surfaces are repeatedly brought in and out of contact, and where the charge transfer is turned into electrical energy.This thesis concerns nanomechanics addressing whether quantum mechanics play a role in elastic deformation, as well as various mechanical aspects of nanocontacts including electric charging. The objectives are to contribute to the understanding when quantum effects are of importance at the nanolevel, increase the fundamental understanding of the mechanisms responsible for triboelectric phenomena and apply the triboelectric effect to a wind harvesting device.For more insight into whether quantum effects are of importance in nanomechanics, we use a one dimensional jellium model and the standard beam theory allowing the spring constant of an oscillating nanowire cantilever to be calculated. As the nanowire bends, more electron states fit in its cross section, giving rise to an amplitude dependent resonance frequency of the nanowire oscillations.Furthermore, a model for electric field induced surface diffusion of adatoms was developed. The model takes electrostatic forces and van der Waals forces into account as a voltage is applied between a scanning tunneling microscope tip and a sample. The calculated force on the adatoms at the surface of the sample, which is stemming from the inhomogeneous electric field and the dipole moment of the adatoms, is relatively small, but due to thermal vibrations adatoms diffuse and form mounds at the sample.When bringing two different materials into contact, the difference in triboelectric potentials between the materials results in electric charging. To increase the understanding of triboelectricity, a two-level Schottky model, assuming ion transfer, was developed to describe the temperature dependence of the triboelectric effect for a TENG. The two levels correspond to the binding energy for ions on the two surfaces that are brought into contact, where the difference in binding energy enters the Boltzmanndistribution. The model describes the decreasing triboelectric effect in TENG:s with increasing temperature as described in the literature, and results in a separation energy, which is of the right order of magnitude for physically adsorbed atoms.It was recently demonstrated that TENGs can convert wind energy into electrical energy. Here, a TENG based on a plastic film fluttering between two copper electrodes was constructed. It was found that the frequency of the the fluttering film increases linearly with the wind speed. TENG:s designed in this way generate electricity already at low wind speed, and we therefore expect such TENG:s to be useful both as generators and speed sensors in the future.While quantum mechanics is of importance in a limited number of nanomechanical systems, nanocontacts have a broader meaning, and are crucial for the understanding of triboelectric phenomena. We anticipate that the findings in this thesis will contribute to a better understanding of nanomechanics, in particular the mechanism of triboelectricity.
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| 24. |
- Olsen, Martin, 1971-, et al.
(author)
-
Schottky model for triboelectric temperature dependence
- 2018
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
-
Journal article (peer-reviewed)abstract
- The triboelectric effect, charging by contact, is the working principle in a device called a triboelectric nanogenerator. They are used as efficient energy transducers in energy harvesting. In such generators the charging of surfaces at contact is followed by a separation of the surfaces increasing the electrical energy which can subsequently be used. Different materials have different triboelectric potentials leading to charging at contact. The temperature dependence of the charging has just recently been studied: the triboelectric effect is decreasing with temperature for a generator of Al-PTFE-Cu. Here, we suggest a mechanism to explain this effect assuming ion transfer using a two-level Schottky model where the two levels corresponds to the two surfaces. The difference in binding energy for ions on the two surfaces then enters the formula for charging. We fit the triboelectric power density as a function of temperature obtained from a two-level Schottky model to measured data for nanogenerators made of Al-PTFE-Cu found in three references. We obtain an average separation energy corresponding to a temperature of 365 K which is of the right magnitude for physically adsorbed atoms. We anticipate that this model could be used for many types of triboelectric nanogenerators.
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| 25. |
- Patil, Rohan, 1983-
(author)
-
A scalable furnace technique to grow silicon nanoparticles for high-performance Li-ion battery anodes
- 2023
-
Licentiate thesis (other academic/artistic)abstract
- Lithium-ion batteries are one of the key technologies to address the global climate challenge. Higher battery capacity could also be seen as indirectly influencing the entire value chain. One way to increase capacity is to add silicon to the graphite anode, since silicon can store much more lithium ions than graphite. Several high-performance schemes utilizing silicon nano solutions have been demonstrated. However, industrial-scale implementation of these solutions still poses a challenge. In this thesis I present a novel scalable furnace technique to create silicon nanoparticles attached to the nanographite flakes. The novel furnace technique allows compatibility with already established industrial-scale electrode manufacturing techniques, presenting itself as a promising strategy for engineering electrodes with endurable performance.
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| 26. |
- Patil, Rohan, 1983-, et al.
(author)
-
Highly Stable Cycling of Silicon-Nanographite Aerogel-Based Anode for Lithium-Ion Batteries
- 2021
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:10, s. 6600-6606
-
Journal article (peer-reviewed)abstract
- Silicon anodes are considered as promising electrode materials for next-generation high-capacity lithium-ion batteries (LIBs). However, the capacity fading due to the large volume changes (∼300%) of silicon particles during the charge−discharge cycles is still a bottleneck. The volume changes of silicon lead to a fracture of the silicon particles, resulting in the recurrent formation of a solid electrolyte interface (SEI) layer, leading to poor capacity retention and short cycle life. Nanometer-scaled silicon particles are the favorable anode material to reduce some of the problems related to the volume changes, but problems related to SEI layer formation still need to be addressed. Herein, we address these issues by developing a composite anode material comprising silicon nanoparticles and nano graphite. The method developed is simple, cost-efficient, and based on an aerogel process. The electrodes produced by this aerogel fabrication route formed a stable SEI layer and showed high specific capacity and improved cyclability even at high current rates. The capacity retentions were 92 and 72% of the initial specific capacity at the 171st and the 500th cycle, respectively.
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| 27. |
- Phadatare, Manisha R., et al.
(author)
-
Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries
- 2019
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Journal article (peer-reviewed)abstract
- To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films. However, a method that allows the large-scale production of silicon anodes remains to be demonstrated. Herein, we address this question by suggesting new scalable nanomaterial-based anodes. Si nanoparticles were grown on nanographite flakes by aerogel fabrication route from Si powder and nanographite mixture using polyvinyl alcohol (PVA). This silicon-nanographite aerogel electrode has stable specific capacity even at high current rates and exhibit good cyclic stability. The specific capacity is 455 mAh g−1 for 200th cycles with a coulombic efficiency of 97% at a current density 100 mA g−1.
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| 28. |
- Razaz, Ghadir, et al.
(author)
-
Aluminum Alloy Anode with Various Iron Content Influencing the Performance of Aluminum-Ion Batteries
- 2023
-
In: Materials. - : MDPI AG. - 1996-1944. ; 16:3
-
Journal article (peer-reviewed)abstract
- Considerable research has been devoted to the development of cathode materials for Al-ion batteries, but challenges remain regarding the behavior of aluminum anodes. Inert oxide (Al2O3) film on Al surfaces presents a barrier to electrochemical activity. The structure of the oxide film needs to be weakened to facilitate ion transfer during electrochemical activity. This study addresses oxide film challenges by studying Al alloy anodes with different iron content. The results reveal that using an anode of 99% Al 1% Fe in a cell increases the cycling lifetime by 48%, compared to a 99.99% Al anode. The improvement observed with the 99% Al 1% Fe anode is attributed to its fractional surface area corrosion being about 12% larger than that of a 99.99% Al anode. This is coupled to precipitation of a higher number of Al3Fe particles, which are evenly scattered in the Al matrix of 99% Al 1% Fe. These Al3Fe particles constitute weak spots in the oxide film for the electrolyte to attack, and access to fresh Al. The addition of iron to an Al anode thus offers a cheap and easy route for targeting the oxide passivating film challenge in Al-ion batteries.
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| 29. |
- Zhang, Renyun, et al.
(author)
-
A review of the advances in composites/nanocomposites for triboelectric nanogenerators
- 2022
-
In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 33:21
-
Research review (peer-reviewed)abstract
- Material development is essential when studying triboelectric nanogenerators (TENGs). This importance is because the performance of TENGs is highly dependent on the properties of the utilized triboelectric materials. To obtain more specific properties, composites have been developed that combine the features of their components. According to Google Scholar, 55% of published papers related to triboelectric nanogenerators have utilized or mentioned composites. This number is 34.5% if one searches with the keyword nanocomposites instead of composites. The importance of composites is because they can exhibit new dielectric properties, better mechanical strength, enhanced charge affinities, etc. Therefore, the development of new composites has great importance in TENG studies. In this paper, we review the production of nanocomposites, the types of nanocomposites, and their application in TENG studies. This review gives an overview of how nanocomposites boost the performance of TENGs and provides guidance for future studies.
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| 30. |
- Zhang, Renyun, et al.
(author)
-
All-inorganic triboelectric nanogenerators based on Mo6S3I6 and indium tin oxide
- 2021
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 89
-
Journal article (peer-reviewed)abstract
- Triboelectrification can occur between any two materials with different charge affinities. This phenomenon represents the fundamental physics of triboelectric nanogenerators (TENGs). Organic materials such as polymers have been widely used in TENGs because of their dielectric properties. Inorganic materials are, however, not widely studied despite the increasing attention paid to perovskite materials. In this paper, a new type of TENG has been fabricated based only on inorganic materials such as Mo6S3I6 and indium tin oxide (ITO). The output power density of the TENG operating in contact-separation mode reaches 18 W m−2. Mechanisms of the high output involve the unique semiconducting property of Mo6S3I6 and the unique chemical composition of ITO. The findings in this study indicate that inorganic materials can be used for fabricating high-output TENGs for energy harvesting.
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| 31. |
- Zhang, Renyun, et al.
(author)
-
Cellulose-Based Fully Green Triboelectric Nanogenerators with Output Power Density of 300 W m−2
- 2020
-
In: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 32:38
-
Journal article (peer-reviewed)abstract
- Triboelectric nanogenerators (TENGs) have attracted increasing attention because of their excellent energy conversion efficiency, the diverse choice of materials, and their broad applications in energy harvesting devices and self-powered sensors. New materials have been explored, including green materials, but their performances have not yet reached the level of that for fluoropolymers. Here, a high-performance, fully green TENG (FG-TENG) using cellulose-based tribolayers is reported. It is shown that the FG-TENG has an output power density of above 300 W m−2, which is a new record for green-material-based TENGs. The high performance of the FG-TENG is due to the high positive charge density of the regenerated cellulose. The FG-TENG is stable after more than 30 000 cycles of operations in humidity of 30%–84%. This work demonstrates that high-performance TENGs can be made using natural green materials for a broad range of applications.
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| 32. |
- Zhang, Renyun, et al.
(author)
-
Energy Harvesting Using Wastepaper-Based Triboelectric Nanogenerators
- 2023
-
In: Advanced Engineering Materials. - : Wiley. - 1438-1656 .- 1527-2648. ; 25:11
-
Journal article (peer-reviewed)abstract
- Inks and toners used for printing contain materials, such as polyester, with strong triboelectric properties to enhance the binding effects, making wastepaper, such as magazines and newspapers, good candidates for triboelectric materials. Herein, high-output power triboelectric nanogenerators (TENGs) that utilize wastepaper as triboelectric layers (wastepaper-based triboelectric nanogenerators (WP–TENGs)) are reported. Journal paper and office copy paper wastes are investigated. The results show that the maximum power densities of the WP–TENGs reach 43.5 W m−2, which is approximately 250 times the previously reported output of the TENG with a recycled triboelectric layer made from wastepaper. The maximum open circuit voltage (V OC) and short circuit current (I SC) are 774 V and 3.92 mA (784 mA m−2), respectively. These findings can be applied to extend the life cycle of printed papers for energy harvesting, and they can later be applied for materials recycling to enhance the sustainable development of our society.
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| 33. |
- Zhang, Renyun, et al.
(author)
-
Harvesting triboelectricity from the human body using non-electrode triboelectric nanogenerators
- 2018
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 45, s. 298-303
-
Journal article (peer-reviewed)abstract
- Triboelectrification has been known and discussed since antiquity. Triboelectrification occurs in the human body due to friction between human skin and other materials such as clothing. However, charges on the body have not been harvested to power small electronics. Here, we report for the first time that the electricity generated on the human body due to triboelectrification can be measured and harvested using human body-based non-electrode triboelectric nanogenerators (H-TENGs). The H-TENGs can have an output of up to 3.3 W/m(2) and can spontaneously harvest energy from several people. The functions of the human body in the H-TENGs are analyzed and experimentally proven to be those of a triboelectric material, conductor and capacitor. Our results demonstrate that the triboelectricity generated on a human body can be harvested using H-TENGs and provide scientific insights into body functions that will promote further studies of TENGs.
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| 34. |
- Zhang, Renyun, et al.
(author)
-
High performance single material-based triboelectric nanogenerators made of hetero-triboelectric half-cell plant skins
- 2022
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 94
-
Journal article (peer-reviewed)abstract
- Engineering polymers with quantified charge affinities are commonly used materials in triboelectric nanogenerators (TENGs). A polymer can have only one specific charge affinity due to its uniform chemical composition, leading to the need for two different materials to make an effective TENG. However, unlike engineering polymers, half-cell plant skins can have different charge affinities on their outer and inner surfaces. Here, we report a study on the hetero-triboelectric effects (HTEs) of half-cell allium plant skins such as leek, scallion and onion. Single-material TENGs (SM-TENGs) have been fabricated based on the two surfaces of these plant skins, taking advantage of their HTEs. The highest output power density of up to 35 W m−2 has been achieved with an output stability of over 5400 cycles. Multiple applications of SM-TENGs have been discovered, including energy harvesting, gas sensing, and humidity sensing, which are unique from other TENGs. Additionally, these SM-TENGs have an advantage due to the natural biological and chemical structures of the skins.
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| 35. |
- Zhang, Renyun, et al.
(author)
-
High-performance transparent and flexible electrodes made by flash-light sintering of gold nanoparticles
- 2018
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:12, s. 7191-7198
-
Journal article (peer-reviewed)abstract
- Metallic nanowire-based transparent electrodes (TEs) are potential alternatives to indium tin oxide (ITO). To achieve a high performance [sheet resistance (Rs) < 100 Ω/sq, transmittance (T%) > 90%], the nanowires must have a high length-to-diameter (L/D) ratio to minimize the number of wire-to-wire junctions. Attempts to produce TEs with gold nanowires have been made, and the results reveal difficulties in achieving the requirements. A successful strategy involves creating templated gold nanonetworks through multiple procedures. Here, we present a simple and efficient method that uses flash-light sintering of a gold nanonetwork film into gold TEs (Rs: 82.9 Ω/sq, T %: 91.79%) on a thin polycarbonate film (25 μm). The produced gold TEs have excellent mechanical, electrical, optical, and chemical stabilities. Mechanisms of the formation of gold nanonetworks and the effect of flash-light have been analyzed. Our findings provide a scalable process for producing transparent and flexible gold electrodes with a total processing time of less than 8 min without the use of heating, vacuum processing, and organic chemicals and without any material loss. This is possible because all the gold nanoparticles have been aggregated and filtrated on the filter membranes. The area density of gold is 0.094 g/m2 leading low material costs, which is very competitive with the price of commercial TEs.
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| 36. |
- Zhang, Renyun, et al.
(author)
-
Human body constituted triboelectric nanogenerators as energy harvesters, code transmitters and motion sensors
- 2018
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:6, s. 2955-2960
-
Journal article (peer-reviewed)abstract
- Human skin is a dielectric material that can be used as a triboelectric material for harvesting energy from body motions. The output power of such a human skin-based triboelectric nanogenerator (TENG) is relatively low. Here, we assembled high-output human body constituted TENGs (H-TENGs) by taking advantage of the unique electrical properties of the human body, such as high skin impedance, low tissue resistance, body capacitance, and conductivity. The output of a H-TENG can reach 30 W/m2, which is enough to drive small electronic devices, such as a timer or a calculator. The unique feature of the H-TENG is that it can perform the four fundamental modes of TENGs, which has not been reported elsewhere. Such a feature allows the H-TENG to act as a code transmitter to send light and electrical signals, such as Morse code. H-TENGs also benefit the development of high-performance, self-powered body motion sensors. Our findings suggest new strategies for harvesting energy from human body motions, as well as new types of motion sensors and signal senders.
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| 37. |
- Zhang, Renyun, et al.
(author)
-
Interaction of the human body with triboelectric nanogenerators
- 2019
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 57, s. 279-292
-
Journal article (peer-reviewed)abstract
- The use of triboelectric nanogenerators (TENGs) is a new technique for energy harvesting at both small and large scales. Almost all types of mechanical energy can be harvested with TENGs by using four modes of operation that cover almost all mechanical motions. The interactions of the human body with TENGs range from energy harvesting, motion sensing, and biomedical applications to human-computer communications. Different types of TENGs have been developed to directly or indirectly involve the human body. This review will summarize the recent advances in the interaction of the human body with TENGs.
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| 38. |
- Zhang, Renyun, et al.
(author)
-
Nanogenerator made of ZnO nanosheet networks
- 2017
-
In: Semiconductor Science and Technology. - : IOP Publishing. - 0268-1242 .- 1361-6641. ; 32:5
-
Journal article (peer-reviewed)abstract
- The piezoelectricity of nanomaterials attracts a great deal of attention due to its broad application, including the harvesting of ambient mechanical energy to power small electronics devices. We report here a simple method to fabricate piezoelectric nanogenerators consisting of networks of ZnO nanosheets grown on aluminum (Al) foils, where the Al acts as both a substrate for growth and as an electrode contacting the ZnO network. A second, top electrode was tapped, rolled, or rubbed against the ZnO to generate piezoelectricity. This second electrode was either a copper foil or fluorine doped tin oxide (FTO) glass. A piezo voltage of up to 0.924 V was detected during rolling and 6 μA was the highest current observed when rubbing the ZnO film with a FTO glass. Due to its simplicity, this nanogenerator fabrication method has the potential to be scaled up for the industrial production of piezoelectric energy harvesting devices.
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| 39. |
- Zhang, Renyun, et al.
(author)
-
Photoconductivity of acid exfoliated and flash-light-processed MoS2 films
- 2018
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
-
Journal article (peer-reviewed)abstract
- MoS2 has been studied intensively during recent years as a semiconducting material in several fields, including optoelectronics, for applications such as solar cells and phototransistors. The photoresponse mechanisms of MoS2 have been discussed but are not fully understood, especially the phenomenon in which the photocurrent slowly increases. Here, we report on a study of the photoresponse flash-light-processed MoS2 films of different thicknesses and areas. The photoresponse of such films under different light intensities and bias voltages was measured, showing significant current changes with a quick response followed by a slow one upon exposure to pulsed light. Our in-depth study suggested that the slow response was due to the photothermal effect that heats the MoS2; this hypothesis was supported by the resistivity change at different temperatures. The results obtained from MoS2 films with various thicknesses indicated that the minority-carrier diffusion length was 1.36 mu m. This study explained the mechanism of the slow response of the MoS2 film and determined the effective thickness of MoS2 for a photoresponse to occur. The method used here for fabricating MoS2 films could be used for fabricating optoelectronic devices due to its simplicity.
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| 40. |
- Zhang, Renyun, et al.
(author)
-
Sensing body motions based on charges generated on the body
- 2019
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 63
-
Journal article (peer-reviewed)abstract
- The sensing of body motions is of great importance in areas such as healthcare, rehabilitation, and human-computer interactions. Different methods have been developed based on visual or electrical signals. However, such signals are acquired by external devices and are not intrinsic signals that are created on the body. Here, we report a new universal body motion sensor (UBS) to detect motions based on the intrinsic contact electrification (CE) of the skin or electrical induction (EI) of the body. The CE or EI generates charges on the body, leading to potential differences between the body and ground that can be measured to identify different body motions, such as motions of the head, arms, fingers, waist, legs, feet and toes. Proof-of-concept experiments have demonstrated that the UBS can be used to monitor the conditions of people with Parkinson's disease (PD) and to quantitatively monitor the recovery of those with a leg injury, suggesting great potential for healthcare applications.
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| 41. |
- Zhang, Renyun, et al.
(author)
-
The triboelectricity of the human body
- 2021
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 86
-
Research review (peer-reviewed)abstract
- Triboelectrification (contact electrification) as a physical phenomenon appeared for the first time in a dialogue by Plato around 400 B.C. The phenomenon described in the dialogue is about amber that people wear attracting dry hair. The description also indicated that triboelectrification was first discovered on the human body. However, the studies that have been carried out on triboelectrification were mostly based on other materials, such as polymers, rather than on the human body. The invention of triboelectric nanogenerators (TENGs) has recently opened a door for both fundamental and applied research and brought triboelectrification into real applications. The human body's triboelectricity, as a vital part of studies, has also attracted much interest in the past ten years. Research and review articles were published during this period. However, few articles included the biological fundamentals of the triboelectrification of the human body. Moreover, most of the review articles missed two important parts: the electrostatic discharge (ESD) of the human body, which has been widely studied in electronics, and the cosmetics that reduce the triboelectrification of hair. A systematic review including the fundamentals and the applications could help readers understand the human body's triboelectricity. Given this, we proposed this review article on the human body's triboelectricity. The paper will cover a brief history and a brief mechanism summary of triboelectrification; the epidermis structure of the human hair and skin, including how the chemicals on the epidermal layer contribute to the skin's triboelectricity; fundamental studies of the human body's triboelectricity; and applications that utilize the human body's triboelectricity. Perspectives for future studies and conclusions will be given at the end of the review.
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| 42. |
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| 43. |
- Zhang, Renyun, et al.
(author)
-
Triboelectric biometric signature
- 2022
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 100
-
Journal article (peer-reviewed)abstract
- Biometric signatures based on either the physiological or behavioural features of a person have been widely used for identification and authentication. However, few strategies have been developed that combine the two types of features in one signature. Here, we report a type of biometric signature based on the triboelectricity of the human body (TEHB) that combines these two types of features. This triboelectric biometric signature (TEBS) can be accomplished by anyone regardless of the physical condition, as it can be performed by many parts of the body. Different TEBS can be identified using a convolutional neural network (CNN) model with a test accuracy of up to 1.0. The TEBS has been further used for text encryption and decryption with a high sensitivity to changes. Moreover, a dual signed digital signature for enhanced security has been proposed. Our findings provide a new type of TEBS that can be generally used and demonstrated in applications.
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| 44. |
- Zhang, Renyun, et al.
(author)
-
Triboelectric nanogenerators with ultrahigh current density enhanced by hydrogen bonding between nylon and graphene oxide
- 2023
-
In: Nano Energy. - 2211-2855 .- 2211-3282. ; 115
-
Journal article (peer-reviewed)abstract
- The triboelectric properties of the tribolayers are essential factors affecting the current density of triboelectric nanogenerators (TENGs). To enhance the current density, composites have been developed to tune their triboelectric properties. Previous studies have reported enhanced TENG performance with composite materials, primarily based on their composition, while chemical interactions between the components have been less analyzed. In this study, we report a novel approach to improve the current density of a TENG by introducing dipole-dipole interactions between a nylon filter membrane and graphene oxide (GO) through hydrogen bonds. The Raman spectroscopy confirmed the occurrence of the interactions resulting from hydrogen bonding. The enhancing mechanisms of hydrogen bonds were further analyzed by Kelvin probe force microscope (KPFM) measurement, which demonstrated that hydrogen bonding could influence the surface potential of the coated GO, leading to increased output of the nylon/GO@NFM TENG (NGN-TENG). Our results show that an ultrahigh current density of 1757 mA·m−2 was obtained with a 2 × 2 cm2 NGN-TENG. Additionally, we demonstrated the feasibility of using the NGN-TENG as a motion sensor to sense finger motions. These findings suggest that the introduction of hydrogen bonds in TENG composites can provide a promising route for improving their performance.
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| 45. |
- Zhang, Renyun, et al.
(author)
-
Utilising the triboelectricity of the human body for human-computer interactions
- 2022
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 100
-
Journal article (peer-reviewed)abstract
- Human-computer interaction (HCI) strategies communicate the human mind and machine intelligence based on different devices and technologies. The majority of HCI strategies assume normal physical conditions that limit accessibility for users with disabilities. Certain products, such as Braille keyboards, work fine for people with specific disabilities. However, a more general HCI strategy that can neglect users’ physical conditions would enhance the accessibility of these tools for disabled persons. Here, we report an HCI strategy that utilises triboelectricity of the human body (TEHB) for HCI. The TEHB can be generated by many parts of the human body, eliminating the obstacles imposed by physical function disabilities. Such an HCI approach has been used for text inputs, graphical inputs, and mimicked mouse functions. With the assistance of deep learning, an accuracy of approximately 98.4 % is achieved for text inputs obtained directly from handwriting. Our findings provide a new approach for HCI and demonstrate the feasibility of multiple interaction modes.
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| 46. |
- Zhang, Renyun, et al.
(author)
-
Wastepaper-based Triboelectric Nanogenerators
- 2023
-
In: Book of Abstracts EPNOE 2023. - : Graz University of Technology.
-
Conference paper (other academic/artistic)abstract
- nks and toners used for printing contain materials, such as polyester, with strong triboelectric properties to enhance the binding effects, making wastepaper, such as magazines and newspapers, good candidates for triboelectric materials. In this study, we report high- output power triboelectric nanogenerators (TENGs) that utilize wastepaper as triboelectric layers (wastepaper-based triboelectric nanogenerators (WP–TENGs)) [1]. Journal paper and office copy paper wastes are investigated. The results show that the maximum power densities of the WP–TENGs reach 43.5 W·m-2, which is approximately 250 times the previously reported output of the TENG with a recycled triboelectric layer made from wastepaper [2]. The maximum open circuit voltage (VOC) and short circuit current (ISC) are 774 V and 3.92 mA (784 mA m-2), respectively. These findings can be applied to extend the life cycle of printed papers for energy harvesting, and they can later be applied for materials recycling to enhance the sustainable development of our society.[1] Zhang, R., Hummelgård, M., Örtegren, J., Andersson, H., Olsen, M., Chen, W., Wang, P., Eivazi, A., Dahlström, C. & Norgren, M. Adv. Engin. Mater., in press, 2023; https://doi.org/10.1002/adem.202300107[2] Zhang, Z., Jie, Y., Zhu, J., Zhu, Z., Chen, H, Lu, Q., Zeng, Y., Cao, X., Wang, N. & Wang, Z. Nano Res. 15, 1109, 2022; https://doi.org/10.1007/s12274-021-3612-8
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| 47. |
- Öhlund, Thomas, 1973-, et al.
(author)
-
Paper Surfaces for Metal Nanoparticle Inkjet Printing
- 2012
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In: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 259, s. 731-739
-
Journal article (peer-reviewed)abstract
- The widespread usage of paper and board offer largely unexploited possibilities for printed electronics applications. Reliability and performance of printed devices on comparatively rough and inhomogenous surfaces of paper does however pose challenges.Silver nanoparticle ink has been deposited on ten various paper substrates by inkjet printing. The papers are commercially available, and selected over a range of different types and construction. A smooth nonporous polyimide film was included as a nonporous reference substrate. The substrates have been characterized in terms of porosity, absorption rate, apparent surface energy, surface roughness and material content. The electrical conductivity of the resulting printed films have been measured after drying at 60°C and again after additional sintering at 110°C. A qualitative analysis of the conductivity differences on the different substrates based on surface characterization and SEM examination is presented. Measurable parameters of importance to the final conductivity are pointed out, some of which are crucial to achieve conductivity. When certain criteria of the surfaces are met, paper media can be used as low cost, but comparably high performance substrates for metal nanoparticle inks in printed electronics applications.
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| 48. |
- Örtegren, Jonas, 1970-
(author)
-
Liquid crystalline polymers for nonlinear optics : pyroelectric polymers and ferroelectric dendrimers
- 2001
-
Doctoral thesis (other academic/artistic)abstract
- This thesis deals with liquid crystalline materialsincluding monomers, side-chain polymers, crosslinked polymers,and dendrimers. The materials are pyroelectric, meaning thatthere is a macroscopic electric polarization in the material,which is energetically stable in the absence of externalfields. The energetically stable, or spontaneous, polarizationmakes the material suitable for second-order nonlinear optics(NLO). Examples of second order NLO processes are secondharmonic generation (SHG), optical parametric amplification,and processes involving modulations of the refractive indices.In isotropic polymeric systems, the material is made secondorder NLO active by applying an electric field at hightemperatures, thereby inducing polar order, and by cooling toroom temperature with the field applied. The polarization isthereby "locked-in" into the polymer, and the material issecond-order NLO active. Such systems often loose polar order,and thereby second order NLO response, quite rapidly. The polarorder in pyroelectric materials is however energeticallystable, and one may therefore expect better time-dependentsecond order NLO properties in these materials. In this work,pyroelectric polymers were prepared by photopolymerization ofsurface stabilized ferroelectricliquid crystals. Thephotopolymerized material showed a clear second order NLOresponse, as measured by SHG, also in the absence of anexternal electric field. The d23-coefficient was 0.25 pm V-1. Furthermore, the pyroelectric polymers werestable at room temperature for approximately 50 days. In orderto improve the thermal stability of the polymers, a crosslinkedpolymer system was prepared, which exhibited improved thermalstability, compared to the uncrosslinked polymers. Thecrosslinked polymers were unaffected by aging at 130°C forseveral hours. The thermal stability of the polymers wasfurther analyzed by a pyroelectric technique. The largestestimated pyroelectric coefficient was 2 nC cm-2K-1. The crosslinked polymer showed a weak but clearpyroeletric response even after being heated to 260 °C.Novel liquid crystalline dendrimers of different generationwere also studied. The dendrimers were ferroelectric, meaningthat there are two stable polarization states in the material,and that the polarization may be reversed by application of anelectric field. The dendrimers showed a slightly lower value ofspontaneous polarization than their low molar mass analogue.The spontaneous polarization of the LC dendrimers wasapproximately 40 nC cm-2, and was basically independent of the generationnumber of the dendrimer. A clear, but rather small SHG responsewas recorded in these systems. By incorporating a nitro-groupin the mesogen of the LC dendrimer, the d23- coefficient of the second order NLO responsecould be improved by a factor 3, to 0.03 pm V-1. This thesis gives an introduction topyroelectricity, ferroelectricity, and linear and nonlinearoptical effects in materials. It further contains descriptionsof various techniques that were used to characterize the novelliquid crystalline materials. It discusses the results from themeasurements and the properties of the liquid crystallinematerials, with focus on second order NLO.
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