| 1. |
- He, W., et al.
(författare)
-
Deep learning-assisted flexible piezoresistive sensor with liquid-phase reduced metal electrodes for fitness movement recognition and correction
- 2024
-
Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 495
-
Tidskriftsartikel (refereegranskat)abstract
- Flexibility and wearability in electronic devices gain prominence with the rise of national fitness campaigns. Among them, piezoresistive sensors stand out for their ability to accurately monitor health signals due to their high sensitivity. However, conventional metal nanoparticle ink electrodes face issues like peeling, chemical instability, and substrate limitations. This study introduces a novel method for fabricating high-performance flexible piezoresistive sensors using liquid-phase reduced metal electrodes. Integration of porous polydimethylsiloxane (PDMS) substrates with highly conductive interdigital silver electrodes (1.6 × 10−6 Ω·m) addresses conventional electrode shortcomings, offering permeability, flexibility, and outstanding conductivity. Incorporation of a graphene (GR)/carbon nanotube (CNT)/Ecoflex composite enhances sensor piezoresistive sensing capabilities, with features including high sensitivity (3.57 KPa−1), rapid response time (58 ms/72 ms), and excellent cycle stability (>10000 cycles). The sensor finds utility in various applications, including human physiological signal monitoring, pressure array recognition, and handwriting recognition. Additionally, with deep learning techniques, the system achieves accurate recognition (99.25 %) and correction (98.75 %) of diverse fitness movements, aiming to promote safer exercise practices, enhance training efficiency, and advance intelligent wearable fitness devices.
|
|
| 2. |
- Wang, Weichao, et al.
(författare)
-
Remarkably enhanced hybrid piezo/triboelectric nanogenerator via rational modulation of piezoelectric and dielectric properties for self-powered electronics
- 2020
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 116:2
-
Tidskriftsartikel (refereegranskat)abstract
- The hybridization of different materials for energy scavenging techniques based on piezoelectric and triboelectric effects has been studied widely for various applications of nanogenerators. However, there are few reports utilizing the same oxide matrix materials with appropriate doping to simultaneously enhance the piezoelectric and triboelectric outputs. Herein, a hybrid nanogenerator (HG) consisting of a piezoelectric nanogenerator (PENG) and a triboelectric nanogenerator (TENG) was constructed using (Ba0.838Ca0.162)(Ti0.9072Zr0.092)O3 (BCZTO)/polydimethylsiloxane (PDMS) as a piezoelectric layer and Ba(Ti0.8Zr0.2)O3 (BZTO)/PDMS as a triboelectric layer. For the PENG, how the electrical output was related to the BCZTO ratio in the BCZTO/PDMS composite films was systematically investigated. For the TENG, remarkably enhanced output performance is attributed to the ferroelectric polarization and large permittivity of the BZTO/PDMS. The Kelvin probe force microscopy measurements show that the poled BZTO/PDMS composite film with a 20 wt. % mass ratio of BZTO has the highest surface charge potential, in line with the macroscopic electrical outputs of the TENG. Interestingly, the output performance of the PENG in the HG is significantly enhanced compared to the PENG acting alone, which is also verified by COMSOL simulation. After rectification, the HG can produce a maximum output voltage of 390 V and a current density of 47 mA/m2. This work not only provides a feasible solution to enhance the output performance of the HG but also offers an effective approach to develop a small, portable power source with promising application in self-powered electronics.
|
|
| 3. |
- Guo, Y., et al.
(författare)
-
A self-powered flexible piezoelectric sensor patch for deep learning-assisted motion identification and rehabilitation training system
- 2024
-
Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 123
-
Tidskriftsartikel (refereegranskat)abstract
- Artificial intelligence-assisted wearable devices have attracted great interest in medical treatment and healthcare. However, wearable electronic devices are expensive to manufacture and usually depend on external power supply. Herein, a flexible self-powered piezoelectric sensor patch (SPP) using Polyvinylidene fluoride (PVDF) fibrous film as the functional layer is demonstrated for the assessment and motion identification of wrist joint rehabilitation training. PVDF fibrous film is prepared by a triboelectric nanogenerator (TENG)-driven near-field electrospinning system with a special designed synchronous mechanical switch. The results show that this flexible SPP has a high sensitivity of 0.2768 V KPa−1 at pressures from 1 to 75 kPa. Such excellent flexibility allows us to attach the SPP to the finger as a tactile sensor for rehabilitation assessment of wrist joint flexibility. In addition, long short-term memory network model is used to process the collected data from the SPP for motion identification. The test accuracy of the SPP wrist motion identification reaches 92.6%, which afford a potential way to understand the progress of the rehabilitation training of patients' wrists. Generally, this flexible SPP shows great promise for applications in the fields of motion monitoring, medical diagnosis and rehabilitation training based on artificial intelligence.
|
|
| 4. |
- Pecunia, Vincenzo, et al.
(författare)
-
Roadmap on energy harvesting materials
- 2023
-
Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:4
-
Tidskriftsartikel (refereegranskat)abstract
- Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.
|
|
| 5. |
- Wang, N., et al.
(författare)
-
Structure, Performance, and Application of BiFeO3 Nanomaterials
- 2020
-
Ingår i: Nano-Micro Letters. - : Springer Science and Business Media LLC. - 2150-5551 .- 2311-6706. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Multiferroic nanomaterials have attracted great interest due to simultaneous two or more properties such as ferroelectricity, ferromagnetism, and ferroelasticity, which can promise a broad application in multifunctional, low-power consumption, environmentally friendly devices. Bismuth ferrite (BiFeO3, BFO) exhibits both (anti)ferromagnetic and ferroelectric properties at room temperature. Thus, it has played an increasingly important role in multiferroic system. In this review, we systematically discussed the developments of BFO nanomaterials including morphology, structures, properties, and potential applications in multiferroic devices with novel functions. Even the opportunities and challenges were all analyzed and summarized. We hope this review can act as an updating and encourage more researchers to push on the development of BFO nanomaterials in the future.
|
|
| 6. |
- Zhang, Xiaoyun, et al.
(författare)
-
Metal–Support Interaction of Carbon–Based Electrocatalysts for Oxygen Evolution Reaction
- 2023
-
Ingår i: nanoenergy advances. - : MDPI AG. - 2673-706X. ; 3:1, s. 48-72
-
Forskningsöversikt (refereegranskat)abstract
- Metal–support interaction (MSI) is considered a key effect of electronic and geometric structures of catalysts on tuning catalytic performance. The oxygen evolution reaction (OER) is a crucial process during energy conversion and storage. However, the OER process requires the help of noble metal catalysts to reduce the reaction overpotential, enhance reactivity with intermediates, and maintain good operating stability. Carbon–supported metal catalysts have been considered candidates for noble metal catalysts for OER. MSI occurs at the interface of carbon supports and metals, affecting the catalytic performance through electronic and geometric modulation. MSI can influence the catalytic performance and change reaction pathways from charge redistribution, electron transfer, chemical coordination and bonding, and steric effect. Connecting MSI effects with the OER mechanism can provide theoretical guidance and a practical approach to the design of efficient catalysts, including the modulation of particle size, morphology, heteroatom doping, defect engineering, and coordination atom and number. Advantage can be taken of MSI modulation between metal compounds and carbon supports to provide guidance for catalyst design.
|
|
| 7. |
- Alecrim, Viviane, et al.
(författare)
-
Exfoliated Layered Materials for Digital Fabrication
- 2015
-
Ingår i: NIP & Digital Fabrication Conference. ; , s. 192-194
-
Konferensbidrag (refereegranskat)abstract
- We introduced an exfoliation method of MoS2 in a 3% solution of sodium dodecyl surfactant at high concentration (i.e. 2 g/L). The bulk MoS2 was thinned by mechanical exfoliation between sand papers and the resulting powder was used to prepare dispersions by liquid exfoliation through probe sonication. The resulting dispersion consisted of very thin MoS2 nanosheets in surfactant solution with average lateral size around 126 nm. This may be interesting for applications in inkjet printed electronics.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Andersson, Henrik, et al.
(författare)
-
Contacting paper-based supercapacitors to printed electronics on paper substrates
- 2012
-
Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:2, s. 476-480
-
Tidskriftsartikel (refereegranskat)abstract
- Hybrid printed electronics, in which printed structures and silicon-based components co-exist will likely be among the first commercial solutions. In this case the paper substrate acts much in the same way as circuit boards, containing conductive tracks and acting as a carrier for the electrical components. It is important to consider the contacting of the components to be able to produce low resistance electrical contacts to the conductive tracks. Supercapacitors are able to deliver a large amount of current in a short time and are a good option for short term energy storage and if the printed product is to be used only one, or a few times, it can be the only power source needed. When manufacturing printed electronics, the overall resistance of the printed tracks as well as the contact resistance of the mounted components will add up to the total resistance of the system. A high resistance will cause a voltage drop from the power source to the component. This will waste power that goes to Joule heating and also the voltage and current available to components may be too low to drive them. If the intention is to use a power supply such as batteries or solar cells this becomes a limitation. In this article have been tested several conductive adhesives used to contact paper based supercapacitors to ink jet printed silver tracks on paper. The best adhesive gives about 0.3 Ω per contact, a factor 17 better compared to the worst which gave 5 Ω. The peak power that is possible to take out from a printed system with a flexible battery and super capacitors is about 10 times higher than compared with the same system with only the battery.
|
|
| 12. |
- Andersson, Henrik, Dr, 1975-, et al.
(författare)
-
PEDOT : PSS thermoelectric generators printed on paper substrates
- 2019
-
Ingår i: Journal of Low Power Electronics and Applications. - : MDPI AG. - 2079-9268. ; 9:2
-
Tidskriftsartikel (refereegranskat)abstract
- Flexible electronics is a field gathering a growing interest among researchers and companies with widely varying applications, such as organic light emitting diodes, transistors as well as many different sensors. If the circuit should be portable or off-grid, the power sources available are batteries, supercapacitors or some type of power generator. Thermoelectric generators produce electrical energy by the diffusion of charge carriers in response to heat flux caused by a temperature gradient between junctions of dissimilar materials. As wearables, flexible electronics and intelligent packaging applications increase, there is a need for low-cost, recyclable and printable power sources. For such applications, printed thermoelectric generators (TEGs) are an interesting power source, which can also be combined with printable energy storage, such as supercapacitors. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), or PEDOT:PSS, is a conductive polymer that has gathered interest as a thermoelectric material. Plastic substrates are commonly used for printed electronics, but an interesting and emerging alternative is to use paper. In this article, a printed thermoelectric generator consisting of PEDOT:PSS and silver inks was printed on two common types of paper substrates, which could be used to power electronic circuits on paper.
|
|
| 13. |
- Andersson, Henrik, Dr, 1975-, et al.
(författare)
-
Variable low-density polylactic acid and microsphere composite material for additive manufacturing
- 2021
-
Ingår i: Additive Manufacturing. - : Elsevier BV. - 2214-8604 .- 2214-7810. ; 40
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 14. |
- Andres, Britta, 1986-
(författare)
-
Low-Cost, Environmentally Friendly Electric Double-Layer Capacitors : Concept, Materials and Production
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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.
|
|
| 15. |
- Andres, Britta, et al.
(författare)
-
Supercapacitors with graphene coated paper electrodes
- 2012
-
Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:2, s. 481-485
-
Tidskriftsartikel (refereegranskat)abstract
- Paper based supercapacitors are prepared by stacking a paper between two graphene electrodes and soaking these in an aqueous electrolyte. We demonstrate that supercapacitors can easily be manufactured by using proven paper technologies. Several different electrode materials were compared and two types of contacting material, silver and graphite foil were tested. The influence of the paper used as separator was also investigated. The supercapacitors with a graphene-gold nanoparticle composite as electrodes showed a specific capacitance of up to 100 F/g and an energy density of 1.27 Wh/kg. The energy density can further be increased by using other electrolytes. The silver contacts showed a pseudo capacitance, which the graphite contacts did not. The papers tested had a minor effect on the capacitance, but they have an influence on the weight and the volume of the supercapacitor.
|
|
| 16. |
- Balliu, Enkeleda, PhD student, et al.
(författare)
-
Laser processing of graphene oxide on different coated paper substrates
- 2016
-
Ingår i: 14th TAPPI Advanced Coating Symposium 2016. - : TAPPI Press. - 9781510877658 ; , s. 97-101
-
Konferensbidrag (refereegranskat)abstract
- Development of printed electronics is increasing each year, where many electrical components such as transistors and sensors are now printable. The most commonly used substrate have been plastics, but there is an increasing interest in using paper as substrate. The paper industry is a very large and mature industry with large production capacity and well developed processes. It is therefore of interest to investigate how it would be possible to combine printed electronics and paper based products. This can for example be to print sensors on packages, to use large scale roll-to-roll production for solar cells. To be able to achieve such goals it is of importance to develop methods of applying electrically active materials in the large, high speed roll-to-roll processes used in the paper industry. In this article we discuss coating of graphene oxide (GO) on large areas after which it is selectively reduced into electrically conductive reduced graphene oxide (rGO) by laser processing. Graphene oxide is an inexpensive, carbon based material very suitable to be deposited as a coating, and the selective activation of makes it possible to fabricate conductive patterns at high speeds. We have evaluated several different paper substrates on which GO was coated. The reduction was performed using an 532 nm laser source and the results are promising, showing that it is possible to fabricate selectively conductive patterns on paper substrates by coating and reduction of GO.
|
|
| 17. |
- Blomquist, Nicklas, 1987-
(författare)
-
Large-Scale Graphene Production for Environmentally Friendly and Low-Cost Energy Storage : Production, Coating, and Applications
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is great demand for energy-efficient, environmentally sustainable, and cost-effective electrical energy storage devices. One important aspect of this demand is the need for automotive electrification to achieve more energy-efficient transportation at a reasonable cost, thus supporting a fossil-fuel free society. Another important aspect is the requirement for energy storage in the growing field of renewable energy production from wind and solar sources, which generates an irregular supply of electricity due to weather conditions.Much of the research in this area has been conducted in the field of battery technology with impressive results, but the need for rapid storage devices such as supercapacitors is growing. Due to the excellent ability of supercapacitors to handle short peak power pulses with high efficiency along with their long lifetime and superior cyclability, their implementations range from small consumer electronics to electric vehicles and stationary grid applications. Supercapacitors also have the potential to complement batteries to improve pulse efficiency and lifetime of the system, however, the cost of supercapacitors is a significant issue for large-scale commercial use, leading to a demand for sustainable, low-cost materials and simplified manufacturing processes. An important way to address this need is to develop a cost-efficient and environment-friendly large-scale process to produce highly conductive nanographites, such as graphene and graphite nanoplatelets, along with methods to manufacture low-cost electrodes from large area coating.In this thesis, I present a novel process to mechanically exfoliate industrial quantities of nanographite from graphite in an aqueous environment with low energy consumption and at controlled shear conditions. The process is based on hydrodynamic tube-shearing and can produce both multilayer graphene and nanometer-thick and micrometer-wide flakes of nanographite. I also describe the production of highly conductive and robust carbon composites based on the addition of nanocellulose during production; these are suitable as electrodes in applications ranging from supercapacitors and batteries to printed electronics and solar cells.Furthermore I demonstrate a scalable route for roll-to-roll coating of the nanographite-nanocellulose electrode material and propose a novel aqueous, low-cost, and metal-free supercapacitor concept with graphite foil functioning as the current collector. The supercapacitors possessedmore than half the specific capacitance of commercial units but achieved a material cost reduction of more than 90 %, demonstrating anenvironment-friendly, low-cost alternative to conventional supercapacitors.
|
|
| 18. |
|
|
| 19. |
- Dahlström, Christina, 1977-, et al.
(författare)
-
Regenerated cellulose properties tailored for optimized triboelectric output and the effect of counter-tribolayers
- 2024
-
Ingår i: Cellulose. - : Springer Nature. - 0969-0239 .- 1572-882X. ; 31:4, s. 2047-2061
-
Tidskriftsartikel (refereegranskat)abstract
- Cellulose has shown great potential in the development of green triboelectric nanogenerators. Particularly, regenerated cellulose (R-cellulose) has shown remarkably high output power density but the structural features and key parameters that explain such superior performance remain unexplored. In this work, wood cellulose fibers were dissolved in a LiOH(aq)-based solvent to produce a series of R-cellulose films. Regeneration in different alcohols (from methanol to n-pentanol) was performed and the films’ structural features and triboelectric performance were assessed. Nonsolvents of increased hydrophobicity led to R-cellulose films with a more pronounced (1–10) diffraction peak. An open-circuit voltage (VOC) of up to ca. 260 V and a short-circuit current (ISC) of up to ca. 150 µA were measured for R-cellulose against polytetrafluoroethylene (as negative counter-layer). However, R-cellulose showed an increased VOC of 175% (from 88.1 V) against polydimethylsiloxane when increasing the alcohol hydrocarbon chain length from methanol to n-pentanol. The corresponding ISC and output power also increased by 76% (from 89.9 µA) and by 382% (from 8.8 W m–2), respectively. The higher R-cellulose hydrophilicity, combined with soft counter-tribolayer that follow the surface structures increasing the effective contact area, are the leading reasons for a superior triboelectric performance.
|
|
| 20. |
- Dahlström, Christina, 1977-, et al.
(författare)
-
Triboelectric Performance Of Regenerated Cellulose
- 2023
-
Ingår i: Book of Abstracts EPNOE 2023. - : Graz University of Technology. ; , s. 116-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cellulose has shown great potential in the development of green triboelectric nanogenerators (TENG) [1]. Particularly, regenerated cellulose (R-cellulose) has shown remarkably high output power density but the structural features and key parameters that explain such superior performance remain unexplored. In this work, wood cellulose fibers were dissolved in a LiOH(aq)-based solvent to produce a series of R-cellulose films. Regeneration in different alcohols (from methanol to n-pentanol) was performed and the films’ structural features and triboelectric performance were assessed. Nonsolvents of increased hydrophobicity led to R-cellulose films with higher hydrophilic character; the films showed a (1- 10) diffraction peak of larger amplitude and higher apparent crystallinity. An open-circuit voltage (VOC) of up to ca. 260 V and a short-circuit current (ISC) of up to ca. 150 μA were measured for R-cellulose against polytetrafluoroethylene (as negative counter-layer). However, R-cellulose showed an increased VOC of 175% (from 88.1 V) against polydimethylsiloxane from methanol to n-pentanol. The corresponding ISC and output power also increased by 76% (from 89.9 μA) and by 382% (from 8.8 W m–2), respectively. The higher R-cellulose hydrophilicity, combined with soft counter-layer that follow the surface structures increasing the effective contact area, are the leading reasons for a superior triboelectric performance.[1] Zhang, R., Dahlström, C., Zou, H., Jonzon, J., Hummelgård, M., Örtegren, J., Blomquist, N., Yang, Y., Andersson, H., Olsen, M., Norgren, M., Olin, H. & Wang, Z.L. Adv. Mater. 32, 2002824, 2020; https://doi.org/10.1002/adma.202002824
|
|
| 21. |
- Deiana, Luca, et al.
(författare)
-
Efficient and Highly Enantioselective Aerobic Oxidation-Michael-Carbocyclization Cascade Transformations by Integrated Pd(0)-CPG Nanoparticle/Chiral Amine Relay Catalysis
- 2014
-
Ingår i: Synthesis (Stuttgart). - : Georg Thieme Verlag KG. - 0039-7881 .- 1437-210X. ; 46:10, s. 1303-1310
-
Tidskriftsartikel (refereegranskat)abstract
- A series of highly diastereo- and enantioselective aerobic oxidation-Michael-carbocyclization cascade transformations by integrated heterogeneous Pd(0)-CPG nanoparticle/chiral amine relay catalysis are disclosed. The heterogeneous Pd(0)-CPG nanoparticle catalysts were efficient for both the sequential aerobic oxidation and dynamic kinetic asymmetric Michael-carbocyclization transformations, resulting in 1) oxidation of a variety of allylic alcohols to enals and 2) formation of cyclopentenes containing an all-carbon quaternary stereocenter in good to high yields with up to 20:1 dr and 99.5:0.5 er.
|
|
| 22. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
Cellulose stabilizers for 2D materials inkjet inks
- 2017
-
Konferensbidrag (refereegranskat)abstract
- To date, the most promising scalable method for achieving 2D materials dispersions is through liquidbasedexfoliation of nanosheets in solvents. We study the use of high throughput shear exfoliation insteadof sonication to exfoliate water dispersions of MoS2 using environmental friendly stabilizers based oncellulose. The resulted dispersion was then concentrated and inkjet printed on a flexible substrate. We usedethyl cellulose, cellulose nanofibers (CNF) and ultra-fine cellulose nanofibers (UF-CNF). The stability wasevaluated by measuring the differences in concentration over time. The particle size distribution (PSD) ofthe dispersed particles was evaluated using statistical methods applied to SEM images of the dispersions(See Fig 1 and 2). The zeta potential and the mechanisms of stabilization involved was evaluated (See Fig4). All three stabilizers appear to work very well for MoS2 nanosheets even though the mechanisms ofstabilization were different i.e. steric stabilization for MoS2-EC and electrostatic stabilization for MoS2-CNF and MoS2-UF-CNF dispersions. For the MoS2-EC dispersions we achieved a broader PSD (Fig. 1)and higher stability. Thin nanosheets was observed from the SEM image of MoS2-EC dispersions depositedonto cellulose filters by vacuum filtration (Fig. 5) which demonstrated that the exfoliation technique usedwas successful. The estimated concentration of the MoS2-EC dispersion after 8 days of sample preparationwas 0.24 mg/mL, 77% of the initial concentration (see Fig. 6) and it was relatively steady after 40 days ofsample preparation (0.22 mg/mL). To adjust the concentration and the viscosity of the MoS2-EC dispersion,we concentrated it using a rotary evaporator solvent exchange technique. For this we used terpineol andadjusted the viscosity using ethanol. This paper presents the results of an inkjet 2D material ink usingenvironmental friendly components different than previous 2D materials inks that used organic solvents orwater based dispersions containing surfactants.
|
|
| 23. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
Exfoliated MoS2 in Water without Additives
- 2016
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- Many solution processing methods of exfoliation of layered materials have been studied during the last few years; most of them are based on organic solvents or rely on surfactants andother funtionalization agents. Pure water should be an ideal solvent, however, it is generallybelieved, based on solubility theories that stable dispersions of water could not be achievedand systematic studies are lacking. Here we describe the use of water as a solvent and thestabilization process involved therein. We introduce an exfoliation method of molybdenumdisulfide (MoS2) in pure water at high concentration (i.e., 0.14±0.01 g L−1). This was achieved by thinning the bulk MoS2by mechanical exfoliation between sand papers and dis-persing it by liquid exfoliation through probe sonication in water. We observed thin MoS2nanosheets in water characterized by TEM, AFM and SEM images. The dimensions of thenanosheets were around 200 nm, the same range obtained in organic solvents. Electropho-retic mobility measurements indicated that electrical charges may be responsible for the sta-bilization of the dispersions. A probability decay equation was proposed to compare thestability of these dispersions with the ones reported in the literature. Water can be used as asolvent to disperse nanosheets and although the stability of the dispersions may not be ashigh as in organic solvents, the present method could be employed for a number of applications where the dispersions can be produced on site and organic solvents are not desirable.
|
|
| 24. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
Liquid Exfoliation of Layered Materials in Water for Inkjet Printing
- 2016
-
Ingår i: Printing for Fabrication 2016. - USA : Curran Associates, Inc.. - 9780892083220 - 9780892083237 - 9780892083213 ; 60:4, s. 1-7
-
Konferensbidrag (refereegranskat)abstract
- MoS2 is a layered material which is abundant and non-toxic and has been increasingly studied during the last few years as a semiconducting alternative to graphene. While most studies have been performed on single MoS2 nanosheets, for example to demonstrate high-performance electronic transistors, more work is needed to explore the use of MoS2 in printed electronics. The importance of using MoS2 as a printed electronic material could be understood by considering the several orders higher electron mobility in MoS2, even in several nanometer thick layers, compared to the organic and other materials used today. In the few studies performed so far on printing MoS2, the developed dispersions used mainly organic solvents that might be detrimental for the environment. Here, we show an environmentally friendly liquid-based exfoliation method in water where the solution was stabilized by sodium dodecyl sulfate (SDS) surfactant. The dispersions consisted of very thin MoS2 nanosheets with average lateral size of about 150 nm, surface tension of 28 mN m-1 and a shelf life of a year. Although both the concentration and viscosity was less than optimal, we were able to inkjet print the MoS2 solution on paper and on PET films, using multiple printing passes. By tuning the concentration/viscosity, this approach might lead to an environmentally friendly MoS2 ink suitable for printed electronics.
|
|
| 25. |
- Forsberg, Viviane, 1981-
(författare)
-
Liquid Exfoliation of Molybdenum Disulfide for Inkjet Printing
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since the discovery of graphene, substantial effort has been put toward the synthesis and production of 2D materials. Developing scalable methods for the production of high-quality exfoliated nanosheets has proved a significant challenge. To date, the most promising scalable method for achieving these materials is through the liquid-based exfoliation (LBE) of nanosheetsin solvents. Thin films of nanosheets in dispersion can be modified with additives to produce 2D inks for printed electronics using inkjet printing. This is the most promising method for the deposition of such materials onto any substrate on an industrial production level. Although well-developed metallic and organic printed electronic inks exist on the market, there is still a need to improve or develop new inks based on semiconductor materials such as transition metal dichalcogenides (TMDs) that are stable, have good jetting conditions and deliver good printing quality.The inertness and mechanical properties of layered materials such as molybdenum disulfide (MoS2) make them ideally suited for printed electronics and solution processing. In addition,the high electron mobility of the layered semiconductors, make them a candidate to become a high-performance semiconductor material in printed electronics. Together, these features make MoS2 a simple and robust material with good semiconducting properties that is also suitable for solution coating and printing. It is also environmentally safe.The method described in this thesis could be easily employed to exfoliate many types of 2D materials in liquids. It consists of two exfoliation steps, one based on mechanical exfoliation of the bulk powder utilizing sand paper, and the other inthe liquid dispersion, using probe sonication to liquid-exfoliate the nanosheets. The dispersions, which were prepared in surfactant solution, were decanted, and the supernatant was collected and used for printing tests performed with a Dimatix inkjetprinter. The printing test shows that it is possible to use the MoS2 dispersion as a printed electronics inkjet ink and that optimization for specific printer and substrate combinations should be performed. There should also be advances in ink development, which would improve the drop formation and break-off at the inkjet printing nozzles, the ink jetting and, consequently, the printing quality.
|
|
| 26. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
Photodetector of multilayer exfoliated MoS2 deposited on polyimide films
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We fabricated a photodetector based on multilayer molybdenum disulfide (MoS2) by micromechanical cleavage of a molybdenite crystal using a polyimide film. We deposited 40 nm of gold by vacuum sputtering and copper tape was used for the contacts. Without any surface treatment, we achieved high responsivity at different incident optical power. The calculated responsivity was 23 mA/W of incident optical power in the range between 400 and 800 nm. For the responsivity measurement it was estimated that MoS2 have a bandgap of 1.6 eV, which lies between monolayer and multilayer films. The thickness of the MoS2 thin film was determined by Raman spectroscopy evaluating the difference between the in plane and out of plane Raman modes. The measurement of IV curves indicated Ohmic contacts in respect to the Au regardless of the incident optical power. Our device fabrication was much simpler than previous reported devices and can be used to test the light absorption and luminescence capabilities of exfoliated MoS2.
|
|
| 27. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
The Influence of pH on the Stability of Inks of Two-Dimensional Materials for Digital Fabrication
- 2017
-
Konferensbidrag (refereegranskat)abstract
- We aim to achieve stable printable 2D inks with environmental friendly solvents using a surfactant as a stabilizer. This study focuses on the influence of the pH on the stability of the MoS2 dispersionsin acetic acid at concentrations ranging from pH 1 to 5.The effectiveness of liquid-based exfoliation using shear exfoliation was also evaluated though SEM images and resulted in very thin nanosheets. We observed that at pH concentrations higher than 2, the dispersions were more stable.
|
|
| 28. |
- Forsberg, Viviane, 1981-, et al.
(författare)
-
Towards flexible and cheap printed electronics using inks of exfoliated 2D materials stabilized by cellulose
- 2017
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Flexible and cheap electronics are needed for simple applications such as sensors and solar cells. To achieve this, thin functional materials should be deposited efficiently to flexible substrates such as paper. A promising method for the deposition of such materials is through inkjet printing that said a stable and printable dispersion is necessary. We achieved this through liquid-based exfoliation of 2D materials in water using shear exfoliation and cellulose stabilizers. The resulted dispersion was then concentrated and inkjet printed on a flexible substrate. We used ethyl cellulose, cellulose nanofibers (CNF) and ultra-fine cellulose nanofibers (UF-CNF). All three stabilizers appear to work very well for MoS2 nanosheets even though the mechanisms of stabilization were different among them. For the MoS2-EC dispersions we achieved a broader PSD and higher dispersion stability. Thin nanosheets were observed from the SEM image of MoS2-EC dispersions deposited onto cellulose filters. The estimated concentration of the MoS2-EC dispersion after 20 days of sample preparation was 0.20 mg/mL. This dispersion was further processed to adjust the concentration and viscosity. Good coverage of the substrate was achieved after 50 printing passes. If the same technique is applied to other 2D materials such as graphene (conductor) and boro nitride (insulator), a transistor can be fabricated.
|
|
| 29. |
|
|
| 30. |
- Hammarling, Krister, 1968-, et al.
(författare)
-
FBG based upon evaporated Silica nano particles
- 2011
-
Ingår i: 1st EOS Topical Meetingon On Micro- and Nano-Optoelectronic Systems, Bremen, December 7-9, 2011.
-
Konferensbidrag (refereegranskat)abstract
- A fiber bragg grating was made by evaporating silica nano particles on the outside of a multimode silica fiber core using EISA method. We demonstrate that a cost effective bragg filter may be built by evaporating nano particles directly on a fiber core, which is tunable with the particle size.
|
|
| 31. |
- Hammarling, Krister, 1968-, et al.
(författare)
-
Fiber Bragg Grating filter using Evaporated Induced Self Assembly of silica nano particles
- 2014
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. ; , s. Art. no. 898225-
-
Konferensbidrag (refereegranskat)abstract
- In the present work we conduct a study of ber lters produced by evaporation of silica particles upon aMM-ber core. A band lter was designed and theoretically veried using a 2D Comsol simulation model ofa 3D problem, and calculated in the frequency domain in respect to refractive index. The ber lters werefabricated by stripping and chemically etching the middle part of an MM-ber until the core was exposed. Amono layer of silica nano particles were evaporated on the core using an Evaporation Induced Self-Assembly(EISA) method. The experimental results indicated a broader bandwidth than indicated by the simulationswhich can be explained by the mismatch in the particle size distributions, uneven particle packing and nallyby eects from multiple mode angles. Thus, there are several closely connected Bragg wavelengths that buildup the broader bandwidth. The experimental part shows that it is possible by narrowing the particle sizedistributing and better control of the particle packing, the lter eectiveness can be greatly improved.
|
|
| 32. |
- Hummelgård, Magnus, et al.
(författare)
-
Electrical Sintering of Silver Nanoparticle Ink Studied by In-Situ TEM Probing
- 2011
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:2, s. Art. no. e17209-
-
Tidskriftsartikel (refereegranskat)abstract
- Metallic nanoparticle inks are used for printed electronics, but to reach acceptable conductivity the structures need to be sintered, usually using a furnace. Recently, sintering by direct resistive heating has been demonstrated. For a microscopic understanding of this Joule heating sintering method, we studied the entire process in real time inside a transmission electron microscope equipped with a movable electrical probe. We found an onset of Joule heating induced sintering and coalescence of nanoparticles at power levels of 0.1-10 mW/mu m(3). In addition, a carbonization of the organic shells that stabilize the nanoparticles were found, with a conductivity of 4 10(5) Sm-1
|
|
| 33. |
- Hummelgård, Magnus, et al.
(författare)
-
Nanowire Transformation and Annealing by Joule Heating
- 2010
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 21:16, s. 165704-165704
-
Tidskriftsartikel (refereegranskat)abstract
- Joule heating of bundles of Mo6S3I6 nanowires, in real time, was studied using in situ TEM probing. TEM imaging, electron diffraction, and conductivity measurements showed a complete transformation of Mo6S3I6 into Mo via thermal decomposition. The resulting Mo nanowires had a conductivity that was 2-3 orders higher than the starting material. The conductivity increased even further, up to 1.8 x 10(6) S m(-1), when the Mo nanowires went through annealing phases. These results suggest that Joule heating might be a general way to transform or anneal nanowires, pointing to applications such as metal nanowire fabrication, novel memory elements based on material transformation, or in situ improvement of field emitters.
|
|
| 34. |
- Jiang, Yuting, et al.
(författare)
-
Laser-Etched Stretchable Graphene–Polymer Composite Array for Sensitive Strain and Viscosity Sensors
- 2019
-
Ingår i: Nano-Micro Letters. - : Springer Science and Business Media LLC. - 2150-5551 .- 2311-6706. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- The ability to control surface wettability and liquid spreading on textured surfaces is of interest for extensive applications. Soft materials have prominent advantages for producing the smart coatings with multiple functions for strain sensing. Here, we report a simple method to prepare flexible hydrophobic smart coatings using graphene–polymer films. Arrays of individual patterns in the films were created by laser engraving and controlled the contact angle of small drops by pinning the contact lines in a horizontal tensile range of 0–200%. By means of experiments and model, we demonstrate that the ductility of drops is relied on the height-to-spacing ratio of the individual pattern and the intrinsic contact angle. Moreover, the change of drop size was utilized to measure the applied strain and liquid viscosity, enabling a strain sensitivity as high as 1068 μm2/%. The proposed laser-etched stretchable graphene–polymer composite has potential applications in DNA microarrays, biological assays, soft robots, and so on.
|
|
| 35. |
|
|
| 36. |
- Maslik, Jan, et al.
(författare)
-
PEDOT:PSS temperature sensor ink-jet printed on paper substrate
- 2018
-
Ingår i: Journal of Instrumentation. - : Institute of Physics (IOP). - 1748-0221. ; 13
-
Forskningsöversikt (refereegranskat)abstract
- In this work we present an ink-jet printed temperature sensor consisting of PEDOT:PSSprinted on paper suitable for packaging, flexible electronics and other printed applications. Thesubstrate showed to have a large influence on both the resistance aswell as the temperature sensitivityof the PEDOT:PSS ink. This effect is most likely due to NaCl content in the photo paper coating,which reacts with the PEDOT:PSS. The temperature coefficient of a prepared device of α= -0.030 relative to room temperature (22°C) was measured, which is higher than compared to for exampleSilicon α = -0.075.
|
|
| 37. |
- Mazlik, Jan, et al.
(författare)
-
Temperature sensor based on PEDOT : PSS ink-jet printed on paper substrate
- 2018
-
Konferensbidrag (refereegranskat)abstract
- Printed electronics is rapidly developing, where more and more components are printable. High speed roll-to-roll processesare preferred for low cost production of flexible electronics. Often, the substrates used for printed electronics are some typeof plastic such as PET or Kapton. An alternative to plastic is to use paper substrate that has the benefits of beingenvironmentally friendly, recyclable and renewable. Paper is also the material of choice for packages of various goods.In this work we have developed an ink-jet printable temperature sensor, a thermistor, consisting ofpoly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)( PEDOT:PSS) on paper substrate. The starting material is acommercial PEDOT:PSS ink-jet ink (Orgacon IJ-1005, Agfa). This ink was then modified to increase the thermal sensitivityby addition of the co-solvents Dimethyl sulfoxide (DMSO) and Polyethylene glycol (PEG) in different quantities. DMSO hasbeen shown to increase the conductance by arranging the PEDOT into more conductive pathways and by removing PSS[1] and PEG to increase the carrier density and mobility [2].The sensors consisted of modified PEDOT:PSS lines printed on photo-paper substrate between contacts printed usingsilver nano-particle ink. The line widths were varied from one pixel, corresponding to one pass of one nozzle up-to 20pixels. The linewidths were then measured to be from 45 μm up-to 450 μm. The thickness of the sensor was also varied asone, two or three printed layers. The characterization as a temperature sensor was performed by using a setup consistingof a Peltier cooler and a heating element to step the temperature. As a reference a PT-100 element fixed to the surface ofthe cooler/heater was used.An increase in resistance from 30.5 MΩ to 85 MΩ, corresponding to a change of 2.8 times, were measured when thetemperature were changed from 22 °C to -12 °C as can be seen in the figure. This gives a ΔR/ΔT of 0.093.Such a printed sensor can be used for applications where a low cost, printable solution is needed, such as printed directlyon packages, for environmental monitoring and similar.[1] C.S. Pathak, J.P. Singh, R. Singh, Effect of dimethyl sulfoxide on the electrical properties of PEDOT:PSS/ n-Siheterojunction diodes, Current Applied Physics, 15, (2015), 528-534[2] Yow-Jon Lin, Wei-Shih Ni and Jhe-You Lee, Effect of incorporation of ethylene glycol into PEDOT:PSS on electronphonon coupling and conductivity, Journal of Applied Physics 117, (2015), 215501
|
|
| 38. |
- Mondal, Rajib, et al.
(författare)
-
Nanogenerators-Based Self-Powered Sensors
- 2022
-
Ingår i: Advanced Materials Technologies. - : Wiley. - 2365-709X. ; 7:12
-
Forskningsöversikt (refereegranskat)abstract
- With the rapid technological development, self-powered sensor systems that are capable of operating without an external power supply are becoming more and more crucial in the field of sensing and detection. One of the major drawbacks of a typical sensor is the necessity of an external power supply or batteries, which makes sensor systems more complex and less handy for mobile devices. In the last decade's improvement of triboelectric, piezoelectric, pyroelectric, and thermoelectric nanogenerators and their performance in electrical output and mechanical stability, it becomes widely used in the field of self-power sensing systems for healthcare, mechanical and environmental applications. Here in this review, the various types of nanogenerators working principles is first discussed, the output performance is analyzed, and then their recent progress in the application of self-powered sensor systems, including biomedical and healthcare, wearable devices, physical applications, robotics, environmental monitoring, and smart cities, is highlighted. Except for the practical application of self-powered sensors, a future outlook of the self-powered sensor systems is prognosticated.
|
|
| 39. |
- Olsen, Martin, 1971-, et al.
(författare)
-
Frequency and voltage response of a wind-driven fluttering triboelectric nanogenerator
- 2019
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 40. |
- Olsen, Martin, 1971-, et al.
(författare)
-
Schottky model for triboelectric temperature dependence
- 2018
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 41. |
- Ouyang, Bangsen, et al.
(författare)
-
Dual-polarity output response-based photoelectric devices
- 2021
-
Ingår i: Cell Reports Physical Science. - : Elsevier BV. - 2666-3864. ; 2:5
-
Tidskriftsartikel (refereegranskat)abstract
- Photoelectric devices converting information carried by light into useful electrical signals are widely studied. To date, many mechanisms are applied to the design of photoelectric devices, such as the photovoltaic (PV) effect, photothermoelectric (PTE) effect, and photoelectrochemical (PEC) effect. When designing photoelectric devices that take advantage of these mechanisms, the polarity of the photocurrent is sensitive not only to light intensity but also to other parameters, including the wavelength of the incident light, pressure, and solutes. Here, development of these devices is summarized with a focus on working mechanisms, strategies to control the polarity of photocurrents, general performance, and potential applications, especially PEC effect-based devices for biosensing and PV effect-based devices for wavelength discrimination. The polarity switching phenomenon endows photoelectric devices with multi-functional characteristics that may offer new solutions to address traditional issues and meet the requirements of future technologies.
|
|
| 42. |
- Shi, Xue, et al.
(författare)
-
A strong, biodegradable, and recyclable all-lignocellulose fabricated triboelectric nanogenerator for self-powered disposable medical monitoring
- 2023
-
Ingår i: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 11:22, s. 11730-11739
-
Tidskriftsartikel (refereegranskat)abstract
- The growing demand for fast, reliable, and accessible information in the vastly connected world makes disposable sensors increasingly important. However, reducing their costs, environmental impact, and usability remains challenging. Here, we report a low-cost, biodegradable, and recyclable all-lignocellulosic triboelectric nanogenerator (AL-TENG) for self-powered disposable medical monitoring. Based on a facile in situ lignin regeneration & chemical crosslinking modification strategy, a high-performance lignocellulosic bioplastic is synthesized from resource-abundant and renewable biomass for fabricating the AL-TENG. The whole device has a low environmental impact as it can be easily recycled and biodegraded at its end-of-life. Furthermore, a self-powered smart ward system and a self-powered contactless medical monitoring system are developed to improve the convenience for patients and reduce the risk of mutual infection. This work can expand the application of self-powered systems to disposable medical sensing, which may greatly promote the development of intelligent wards and disposable electronics.
|
|
| 43. |
- Song, Y., et al.
(författare)
-
Direct Current Triboelectric Nanogenerators
- 2020
-
Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 10:45
-
Tidskriftsartikel (refereegranskat)abstract
- The triboelectric nanogenerator (TENG) as a promising energy scavenging technology has been utilized to convert ambient mechanical energy into electric energy for meeting ever-increasing energy consumption and the need for sustainable energy in modern life. However, the electric energy generated by the conventional TENG based on coupling the contact electrification and electrostatic induction is pulsed alternating current, which requires rectification measures to obtain the direct current (DC) power suitable for storing and driving electronic equipment, resulting in the limitation of its portability and energy utilization efficiency. Through the use of new materials and structures, novel direct current triboelectric nanogenerators (DC-TENGs) with constant DC output characteristics provide an intelligent solution. Here, the development of DC-TENG is reviewed, focusing on the working mechanisms of DC-TENG based on various strategies. The important factors affecting the outputs and the main applications of DC-TENGs are summarized. Moreover, the possible challenges and future direction for DC-TENGs are also discussed.
|
|
| 44. |
- Stolpe, Amanda, et al.
(författare)
-
Regenerated cellulose TENG with colour printed surface for increased performance
- 2023
-
Ingår i: Book of Abstracts EPNOE 2023. - : Graz University of Technology. ; , s. 132-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Triboelectric nanogenerators (TENGs) are ideal to meet the increasing need for green and efficient energy solutions, e.g., in small wireless and/or wearable applications. Regenerated cellulose is an exemplary material regarding both power output and mechanical performance, and it is environmentally friendly and economically favourable. To further improve the triboelectric performance of the cellulose, colour printing was done on the surface with conventional laser printing. Printer toners commonly contain substances with different triboelectric properties. [1] In this work, cellulose fibres were dissolved using a LiOH/urea solvent and regenerated in an ethanol bath and eventually dried under controlled conditions. Thereafter the resulting transparent cellulose films were run through a conventional laser paper printer to apply toners of different colour and patterns on the surface. Cyan, magenta, yellow and black was printed in one layer. In addition, black was printed in certain patterns from low to high coverage and in several layers to evaluate the effect of applied amount. The samples were analysed using SEM, AFM, XRD, FTIR and a TENG was assembled in the contact-separation mode to investigate the triboelectric performance. The printed cellulose films were found to give enhanced triboelectric output. The results show an interesting and simple processing route to enhance the performance of cellulose- based TENG materials that can be useful in the development of cheap and sustainable small wireless electrical generators or sensors.[1] Zhang, R.; Hummelgård, M.; Örtegren, J.; Andersson, H.; Olsen, M.; Chen, W.; Wang, P.; Eivazi, A.; Dahlström, C.; Norgren, M., Adv. Engin. Mater., 2023, in press, https://doi.org/10.1002/adem.202300107
|
|
| 45. |
- Wang, Z., et al.
(författare)
-
Biodegradable, conductive, moisture-proof, and dielectric enhanced cellulose-based triboelectric nanogenerator for self-powered human-machine interface sensing
- 2023
-
Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 107
-
Tidskriftsartikel (refereegranskat)abstract
- With the rapid development of sensors and triboelectric nanogenerators (TENGs), multifunctional self-powered sensors have received extensive attention. In this study, we prepare cellulose carbon nanotubes aerogel TENG (CCA-TENG) with high output, moisture-proof, simplified structure, and biodegradability for ambient energy harvesting and self-powered sensing. The cellulose carbon nanotubes aerogel (CCA) can be used not only acts as a tribolayer, but also as an electrode, with the characteristics of a 3D porous structure, high specific surface area, and dielectric enhancement. CCA-TENG exhibits improved output performance due to the advantages of the enhanced dielectric constant and 3D porous structure. Since regenerated cellulose is a dense polymer, it still keeps high output performance under high humidity. More importantly, CCA-TENG can be rapidly degraded in cellulase, and the output performance of the CCA-TENG prepared from recycled CNTs reaches 91.04% output of the original TENG. This study demonstrates the preparation, degradation, and reuse of CCA-TENGs and their applications, providing new avenues for high-performance, moisture-proof, and ambient self-powered systems.
|
|
| 46. |
- Xu, S., et al.
(författare)
-
Multi-dimensional, transparent and foldable cellulose-based triboelectric nanogenerator for touching password recognition
- 2022
-
Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 98
-
Tidskriftsartikel (refereegranskat)abstract
- Transparent power sources are required for emerging electronics and energy devices. However, most transparent materials/systems present certain problems: they are often fragile and unsuitable for shaping into fixed three-dimensional structures. Here, we attempted to overcome these challenges by constructing a cellulose-based multilayer film as a single-electrode triboelectric nanogenerator (TENG). The TENG was simply fabricated by the step-by-step deposition of a cellulose triboelectric layer, a silver nanowire electrode layer, and a protective cellulose layer. The tightly packed thin film is transparent, flexible and foldable. Four TENGs were spontaneously assembled into one film, and various spatial configurations were generated by a series of cutting and folding processes. We proved the practicality of a TENG-containing cellulose-based multilayer film by developing a multi-dimensional touch password switch, and expect that it will be widely used in film-based intelligent electronics.
|
|
| 47. |
|
|
| 48. |
- Zhang, Renyun, et al.
(författare)
-
A facile one-step method for synthesising a parallelogram-shaped single-crystalline ZnO nanosheet
- 2014
-
Ingår i: Materials Science and Engineering: B. - : Elsevier. - 0921-5107. ; 184, s. 1-6
-
Tidskriftsartikel (refereegranskat)abstract
- ZnO nanosheets are found to be useful in many fields such as sensors and electronics. Non-uniform- shaped ZnO nanosheets are synthesised using several methods; moreover, uniformly shaped ones are less studied. Here, we report on a simple one-step method to synthesise parallelogram-shaped single- crystalline ZnO nanosheets. By controlling the reaction of Zn(NO3 )2 and hexamethylenetetramine (HMT) in ethanol, average 30 nm-thick nanosheets with a high aspect ratio of 1:100 were obtained. The par- allelogram angles were between 97◦ and 99◦. Transmission electron microscopy (TEM) diffraction and X-ray diffraction (XRD) showed that the nanosheets were wurtzite-structured single-crystalline ZnO. Moreover, a growth mechanism of these parallelogram nanosheets is suggested based on the experi- mental results. These results suggest a new simple solution process to synthesise uniformly shaped ZnO nanosheets allowing large-scale production to be employed.
|
|
| 49. |
- Zhang, Renyun, et al.
(författare)
-
A review of the advances in composites/nanocomposites for triboelectric nanogenerators
- 2022
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 33:21
-
Forskningsöversikt (refereegranskat)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.
|
|
| 50. |
- Zhang, Renyun, et al.
(författare)
-
Advances in Inorganic Nanomaterials for Triboelectric Nanogenerators
- 2022
-
Ingår i: ACS Nanoscience Au. - : American Chemical Society (ACS). - 2694-2496. ; 2:1, s. 12-31
-
Forskningsöversikt (refereegranskat)abstract
- Triboelectric nanogenerators (TENGs) that utilize triboelectrification and electrostatic induction to convert mechanical energy to electricity have attracted increasing interest in the last 10 years. As a universal physical phenomenon, triboelectrification can occur between any two surfaces that experience physical contact and separation regardless of the type of material. For this reason, many materials, including both organic and inorganic materials, have been studied in TENGs with different purposes. Although organic polymers are mainly used as triboelectric materials in TENGs, the application of inorganic nanomaterials has also been intensively studied because of their unique dielectric, electric, piezoelectric, and optical properties, which can improve the performance of TENGs. A review of how inorganic nanomaterials are used in TENGs would help researchers gain an overview of the progress in this area. Here, we present a review to summarize how inorganic nanomaterials are utilized in TENGs based on the roles, types, and characteristics of the nanomaterials.
|
|
