| 1. |
- Abdollahi Sani, Negar, et al.
(författare)
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Flexible lamination-fabricated ultra-high frequency diodes based on self-supporting semiconducting composite film of silicon micro-particles and nano-fibrillated cellulose
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Low cost and flexible devices such as wearable electronics, e-labels and distributed sensors will make the future "internet of things" viable. To power and communicate with such systems, high frequency rectifiers are crucial components. We present a simple method to manufacture flexible diodes, operating at GHz frequencies, based on self-adhesive composite films of silicon micro-particles (Si-ΌPs) and glycerol dispersed in nanofibrillated cellulose (NFC). NFC, Si-ΌPs and glycerol are mixed in a water suspension, forming a self-supporting nanocellulose-silicon composite film after drying. This film is cut and laminated between a flexible pre-patterned Al bottom electrode and a conductive Ni-coated carbon tape top contact. A Schottky junction is established between the Al electrode and the Si-ΌPs. The resulting flexible diodes show current levels on the order of mA for an area of 2 mm2, a current rectification ratio up to 4 × 103 between 1 and 2 V bias and a cut-off frequency of 1.8 GHz. Energy harvesting experiments have been demonstrated using resistors as the load at 900 MHz and 1.8 GHz. The diode stack can be delaminated away from the Al electrode and then later on be transferred and reconfigured to another substrate. This provides us with reconfigurable GHz-operating diode circuits.
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| 2. |
- Ail, Ujwala, et al.
(författare)
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Room temperature synthesis of transition metal silicide-conducting polymer micro-composites for thermoelectric applications
- 2017
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Ingår i: Synthetic metals. - : Elsevier BV. - 0379-6779 .- 1879-3290. ; 225, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- Organic polymer thermoelectrics (TE) as well as transition metal (TM) silicides are two thermoelectric class of materials of interest because they are composed of atomic elements of high abundance; which is a prerequisite for mass implementation of thermoelectric (TE) solutions for solar and waste heat recovery. But both materials have drawbacks when it comes to finding low-cost manufacturing. The metal silicide needs high temperature (>1000 °C) for creating TE legs in a device from solid powder, but it is easy to achieve long TE legs in this case. On the contrary, organic TEs are synthesized at low temperature from solution. However, it is difficult to form long legs or thick films because of their low solubility. In this work, we propose a novel method for the room temperature synthesis of TE composite containing the microparticles of chromium disilicide; CrSi2 (inorganic filler) in an organic matrix of nanofibrillated cellulose- poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (NFC-PEDOT:PSS). With this method, it is easy to create long TE legs in a room temperature process. The originality of the approach is the use of conducting polymer aerogel microparticles mixed with CrSi2 microparticles to obtain a composite solid at room temperature under pressure. We foresee that the method can be scaled up to fabricate and pattern TE modules. The composite has an electrical conductivity (σ) of 5.4 ± 0.5 S/cm and the Seebeck coefficient (α) of 88 ± 9 ΌV/K, power factor (α2σ) of 4 ± 1 ΌWm−1K−2 at room temperature. At a temperature difference of 32 °C, the output power/unit area drawn across the load, with the resistance same as the internal resistance of the device is 0.6 ± 0.1 ΌW/cm2.
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| 3. |
- Béland, Marie-Claude, et al.
(författare)
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Exploring How Material Demonstrators Accelerate the Transition to a Circular Bioeconomy
- 2023
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Ingår i: diid disegno industriale industrial design. - 2785-2245. ; :79, s. 44-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Taking ideas to market can be a long, iterative, and complex process. When dealing with new bio-based materials, under-standing factors that help bridge the lab-to-market gap and how materials are selected for new product development have the potential to speed up the transition to a circular bioeconomy. This article defines abstract and conceptual material demonstrators and explores how they support the innovation process in different ways. Nine roles are iden-tified, including how material demonstrators contribute to generating and expressing new ideas, enable a shared understanding of technology, support the discovery of market value and the visualization of potential applications as well as helping to articulate internal and external strategies and communications. Abstract and conceptual material dem-onstrators are exemplified with both technology-driven and market-driven bio-based materials used in packaging.
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| 4. |
- Breijaert, T. C., et al.
(författare)
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Self-assembly of ferria – nanocellulose composite fibres
- 2022
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Ingår i: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 291
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Tidskriftsartikel (refereegranskat)abstract
- An environmentally benign synthesis of a magnetically responsive carboxymethylated cellulose nanofibril-based material is reported. Applied experimental conditions lead to the in-situ formation of magnetite nanoparticles with primary particle sizes of 2.0–4.0 nm or secondary particles of 3.6–16.4 nm depending on whether nucleation occurred between individual carboxymethylated cellulose nanofibrils, or on exposed fibril surfaces. The increase in magnetite particle size on the cellulose fibril surfaces was attributed to Ostwald ripening, while the small particles formed within the carboxymethyl cellulose aggregates were presumably due to steric interactions. The magnetite nanoparticles were capable of coordinating to carboxymethylated cellulose nanofibrils to form large “fibre-like” assemblies. The confinement of small particles within aggregates of reductive cellulose molecules was most likely responsible for excellent conservation of magnetic characteristics on storage of this material. The possibility for using the material in drug delivery applications with release rate controlled by daylight illumination is presented. © 2022 The Author(s)
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| 5. |
- Edberg, Jesper, et al.
(författare)
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Electrochemical circuits from 'cut and stick' PEDOT : PSS-nanocellulose composite
- 2017
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Ingår i: Flexible and Printed Electronics. - : Institute of Physics Publishing (IOPP). - 2058-8585. ; 2:4
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Tidskriftsartikel (refereegranskat)abstract
- We report a flexible self-standing adhesive composite made from PEDOT:PSS and nanofibrillated cellulose. The material exhibits good combined mechanical and electrical characteristics (an elastic modulus of 4.4 MPa, and an electrical conductivity of 30 S cm(-1)). The inherent self-adhesiveness of the material enables it to be laminated and delaminated repeatedly to form and reconfigure devices and circuits. This modular property opens the door for a plethora of applications where reconfigurability and ease-of-manufacturing are of prime importance. We also demonstrate a paper composite with ionic conductivity and combine the two materials to construct electrochemical devices, namely transistors, capacitors and diodes with high values of transconductance, charge storage capacity and current rectification. We have further used these devices to construct digital circuits such as NOT, NAND and NORlogic.
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| 6. |
- Edberg, Jesper, et al.
(författare)
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Improving the Performance of Paper Supercapacitors Using Redox Molecules from Plants
- 2019
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Ingår i: ADVANCED SUSTAINABLE SYSTEMS. - : WILEY-V C H VERLAG GMBH. - 2366-7486. ; 3:8
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Tidskriftsartikel (refereegranskat)abstract
- A supercapacitor made from organic and nature-based materials, such as conductive polymers (PEDOT:PSS), nanocellulose, and an the organic dye molecule (alizarin), is demonstrated. The dye molecule, which historically was extracted from the roots of the plant rubia tinctorum, is here responsible for the improvement in energy storage capacity, while the conductive polymer provides bulk charge transport within the composite electrode. The forest-based nanocellulose component provides a mechanically strong and nonporous network onto which the conductive polymer self-organizes. The electrical and electrochemical properties of the material composition are investigated and prototype redox-enhanced supercapacitor devices with excellent specific capacitance exceeding 400 F g(-1) and an operational stability over >1000 cycles are demonstrated. This new class of supercapacitors, which in part are based on organic materials from plants, represents an important step toward a green and sustainable energy technology.
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| 7. |
- Eita, Mohamed, et al.
(författare)
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Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films
- 2011
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 363:2, s. 566-572
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Tidskriftsartikel (refereegranskat)abstract
- Over the last decade, the use of nanocellulose in advanced technological applications has been promoted both due the excellent properties of this material in combination with its renewability. In this study, multilayered thin films composed of nanofibrillated cellulose (NFC), polyvinyl amine (PVAm) and silica nanoparticles were fabricated on polydimethylsiloxane (PDMS) using a layer-by-layer adsorption technique. The multilayer build-up was followed in situ by quartz crystal microbalance with dissipation, which indicated that the PVAm-SiO(2)-PVAm-NFC system adsorbs twice as much wet mass material compared to the PVAm-NFC system for the same number of bilayers. This is accompanied with a higher viscoelasticity for the PVAm-SiO(2)-PVAm-NFC system. Ellipsometry indicated a dry-state thickness of 2.2 and 3.4 nm per bilayer for the PVAm-NFC system and the PVAm-SiO(2)-PVAm-NFC system, respectively. Atomic force microscopy height images indicate that in both systems, a porous network structure is achieved. Youngs modulus of these thin films was determined by the Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) technique. The Youngs modulus of the PVAm/NFC films was doubled, from 1 to 2 GPa, upon incorporation of silica nanoparticles in the films. The introduction of the silica nanoparticles lowered the refractive index of the films, most probably due to an increased porosity of the films.
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| 8. |
- Engquist, Isak, et al.
(författare)
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Highly conducting nanographite-filled paper fabricated via standard papermaking techniques
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society. - 1944-8244 .- 1944-8252. ; 12:43, s. 48828-48835
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Tidskriftsartikel (refereegranskat)abstract
- Eco-friendly and cost-effective materials and processes to manufacture functional substrates are crucial to further advance the area of printed electronics. One potential key component in the printed electronics platform is an electrically functionalized paper, produced by simply mixing common cellulosic pulp fibers with high-performance electroactive materials. Herein, an electronic paper including nanographite has been prepared using a standardized and scalable papermaking technique. No retention aid was needed to achieve a conducting nanographite loading as high as 50 wt %. The spontaneous retention that provides the integrity and stability of the nanographite paper, likely originates partially from an observed water-stable adhesion of nanographite flakes onto the fiber surfaces. The resulting paper exhibits excellent electrical characteristics, such as an in-plane conductivity of 107 S/cm and an areal capacitance of 9.2 mF/cm2, and was explored as the back-electrode in printed electrochromic displays.
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| 9. |
- Erlandsson, Johan, et al.
(författare)
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Cross-Linked and Shapeable Porous 3D Substrates from Freeze-Linked Cellulose Nanofibrils.
- 2019
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 20:2, s. 728-737
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Tidskriftsartikel (refereegranskat)abstract
- Chemically cross-linked highly porous nanocellulose aerogels with complex shapes have been prepared using a freeze-linking procedure that avoids common post activation of cross-linking reactions and freeze-drying. The aerogel shapes ranged from simple geometrical three-dimensional bodies to swirls and solenoids. This was achieved by molding or extruding a periodate oxidized cellulose nanofibril (CNF) dispersion prior to chemical cross-linking in a regular freezer or by reshaping an already prepared aerogel by plasticizing the structure in water followed by reshaping and locking the aerogel into its new shape. The new shapes were most likely retained by new cross-links formed between CNFs brought into contact by the deformation during reshaping. This self-healing ability to form new bonds after plasticization and redrying also contributed to the mechanical resilience of the aerogels, allowing them to be cyclically deformed in the dry state, reswollen with water, and redried with good retention of mechanical integrity. Furthermore, by exploiting the shapeability and available inner structure of the aerogels, a solenoid-shaped aerogel with all surfaces coated with a thin film of conducting polypyrrole was able to produce a magnetic field inside the solenoid, demonstrating electromagnetic properties. Furthermore, by biomimicking the porous interior and stiff exterior of the beak of a toucan bird, a functionalized aerogel was created by applying a 300 μm thick stiff wax coating on its molded external surfaces. This composite material displayed a 10-times higher elastic modulus compared to that of the plain aerogel without drastically increasing the density. These examples show that it is possible to combine advanced shaping with functionalization of both the inner structure and the surface of the aerogels, radically extending the possible use of CNF aerogels.
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| 10. |
- Erlandsson, Johan, et al.
(författare)
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Macro- and mesoporous nanocellulose beads for use in energy storage devices
- 2016
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Ingår i: APPLIED MATERIALS TODAY. - : Elsevier. - 2352-9407. ; 5, s. 246-254
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Tidskriftsartikel (refereegranskat)abstract
- Chemically cross-linked, wet-stable cellulose nanofibril (CNF) aerogel beads were fabricated using a novel procedure. The procedure facilitated controlled production of millimetre-sized CNF aerogel beads without freeze-drying or critical point drying, while still retaining a highly porous structure with low density. The aerogel beads were mechanically robust in the dry state, supporting loads of 1.3 N at 70% compression, even after being soaked in water and re-dried. Furthermore, they displayed both a good stability in water and a remarkably good shape recovery after wet compression. Owing to the stability in water, the entire surface of the highly porous aerogel beads could be successfully functionalized with polyelectrolytes and carboxyl-functionalized single-wall carbon nanotubes (CF-SWCNTs) using the Layer-by-Layer technique, introducing a significant electrical conductivity (1.6 mS/cm) to the aerogel beads. The functionalized, electrically conducting aerogel beads could carry as much as 2 kA/cm(2) and act as electrodes in a supercapacitor displaying a stabilized charge storage capacity of 9.8 F/g after 50 charging-discharging cycles.
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