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  • 1.
    Bayrak Pehlivan, İlknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Functionalization of polymer electrolytes for electrochromic windows2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Saving energy in buildings is of great importance because about 30 to 40 % of the energy in the world is used in buildings. An electrochromic window (ECW), which makes it possible to regulate the inflow of visible light and solar energy into buildings, is a promising technology providing a reduction in energy consumption in buildings along with indoor comfort. A polymer electrolyte is positioned at the center of multi-layer structure of an ECW and plays a significant role in the working of the ECW.

    In this study, polyethyleneimine: lithium (bis(trifluoromethane)sulfonimide (PEI:LiTFSI)-based polymer electrolytes were characterized by using dielectric/impedance spectroscopy, differential scanning calorimetry, viscosity recording, optical spectroscopy, and electrochromic measurements.

    In the first part of the study, PEI:LiTFSI electrolytes were characterized at various salt concentrations and temperatures. Temperature dependence of viscosity and ionic conductivity of the electrolytes followed Arrhenius behavior. The viscosity was modeled by the Bingham plastic equation. Molar conductivity, glass transition temperature, viscosity, Walden product, and iso-viscosity conductivity analysis showed effects of segmental flexibility, ion pairs, and mobility on the conductivity. A connection between ionic conductivity and ion-pair relaxation was seen by means of (i) the Barton-Nakajima-Namikawa relation, (ii) activation energies of the bulk relaxation, and ionic conduction and (iii) comparing two equivalent circuit models, containing different types of Havriliak-Negami elements, for the bulk response.

    In the second part, nanocomposite PEI:LiTFSI electrolytes with SiO2, In2O3, and In2O3:Sn (ITO) were examined. Adding SiO2 to the PEI:LiTFSI enhanced the ionic conductivity by an order of magnitude without any degradation of the optical properties. The effect of segmental flexibility and free ion concentration on the conduction in the presence of SiO2 is discussed. The PEI:LiTFSI:ITO electrolytes had high haze-free luminous transmittance and strong near-infrared absorption without diminished ionic conductivity. Ionic conductivity and optical clarity did not deteriorate for the PEI:LiTFSI:In2O3 and the PEI:LiTFSI:SiO2:ITO electrolytes.

    Finally, propylene carbonate (PC) and ethylene carbonate (EC) were added to PEI:LiTFSI in order to perform electrochromic measurements. ITO and SiO2 were added to the PEI:LiTFSI:PC:EC and to a proprietary electrolyte. The nanocomposite electrolytes were tested for ECWs with the configuration of the ECWs being plastic/ITO/WO3/polymer electrolyte/NiO (or IrO2)/ITO/plastic. It was seen that adding nanoparticles to polymer electrolytes can improve the coloring/bleaching dynamics of the ECWs.

    From this study, we show that nanocomposite polymer electrolytes can add new functionalities as well as enhancement in ECW applications.

    List of papers
    1. PEI-LiTFSI electrolytes for electrochromic devices: Characterization by differential scanning calorimetry and viscosity measurements
    Open this publication in new window or tab >>PEI-LiTFSI electrolytes for electrochromic devices: Characterization by differential scanning calorimetry and viscosity measurements
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    2010 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 94, no 12, p. 2399-2404Article in journal (Refereed) Published
    Abstract [en]

    Polymer electrolytes containing poly(ethylene imine) (PEI) and lithium bis(trifluoromethylsulfonyl) imide (LiTFSI) can serve as model electrolytes for electrochromic devices. Such electrolytes were characterized by differential scanning calorimetry, conductivity, and viscosity measurements. The glass transition temperature (T-g) and viscosity of the PEI-LiTESI electrolytes have minima at a [N]:[Li] ratio of 100:1. Both T-g and viscosity increased at high salt concentrations. The temperature dependences of ionic conductivity and viscosity followed an Arrhenius equation with parameters depending only weakly on the salt concentration. The fluid behavior of the electrolytes could be reconciled with the Bingham plastic model with parameters being functions of salt concentration.

    Keywords
    Polymer electrolyte, Electrochromic, Smart window, PEI, DSC, Viscosity
    National Category
    Chemical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-135307 (URN)10.1016/j.solmat.2010.08.025 (DOI)000283959500066 ()
    Available from: 2011-09-21 Created: 2010-12-06 Last updated: 2017-12-11Bibliographically approved
    2. Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes
    Open this publication in new window or tab >>Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes
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    2011 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, p. 201-206Article in journal (Refereed) Published
    Abstract [en]

    Ionic conductivity of polymer electrolytes containing branched poly (ethylene imine) (BPEI) and lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) was measured between temperatures of 20 and 70◦C and molar ratios of 20:1 and 400:1. The electrolytes were characterized by impedance spectroscopy, differential scanning calorimetry, and viscosity measurements. At room temperature, the maximum conductivity was 2×10−6 S/cm at a molar ratio of 50:1. The molar conductivity of the electrolytes displayed first a minimum and then a maximum upon increasing salt concentration. A proportionality of molar conductivity to segmental mobility was seen from glass transition temperature and viscosity measurements. Analysis of the Walden product and isoviscosity conductivity showed that the percentage of ions bound in ion pairs increased at low concentrations below 0.1 mol/kg. The average dipole moment decreased with salt concentration. The temperature dependence of the ionic conductivity showed an Arrhenius behavior.

    Keywords
    Ionic conductivity, Poly (ethylene imine), Arrhenius behavior, Walden rule, Ion pairing
    National Category
    Other Materials Engineering
    Research subject
    Chemistry with specialization in Polymer Chemistry; Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-163443 (URN)10.1016/j.electacta.2011.04.040 (DOI)000298463900029 ()
    Available from: 2011-12-12 Created: 2011-12-12 Last updated: 2017-12-08Bibliographically approved
    3. Ionic relaxation in polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide polymer electrolytes
    Open this publication in new window or tab >>Ionic relaxation in polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide polymer electrolytes
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    2010 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, no 7, p. 074102-Article in journal (Refereed) Published
    Abstract [en]

    Polymer electrolytes containing polyethyleneimine and different concentrations of lithium bis(trifluoromethylsulfonyl) imide were investigated by impedance spectroscopy at different temperatures. Two equivalent circuit models were compared for the bulk impedance response. The first one includes a conductive Havriliak-Negami (HN) element which represents ionic conductivity and ion pair relaxation in a single process, and the second model includes a dielectric HN element, which represents ion pair relaxation, in parallel with ion conductivity. Comparison of the two circuit models showed that the quality of the fit was similar and in some cases better for the conductive model. The experimental data follow the Barton-Nakajima-Namikawa relation, which relates the ion conductivity and the parameters of the relaxation. This indicates that ion conductivity and ion pair relaxation are two parts of the same process and should be described by the conductive model.

    National Category
    Physical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-133611 (URN)10.1063/1.3490133 (DOI)000283222200101 ()
    Available from: 2011-09-21 Created: 2010-11-11 Last updated: 2017-12-12Bibliographically approved
    4. [PEI-SiO2]:[LiTFSI] nanocomposite polymer electrolytes: Ion conduction and optical properties
    Open this publication in new window or tab >>[PEI-SiO2]:[LiTFSI] nanocomposite polymer electrolytes: Ion conduction and optical properties
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    2012 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 98, p. 465-471Article in journal (Refereed) Published
    Abstract [en]

    Ion conductivity and optical properties were investigated for polymer electrolytes based on poly (ethyleneimine) and lithium bis(trifluoromethylsulfonyl)imide and also containing up to 9 wt.% of 7-nm-diameter SiO2 nanoparticles. The [N]:[Li] molar ratio was kept constant at 50:1. Impedance measurements were performed in the frequency range 10(-2)-10(7) Hz and between the temperatures 20 and 70 degrees C with an applied ac voltage of 1 V. Spectrophotometric data of total and diffuse transmittance were taken between the wavelengths 300 and 2500 nm. The bulk impedance was fitted to a conductive Havriliak-Negami circuit model. The ion conductivity increased monotonically for increasing SiO2 contents: specifically its room temperature value went from 8.5 x 10(-7) S/cm without nanoparticles to 3.8 x 10(-5) S/cm for 8 wt.% of SiO2 while the diffuse transmittance remained at similar to 1% so that optical clarity prevailed.

    Keywords
    Polymer electrolyte, Nanocomposite, PEI, LiTFSI, SiO2
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-171404 (URN)10.1016/j.solmat.2011.11.021 (DOI)000300536500065 ()
    Available from: 2012-03-20 Created: 2012-03-19 Last updated: 2017-12-07Bibliographically approved
    5. Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica
    Open this publication in new window or tab >>Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica
    2014 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 119, p. 164-168Article in journal (Refereed) Published
    National Category
    Nano Technology
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-204451 (URN)10.1016/j.electacta.2013.12.032 (DOI)000335877000023 ()
    Available from: 2013-08-05 Created: 2013-08-05 Last updated: 2017-12-06Bibliographically approved
    6. A polymer electrolyte with high luminous transmittance and low solar throughput: Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals
    Open this publication in new window or tab >>A polymer electrolyte with high luminous transmittance and low solar throughput: Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals
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    2012 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 24, p. 241902-Article in journal (Refereed) Published
    Abstract [en]

    Chemically prepared similar to 13-nm-diameter nanocrystals of In2O3:Sn were included in a polyethyleneiminelithium bis(trifluoromethylsulfonyl) imide electrolyte and yielded high haze-free luminous transmittance and strong near-infrared absorption without deteriorated ionic conductivity. The optical properties could be reconciled with effective medium theory, representing the In2O3:Sn as a free electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange. This type of polymer electrolyte is of large interest for opto-ionic devices such as laminated electrochromic smart windows.

    National Category
    Physical Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-178647 (URN)10.1063/1.4728994 (DOI)000305269200024 ()
    Available from: 2012-08-02 Created: 2012-08-01 Last updated: 2017-12-07Bibliographically approved
    7. Electrochromic Devices with Polymer Electrolytes Functionalized by SiO2 and In2O3:Sn Nanoparticles: Rapid Coloring/Bleaching Dynamics and Strong Near-Infrared Absorption
    Open this publication in new window or tab >>Electrochromic Devices with Polymer Electrolytes Functionalized by SiO2 and In2O3:Sn Nanoparticles: Rapid Coloring/Bleaching Dynamics and Strong Near-Infrared Absorption
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    2014 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 126, p. 241-247Article in journal (Refereed) Published
    Abstract [en]

    We studied the optical properties and coloring/bleaching dynamics of electrochromic devices based on tungsten oxide and nickel oxide and incorporating polymer electrolytes functionalized by adding about one percent of nanoparticles of SiO2 (fumed silica) or In2O3:Sn. SiO2 improved the coloring/bleaching dynamics and In2O3:Sn quenched the near-infrared transmittance. Both of these effects can be important in electrochromic smart windows, and our results point at the advantage of a polymer laminated construction over a monolithic one.

    National Category
    Nano Technology
    Research subject
    Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-204448 (URN)10.1016/j.solmat.2013.06.010 (DOI)000338395100035 ()
    Conference
    10th International Meeting on Electrochromism (IME), Holland, MI, August 12-16, 2012
    Available from: 2013-08-05 Created: 2013-08-05 Last updated: 2017-12-06Bibliographically approved
  • 2.
    Bergman, Henrik Dan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Increasing the Writing Resolution for Electro-hydrodynamic 3D-Printing: by Active Steering of e-jet2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing has grown considerably during the last couple of decades, whether it comes to the printing of metal structure or living cells. Additive manufacturing techniques relays on the successive addition of material to create the wanted structure. Among the diversity of these many printing techniques, electrohydrodynamic 3D-printing is of particular interest, as the technique has a promising outlook for high-resolution printing on the microscale. The technique is compatible with a myriad of thermoplastics, but its writing resolution is limited due to the inherent affect the manufacturing process has on the material. Electrostatic forces between already deposited fibres and the fibre in light affect the final position of printed fibre. This thesis evaluates the possibility to increase the writing resolution in melt electrohydrodynamic 3D printing by a closed-loop feedback system. Components were built and added to an already existing printing setup to implement in-situ measurements of the fibres position as well as active electrostatic guiding of the fibre. The setup consisted of a camera that determined the position of the fibre; the position was then used in a PID controller to calculate an appropriate potential. The potential was forwarded to a high voltage amplifier, connected to a steering electrode, mounted in the vicinity of the jet. The setup built for one-dimensional steering of the fibre improved the printing accuracy by ten times through suppressing the repulsive/attractive forces, where the process variable of the PID controller was measured. However, the precision decreased roughly four times as it was deposited on the substrate. The limitations of the system have been evaluated, and possible improvements for the two-dimensional control of the fibre are further discussed.

  • 3.
    Espadas Escalante, Juan José
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. Uppsala University.
    On numerical analyses of woven composite laminates: Homogenization, damage and fracture2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation analyzes various mechanical properties of textile reinforced composite laminates.

    The dissertation is based on a total of six published works, which are essentially numerical, although experimental elements are available. The numerical methods used are based on high-resolution finite element models in combination with sophisticated phase-field theories for brittle fracture. A key result is that important mechanical properties in engineering applications, such as fracture or damage resistance, can be substantially affected by the arrangement of the constituent materials at the meso level.

    List of papers
    1. A phase-field model for strength and fracture analyses of fiber-reinforced composites
    Open this publication in new window or tab >>A phase-field model for strength and fracture analyses of fiber-reinforced composites
    2019 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 174, p. 58-67Article in journal (Refereed) Published
    Abstract [en]

    A phase-field model for brittle fracture is proposed and evaluated for strength and fracture analyses of composites. In addition to the elastic properties, this approach makes use of only the fracture toughness and the strength of the material. The capability of the method is shown in analyses of composites at two scales. In laminates, strengths of notched laminates are estimated, including hole size effects. In a lamina, cracks developed in both transverse tension and compression are analyzed and compared to other numerical methods in the literature. The effects of a spectral and a hydrostatic-deviatoric decomposition of the strain energy density, two variants often used in phase-field formulations, are studied. It is shown that the choice of the decomposition affects the fracture development. Results are compared to experiments and simulations in the literature showing the capabilities of the phase-field approach.

    Place, publisher, year, edition, pages
    Elsevier, 2019
    Keywords
    Computational mechanics, Strength, Fracture, Finite element analysis (FEA)
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:uu:diva-368254 (URN)10.1016/j.compscitech.2018.10.031 (DOI)000469407500008 ()
    Available from: 2018-12-03 Created: 2018-12-03 Last updated: 2019-07-05Bibliographically approved
    2. A study on the influence of boundary conditions in computational homogenization of periodic structures with application to woven composites
    Open this publication in new window or tab >>A study on the influence of boundary conditions in computational homogenization of periodic structures with application to woven composites
    2017 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 160, p. 529-537Article in journal (Refereed) Published
    Abstract [en]

    The influence of boundary conditions (BCs) in the estimation of elastic properties of periodic structures is investigated using computational homogenization with special focus on planar structures. Uniform displacement, uniform traction, periodic, in-plane periodic and a proposed mix of periodic and traction BCs are used. First, the effect of the BCs is demonstrated in structures with one-, two- and three-dimensional periodicity. Mixed BCs are shown to most accurately represent the behavior of layered structures with a small number of repeating unit cells. Then, BCs are imposed on a twill woven composite architecture. Special attention is devoted to investigate the sensitivity of the estimated properties with respect to the BCs and to show differences when considering a single lamina or a laminate. High sensitivity of the in-plane extensional modulus and Poisson's ratio with respect to the type of BCs is found. Moreover, it is shown that the mix of BCs and in-plane periodic BCs are capable to represent an experimental strain field.

    Keywords
    Computational homogenization, Mixed boundary conditions, Heterogeneous structures, Elastic properties, Woven composites, Finite element method
    National Category
    Composite Science and Engineering
    Identifiers
    urn:nbn:se:uu:diva-359307 (URN)10.1016/j.compstruct.2016.10.082 (DOI)000390470300044 ()
    Available from: 2018-08-31 Created: 2018-08-31 Last updated: 2019-07-05Bibliographically approved
    3. The effect of free-edges and layer shifting on intralaminar and interlaminar stresses in woven composites
    Open this publication in new window or tab >>The effect of free-edges and layer shifting on intralaminar and interlaminar stresses in woven composites
    2018 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 185, p. 212-220Article in journal (Refereed) Published
    Abstract [en]

    The free-edge effects and relative layer shifting in the interlaminar and intralaminar stresses of plain woven composite laminates under uniaxial extension is investigated numerically using a finite element approach. A computational framework of the free-edge problem for periodic structures with finite width is applied to woven laminates. First, two-layered laminates with three different shifting configurations are studied considering repeating unit cells simulating finite and infinite width. For each configuration, two different widths are considered by trimming the model at different locations in order to investigate different free-edge effects. Then, two four-layered laminates with no shifting and a maximum shifting configuration are analyzed to illustrate the effect of neighboring layers in the stresses. For each shifting configuration, different delamination mechanisms are expected. When considering more layers, it is found that the stacking configuration affects the state of stress and the free-edge effects depending on the shifting. In general, a different behavior than that of unidirectional tape laminates is found, since the interlaminar and intralaminar stresses can be higher than those generated at the free-edges. Particularly, for the maximum shifting configuration results are in agreement with experimental results in the literature where no debonding between yarns was observed at the free-edges.

    Keywords
    Woven composites, Finite element method, Intralaminar stresses, Interlaminar stresses, Free-edge effects, Multiscale modeling
    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-341485 (URN)10.1016/j.compstruct.2017.11.014 (DOI)000418961000018 ()
    Available from: 2018-02-28 Created: 2018-02-28 Last updated: 2019-07-05Bibliographically approved
    4. A study of induced delamination and failure in woven composite laminates subject to short-beam shear testing
    Open this publication in new window or tab >>A study of induced delamination and failure in woven composite laminates subject to short-beam shear testing
    2019 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 205, p. 359-369Article in journal (Refereed) Published
    Abstract [en]

    Failure in woven composite laminates subject to global shear load is studied. Laminates are manufactured, tested and analyzed using X-ray computed tomography, scanning electron microscopy and finite element models. It is found that the stress distribution along the thickness direction is dependent on the layer shifting that alters different yarn interactions, which in turn, affects delamination and failure onset A suggested failure mechanism is in agreement with experimental observations.

    National Category
    Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-368250 (URN)10.1016/j.engfracmech.2018.10.015 (DOI)000453766000026 ()
    Available from: 2018-12-03 Created: 2018-12-03 Last updated: 2019-07-05Bibliographically approved
    5. Analysis of the Influence of Layer Shifting on the Elastic Response and Damage Nucleation and Growth in Woven Composite Laminates
    Open this publication in new window or tab >>Analysis of the Influence of Layer Shifting on the Elastic Response and Damage Nucleation and Growth in Woven Composite Laminates
    2018 (English)In: NASA Technical MemorandumsArticle in journal (Refereed) Published
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-368253 (URN)
    Available from: 2018-12-03 Created: 2018-12-03 Last updated: 2019-07-05
    6. Mesoscale analysis of the transverse cracking kinetics in woven composite laminates using a phase-field fracture theory
    Open this publication in new window or tab >>Mesoscale analysis of the transverse cracking kinetics in woven composite laminates using a phase-field fracture theory
    2019 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 216, article id 106523Article in journal (Refereed) Published
    Abstract [en]

    A phase-field approach to fracture is used to simulate transverse cracking kinetics in composite laminates. First, a typical unidirectional tape laminate is modeled and the transverse cracking evolution with the consequent reduction in the in-plane modulus of elasticity is estimated. Then, a four-layered plain weave composite is modeled using different layer shifting configurations. Predictions in the transverse cracking evolution become improved as the shifting configuration of the laminate model become closer to experimental observations. Simulations predict that some cracks do not form perpendicularly to the loading direction, as it has been observed experimentally in similar locations. Only the fracture toughness and the in situ transverse strength of the ply are required without prior knowledge of the position of the cracks or an ad hoc criterion for crack evolution. All the simulations are compared qualitatively and quantitatively to experiments published elsewhere.

    Keywords
    Composites, Fibre reinforced materials, Fracture mechanics, Damage mechanics, Crack growth
    National Category
    Applied Mechanics
    Research subject
    Engineering science with specialization in Applied Mechanics
    Identifiers
    urn:nbn:se:uu:diva-388533 (URN)10.1016/j.engfracmech.2019.106523 (DOI)000477573000028 ()
    Available from: 2019-07-01 Created: 2019-07-01 Last updated: 2019-09-20Bibliographically approved
  • 4.
    Holmgren, Jonna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Friction and wear studies of some PEEK materials2014In: 16th Nordic Symposium on Tribology (NORDTRIB), 2014Conference paper (Other academic)
  • 5.
    Holmgren Lind, Jonna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of PTFE on the tribological behaviour of PPS with glass fiber2014In: 1st International conference on polymer tribology (PolyTrib), 2014Conference paper (Other academic)
  • 6.
    Jeong, Seung Hee
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Soft Intelligence: Liquids Matter in Compliant Microsystems2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Soft matter, here, liquids and polymers, have adaptability to a surrounding geometry. They intrinsically have advantageous characteristics from a mechanical perspective, such as flowing and wetting on surrounding surfaces, giving compliant, conformal and deformable behavior. From the behavior of soft matter for heterogeneous surfaces, compliant structures can be engineered as embedded liquid microstructures or patterned liquid microsystems for emerging compliant microsystems.

    Recently, skin electronics and soft robotics have been initiated as potential applications that can provide soft interfaces and interactions for a human-machine interface. To meet the design parameters, developing soft material engineering aimed at tuning material properties and smart processing techniques proper to them are to be highly encouraged. As promising candidates, Ga-based liquid alloys and silicone-based elastomers have been widely applied to proof-of-concept compliant structures.

    In this thesis, the liquid alloy was employed as a soft and stretchable electrical and thermal conductor (resistor), interconnect and filler in an elastomer structure. Printing-based liquid alloy patterning techniques have been developed with a batch-type, parallel processing scheme. As a simple solution, tape transfer masking was combined with a liquid alloy spraying technique, which provides robust processability. Silicone elastomers could be tunable for multi-functional building blocks by liquid or liquid-like soft solid inclusions. The liquid alloy and a polymer additive were introduced to the silicone elastomer by a simple mixing process. Heterogeneous material microstructures in elastomer networks successfully changed mechanical, thermal and surface properties.

    To realize a compliant microsystem, these ideas have in practice been useful in designing and fabricating soft and stretchable systems. Many different designs of the microsystems have been fabricated with the developed techniques and materials, and successfully evaluated under dynamic conditions. The compliant microsystems work as basic components to build up a whole system with soft materials and a processing technology for our emerging society.

    List of papers
    1. Liquid alloy printing of microfluidic stretchable electronics
    Open this publication in new window or tab >>Liquid alloy printing of microfluidic stretchable electronics
    Show others...
    2012 (English)In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 22, no 12, p. 4657-4664Article in journal (Refereed) Published
    Abstract [en]

    Recently, microfluidic stretchable electronics has attracted great interest from academia since conductive liquids allow for larger cross-sections when stretched and hence low resistance at longer lengths. However, as a serial process it has suffered from low throughput, and a parallel processing technology is needed for more complex systems and production at low costs. In this work, we demonstrate such a technology to implement microfluidic electronics by stencil printing of a liquid alloy onto a semi-cured polydimethylsiloxane (PDMS) substrate, assembly of rigid active components, encapsulation by pouring uncured PDMS on-top and subsequent curing. The printing showed resolution of 200 mm and linear resistance increase of the liquid conductors when elongated up to 60%. No significant change of resistance was shown for a circuit with one LED after 1000 times of cycling between a 0% and an elongation of 60% every 2 s. A radio frequency identity (RFID) tag was demonstrated using the developed technology, showing that good performance could be maintained well into the radio frequency (RF) range.

    Place, publisher, year, edition, pages
    Royal society of chemistry, 2012
    Keywords
    liquid alloy, printing, stretchable electronics, wireless communication
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering Other Materials Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-183278 (URN)10.1039/C2LC40628D (DOI)000310865200010 ()
    Available from: 2012-10-23 Created: 2012-10-23 Last updated: 2017-12-07Bibliographically approved
    2. Adhesive transfer soft lithography: low-cost and flexible rapid prototyping of microfluidic devices, Micro and Nanosystems
    Open this publication in new window or tab >>Adhesive transfer soft lithography: low-cost and flexible rapid prototyping of microfluidic devices, Micro and Nanosystems
    2014 (English)In: micro and nanosystems, ISSN 1876-4037, Vol. 6, p. 42-49Article in journal (Refereed) Published
    Abstract [en]

    A simple and low-cost approach was proposed for prototyping PDMS based microfluidic devices by transferringadhesive film microstructures onto a flexible substrate as a mould for PDMS replicas. The microstructures were engravedon an adhesive coated film using a commercial cutting plotter and then transferred (or laminated) onto a flexiblesubstrate, allowing for engraved isolated patterns. The proposed technique was demonstrated by a hydrodynamic focusingmicrofluidic device, having splitting and re-combining sheath channels. The whole processing could be finished within 1h in a normal laboratory environment. This approach offers an easy, flexible and rapid prototyping of microfluidic andlab-on-a-chip devices to users without expertise in microfabrication. In addition, by minimizing the use of chemicals, theprocess becomes more environmentally friendly than conventional photolithography based micro-fabrication techniques.

    Place, publisher, year, edition, pages
    Bentham Science Publishers, 2014
    Keywords
    liquid alloy, printing, soft lithography, rapid prototyping
    National Category
    Other Engineering and Technologies
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-239241 (URN)
    Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2016-04-22
    3. Tape Transfer Printing of a Liquid Metal Alloy for Stretchable RF Electronics
    Open this publication in new window or tab >>Tape Transfer Printing of a Liquid Metal Alloy for Stretchable RF Electronics
    2014 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, no 9, p. 16311-16321Article in journal (Refereed) Published
    Abstract [en]

    In order to make conductors with large cross sections for low impedance radio frequency (RF) electronics, while still retaining high stretchability, liquid-alloy-based microfluidic stretchable electronics offers stretchable electronic systems the unique opportunity to combine various sensors on our bodies or organs with high-quality wireless communication with the external world (devices/systems), without sacrificing enhanced user comfort. This microfluidic approach, based on printed circuit board technology, allows large area processing of large cross section conductors and robust contacts, which can handle a lot of stretching between the embedded rigid active components and the surrounding system. Although it provides such benefits, further development is needed to realize its potential as a high throughput, cost-effective process technology. In this paper, tape transfer printing is proposed to supply a rapid prototyping batch process at low cost, albeit at a low resolution of 150 mu m. In particular, isolated patterns can be obtained in a simple one-step process. Finally, a stretchable radio frequency identification (RFID) tag is demonstrated. The measured results show the robustness of the hybrid integrated system when the tag is stretched at 50% for 3000 cycles.

    Keywords
    tape transfer printing, liquid metal alloy, microfluidic stretchable electronics, stretchable RF electronics, radio frequency identification (RFID) tag
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-237588 (URN)10.3390/s140916311 (DOI)000343106600041 ()
    Available from: 2014-12-05 Created: 2014-12-03 Last updated: 2017-12-05Bibliographically approved
    4. Tape transfer atomization patterning of liquid alloys for microfluidic stretchable wireless power transfer
    Open this publication in new window or tab >>Tape transfer atomization patterning of liquid alloys for microfluidic stretchable wireless power transfer
    2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, p. 8419-Article in journal (Refereed) Published
    Abstract [en]

    Stretchable electronics offers unsurpassed mechanical compliance on complex or soft surfaces like the human skin and organs. To fully exploit this great advantage, an autonomous system with a self-powered energy source has been sought for. Here, we present a new technology to pattern liquid alloys on soft substrates, targeting at fabrication of a hybrid-integrated power source in microfluidic stretchable electronics. By atomized spraying of a liquid alloy onto a soft surface with a tape transferred adhesive mask, a universal fabrication process is provided for high quality patterns of liquid conductors in a meter scale. With the developed multilayer fabrication technique, a microfluidic stretchable wireless power transfer device with an integrated LED was demonstrated, which could survive cycling between 0% and 25% strain over 1,000 times.

    National Category
    Mechanical Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-247504 (URN)10.1038/srep08419 (DOI)000349245600018 ()25673261 (PubMedID)
    Available from: 2015-03-19 Created: 2015-03-19 Last updated: 2017-12-04Bibliographically approved
    5. Stretchable wireless power transfer with a liquid alloy coil
    Open this publication in new window or tab >>Stretchable wireless power transfer with a liquid alloy coil
    2015 (English)In: Micro Electro Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, 2015, p. 1137-1140Conference paper, Published paper (Refereed)
    Abstract [en]

    An integrated stretchable wireless power transfer device was demonstrated by packaging rigid electronic chips onto a liquid alloy coil patterned on a half-cured polydimethylsiloxane (PDMS) surface. To obtain low enough resistance, the long liquid alloy coil with a large cross section was made with a tape transfer masking followed by spray deposition of the liquid alloy. The measured results indicated the wireless power transfer efficiency reached 10% at 140 kHz and good performance under 25% overall strain. Different sizes of liquid alloy coils and a soft magnetic composite core were tested to improve the efficiency of the system.

    Series
    Proceedings IEEE Micro Electro Mechanical Systems, ISSN 1084-6999
    Keywords
    Liquid alloy, Stretchable electronics, Wireless power transfer, Smart system integration
    National Category
    Engineering and Technology
    Research subject
    Materials Science
    Identifiers
    urn:nbn:se:uu:diva-265529 (URN)10.1109/MEMSYS.2015.7051165 (DOI)000370382900296 ()978-1-4799-7955-4 (ISBN)
    Conference
    Micro Electro Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, Estoril, January 18-22, 2015
    Available from: 2015-10-31 Created: 2015-10-31 Last updated: 2016-04-21Bibliographically approved
    6. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment
    Open this publication in new window or tab >>Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment
    Show others...
    2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 18257Article in journal (Refereed) Published
    Abstract [en]

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

    National Category
    Textile, Rubber and Polymeric Materials Mechanical Engineering
    Identifiers
    urn:nbn:se:uu:diva-272055 (URN)10.1038/srep18257 (DOI)000366451800001 ()26671673 (PubMedID)
    Funder
    Swedish Research Council, 621-2010-5443 621-2014-5596Swedish Foundation for Strategic Research , EM11-0002 SE13-0061
    Available from: 2016-01-12 Created: 2016-01-11 Last updated: 2017-11-30Bibliographically approved
    7. PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics
    Open this publication in new window or tab >>PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics
    Show others...
    2016 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 28, p. 5830-5836Article in journal (Refereed) Published
    Abstract [en]

    Targeting good user experiences, softness and stretchability are essential features for epidermal devices in body signal monitoring and body area stimulation. A highly soft, stretchable and sticky polydimethylsiloxane based elastomer (S3-PDMS) is achieved by a simple process with a widely used siloxane precursors, the properties of which are tuned by adding small fractions of an amine-based polymer, ethoxylated polyethylenimine (EPEI). This allows formation of a thick unobstrusive patch and may ease implementation of epidermal electronics in wearable healthcare applications. 

    Keywords
    Adhesion, Compliance, Elongation at break, Epidermal electronics, PDMS-based elastomer tuning
    National Category
    Textile, Rubber and Polymeric Materials Applied Mechanics Polymer Chemistry
    Research subject
    Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-281212 (URN)10.1002/adma.201505372 (DOI)000382400900004 ()
    Funder
    Swedish Research Council, 2010-5443
    Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2017-11-30Bibliographically approved
    8. Stretchable thermoelectric generators metallized with liquid alloy
    Open this publication in new window or tab >>Stretchable thermoelectric generators metallized with liquid alloy
    Show others...
    2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 18, p. 15791-15797Article in journal (Refereed) Published
    Abstract [en]

    Conventional thermoelectric generators (TEGs) are normally hard, rigid, and flat. However, most objects have curvy surfaces, which require soft and even stretchable TEGs for maximizing efficiency of thermal energy harvesting. Here, soft and stretchable TEGs using conventional rigid Bi2Te3 pellets metallized with a liquid alloy is reported. The fabrication is implemented by means of a tailored layer-by-layer fabrication process. The STEGs exhibit an output power density of 40.6 mu W/cm(2) at room temperature. The STEGs are operational after being mechanically stretched-and-released more than 1000 times, thanks to the compliant contact between the liquid alloy interconnects and the rigid pellets. The demonstrated interconnect scheme will provide a new route to the development of soft and stretchable energy-harvesting avenues for a variety of emerging electronic applications.

    National Category
    Energy Engineering Textile, Rubber and Polymeric Materials Other Engineering and Technologies not elsewhere specified
    Identifiers
    urn:nbn:se:uu:diva-281213 (URN)10.1021/acsami.7b04752 (DOI)000401307100064 ()28453282 (PubMedID)
    Funder
    Swedish Foundation for Strategic Research , EM11-0002, SE13-0061Swedish Research Council, 621-2014-5596
    Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2017-07-04Bibliographically approved
  • 7.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Si
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden..
    Huo, Jinxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Gamstedt, Erik Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Liu, Johan
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden..
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 18257Article in journal (Refereed)
    Abstract [en]

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

  • 8.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Cruz, Javier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Chen, Si
    Chalmers, Dept Microtechnol & Nanosci MC2, Kemivagen 9, SE-41296 Gothenburg, Sweden.
    Gravier, Laurent
    Univ Appl Sci & Arts Western Switzerland, Inst Micro & Nano Tech, CH-1401 Yverdon, Switzerland.
    Liu, Johan
    Chalmers, Dept Microtechnol & Nanosci MC2, Kemivagen 9, SE-41296 Gothenburg, Sweden.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stretchable thermoelectric generators metallized with liquid alloy2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 18, p. 15791-15797Article in journal (Refereed)
    Abstract [en]

    Conventional thermoelectric generators (TEGs) are normally hard, rigid, and flat. However, most objects have curvy surfaces, which require soft and even stretchable TEGs for maximizing efficiency of thermal energy harvesting. Here, soft and stretchable TEGs using conventional rigid Bi2Te3 pellets metallized with a liquid alloy is reported. The fabrication is implemented by means of a tailored layer-by-layer fabrication process. The STEGs exhibit an output power density of 40.6 mu W/cm(2) at room temperature. The STEGs are operational after being mechanically stretched-and-released more than 1000 times, thanks to the compliant contact between the liquid alloy interconnects and the rigid pellets. The demonstrated interconnect scheme will provide a new route to the development of soft and stretchable energy-harvesting avenues for a variety of emerging electronic applications.

  • 9.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Shou, Zhang
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
    PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics2016In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 28, p. 5830-5836Article in journal (Refereed)
    Abstract [en]

    Targeting good user experiences, softness and stretchability are essential features for epidermal devices in body signal monitoring and body area stimulation. A highly soft, stretchable and sticky polydimethylsiloxane based elastomer (S3-PDMS) is achieved by a simple process with a widely used siloxane precursors, the properties of which are tuned by adding small fractions of an amine-based polymer, ethoxylated polyethylenimine (EPEI). This allows formation of a thick unobstrusive patch and may ease implementation of epidermal electronics in wearable healthcare applications. 

  • 10.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University.
    Shou, ZhangHuazhong University of Science and Technology.Hjort, KlasUppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.Wu, ZhigangUppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Sticky elstomer composites for microfluidic stretchable sensor patches2015Conference proceedings (editor) (Refereed)
    Abstract [en]

    Epidermal electronics and soft robotics are harnessing the advantages of the adaptable and compliantsoft contacts of soft materials. Soft materials can conformally match the morphology of the contact surfaces, which isthe vital point in the implementation of epidermal sensors or soft actuators (S. Xu et al., Soft Microfluidic Assemblies ofSensors, Circuits, and Radios for the Skin, Science, 2014, 344, 70-74). Unfortunately, this conformality can suffer fromdelamination or air trapping at the interface during contact movement. Here, adhesion of soft material surfaces is thecritical parameter. For example, an epidermal sensor on human internal organs and skin, or soft-robotic fingers forgrabbing or climbing needs proper adhesion to its targeted contact surface. Mechanical softness of elastomermaterials provides a good ensemble with surface adhesion because the conformal contact of the soft materials assiststhe adhesion on the target surfaces. Alas, when the soft device is thicker, with its inherent adhesion its compliancemay not suffice but an adhesive layer is needed to ensure good contact.Sticky surfaces of soft materials will significantly help to improve adhesion on target surfaces by preventing sliding.Therefore, more reliable immobilization and manipulation of contacted objects can be secured. Physical and chemicaladhesion forces of the soft material surfaces can be utilized for this purpose. We have developed a sticky elastomercomposite based on PDMS, which has a tape-like adhesive surface after curing. This sticky elastomer composite isstretchable and compliant. The processability of it is compatible with PDMS processes for microfluidic stretchabledevices. It can be easily shaped with laminating, spinning and casting before curing. And, it is reusable several timeswithout leaving residues on the adhered surfaces after detaching and its adhesive strength is tunable with differentmixing ratios with the additive.The sticky elastomer composite showed high enough adhesion to secure attachment on human skin and to lift smallobjects with different surface roughness. Here, soft fingers lifting masses which have different surface morphologieswere tested to verify the compatibility of adhesion force on various surface conditions for soft-robotic manipulationapplication. To show the easy and robust implementation, the sticky elastomer composite is demonstrated with astretchable sensor patch that can be secured to human skin, using much of our recently developed pamphlet ofprocessing technologies (Z.G. Wu, K. Hjort, S.H. Jeong, Microfluidic Stretchable Radio Frequency Devices,Proceedings of the IEEE, 2015, 99, 1-15). Such sensor patches may be suitable as wireless sensor nodes inepidermal body area networks for fitness and healthcare monitoring.

  • 11.
    Karlsson, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Investigation of the dielectric breakdown strength of polymer nanocomposites2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis is to investigate the possibility of enhancing the dielectric breakdown strength (DBS) of low density polyethylene (LDPE) with addition of voltage stabilizing additives. In the first part of the thesis, the influence of various process parameters on the alternating current DBS of pure LDPE and LDPE containing either 3 or 30 wt% magnesium oxide nanoparticles was investigated. It was found that the influence of moisture, crystalline structure and process stabilizing additives did not affect the DBS. In the second part of the thesis the effect of five different voltage stabilizing additives was investigated to enhance the DBS. No significant improvement in DBS could be seen for additives mixed with neat LDPE or LDPE nanocomposites by extrusion (typical DBS values ranged between 109-116 kV/mm for neat LDPE). However, the compounding by extrusion resulted in better stability of the breakdown data. A method to swell voltage stabilizing additives into the polymer matrix with solvents have been developed and evaluated. No significant improvements in breakdown strength could be seen for neat LDPE, but the DBS was increased by 15-20 % at low probability of failure for the LDPE nanocomposites. Further work is required to investigate if this increase is significant. It is believed that it is critical to dissolve a higher amount of the voltage stabilizing additives into the polymer matrix. The actual concentrations of the additives need to be quantified with chromatographic methods or infrared spectroscopy.

  • 12.
    Kassman Rudolphi, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Edling, Erika
    ABB Corporate Research.
    Zhao, Su
    ABB Corporate Research.
    Öberg, Åke
    ABB Corporate Research.
    A test method for mapping the contact force limit of polymer materials in sliding contact2016Conference paper (Other academic)
  • 13.
    Lind, Jonna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Cross section microscopy studies of wear tested polymer composites2016Conference paper (Other academic)
  • 14.
    Lind, Jonna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Cross sections studies of polymer composites2016Conference paper (Other academic)
  • 15.
    Lind, Jonna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of temperature on the performance of some polymer composites2015Conference paper (Refereed)
  • 16.
    Lind, Jonna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Friction and wear of PA66-PPA composites sliding against anodized aluminium cylinders2015Conference paper (Refereed)
  • 17.
    Lind, Jonna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Kassman Rudolphi, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lindholm, Per O
    Qin, Jian
    Friction and wear studies of some PEEK materials2015In: Tribologia - Finnish Journal of Tribology, ISSN 0780-2285, Vol. 33, no 2, p. 20-28Article in journal (Refereed)
    Abstract [en]

    The friction and wear behavior of several types of PEEK polymers and composites were studied. The influence of carbon fiber, lubricant and thermally conductive fillers were evaluated, as well as the effects of contact load and temperature. The tests were done using a reciprocating ball-on-disc set-up. The materials were tested under the load of 5 N and 15 N, at room temperature, 80 °C, 120 °C and 150 °C. The difference between the materials was substantial, with a friction coefficient varying between 0.03 and 0.3 for the different materials at 120 °C. PEEK with carbon fiber filler showed an improvement in both friction and wear compared to unfilled PEEK. When adding lubricant, PTFE, to the composite the friction and wear were improved even more. PEEK with thermally conductive filler on the other hand had both highest friction and wear. Increasing the temperature slightly decreased both friction and wear for most of the PEEK materials. At 150 °C, only the composite with PTFE lubricant had a low friction and wear.

  • 18.
    Liu, Jun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Åbo Akad Univ, Lab Wood & Paper Chem, Johan Gadolin Proc Chem Ctr, Porthansgatan 3-5, FI-20500 Turku, Finland..
    Willfor, Stefan
    Abo Akad Univ, Lab Wood & Paper Chem, Johan Gadolin Proc Chem Ctr, Porthansgatan 3-5, FI-20500 Turku, Finland..
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Uppsala Univ, Dept Engn Sci, Nanotechnol & Funct Mat, Box 534, S-75121 Uppsala, Sweden..
    On importance of impurities, potential leachables and extractables in algal nanocellulose for biomedical use2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 172, p. 11-19Article in journal (Refereed)
    Abstract [en]

    Nanocellulose-based biomaterials for biomedical and pharmaceutical applications have been extensively explored. However, studies on different levels of impurities in the nanocellulose and their potential risks are lacking. This article is the most comprehensive to date survey of the importance and characterization kof possible leachables and extractables in nanocellulose for biomedical use. In particular, the (1,3)-beta-D-glucan interference in endotoxin detection in algal nanocellulose was addressed. Potential lipophilic and hydrophilic leachables, toxic heavy metals, and microbial contaminants are also monitored. As a model system, nanocellulose from Cladophora sp. algae is investigated. The leachable (1,3)-beta-D-glucan and endotoxin, which possess strong immunogenic potential, from the cellulose were minimized to clinically insignificant levels of 4.7 mu g/g and 2.5 EU/g, respectively. The levels of various impurities in the Cladophora cellulose are acceptable for future biomedical applications. The presented approach could be considered as a guideline for other types of nanocellulose.

  • 19.
    Persson, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Robert, Elise
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Carlsson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Robo, Céline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lopez, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Godoy-Gallardo, Maria
    Technical University of Catalonia, Spain.
    Ginebra, Maria-Pau
    Technical University of Catalonia, Spain.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    The effect of unsaturated fatty acid and triglyceride oil addition on the mechanical and antibacterial properties of acrylic bone cements2015In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 30, no 3, p. 279-289Article in journal (Refereed)
  • 20.
    Poluektov, Mikhail
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    van Dommelen, Johannes A. W.
    Govaert, Leon E.
    MacKerron, Duncan H.
    Geers, Marc G. D.
    Micromechanical modeling of roll-to-roll processing of oriented polyethylene terephthalate films2016In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, no 18, p. 43384:1-11, article id 43384Article in journal (Refereed)
  • 21.
    Schönström, Linus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Nordh, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Strignert, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Lemel, Frida
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Ekengard, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Wallin, Sofie
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Jabri, Zargham
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    A process recipe for bonding a silicone membrane to a plastic substrate2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A spin-cast silicone membrane has been successfully bonded between two injection-molded microstructured plastic discs. This sandwich structure creates a useful platform for mass production of microfluidic systems, provided that the bonds are leakproof. The bonds were achieved by a silicon dioxide coating deposited on the plastic discs by evaporation. This investigation is concerned with the process and the result only, no theory is discussed.

  • 22. van Dommelen, Johannes A. W.
    et al.
    Poluektov, Mikhail
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Sedighiamiri, Amin
    Govaert, Leon E.
    Micromechanics of semicrystalline polymers: Towards quantitative predictions2017In: Mechanics research communications, ISSN 0093-6413, E-ISSN 1873-3972, Vol. 80, p. 4-9Article in journal (Refereed)
  • 23.
    Wallin, Sofie
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Optimization of Transport Simulation for Infusion Bags: - A Study of Wear on Plastic Packaging2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report presents a method for transport simulation of infusion bags. A cardboard box filled with infusion bags have been vibrated with an in house developed shake rig, using fixed frequency and horizontal direction. The method has been able to fabricate the same transport damages in the plastic packaging as seen on reclaimed products, but has also produced some other damages. Heating of the plastic packaging due to the frequent high acceleration strokes that initiate adhesion wear probably causes the additional damages.  Further testing is needed for the method to be fully optimized.

    Analyzing the motion of the bags within the cardboard box when vibrated by making tests with an open lid and then analyzing the motion with a high-speed camera have distinguished the motions causing transport damages.

    To normalize between different vibration tests a formula using impulse to describe accumulative fatigue wear has been derived. Basquin´s formula for time compression together with literature data has been used for simulation of transports to China and Mexico.

    A tribology wear test rig has also been developed for testing of plastic films against different counter surfaces. The set up tests the films against abrasive and adhesive wear and have a good repeatability. Optical light microscopy has been used to analyze the wear marks. 

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