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Niskanen, I., Forsberg, V., Zakrisson, D., Reza, S., Hummelgård, M., Andres, B., . . . Thungström, G. (2019). Determination of nanoparticle size using Rayleigh approximation and Mie theory. Chemical Engineering Science, 201(29), 222-229
Open this publication in new window or tab >>Determination of nanoparticle size using Rayleigh approximation and Mie theory
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2019 (English)In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 201, no 29, p. 222-229Article in journal (Refereed) Published
Abstract [en]

Accurate determination of the size of nanoparticles has an important role in many different scientific and industrial purposes, such as in material, medical and environment sciences, colloidal chemistry and astrophysics. We describe an effective optical method to determine the size of nanoparticles by analysis of transmission and scattering of visible spectral range data from a designed UV-Vis multi-spectrophotometer. The size of the nanoparticles was calculated from the extinction cross section of the particles using Rayleigh approximation and Mie theory. We validated the method using polystyrene nanospheres, cellulose nanofibrils, and cellulose nanocrystals. A good agreement was achieved through graphical analysis between measured extinction cross section values and theoretical Rayleigh approximation and Mie theory predictions for the sizes of polystyrene nanospheres at wavelength range 450 - 750 nm. Provided that Rayleigh approximation's forward scattering (FS)/back scattering (BS) ratio was smaller than 1.3 and Mie theory's FS/BS ratio was smaller than 1.8. A good fit for the hydrodynamic diameter of nanocellulose was achieved using the Mie theory and Rayleigh approximation. However, due to the high aspect ratio of nanocellulose, the obtained results do not directly reflect the actual cross-sectional diameters of the nanocellulose. Overall, the method is a fast, relatively easy, and simple technique to determine the size of a particle by a spectrophotometer. Consequently, the method can be utilized for example in production and quality control purposes as well as for research and development applications.

Keywords
Nanoparticles, size, Rayleigh approximation, Mie theory, spectrophotometer, nanocellulose
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-35764 (URN)10.1016/j.ces.2019.02.020 (DOI)000462034900020 ()2-s2.0-85062846560 (Scopus ID)
Available from: 2019-03-08 Created: 2019-03-08 Last updated: 2019-05-20Bibliographically approved
Blomquist, N., Alimadadi, M., Hummelgård, M., Dahlström, C., Olsen, M. & Olin, H. (2019). Effects of Geometry on Large-scale Tube-shear Exfoliation of Multilayer Graphene and Nanographite in Water. Scientific Reports, 9(1), Article ID 8966.
Open this publication in new window or tab >>Effects of Geometry on Large-scale Tube-shear Exfoliation of Multilayer Graphene and Nanographite in Water
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, no 1, article id 8966Article in journal (Refereed) Published
Abstract [en]

Industrially scalable methods for the production of graphene and other nanographites are needed to achieve cost-efficient commercial products. At present, there are several available routes for the production of these materials but few allow large-scale manufacturing and environmentally friendly low-cost solvents are rarely used. We have previously demonstrated a scalable and low-cost industrial route to produce nanographites by tube-shearing in water suspensions. However, for a deeper understanding of the exfoliation mechanism, how and where the actual exfoliation occurs must be known. This study investigates the effect of shear zone geometry, straight and helical coil tubes, on this system based on both numerical simulation and experimental data. The results show that the helical coil tube achieves a more efficient exfoliation with smaller and thinner flakes than the straight version. Furthermore, only the local wall shear stress in the turbulent flow is sufficient for exfoliation since the laminar flow contribution is well below the needed range, indicating that exfoliation occurs at the tube walls. This explains the exfoliation mechanism of water-based tube-shear exfoliation, which is needed to achieve scaling to industrial levels of few-layer graphene with known and consequent quality.

National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-36084 (URN)10.1038/s41598-019-45133-y (DOI)2-s2.0-85067662886 (Scopus ID)
Available from: 2019-05-06 Created: 2019-05-06 Last updated: 2019-07-10Bibliographically approved
Zhang, R., Hummelgård, M., Örtegren, J., Olsen, M., Andersson, H. & Olin, H. (2019). Interaction of the human body with triboelectric nanogenerators. Nano Energy, 57, 279-292
Open this publication in new window or tab >>Interaction of the human body with triboelectric nanogenerators
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2019 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 57, p. 279-292Article in journal (Refereed) Published
Abstract [en]

The use of triboelectric nanogenerators (TENGs) is a new technique for energy harvesting at both small and large scales. Almost all types of mechanical energy can be harvested with TENGs by using four modes of operation that cover almost all mechanical motions. The interactions of the human body with TENGs range from energy harvesting, motion sensing, and biomedical applications to human-computer communications. Different types of TENGs have been developed to directly or indirectly involve the human body. This review will summarize the recent advances in the interaction of the human body with TENGs.

Keywords
Energy harvesting, Healthcare, Human body, Human-robot interactions, Sensors, Triboelectric nanogenerators
National Category
Other Physics Topics
Identifiers
urn:nbn:se:miun:diva-35386 (URN)10.1016/j.nanoen.2018.12.059 (DOI)000458419000028 ()2-s2.0-85059038089 (Scopus ID)
Available from: 2019-01-06 Created: 2019-01-06 Last updated: 2019-03-18Bibliographically approved
Zhang, R., Hummelgård, M., Örtegren, J., Yang, Y., Andersson, H., Balliu, E., . . . Olin, H. (2019). Sensing body motions based on charges generated on the body. Nano Energy, 63, Article ID 103842.
Open this publication in new window or tab >>Sensing body motions based on charges generated on the body
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2019 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 63, article id 103842Article in journal (Refereed) Published
Abstract [en]

The sensing of body motions is of great importance in areas such as healthcare, rehabilitation, and human-computer interactions. Different methods have been developed based on visual or electrical signals. However, such signals are acquired by external devices and are not intrinsic signals that are created on the body. Here, we report a new universal body motion sensor (UBS) to detect motions based on the intrinsic contact electrification (CE) of the skin or electrical induction (EI) of the body. The CE or EI generates charges on the body, leading to potential differences between the body and ground that can be measured to identify different body motions, such as motions of the head, arms, fingers, waist, legs, feet and toes. Proof-of-concept experiments have demonstrated that the UBS can be used to monitor the conditions of people with Parkinson's disease (PD) and to quantitatively monitor the recovery of those with a leg injury, suggesting great potential for healthcare applications.

Keywords
Body motions, Sensors, Charges, Contact electrification, Electrical induction, Healthcare
Identifiers
urn:nbn:se:miun:diva-36826 (URN)10.1016/j.nanoen.2019.06.038 (DOI)000480422400034 ()
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-09-02Bibliographically approved
Zhang, R., Carlsson, F., Edman, M., Hummelgård, M., Jonsson, B.-G., Bylund, D. & Olin, H. (2018). Escherichia coli Bacteria Develop Adaptive Resistance to Antibacterial ZnO Nanoparticles. Advanced Biosystem, 2(5), Article ID 1800019.
Open this publication in new window or tab >>Escherichia coli Bacteria Develop Adaptive Resistance to Antibacterial ZnO Nanoparticles
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2018 (English)In: Advanced Biosystem, ISSN 2366-7478, Vol. 2, no 5, article id 1800019Article in journal (Refereed) Published
Abstract [en]

Antibacterial agents based on nanoparticles (NPs) have many important applications, e.g., for the textile industry, surface disinfection, wound dressing, water treatment, and food preservation. Because of their prevalent use it is important to understand whether bacteria could develop resistance to such antibacterial NPs similarly to the resistance that bacteria are known to develop to antibiotics. Here, it is reported that Escherichia coli(E. coli) develops adaptive resistance to antibacterial ZnO NPs after several days' exposure to the NPs. But, in contrast to antibiotics‐resistance, the observed resistance to ZnO NPs is not stable—after several days without exposure to the NPs, the bacteria regain their sensitivity to the NPs' antibacterial properties. Based on the analyses it is suggested that the observed resistance is caused by changes in the shape of the bacteria and the expressions of membrane proteins. The findings provide insights into the response of bacteria to antibacterial NPs, which is important to elucidate for designing and evaluating the risk of applications based on antibacterial NPs.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Nano Technology
Identifiers
urn:nbn:se:miun:diva-34436 (URN)10.1002/adbi.201800019 (DOI)000446970000008 ()2-s2.0-85065053901 (Scopus ID)
Available from: 2018-09-18 Created: 2018-09-18 Last updated: 2019-07-08Bibliographically approved
Zhang, R., Örtegren, J., Hummelgård, M., Olsen, M., Andersson, H. & Olin, H. (2018). Harvesting triboelectricity from the human body using non-electrode triboelectric nanogenerators. Nano Energy, 45, 298-303
Open this publication in new window or tab >>Harvesting triboelectricity from the human body using non-electrode triboelectric nanogenerators
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2018 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 45, p. 298-303Article in journal (Refereed) Published
Abstract [en]

Triboelectrification has been known and discussed since antiquity. Triboelectrification occurs in the human body due to friction between human skin and other materials such as clothing. However, charges on the body have not been harvested to power small electronics. Here, we report for the first time that the electricity generated on the human body due to triboelectrification can be measured and harvested using human body-based non-electrode triboelectric nanogenerators (H-TENGs). The H-TENGs can have an output of up to 3.3 W/m(2) and can spontaneously harvest energy from several people. The functions of the human body in the H-TENGs are analyzed and experimentally proven to be those of a triboelectric material, conductor and capacitor. Our results demonstrate that the triboelectricity generated on a human body can be harvested using H-TENGs and provide scientific insights into body functions that will promote further studies of TENGs.

Keywords
Human body, Non-electrode TENG, Mechanisms, Charges
National Category
Medical Biotechnology
Identifiers
urn:nbn:se:miun:diva-33301 (URN)10.1016/j.nanoen.2017.12.053 (DOI)000425396400033 ()2-s2.0-85043782783 (Scopus ID)
Available from: 2018-03-19 Created: 2018-03-19 Last updated: 2018-03-28Bibliographically approved
Zhang, R., Engholm, M., Hummelgård, M., Andersson, H., Örtegren, J. & Olin, H. (2018). High-performance transparent and flexible electrodes made by flash-light sintering of gold nanoparticles. ACS Applied Energy Materials, 1(12), 7191-7198
Open this publication in new window or tab >>High-performance transparent and flexible electrodes made by flash-light sintering of gold nanoparticles
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2018 (English)In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 1, no 12, p. 7191-7198Article in journal (Refereed) Published
Abstract [en]

Metallic nanowire-based transparent electrodes (TEs) are potential alternatives to indium tin oxide (ITO). To achieve a high performance [sheet resistance (Rs) < 100 Ω/sq, transmittance (T%) > 90%], the nanowires must have a high length-to-diameter (L/D) ratio to minimize the number of wire-to-wire junctions. Attempts to produce TEs with gold nanowires have been made, and the results reveal difficulties in achieving the requirements. A successful strategy involves creating templated gold nanonetworks through multiple procedures. Here, we present a simple and efficient method that uses flash-light sintering of a gold nanonetwork film into gold TEs (Rs: 82.9 Ω/sq, T %: 91.79%) on a thin polycarbonate film (25 μm). The produced gold TEs have excellent mechanical, electrical, optical, and chemical stabilities. Mechanisms of the formation of gold nanonetworks and the effect of flash-light have been analyzed. Our findings provide a scalable process for producing transparent and flexible gold electrodes with a total processing time of less than 8 min without the use of heating, vacuum processing, and organic chemicals and without any material loss. This is possible because all the gold nanoparticles have been aggregated and filtrated on the filter membranes. The area density of gold is 0.094 g/m2 leading low material costs, which is very competitive with the price of commercial TEs.

Keywords
transparent electrode, flexible electrode, gold nanoparticles, flash-light sintering, high performance
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:miun:diva-35380 (URN)10.1021/acsaem.8b01649 (DOI)000458706800063 ()2-s2.0-85064752503 (Scopus ID)
Available from: 2019-01-03 Created: 2019-01-03 Last updated: 2019-07-08Bibliographically approved
Zhang, R., Hummelgård, M., Örtegren, J., Olsen, M., Andersson, H., Yang, Y. & Olin, H. (2018). Human body constituted triboelectric nanogenerators as energy harvesters, code transmitters and motion sensors. ACS Applied Energy Materials, 1(6), 2955-2960
Open this publication in new window or tab >>Human body constituted triboelectric nanogenerators as energy harvesters, code transmitters and motion sensors
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2018 (English)In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 6, p. 2955-2960Article in journal (Refereed) Published
Abstract [en]

Human skin is a dielectric material that can be used as a triboelectric material for harvesting energy from body motions. The output power of such a human skin-based triboelectric nanogenerator (TENG) is relatively low. Here, we assembled high-output human body constituted TENGs (H-TENGs) by taking advantage of the unique electrical properties of the human body, such as high skin impedance, low tissue resistance, body capacitance, and conductivity. The output of a H-TENG can reach 30 W/m2, which is enough to drive small electronic devices, such as a timer or a calculator. The unique feature of the H-TENG is that it can perform the four fundamental modes of TENGs, which has not been reported elsewhere. Such a feature allows the H-TENG to act as a code transmitter to send light and electrical signals, such as Morse code. H-TENGs also benefit the development of high-performance, self-powered body motion sensors. Our findings suggest new strategies for harvesting energy from human body motions, as well as new types of motion sensors and signal senders.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
code transmitters; energy harvesting; human body; motion sensors; triboelectric nanogenerators
National Category
Other Physics Topics
Identifiers
urn:nbn:se:miun:diva-34433 (URN)10.1021/acsaem.8b00667 (DOI)000458705800070 ()
Available from: 2018-09-18 Created: 2018-09-18 Last updated: 2019-03-15Bibliographically approved
Zhang, R., Hummelgård, M., Forsberg, V., Andersson, H., Engholm, M., Öhlund, T., . . . Olin, H. (2018). Photoconductivity of acid exfoliated and flash-light-processed MoS2 films. Scientific Reports, 8, Article ID 3296.
Open this publication in new window or tab >>Photoconductivity of acid exfoliated and flash-light-processed MoS2 films
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 3296Article in journal (Refereed) Published
Abstract [en]

MoS2 has been studied intensively during recent years as a semiconducting material in several fields, including optoelectronics, for applications such as solar cells and phototransistors. The photoresponse mechanisms of MoS2 have been discussed but are not fully understood, especially the phenomenon in which the photocurrent slowly increases. Here, we report on a study of the photoresponse flash-light-processed MoS2 films of different thicknesses and areas. The photoresponse of such films under different light intensities and bias voltages was measured, showing significant current changes with a quick response followed by a slow one upon exposure to pulsed light. Our in-depth study suggested that the slow response was due to the photothermal effect that heats the MoS2; this hypothesis was supported by the resistivity change at different temperatures. The results obtained from MoS2 films with various thicknesses indicated that the minority-carrier diffusion length was 1.36 mu m. This study explained the mechanism of the slow response of the MoS2 film and determined the effective thickness of MoS2 for a photoresponse to occur. The method used here for fabricating MoS2 films could be used for fabricating optoelectronic devices due to its simplicity.

National Category
Physical Sciences
Identifiers
urn:nbn:se:miun:diva-33302 (URN)10.1038/s41598-018-21688-0 (DOI)000425380900079 ()29459668 (PubMedID)2-s2.0-85061713034 (Scopus ID)
Available from: 2018-03-19 Created: 2018-03-19 Last updated: 2019-03-20Bibliographically approved
Forsberg, V., Andersson, H., Engholm, M., Thungström, G., Zhang, R., Hummelgård, M., . . . Norgren, M. (2018). Photodetector of multilayer exfoliated MoS2 deposited on polyimide films. In: : . Paper presented at 20th International Workshop on Radiation Imaging Detectors, Sundsvall, 24-28 June, 2018.
Open this publication in new window or tab >>Photodetector of multilayer exfoliated MoS2 deposited on polyimide films
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

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.

Keywords
Photodetector, MoS2
National Category
Chemical Engineering Materials Engineering Physical Sciences
Identifiers
urn:nbn:se:miun:diva-34035 (URN)
Conference
20th International Workshop on Radiation Imaging Detectors, Sundsvall, 24-28 June, 2018
Funder
Knowledge Foundation, 2600364
Available from: 2018-06-29 Created: 2018-06-29 Last updated: 2018-08-16Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9137-3440

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