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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)000472137700062 ()2-s2.0-85067662886 (Scopus ID)
Available from: 2019-05-06 Created: 2019-05-06 Last updated: 2019-10-16Bibliographically approved
Olsen, M., Zhang, R., Örtegren, J., Andersson, H., Yang, Y. & Olin, H. (2019). Frequency and voltage response of a wind-driven fluttering triboelectric nanogenerator. Scientific Reports, 9(1), Article ID 5543.
Open this publication in new window or tab >>Frequency and voltage response of a wind-driven fluttering triboelectric nanogenerator
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, no 1, article id 5543Article in journal (Refereed) Published
Abstract [en]

Triboelectric nanogenerators (TENG:s) are used as efficient energy transducers in energy harvesting converting mechanical energy into electrical energy. Wind is an abundant source of mechanical energy but how should a good triboelectric wind harvester be designed? We have built and studied a TENG driven by air flow in a table-top sized wind tunnel. Our TENG constitutes of a plastic film of size10 cm × 2 cm which is fluttering between two copper electrodes generating enough power to light up a battery of LED:s. We measured the voltage and frequency of fluttering at different wind speeds from zero up to 8 m/s for three electrode distances 6 mm, 10 mm and 14 mm. We found that the frequency increases linearly with the wind speed with a cutoff at some low speed. Power was generated already at 1.6 m/s. We seem to be able to explain the observed frequency dependence on wind speed by assuming excitation of the film into different harmonics in response to von Kármán vortices. We also find that the voltage increase linearly with frequency. We anticipate that TENG:s of this design could be useful both as generators and speed sensors because they work at low air speeds.

National Category
Natural Sciences Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-35936 (URN)10.1038/s41598-019-42128-7 (DOI)000463178500004 ()30944397 (PubMedID)2-s2.0-85063884794 (Scopus ID)
Funder
J. Gust. Richert stiftelseSwedish Energy AgencyKnowledge FoundationEuropean Regional Development Fund (ERDF)
Note

Forskningsfinansiär: Länsstyrelsen Västernorrland

Available from: 2019-04-03 Created: 2019-04-03 Last updated: 2019-07-08Bibliographically approved
Zhang, R., Hummelgård, M., Ljunggren, J. & Olin, H. (2019). Gold and Zno-Based Metal-Semiconductor Network for Highly Sensitive Room-Temperature Gas Sensing. Sensors, 19(18), Article ID 3815.
Open this publication in new window or tab >>Gold and Zno-Based Metal-Semiconductor Network for Highly Sensitive Room-Temperature Gas Sensing
2019 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, no 18, article id 3815Article in journal (Refereed) Published
Abstract [en]

Metal-semiconductor junctions and interfaces have been studied for many years due to their importance in applications such as semiconductor electronics and solar cells. However, semiconductor-metal networks are less studied because there is a lack of effective methods to fabricate such structures. Here, we report a novel Au-ZnO-based metal-semiconductor (M-S)n network in which ZnO nanowires were grown horizontally on gold particles and extended to reach the neighboring particles, forming an (M-S)n network. The (M-S)n network was further used as a gas sensor for sensing ethanol and acetone gases. The results show that the (M-S)n network is sensitive to ethanol (28.1 ppm) and acetone (22.3 ppm) gases and has the capacity to recognize the two gases based on differences in the saturation time. This study provides a method for producing a new type of metal-semiconductor network structure and demonstrates its application in gas sensing.

Keywords
gas sensors, gold particles, metal-semiconductor network, room temperature sensors, ZnO nanowires
National Category
Physical Sciences
Identifiers
urn:nbn:se:miun:diva-37307 (URN)10.3390/s19183815 (DOI)000489187800001 ()31487792 (PubMedID)2-s2.0-85071735029 (Scopus ID)
Available from: 2019-09-24 Created: 2019-09-24 Last updated: 2019-11-13Bibliographically 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
Andersson, H., Šuly, P., Thungström, G., Engholm, M., Zhang, R., Mašlík, J. & Olin, H. (2019). PEDOT: PSS thermoelectric generators printed on paper substrates. Journal of Low Power Electronics and Applications, 9(2)
Open this publication in new window or tab >>PEDOT: PSS thermoelectric generators printed on paper substrates
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2019 (English)In: Journal of Low Power Electronics and Applications, ISSN 2079-9268, Vol. 9, no 2Article in journal (Refereed) Published
Abstract [en]

Flexible electronics is a field gathering a growing interest among researchers and companies with widely varying applications, such as organic light emitting diodes, transistors as well as many different sensors. If the circuit should be portable or off-grid, the power sources available are batteries, supercapacitors or some type of power generator. Thermoelectric generators produce electrical energy by the diffusion of charge carriers in response to heat flux caused by a temperature gradient between junctions of dissimilar materials. As wearables, flexible electronics and intelligent packaging applications increase, there is a need for low-cost, recyclable and printable power sources. For such applications, printed thermoelectric generators (TEGs) are an interesting power source, which can also be combined with printable energy storage, such as supercapacitors. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), or PEDOT:PSS, is a conductive polymer that has gathered interest as a thermoelectric material. Plastic substrates are commonly used for printed electronics, but an interesting and emerging alternative is to use paper. In this article, a printed thermoelectric generator consisting of PEDOT:PSS and silver inks was printed on two common types of paper substrates, which could be used to power electronic circuits on paper. 

Keywords
Paper substrates, PEDOT:PSS, Seebeck coefficient, Stencil print, Thermoelectric generator
Identifiers
urn:nbn:se:miun:diva-36667 (URN)10.3390/jlpea9020014 (DOI)2-s2.0-85065493304 (Scopus ID)
Available from: 2019-07-09 Created: 2019-07-09 Last updated: 2019-07-09Bibliographically 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
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-36826 (URN)10.1016/j.nanoen.2019.06.038 (DOI)000480422400034 ()2-s2.0-85068234493 (Scopus ID)
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-10-16Bibliographically approved
Phadatare, M. R., Patil, R., Blomquist, N., Forsberg, S., Örtegren, J., Hummelgård, M., . . . Olin, H. (2019). Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries. Scientific Reports, 9, Article ID 14621.
Open this publication in new window or tab >>Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 14621Article in journal (Refereed) Published
Abstract [en]

To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films. However, a method that allows the large-scale production of silicon anodes remains to be demonstrated. Herein, we address this question by suggesting new scalable nanomaterial-based anodes. Si nanoparticles were grown on nanographite flakes by aerogel fabrication route from Si powder and nanographite mixture using polyvinyl alcohol (PVA). This silicon-nanographite aerogel electrode has stable specific capacity even at high current rates and exhibit good cyclic stability. The specific capacity is 455 mAh g−1 for 200th cycles with a coulombic efficiency of 97% at a current density 100 mA g−1.

Keywords
Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries Supplementary Information
National Category
Nano Technology
Identifiers
urn:nbn:se:miun:diva-37569 (URN)10.1038/s41598-019-51087-y (DOI)000489555900015 ()2-s2.0-85073112106 (Scopus ID)
Available from: 2019-10-24 Created: 2019-10-24 Last updated: 2019-11-14Bibliographically approved
Rastabi, S. A., Mamoory, R. S., Dabir, F., Blomquist, N., Phadatare, M. R. & Olin, H. (2019). Synthesis of NiMoO4/3D-rGO Nanocomposite in Alkaline Environments for Supercapacitor Electrodes. Crystals, 9(1), Article ID 31.
Open this publication in new window or tab >>Synthesis of NiMoO4/3D-rGO Nanocomposite in Alkaline Environments for Supercapacitor Electrodes
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2019 (English)In: Crystals, ISSN 2073-4352, Vol. 9, no 1, article id 31Article in journal (Refereed) Published
Abstract [en]

Although Graphene oxide (GO)-based materials is known as a favorable candidate for supercapacitors, its conductivity needs to be increased. Therefore, this study aimed to investigate the performance of GO-based supercapicitor with new methods. In this work, an ammonia solution has been used to remove the oxygen functional groups of GO. In addition, a facile precipitation method was performed to synthesis a NiMoO4/3D-rGO electrode with purpose of using synergistic effects of rGO conductivity properties as well as NiMoO4 pseudocapacitive behavior. The phase structure, chemical bands and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), Raman spectroscopy, and field emission secondary electron microscopy (FE-SEM). The electrochemical results showed that the NiMoO4/3D-rGO(II) electrode, where ammonia has been used during the synthesis, has a capacitive performance of 932 Fg(-1). This is higher capacitance than NiMoO4/3D-rGO(I) without using ammonia. Furthermore, the NiMoO4/3D-rGO(II) electrode exhibited a power density of up to 17.5 kW kg(-1) and an energy density of 32.36 Wh kg(-1). These results showed that ammonia addition has increased the conductivity of rGO sheets, and thus it can be suggested as a new technique to improve the capacitance.

Keywords
renewable energy systems, pseudocapacitive behavior, electrochemical results, ammonia, oxygen groups
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-35806 (URN)10.3390/cryst9010031 (DOI)000458578100031 ()
Available from: 2019-03-19 Created: 2019-03-19 Last updated: 2019-03-19Bibliographically approved
Andres, B., Dahlström, C., Blomquist, N., Norgren, M. & Olin, H. (2018). Cellulose binders for electric double-layer capacitor electrodes: The influence of cellulose quality on electrical properties. Materials & design, 141, 342-349
Open this publication in new window or tab >>Cellulose binders for electric double-layer capacitor electrodes: The influence of cellulose quality on electrical properties
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2018 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 141, p. 342-349Article in journal (Refereed) Published
Abstract [en]

Cellulose derivatives are widely used as binders and dispersing agents in different applications. Binders composed of cellulose are an environmentally friendly alternative to oil-based polymer binding agents. Previously, we reported the use of cellulose nanofibers (CNFs) as binders in electrodes for electric double-layer capacitors (EDLCs). In addition to good mechanical stability, we demonstrated that CNFs enhanced the electrical performance of the electrodes. However, cellulose fibers can cover a broad range of length scales, and the quality requirements from an electrode perspective have not been thoroughly investigated. To evaluate the influence of fiber quality on electrode properties, we tested seven samples with different fiber dimensions that are based on the same kraft pulp. To capture the length scale from fibers to nanofibrils, we evaluated the performance of the untreated kraft pulp, refined fibers, microfibrillated cellulose (MFC) and CNFs. Electrodes with kraft pulp or refined fibers showed the lowest electrical resistivity. The specific capacitances of all EDLCs were surprisingly similar, but slightly lower for the EDLC with CNFs. The same electrode sample with CNFs also showed a slightly higher equivalent series resistance (ESR), compared to those of the other EDLCs. Graphite dispersions with MFC showed the best dispersion stability. 

Keywords
Cellulose, Electric double-layer capacitor, Graphite, Nanocellulose, Nanocomposite, Supercapacitor
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-32766 (URN)10.1016/j.matdes.2017.12.041 (DOI)000424945300031 ()2-s2.0-85040002856 (Scopus ID)
Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2018-07-19Bibliographically 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
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7329-3359

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