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Edberg, J., Brooke, R., Hosseinaei, O., Fall, A., Wijeratne, K. & Sandberg, M. (2020). Laser-induced graphitization of a forest-based ink for use in flexible and printed electronics. npj Flexible Electron., 4, Article ID 17.
Open this publication in new window or tab >>Laser-induced graphitization of a forest-based ink for use in flexible and printed electronics
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2020 (English)In: npj Flexible Electron., ISSN 2397-4621, Vol. 4, article id 17Article in journal (Refereed) Published
Abstract [en]

Laser-induced graphitization (LIG) is a method of converting a carbon-rich precursor into a highly conductive graphite-like carbon by laser scribing. This method has shown great promise as a versatile and low-cost patterning technique. Here we show for the first time how an ink based on cellulose and lignin can be patterned using screen printing followed by laser graphitization. Screen printing is one of the most commonly used manufacturing techniques of printed electronics, making this approach compatible with existing processing of various devices. The use of forest-based materials opens the possibility of producing green and sustainable electronics. Pre-patterning of the ink enables carbon patterns without residual precursor between the patterns. We investigated the effect of the ink composition, laser parameters, and additives on the conductivity and structure of the resulting carbon and could achieve low sheet resistance of 3.8 Ω sq-1 and a high degree of graphitization. We demonstrated that the process is compatible with printed electronics and finally manufactured a humidity sensor which uses lignin as the sensing layer and graphitized lignin as the electrodes.

Place, publisher, year, edition, pages
Nature Research, 2020
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-46551 (URN)10.1038/s41528-020-0080-2 (DOI)
Note

Supplementary information is available for this paper at https://doi.org/10.1038/s41528-020-0080-2.

Available from: 2020-08-21 Created: 2020-08-21 Last updated: 2023-12-06Bibliographically approved
Sandberg, M., Håkansson, K. & Granberg, H. (2020). Paper machine manufactured photocatalysts: Lateral variations. Journal of Environmental Chemical Engineering, 8, Article ID 104075.
Open this publication in new window or tab >>Paper machine manufactured photocatalysts: Lateral variations
2020 (English)In: Journal of Environmental Chemical Engineering, E-ISSN 2213-3437, Vol. 8, article id 104075Article in journal (Refereed) Published
Abstract [en]

Paper machine manufacturing of photocatalysts can enable low cost devices for removal of low concentratedpollutants. Lateral variations originating from the paper making process leads to variations of the catalyticactivity over the paper area. Paper machine manufactured papers made from tetrapodal ZnO whiskers and kraftpulp were investigated in this test geometry using simulated solar light. Photocatalytic ZnO papers were laminatedbetween polyethylene sheets and an indicator solution seeped into the laminated photocatalytic paper, tocreate a test geometry where the indicator ink is confined to a small volume between the polyethylene sheets.The photocatalyst papers exhibited surprisingly similar photocatalytic behavior although having different catalystloading 15, 30 and 45 wt percent. All papers exhibited lateral variations that peaked during the conversion.The results show that production of effective photocatalytic composite papers can be scaled.Further, the results show that variations must be considered for photocatalytic papers.

Keywords
Paper machine, Photocatalyst, Lateral variations, Laminate, Large scale
National Category
Engineering and Technology
Identifiers
urn:nbn:se:ri:diva-45054 (URN)10.1016/j.jece.2020.104075 (DOI)
Available from: 2020-06-11 Created: 2020-06-11 Last updated: 2023-05-25
Engholm, M., Hammarling, K., Andersson, H., Sandberg, M. & Nilsson, H. E. (2019). A bio-compatible fiber optic pH sensor based on a thin core interferometric technique. Photonics, 6(1), Article ID 11.
Open this publication in new window or tab >>A bio-compatible fiber optic pH sensor based on a thin core interferometric technique
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2019 (English)In: Photonics, ISSN 2304-6732, Vol. 6, no 1, article id 11Article in journal (Refereed) Published
Abstract [en]

There is an increasing demand for compact, reliable and versatile sensor concepts for pH-level monitoring within several industrial, chemical as well as bio-medical applications. Many pH sensors concepts have been proposed, however, there is still a need for improved sensor solutions with respect to reliability, durability and miniaturization but also for multiparameter sensing. Here we present a conceptual verification, which includes theoretical simulations as well as experimental evaluation of a fiber optic pH-sensor based on a bio-compatible pH sensitive material not previously used in this context. The fiber optic sensor is based on a Mach-Zehnder interferometric technique, where the pH sensitive material is coated on a short, typically 20-25 mm thin core fiber spliced between two standard single mode fibers. The working principle of the sensor is simulated by using COMSOL Multiphysics. The simulations are used as a guideline for the construction of the sensors that have been experimentally evaluated in different liquids with pH ranging from 1.95 to 11.89. The results are promising, showing the potential for the development of bio-compatible fiber optic pH sensor with short response time, high sensitivity and broad measurement range. The developed sensor concept can find future use in many medical- or bio-chemical applications as well as in environmental monitoring of large areas. Challenges encountered during the sensor development due to variation in the design parameters are discussed. © 2019 by the authors.

Keywords
Hydrogel, Interferometric, Mach-Zehnder, PH, Sensor, Simulation
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38262 (URN)10.3390/photonics6010011 (DOI)2-s2.0-85063143389 (Scopus ID)
Note

Funding details: Japan Society for the Promotion of Science, JSPS, JP17H01269; Funding details: Japan Society for the Promotion of Science, JSPS, JP18H01499; Funding text 1: This work was partially supported by JSPS KAKENHI, Grant Numbers JP18H01499 and JP17H01269

Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2023-05-25Bibliographically approved
Granberg, H., Sandberg, M. & Håkansson, K. (2019). Pilot scale production of interactive zinc oxide paper and its multiple applicability. In: PaperCon 2019: Proceedings. Paper presented at PaperCon 2019. Proceedings of a conference held in Indianapolis, Indiana, USA, 5-8 May 2019. TAPPI Press, Article ID PF3.3.
Open this publication in new window or tab >>Pilot scale production of interactive zinc oxide paper and its multiple applicability
2019 (English)In: PaperCon 2019: Proceedings, TAPPI Press, 2019, article id PF3.3Conference paper, Published paper (Other academic)
Abstract [en]

A study has been made of the production of zinc oxide (ZnO) paper in a pilot paper machine. Bleached sulphate softwood pulp (70%) and bleached sulphate hardwood pulp (30%) were corefined. Cationic polyacrylamide (CPAM) was used as retention agent, while alkyl ketene dimer (AKD) was used as sizing agent for some samples. Some papers were screen printed with a conducting carbon-based ink to produce a photosensor device. Two methods were used to study the photocatalysis: immersing ZnO papers into kongo red dispersions or resazurin (Rz) based photocatalyst activity indicator ink and exposing the papers to ultraviolet (UV) light in a sunlight simulator. ZnO papers of approximately 60gsm were successfully produced on the pilot scale machine, which was run at a low speed (100m/min) and the retention of ZnO particles was good in all samples. The paper looked like an ordinary white printing paper product, but was a truly interactive material, exhibiting photoconductivity and enabling use as an excellent photosensor.

Place, publisher, year, edition, pages
TAPPI Press, 2019
Keywords
speciality paper, zinc oxide, pilot trial, paper properties, photoconductivity, photoconductor
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:ri:diva-40586 (URN)
Conference
PaperCon 2019. Proceedings of a conference held in Indianapolis, Indiana, USA, 5-8 May 2019
Available from: 2019-10-28 Created: 2019-10-28 Last updated: 2023-05-25Bibliographically approved
Hammarling, K., Engholm, M., Andersson, H., Sandberg, M. & Nilsson, H. E. (2018). Broad-range hydrogel-based pH sensor with capacitive readout manufactured on a flexible substrate. Chemosensors, 6(3), Article ID 30.
Open this publication in new window or tab >>Broad-range hydrogel-based pH sensor with capacitive readout manufactured on a flexible substrate
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2018 (English)In: Chemosensors, ISSN 2227-9040, Vol. 6, no 3, article id 30Article in journal (Refereed) Published
Abstract [en]

Environmental monitoring of land, water and air, is an area receiving greater attention because of human health and safety concerns. Monitoring the type of pollution and concentration levels is vital, so that appropriate contingency plans can be determined. To effectively monitor the environment, there is a need for new sensors and sensor systems that suits these type of measurements. However, the diversity of sensors suitable for low, battery powered- and large area sensor systems are limited. We have manufactured and characterized a flexible pH sensor using laser processing and blade coating techniques that is able to measure pH between 2.94 and 11.80. The sensor consists of an interdigital capacitance with a pH sensitive hydrogel coating. Thin sensors can reach 95% of their final value value within 3 min, and are stable after 4 min. Good repeatability was achieved in regard to cycling of the sensor with different pH and multiple measurements from dry state. We have also studied the relation between an interdigital capacitance penetration depth and hydrogels expansion. We believe that our passive sensor is suitable to be used in low power and large area sensor networks.

Keywords
Coating, Hydrogel, Interdigital, Laser ablation, Oligo (b-amino esters), Penetration depth, PH, Sensor, Thin film
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35154 (URN)10.3390/chemosensors6030030 (DOI)2-s2.0-85052627188 (Scopus ID)
Available from: 2018-09-11 Created: 2018-09-11 Last updated: 2023-05-25Bibliographically approved
Sani, N., Linderhed, U. & Sandberg, M. (2018). Monolithically integrated electrochemical energy storage modules. Journal of Energy Storage, 16, 139-144
Open this publication in new window or tab >>Monolithically integrated electrochemical energy storage modules
2018 (English)In: Journal of Energy Storage, ISSN 2352-152X, Vol. 16, p. 139-144Article in journal (Refereed) Published
Abstract [en]

The concept of monolithic integration of electrochemical energy storage modules was tested on serially connected supercapacitor cells balanced by passive resistive dissipation. Five electrode pairs with collectors, interconnects, corrosion protection layers, electrode material and shunt resistors were printed on a single substrate. The printed patterns, lamination film, and a hot-sealing tool were designed so that upon folding, lamination, and electrolyte filling and sealing, five serial cells were formed with each having a shunt resistance. In an open circuit idling period following charge and discharge, the standard deviation of the individual cell voltages decreased, demonstrating the balancing function of this so called “modulit”, a short term proposed for a monolithically integrated electrochemical energy storage module.

Keywords
Balancing, Monolithic integration, Printed serial modules, Resistive dissipation, Supercapacitors
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33427 (URN)10.1016/j.est.2018.01.004 (DOI)2-s2.0-85041378473 (Scopus ID)
Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2023-05-25Bibliographically approved
Hammarling, K., Sandberg, M., Engholm, M., Andersson, H. & Nilsson, H.-E. (2018). Synthesis, Curing Behavior and Swell Tests of pH-Responsive Coatings from Acryl-Terminated Oligo(beta-Amino Esters). Chemosensors, 6(1), Article ID 10.
Open this publication in new window or tab >>Synthesis, Curing Behavior and Swell Tests of pH-Responsive Coatings from Acryl-Terminated Oligo(beta-Amino Esters)
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2018 (English)In: Chemosensors, ISSN 2227-9040, Vol. 6, no 1, article id 10Article in journal (Refereed) Published
Abstract [en]

The ability of acryl-terminated oligo(beta-amino esters) (AOBAE) to be coated on fibers and printed electronics without solvents and to be cross-linked to a pH-responsive coatings, makes AOBAE-based coatings a potential type of pH-sensor coating. However, there are currently no reports of AOBAEs used as a pH-responsive coating material in sensor applications. Here we present an investigation of the synthesis, curing behavior and swell tests of AOBAEs. AOBAEs were synthesized from reacting an excess of asymmetric diacrylates with piperazine without the use of any solvents. They were then cross-linked to an insoluble network by UV-curing. Nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the AOBAEs. NMR was used to clarify the irregular structure of the AOBAE. FTIR was used to monitor the effects of UV-curing dose and air exposure on monomer conversion during curing. An interferometric technique was used to monitor the swelling behavior of the coating in response to pH variations. Swell experiments showed that the AOBAE also responded to pH variations after polymerization. Therefore, AOBAE is an interesting class of material with potential use as a pH responsive coating in optical-and printed electronics pH-sensors applications.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
oligo(beta-amino esters); acryl-terminated; 1, 3-butanediol diacrylate; piperazine; pH; sensor; coating; thin film
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33641 (URN)10.3390/chemosensors6010010 (DOI)2-s2.0-85045393278 (Scopus ID)
Available from: 2018-04-14 Created: 2018-04-14 Last updated: 2023-05-25Bibliographically approved
Keshmiri, V., Westerberg, D., Andersson Ersman, P., Sandberg, M., Forchheimer, R. & Tu, D. (2017). A Silicon-Organic Hybrid Voltage Equalizer for Supercapacitor Balancing. IEEE Journal on Emerging and Selected Topics in Circuits and Systems, 7(1), 114-122, Article ID 7817802.
Open this publication in new window or tab >>A Silicon-Organic Hybrid Voltage Equalizer for Supercapacitor Balancing
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2017 (English)In: IEEE Journal on Emerging and Selected Topics in Circuits and Systems, ISSN 2156-3357, E-ISSN 2156-3365, Vol. 7, no 1, p. 114-122, article id 7817802Article in journal (Refereed) Published
Abstract [en]

Cell voltage equalizers are an important part in electric energy storage systems comprising series-connected cells, for example, supercapacitors. Hybrid electronics with silicon chips and printed devices enables electronic systems with moderate performance and low cost. This paper presents a silicon-organic hybrid voltage equalizer to balance and protect series-connected supercapacitor cells during charging. Printed organic electrochemical transistors with conducting polymer poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) are utilized to bypass excess current when the supercapacitor cells are fully charged to desired voltages. In this study, low-cost silicon microcontrollers (ATtiny85) are programmed to sense voltages across the supercapacitor cells and control the organic electrochemical transistors to bypass charging current when the voltages exceed 1 V. Experimental results show that the hybrid equalizer with the organic electrochemical transistors works in dual-mode, switched-transistor mode or constant-resistor mode, depending on the charging current applied (0.3-100 mA). With the voltage equalizer, capacitors are charged equally regardless of their capacitances. This work demonstrates a low-cost hybrid solution for supercapacitor balancing modules at large-scale packs.

Keywords
Hybrid electronics, organic electrochemical transistors, printed electronics, supercapacitor balancing, voltage equalizer, Conducting polymers, Conductive plastics, Equalizers, Silicon, Styrene, Transistors, Charging current, Electric energies, Electronic systems, Hybrid solution, Poly(styrene sulfonate), Poly-3, 4-ethylenedioxythiophene, Series-connected, Capacitance
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-31012 (URN)10.1109/JETCAS.2016.2612724 (DOI)2-s2.0-85009877621 (Scopus ID)
Available from: 2017-09-04 Created: 2017-09-04 Last updated: 2024-01-05Bibliographically approved
Brooke, R., Mitraka, E., Sardar, S., Sandberg, M., Sawatdee, A., Berggren, M., . . . Jonsson, M. P. (2017). Infrared electrochromic conducting polymer devices. Journal of Materials Chemistry C, 5(23), 5824-5830
Open this publication in new window or tab >>Infrared electrochromic conducting polymer devices
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2017 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 23, p. 5824-5830Article in journal (Refereed) Published
Abstract [en]

The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is well known for its electrochromic properties in the visible region. Less focus has been devoted to the infrared (IR) wavelength range, although tunable IR properties could enable a wide range of novel applications. As an example, modern day vehicles have thermal cameras to identify pedestrians and animals in total darkness, but road and speed signs cannot be easily visualized by these imaging systems. IR electrochromism could enable a new generation of dynamic road signs that are compatible with thermal imaging, while simultaneously providing contrast also in the visible region. Here, we present the first metal-free flexible IR electrochromic devices, based on PEDOT:Tosylate as both the electrochromic material and electrodes. Lateral electrochromic devices enabled a detailed investigation of the IR electrochromism of thin PEDOT:Tosylate films, revealing large changes in their thermal signature, with effective temperature changes up to 10 °C between the oxidized (1.5 V) and reduced (-1.5 V) states of the polymer. Larger scale (7 × 7 cm) vertical electrochromic devices demonstrate practical suitability and showed effective temperature changes of approximately 7 °C, with good optical memory and fast switching (1.9 s from the oxidized state to the reduced state and 3.3 s for the reversed switching). The results are highly encouraging for using PEDOT:Tosylate for IR electrochromic applications.

Keywords
Conducting polymers, Electrochromic devices, Infrared imaging, Polymer films, Roads and streets, Sulfur compounds, Temperature, Effective temperature, Electro-chromic applications, Electrochromic materials, Electrochromic properties, Infrared wavelengths, Novel applications, Poly(3, 4 ethylenedioxythiophene) (PEDOT), Thermal signatures, Electrochromism
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-31115 (URN)10.1039/c7tc00257b (DOI)2-s2.0-85021669689 (Scopus ID)
Available from: 2017-08-28 Created: 2017-08-28 Last updated: 2023-06-07Bibliographically approved
Andersson Ersman, P., Westerberg, D., Tu, D., Nilsson, M., Åhlin, J., Eveborn, A., . . . Gustafsson, G. (2017). Screen printed digital circuits based on vertical organicelectrochemical transistors. Flexible and Printed Electronics, 2, Article ID 045008.
Open this publication in new window or tab >>Screen printed digital circuits based on vertical organicelectrochemical transistors
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2017 (English)In: Flexible and Printed Electronics, E-ISSN 2058-8585, Vol. 2, article id 045008Article in journal (Refereed) Published
Abstract [en]

Vertical organic electrochemical transistors (OECTs) have been manufactured solely using screenprinting. The OECTs are based on PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid)), which defines the active material for both the transistor channel and the gateelectrode. The resulting vertical OECT devices and circuits exhibit low-voltage operation, relativelyfast switching, small footprint and high manufacturing yield; the last three parameters are explainedby the reliance of the transistor configuration on a robust structure in which the electrolyte verticallybridges the bottom channel and the top gate electrode. Two different architectures of the verticalOECT have been manufactured, characterized and evaluated in parallel throughout this report. Inaddition to the experimental work, SPICE models enabling simulations of standalone OECTs andOECT-based circuits have been developed. Our findings may pave the way for fully integrated, lowvoltageoperating and printed signal processing systems integrated with e.g. printed batteries, solarcells, sensors and communication interfaces. Such technology can then serve a low-cost basetechnology for the internet of things, smart packaging and home diagnostics applications.

Keywords
electrochemical transistor, printed electronic circuit, PEDOT:PSS, electrolyte, SPICE model, hybrid electronics
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:ri:diva-33096 (URN)10.1088/2058-8585/aa903a (DOI)2-s2.0-85040970207 (Scopus ID)
Available from: 2018-01-16 Created: 2018-01-16 Last updated: 2023-06-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0631-3804

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