| 1. |
- Andersson, Henrik, Dr, 1975-, et al.
(författare)
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PEDOT : PSS thermoelectric generators printed on paper substrates
- 2019
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Ingår i: Journal of Low Power Electronics and Applications. - : MDPI AG. - 2079-9268. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Campo Woytuk, Nadia, et al.
(författare)
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Tactful Feminist Sensing : Designing for Touching Vaginal Fluids
- 2023
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Ingår i: DESIGNING INTERACTIVE SYSTEMS CONFERENCE, DIS 2023. - : Association for Computing Machinery (ACM). - 9781450398930 ; , s. 2642-2656
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Konferensbidrag (refereegranskat)abstract
- Observing the texture, color, and conductivity of cervical mucus has the potential to support menstrual cycle and fertility tracking, generating a layer of rich bodily, tactile/haptic knowledge in addition to other collected data, such as cycle length or body temperature. This pictorial presents design explorations, four design concepts, and one prototype of a sensor for measuring the conductivity of cervical mucus in vaginal fluids. We present these as instances in the design space for sensing intimate bodily fluids and provide discussions on the proximities, visibilities, and temporalities of these sensing technologies. We offer the unfolding concept of "tactful feminist sensing", opening up for further engagements with intimate care that attend to the multiplicity and fleshiness of bodies.
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| 3. |
- Forsberg, Viviane, et al.
(författare)
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Electronic performance of printed PEDOT:PSS lines correlated to the physical and chemical properties of coated inkjet papers
- 2019
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Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 9:41, s. 23925-23938
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Tidskriftsartikel (refereegranskat)abstract
- PEDOT:PSS organic printed electronics chemical interactions with the ink-receiving layer (IRL) of monopolar inkjet paper substrates and coating color composition were evaluated through Raman spectroscopy mapping in Z (depth) and (XY) direction, Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDS). Other evaluated properties of the IRLs were pore size distribution (PSD), surface roughness, ink de-wetting, surface energy and the impact of such characteristics on the electronics performance of the printed layers. Resin-coated inkjet papers were compared to a multilayer coated paper substrate that also contained an IRL but did not contain the plastic polyethylene (PE) resin layer. This substrate showed better electronic performance (i.e., lower sheet resistance), which we attributed to the inert coating composition, higher surface roughness and higher polarity of the surface which influenced the de-wetting of the ink. The novelty is that this substrate was rougher and with somewhat lower printing quality but with better electronic performance and the advantage of not having PE in their composite structure, which favors recycling.
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| 4. |
- Forsberg, Viviane, 1981-, et al.
(författare)
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Printability of functional inkjet inks onto commercial inkjet substrates and a taylor made pigmented coated paper
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Printed electronics are of increasing interest. The substrates used have primarily been plastics although the interest for cellulose-based substrates is increasing due to the environmental aspect as well as cost. The requirements of substrates for electronically active inks differs from graphical inks and therefore we have investigated a custom-made pigment based coated paper and compared it to commercial photo-papers and a coated PE film.Our goal with the study of different substrates was to select the most suitable substrate to print water based 2D materials inkjet inks for flexible electronics.The discovery of graphene, a layered material achieved from the exfoliation of graphite, has resulted in the study of other materials with similar properties to cover areas where graphene could not be used due to the absence of a bandgap in the material. For example in thin film transistors (TFT) a semiconductor layer is essential to enable turn on and off the device. This semiconductor layer can be achieved using various materials but particular interest have been dedicated to abundant and cheap 2D materials such as the transition metal dichalcogenide (TMD) molybdenum disulfide (MoS2). To date, most of the dispersions based on TMDs use organic solvents or water solutions of surfactants. Previously we focus on the study of environmental friendly inks produced by liquid phase exfoliation (LPE) of MoS2 in water using cellulose stabilizers such as ethyl cellulose (EC), cellulose nanofibrils (CNF) and nanofibrilcellulose (NFC). We have study various aspects of the ink fabrication includi ng pH range, the source of MoS2, nanosheets thickness, particle size distribution, ink stabilizers, ink concentration, viscosity and surface tension. These inks have very low concentration requiring a number of printing passes to cover the substrate. Therefore the substrate selection is crucial as a large amount of solvent is to be absorb by the substrate. Our goal was to use such an ink to print electrodes of MoS2 into a paper substrate after substrate selection.Commercial photo papers, a commercial coated PE film and a tailor made multilayer pigment coated paper substrate were used for the substrate selection analysis. We print the substrates using a DIMATIX inkjet printer with a 10 pL printing head using the distillated water waveform supplied by the printer manufacturer. The voltage used was 23V and 4 nozzles were used for the print outs. The inkjet ink used was the organic PEDOT:PSS. We printed lines ranging from 1 pixel to 20 pixels with 1, 2 and 3 printing passes. The printing quality was evaluated through measurements of the waviness of the printed lines measured after imaging the printed samples with a SEM microscope. The line width measurement was done using the software from the SEM.We also evaluated the structure of the coatings using SEM and topography measurements. The ink penetration through the substrates was evaluated using Raman Spectroscopy. For the pigmented coated sample we measured 4% of ink penetration through the substrate for the 1pxl printed line printed once onto the paper. Cross-section SEM images of the printed lines were made to visualize the ink penetration into the substrate.Regarding the electrical conductivity of the printed samples, the differences in resistivity varying the width of the printed lines and the number of printed passes were evaluated. The resistivity of the printed electrodes was evaluated using the 2-points probe method. Before the resistivity measurements, the printed substrates were heated at 50°C and 100°C for 30 minutes in an oven.We choose the PEDOT:PSS ink because it is a low price ink compared to metal nanoparticles inks for printed electronics. The print outs had low resistivity at a few printing passes with no need for sintering at high temperatures. The MoS2 ink has a very high resistance at a few printing passes due to lower coverage of the substrate therefore for this ink these measurements were not possible to be made. The main pigment composition of the paper coatings of the substrates was evaluated using FT-IR and EDX, these data plus the coating structure evaluated by SEM was related to the print quality.The best in test papers were used to print MoS2 electrodes. After the printing tests, another step for the optimization of the MoS2 ink properties shall be carried out in future studies for better print quality. We also evaluated the surface energy of the substrates through contact angle measurements to match the surface tension of the PEDOT:PSS ink and later the MoS2 ink. Although the pigmented coated printing substrate did not show better results than the commercial photo papers and PE foil in terms of line quality, it shows the lowest resistivity and sufficient results for low cost recyclable electronics, which do not require high conductivity. Nevertheless, the substrate was very thin and it could even be used in magazines as traditional lightweight coated papers (LWC) are used but with the additional of a printed electronic feature.
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| 5. |
- Maslik, Jan, et al.
(författare)
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PEDOT:PSS temperature sensor ink-jet printed on paper substrate
- 2018
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Ingår i: Journal of Instrumentation. - : Institute of Physics (IOP). - 1748-0221. ; 13
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Forskningsöversikt (refereegranskat)abstract
- In this work we present an ink-jet printed temperature sensor consisting of PEDOT:PSSprinted on paper suitable for packaging, flexible electronics and other printed applications. Thesubstrate showed to have a large influence on both the resistance aswell as the temperature sensitivityof the PEDOT:PSS ink. This effect is most likely due to NaCl content in the photo paper coating,which reacts with the PEDOT:PSS. The temperature coefficient of a prepared device of α= -0.030 relative to room temperature (22°C) was measured, which is higher than compared to for exampleSilicon α = -0.075.
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| 6. |
- Maslik, Jan, et al.
(författare)
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Soft, Stretchable and Wireless Sensor Patch with Digitally Printed Liquid Metal Alloy Interconnects
- 2022
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Ingår i: 2022 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - : Institute of Electrical and Electronics Engineers (IEEE). - 9789189711396 - 9781665491778
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Konferensbidrag (refereegranskat)abstract
- Characteristics of high electrical conductivity, high strain tolerance and resistance to fatigue are vital for electronic circuits of on-skin wearable systems. Gallium-based liquid metals offer a unique combination of these characteristics making them excellent alternatives to conventional conductive stretchable inks. In order to obtain better wearing experience, it is advantageous to fabricate devices using breathable materials. However, effective automation solutions for the production of high-resolution digitally patterned circuits for soft and stretchable devices remain a challenge. The presented manufacturing strategy involves adopting a needle dispensing technique for the precise patterning of liquid metal conductors. The circuitry is deposited onto a soft, thin and highly breathable polyurethane medical film. Further, we investigate and map conditions of reliable printing of liquid metal on the polyurethane film for two sizes of dispensing needles with inner diameters of 150 μm and 360 μm. Despite the increased porosity and surface roughness associated with the high breathability of the film, it is possible to reliably deposit liquid metal interconnects with a line width and height below 100 μm. The technological solution results in a first demonstrator presented: an electrophysiological patch.
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| 7. |
- Verdel, Nina, et al.
(författare)
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A Comparison of a Novel Stretchable Smart Patch for Measuring Runner’s Step Rates with Existing Measuring Technologies
- 2022
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 22:13
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Tidskriftsartikel (refereegranskat)abstract
- A novel wearable smart patch can monitor various aspects of physical activity, including the dynamics of running, but like any new device developed for such applications, it must first be tested for validity. Here, we compare the step rate while running in place as measured by this smart patch to the corresponding values obtained utilizing ‘‘gold standard’’ MEMS accelerometers in combination with bilateral force plates equipped with HBM load cells, as well as the values provided by a three-dimensional motion capture system and the Garmin Dynamics Running Pod. The 15 healthy, physically active volunteers (age = 23 ± 3 years; body mass = 74 ± 17 kg, height = 176 ± 10 cm) completed three consecutive 20-s bouts of running in place, starting at low, followed by medium, and finally at high intensity, all self-chosen. Our major findings are that the rates of running in place provided by all four systems were valid, with the notable exception of the fast step rate as measured by the Garmin Running Pod. The lowest mean bias and LoA for these measurements at all rates were associated consistently with the smart patch.
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| 8. |
- Verdel, Nina, et al.
(författare)
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Reliability and validity of running step rate derived from a novel wearable Smart Patch
- 2024
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Ingår i: IEEE Sensors Journal. - : IEEE. - 1530-437X .- 1558-1748. ; 24:9, s. 14343-14351
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Tidskriftsartikel (refereegranskat)abstract
- A novel, wearable, stretchable Smart Patch can monitor various aspects of physical activity, including the dynamics of running. However, like any new device developed for such applications, it must first be tested for validity and reliability. Here, we compare the step rate while running on a treadmill measured by this smart patch with the corresponding values obtained with the ”gold standard” OptoGait, as well as with other devices commonly used to assess running dynamics, i.e., the MEMS accelerometer and commercially available and widely used Garmin Running Dynamic Pod. The 14 healthy, physically active volunteers completed two identical sessions with a 5-minute rest between. Each session involved two one-minute runs at 11 km/h and 14 km/h separated by a one-min rest. The major finding was that the Smart Patch demonstrated fair to good test-retest reliability. The best test-retest reliability for the Running Pod was observed in connection with running at 11 km/h and both velocities combined (good and excellent, respectively) and for the OptoGait when running at 14 km/h (good). The best concurrent validity was achieved with the Smart Patch, as reflected in the highest Pearson correlation coefficient for this device when running at 11 or 14 km/h, as well as for both velocities combined. In conclusion, this study demonstrates that the novel wearable Smart Patch shows promising reliability and excellent concurrent validity in measuring step rate during treadmill running, making it a viable tool for both research and practical applications in sports and exercise science.
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| 9. |
- Wang, Bei, et al.
(författare)
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Supercooled Liquid Ga Stretchable Electronics
- 2023
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlagsgesellschaft. - 1616-301X .- 1616-3028. ; 33:29
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Tidskriftsartikel (refereegranskat)abstract
- By controlling the properties of its medium, supercooled liquid Ga (SLGa) based stretchable remains stretchable at -22 degrees C, i.e., 52 degrees C below its thermo-dynamic melting point of Ga. Thus far, our oldest deposited SLGa circuit and film have remained liquids for 2 years at room temperature. The study investi-gates the crystallization of SLGa triggered by the surface energy of nucleation agents, temperature, circuit cross-section, and mechanical impact. Based on these parameters, a method is presented to integrate electronic components with SLGa circuits without compromising its supercooling effect. Further, the large stiffness variation induced by phase transition is demonstrated in dif-ferent applications. For the desired stiffness variation, the crystallization rate can be controlled by varying the temperature and cross-section area. Finally, spray-printing an ink of microscale SLGa microscale particles can confor-mally pattern Ga on a rough surface, e.g., to fabricate a stretchable array of SLGa microelectrodes. A smart patch with stretchable SLGa electrode arrays records human electrocardiogram signals in cold water and does not stain the skin after use. Its low and stable impedance in water will enable novel applications in wearable electronics.
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