| 1. |
- Farraj, Yousef, et al.
(författare)
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Ink-Jet Printed Copper Complex MOD Ink for Plastic Electronics
- 2014
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Ingår i: International Conference on Non Impact Printing and Digital Fabrication. - 9780892083114 ; , s. 191-193
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Konferensbidrag (refereegranskat)abstract
- The development of highly conductive copper patterns on low-cost flexible substrates (PET, PEN, etc.) by inkjet printing is reported. Copper films were obtained from a metallo-organic decomposition (MOD) ink composed of a copper complex and suitable low-viscosity solvents. Upon heating the ink decomposed and was converted into metallic copper under nitrogen as inert atmosphere.Additionally samples were prepared using inkjet technology on various substrates. The required layer thickness for current conduction was assessed by printing on PET and sintering at 150 °C in a vacuum oven.
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| 2. |
- Feng, Yi, et al.
(författare)
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Characterization of Inkjet Printed Coplanar Waveguides for Flexible Electronics
- 2011
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Ingår i: NIP27: International Conference on Digital Printing Technologies and Digital Fabrication 2011. - : The Society for Imaging Science and Technology. - 9780892082964 ; , s. 454-457
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Konferensbidrag (refereegranskat)abstract
- The low conductivity and thin layers of the inkjet-printed metal conductors have always been a big concern in paper-based printed electronics for high frequency applications. To provide the fundamental knowledge, the high frequency characteristics of inkjet-printed coplanar waveguides on paper substrate were studied experimentally in terms of characteristic impedance and conductor losses using the time domain reflectometry technique. The influences of different printing settings and of geometric parameters on the waveguide's properties were investigated. Considering the measurement accuracy in high frequency characterization, one sample with an impedance of 51.2Ω was achieved. The electrical stability of the samples was also studied and explained. In addition, one waveguide sample was printed in a way that the pattern area with the highest current density is thickened. This variable ink-layer thickness approach has successfully been proven as a promising solution to reduce the conductor losses and yet consuming less ink.
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| 3. |
- Feng, Yi, et al.
(författare)
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Fabrication and performance evaluation of ultralow-cost inkjet-printed chipless RFID tags
- 2012
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Konferensbidrag (refereegranskat)abstract
- This paper studies the performance of inkjet-printed chipless RFID tags based on planar inductor-capacitor resonant circuits. Besides using double-sided printing, a sandwiching process is introduced to fabricate the tags in order to eliminate the need of through-substrate via and match roll-to-roll processing. Due to lower conductivity (~1.25E+7 S/m) and smaller thickness (~1.7μm) of printed conductors with silver nanoparticle ink, the resonant peaks of inkjet-printed tags exhibit around as twice of half-power bandwidth and 60% of maximum reading distance as the etched tags from bulk copper. Nevertheless, the inkjet-printed tag performance is sufficient for many applications, and it can be adjusted and improved by printing and sintering processes.
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| 4. |
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| 5. |
- Feng, Yi
(författare)
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Printed RFID Humidity Sensor Tags for Flexible Smart Systems
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radio frequency identification (RFID) and sensing are two key technologies enabling the Internet of Things (IoT). Development of RFID tags augmented with sensing capabilities (RFID sensor tags) would allow a variety of new applications, leading to a new paradigm of the IoT. Chipless RFID sensor technology offers a low-cost solution by eliminating the need of an integrated circuit (IC) chip, and is hence highly desired for many applications. On the other hand, printing technologies have revolutionized the world of electronics, enabling cost-effective manufacturing of large-area and flexible electronics. By means of printing technologies, chipless RFID sensor tags could be made flexible and lightweight at a very low cost, lending themselves to the realization of ubiquitous intelligence in the IoT era.This thesis investigated three construction methods of printable chipless RFID humidity sensor tags, with focus on the incorporation of the sensing function. In the first method, wireless sensing based on backscatter modulation was separately realized by loading an antenna with a humidity-sensing resistor. An RFID sensor tag could then be constructed by combining the wireless sensor with a chipless RFID tag. In the second method, a chipless RFID sensor tag was built up by introducing a delay line between the antenna and the resistor. Based on time-domain reflectometry (TDR), the tag encoded ID in the delay time between its structural-mode and antenna-mode scattering pulse, and performed the sensing function by modulating the amplitude of the antenna-mode pulse.In both of the above methods, a resistive-type humidity-sensing material was required. Multi-walled carbon nanotubes (MWCNTs) presented themselves as promising candidate due to their outstanding electrical, structural and mechanical properties. MWCNTs functionalized (f-MWCNTs) by acid treatment demonstrated high sensitivity and fast response to relative humidity (RH), owing to the presence of carboxylic acid groups. The f-MWCNTs also exhibited superior mechanical flexibility, as their resistance and sensitivity remained almost stable under either tensile or compressive stress. Moreover, an inkjet printing process was developed for the f-MWCNTs starting from ink formulation to device fabrication. By applying the f-MWCNTs, a flexible humidity sensor based on backscatter modulation was thereby presented. The operating frequency range of the sensor was significantly enhanced by adjusting the parasitic capacitance in the f-MWCNTs resistor. A fully-printed time-coded chipless RFID humidity sensor tag was also demonstrated. In addition, a multi-parameter sensor based on TDR was proposed.The sensor concept was verified by theoretical analysis and circuit simulation.In the third method, frequency-spectrum signature was utilized considering its advantages such as coding capacity, miniaturization, and immunity to noise. As signal collision problem is inherently challenging in chipless RFID sensor systems, short-range identification and sensing applications are believed to embody the core values of the chipless RFID sensor technology. Therefore a chipless RFID humidity sensor tag based on near-field inductive coupling was proposed. The tag was composed of two planar inductor-capacitor (LC) resonators, one for identification, and the other one for sensing. Moreover, paper was proposed to serve as humidity-sensing substrate for the sensor resonator on accounts of its porous and absorptive features.Both inkjet paper and ordinary packaging paper were studied. A commercial UV-coated packaging paper was proven to be a viable and more robust alternative to expensive inkjet paper as substrate for inkjet-printed metal conductors. The LC resonators printed on paper substrates showed excellent sensitivity and reasonable response time to humidity in terms of resonant frequency. Particularly, the resonator printed on the UV-coated packaging paper exhibited the largest sensitivity from 20% to 70% RH, demonstrating the possibilities of directly printing the sensor tag on traditional packages to realize intelligent packaging at an ultra-low cost.
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| 6. |
- Reinhold, Ingo, 1981-, et al.
(författare)
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Analysis of Formation of an Individual Droplet Using a High-ResolutionMulti-Exposure Imaging System
- 2013
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Ingår i: International Conference on Digital Printing Technologies and Digital Fabrication. ; , s. 354-358
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Konferensbidrag (refereegranskat)abstract
- Localized dispensing of precious functional materials has attracted considerable interest in the academic as well as the industrial society. While the number of publications show numerous fields of applications in printed electronics, photovoltaics, display technologies and thin functional coatings, the transition into the industrial sector is often hindered by challenges resulting from ink-printhead combinations and their implications on reliability and stability of the process, as well as side-effects such as mist accumulation in heavy duty printing equipment.While measuring equipment to quantify various rheological and interfacial parameters foor fluid optimization has been developed with the accompanying mathematical models, the physical jetting experiment as well as high-duty printing trials cannot yet be substituted by these methods. In order to quantify the generation of a droplet alongside with its tailing behavior and mist formation as well as statistics based on cross-talk effects and relaxation-related effects, high-resolution and high-speed imaging are required.This paper examines the optical setup and outlines the required calculations for establishing sharp, high-resolution images using a combination of a high power laser diode with a resonant MEMS micro mirror with a theoretical resolution of 1.8 μm. The limitations of the setup regarding the achievable resolution as well as potential improvements are assessed. Furthermore, the experimental setup, including repetitive generation of nanosecond-pulses necessary for motion-blur-free images, will be discussed. Additionally, results from imaging a droplet formation process using a Xaar 126 printhead are discussed.
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| 7. |
- Reinhold, Ingo, et al.
(författare)
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Electrical through-hole and planar interconnect generation in roll-to-roll LED lighting manufacturing using industrial inkjet printheads
- 2011
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Ingår i: Mater Res Soc Symp Proc. - : Springer Science and Business Media LLC. - 9781618395399 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Despite the availability of many high-volume and low-cost manufacturing processes for LED-based lighting applications, relying mainly on fixed patterns such as LED-backlights and RGB-pixelated displays, novel applications, such as "mood lighting" or interior wall displays call for more complicated and shaped LED arrangements. The presented work is based of a novel roll-to-roll (R2R) process to adaptively and cost-efficiently generate LED arrangements on RMPD® substrates. Inkjet printing of planar and though-hole electrical interconnections is of high importance to the process, as it provides a fully digital way of interconnecting devices electrically, accounting for the actual position of the component and spatially provide different ink film thicknesses. Xaar's industrial inkjet printheads are used to dispense defined volumes of 50 pL of a silver nanoparticle ink in order to provide high reliability and good positioning accuracy while maintaining low satellite drop densities. Specific printing strategies are investigated at a print speed of 0.1 m/s to allow for a reliable electrical connection in case of up to 50 μm deep via connections to the buried component. Due to the low glass-transition nature of the underlying substrates, low sintering temperatures are required to preserve the mechanical properties of the substrate. Low temperature oven sintering yielding sufficient conductivity to drive a current of 40 mA will be discussed.
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| 8. |
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| 9. |
- Reinhold, Ingo, et al.
(författare)
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High-Speed, Low-Volume Inkjet and its Role in Jet and Flash Imprint Lithography
- 2014
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Ingår i: NIP & Digital Fabrication Conference, 2014 International Conference on Digital Printing Technologies. - : The Society for Imaging Science and Technology. ; , s. 408-412
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Konferensbidrag (refereegranskat)abstract
- Imprint lithography is an effective technique for replication of nanoscale features. Jet and Flash™ Imprint Lithography (J-FIL™) uses field-by-field deposition and exposure of a low viscosity resist deposited by inkjet printing onto the substrate. The patterned mask is lowered into the fluid, where capillary action assists to flow the fluid into the relief patterns. Following the filling step, the resist is UV cured, the mask is removed, and a patterned resist is left on the substrate.J-FIL™ is a technique, where the imprint technology provides the nanoscale pattern resolution while the inkjet technology contributes the throughput that is required for industrial applications. The drop volume and drop placement accuracy of the inkjet-printed resist is critical, allowing the volume to be distributed appropriately across the substrate surface to achieve a uniform target thickness and preventing non-filling of the relief patterns. With J– FIL™, it is possible to resolve 28 nm structures with residual layer thickness of 13 and 20 nm on 300 mm and 450 mm Si-wafers.In this study, improvements during the filling step are explored for low droplet volumes at high ejection frequencies when using standard printheads with jetting performance of 12 kHz, <3 pL and modified printheads with jetting performance of 28 kHz, <2 pL.
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| 10. |
- Reinhold, Ingo, et al.
(författare)
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Inkjet Printing of Electrical Connections in Electronic Packaging
- 2011
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Ingår i: NIP27 : 27th International Conference on Digital Printing Technologies, October 2-6, 2011, Minneapolis, Minnesota ; Digital Fabrication 2011. - : The Society for Imaging Science and Technology. - 9780892082964 ; , s. 445-451
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Konferensbidrag (refereegranskat)abstract
- Two aspects were evaluated of an approach to produce inkjet printed electrical connections in a roll-to-roll application. In the first part it was demonstrated that inkjet printing with silver nanoparticles allows to connect LED dies embedded in a flexible polymeric substrate by way of electrical via connections and to operate the LED dies at their nominal 20 mA and 3 V driving conditions. A standard convection oven process was used to sinter the inkjet printed tracks. The second part of the work focused on identifying sinter technologies that provide the required fast processing times needed for roll-to-roll applications. IR irradiation, Rapid Electrical Sintering, and Broadband Photonic Curing were evaluated and compared with Convective Oven Sintering as benchmark technique. All these techniques produced similar track conductivities. Fastest operation was obtained with Broadband Photonic Curing, which enabled a total process time of three seconds as compared with 150°C and 30 min in the convection oven.
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