scholarly journals Flexible biodegradable transparent heaters based on fractal-like leaf skeletons

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Vipul Sharma ◽  
Anastasia Koivikko ◽  
Kyriacos Yiannacou ◽  
Kimmo Lahtonen ◽  
Veikko Sariola
Keyword(s):  
Surface Temperature ◽  
Surface Area ◽  
Sheet Resistance ◽  
Flexible Electronics ◽  
Low Voltage ◽  
Heating Temperature ◽  
Optical Transmittance ◽  
Ag Nanowires ◽  
Significant Change

Abstract We present a facile method to prepare flexible, transparent, biodegradable, and fast resistive heaters by applying silver (Ag) nanowires onto fractal-like leaf skeletons. The fractal-like structure of the leaf skeleton maximizes its surface area, improving the transfer of heat to its surroundings and thus making the heater fast, without compromising transparency. Ag ion layer on the leaf skeleton helps to conformally cover the surface with Ag nanowires. The sheet resistance of the heater can be controlled by the loading of Ag nanowires, without sacrificing the optical transmittance (~80% at 8 Ω sq−1). The heating is uniform and the surface temperature of a 60 mm × 60 mm heater (8 Ω sq−1) can quickly (5–10 s) raise to 125 °C with a low voltage (6 V). The heater displays excellent mechanical flexibility, showing no significant change in resistance and heating temperature when bent up to curvature of 800 m−1. Finally, we demonstrate the potential of the bioinspired heater as a thermotherapy patch by encapsulating it in a biodegradable tape and mounting it on the human wrist and elbow. This study shows that fractal-like structures from nature can be repurposed as fractal designs for flexible electronics.

scholarly journals Flexible, Transparent, and Conductive Film Based on Random Networks of Ag Nanowires

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Shunhua Wang ◽  
Xu Zhang ◽  
Weiwei Zhao
Keyword(s):  
Sheet Resistance ◽  
Optical Transmittance ◽  
Surface Resistivity ◽  
Random Networks ◽  
Transparent Electronics ◽  
Heating Systems ◽  
Conductive Films ◽  
Conductive Film ◽  
Ag Nanowires ◽  
Resistance Decrease

Flexible, transparent, and conductive films based on random networks of Ag nanowires were prepared by vacuum-filtrating method. The size of Ag nanowires prepared by hydrothermal method is uniform, with a relatively smaller diameter and a longer length, thereby achieving a high aspect ratio (>1000). The films fabricated by Ag nanowires exhibit the excellent transparency with a 92% optical transmittance and a low surface resistivity of 11 Ωsq−1. Importantly, both the transmittance and sheet resistance decrease with the increasing of the Ag nanowires contents. When the contents of Ag nanowires are up to 200 mg/m2especially, the surface resistivity quickly falls below 5 Ωsq−1. Also, these films are robust, which have almost no change in sheet resistance after the repeating bends over 200 cycles. These encouraging results may have a potential application in flexible and transparent electronics and other heating systems.

Fabrication of the large-area flexible transparent heaters using electric-field-driven jet deposition micro-scale 3D printing

2019 ◽  
Vol 8 (3-4) ◽  
pp. 217-223 ◽  
Author(s):  
Hefei Zhou ◽  
Xiaoyang Zhu ◽  
Hongke Li ◽  
Hongbo Lan
Keyword(s):  
3D Printing ◽  
Electric Field ◽  
Sheet Resistance ◽  
Heating Temperature ◽  
Low Cost ◽  
Optical Transmittance ◽  
Adhesive Force ◽  
High Viscosity ◽  
Large Area ◽  
Micro Scale

Abstract In order to realize the mass production of the large-area flexible transparent film heater (FTFH) at low-cost, this paper presents a novel method which can achieve the direct fabrication of the large-area FTFH with Ag-grid by using an electric-field-driven jet deposition micro-scale 3D printing. The effects of the line width and the pitch of the printed Ag-grids on the optical transmittance and the sheet resistance are revealed. A typical FTFH with area of 80 mm × 60 mm, optical transmittance of 91.5% and sheet resistance of 4.7 Ω sq−1 is fabricated by the nano-silver paste with a high silver content (80 wt.%) and high viscosity (up to 20 000 mPa · s). Temperature-time response profiles and heating temperature distribution show that the heating performance of the FTFH has good thermal and mechanical properties. Furthermore, the adhesive force grade between the Ag-grid and the PET substrate measured to be 4B by 3M scotch tape. Therefore, the FTFH fabricated here is expected to be widely used in industry, such as window defroster of vehicles and display or touch screens owing to its striking characteristics of large area and low cost fabrication.

Investigation of the Electrical, Optical, and Mechanical Properties of Ag Nanowire Conducting Electrode

2018 ◽  
Vol 775 ◽  
pp. 156-162 ◽  
Author(s):  
Dominic C. Sanchez ◽  
Mary Donnabelle L. Balela
Keyword(s):  
Sheet Resistance ◽  
Optical Transmittance ◽  
Polymer Substrates ◽  
Electrical Stress ◽  
Transparent Conducting ◽  
Ag Nanowires ◽  
Optical And Mechanical Properties ◽  
Transparent Conducting Electrodes ◽  
Ink Formulation ◽  
Ag Nanowire

Silver (Ag) nanowire having mean diameter and length of about 170.42 nm and 20.01 µm were prepared by the polyol process in ethylene glycol. Ag nanowires transparent conducting electrodes were then fabricated by depositing the Ag nanowires in ethanol and ink formulation on polymer substrates using a Meyer rod. The Ag nanowire electrodes exhibit an optical transmittance of about 68 % due to the large diameters of the as synthesized Ag nanowires. On the other hand, the sheet resistance was measured to be about 148 ohms/sq. When expose in air for 10 weeks, the sheet resistance increase to about 13 kohms/sq. Localized Joule heating during application of electrical stress of about 2 V for 7 days has resulted in the Ag nanowire degradation.

Enhancement of Characteristics of Transparent Conductive Electrode on Flexible Substrate by Combination of Solution-Based Oxide and Metallic Layers

2015 ◽  
Vol 15 (10) ◽  
pp. 7997-8003 ◽  
Author(s):  
Sung-Jei Hong ◽  
Yong-Hoon Kim ◽  
Seung-Jae Cha ◽  
Yong-Sung Kim
Keyword(s):  
Thermal Stability ◽  
Sheet Resistance ◽  
Flexible Electronics ◽  
Indium Tin Oxide ◽  
Silver Nanowires ◽  
Flexible Substrate ◽  
Optical Transmittance ◽  
Transparent Conductors ◽  
Transparent Conductor ◽  
Transparent Conductive Electrode

This study investigates solution-processed transparent conductors with hybrid structure consisting of silver nanowires (AgNWs) and indium-tin-oxide nanoparticles (ITO-NPs) layers fabricated on polymeric flexible polyethylene terephthalate (PET) substrate. The transparent conductors had stacked structures of AgNWs/ITO-NPs on 125-μm-thick PET and ITO-NPs/AgNWs/ITO-NPs on 125-μm-thick PET, 188-μm-thick PET, or 700-μm-thick glass substrate, respectively. Successful integrations were possible on the substrates without any deformation or distortion. Sheet resistance of the triplelayered transparent conductor samples exhibits low values ranging from 22.41 Ω/□ to 22.99 Ω/□. Also, their optical transmittance exhibits high values ranging from 83.78 to 87.29% at 550 nm. The triple-layered transparent conductor showed a good thermal stability in terms of sheet resistance and optical transmittance against the high-temperature environment up to 250 °C. All the double and triple-layered transparent conductors fabricated on PET and glass substrates are so stable against the accelerated thermal aging from 110 °C to 130 °C, that ΔR/R0 and ΔT550/T0550 values exhibit less than 0.068 and 0.049, respectively. Furthermore, the layers are so flexible that ΔR/R0 of the layers on PET substrates is lower than 0.1 even at 4.0-mm bending. Especially, triple-layered transparent conductor on 125-μm-thick PET substrates exhibits ΔR/R0 value of 0.042 even at 4.0 mm bending. Thus, it can be concluded that the hybrid structures have the advantage of both thermal stability and flexibility for electrical and optical properties of transparent conductive electrode; which makes them highly applicable in flexible electronics.

Physical and Optical Properties of The Films Ð’i2Te3-Bi2Se3

2015 ◽  
Vol 11 (2) ◽  
pp. 3017-3022
Author(s):  
Gurban Akhmedov
Keyword(s):  
Thin Film ◽  
Optical Properties ◽  
Surface Temperature ◽  
Thermal Evaporation ◽  
Low Voltage ◽  
Internal Surface ◽  
Differential Resistance ◽  
Work Cycle

Results of researches show, that film p-n the structures received by a method of discrete thermal evaporation in a uniform work cycle, are suitable for use in low-voltage devices.  As a result of work are received p-n heterojunctions in thin-film execution, described by high values of differential resistance. Show that, thermo endurance - T0 maybe using as characteristic of thermo endurance of optic materials. If heating flow, destruction temperature and internal surface temperature is measured during test, it is possible to determine value T0 and other necessity characteristics. As a result of the taking test was lead to comparison evaluation of considered materials. Working range of heating flow and up level heating embark have been determined.

scholarly journals Sheet Resistance Measurements of Conductive Thin Films: A Comparison of Techniques

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 960
Author(s):  
Mira Naftaly ◽  
Satyajit Das ◽  
John Gallop ◽  
Kewen Pan ◽  
Feras Alkhalil ◽  
...  
Keyword(s):  
Thin Films ◽  
Sheet Resistance ◽  
Flexible Electronics ◽  
Electronic Devices ◽  
Conductivity Measurements ◽  
Terahertz Time Domain Spectroscopy ◽  
Comparison Of Techniques ◽  
Terahertz Frequencies ◽  
Conductive Thin Films ◽  
Multiple Samples

Conductive thin films are an essential component of many electronic devices. Measuring their conductivity accurately is necessary for quality control and process monitoring. We compare conductivity measurements on films for flexible electronics using three different techniques: four-point probe, microwave resonator and terahertz time-domain spectroscopy. Multiple samples were examined, facilitating the comparison of the three techniques. Sheet resistance values at DC, microwave and terahertz frequencies were obtained and were found to be in close agreement.

Titanium nitride nanopowders produced via sodium reductionin liquid ammonia

2009 ◽  
Vol 24 (2) ◽  
pp. 448-451 ◽  
Author(s):  
Boyan Yuan ◽  
Mei Yang ◽  
Hongmin Zhu
Keyword(s):  
Titanium Nitride ◽  
Surface Area ◽  
Liquid Ammonia ◽  
Heating Temperature ◽  
Chemical Reduction ◽  
Atomic Ratio ◽  
Area Measurement ◽  
Bet Surface Area ◽  
Cubic Phase ◽  
Tem Analysis

Titanium nitride nanopowders were synthesized through a chemical reduction of titanium tetrachloride by sodium in liquid ammonia. The products of the reaction were the mixture of sodium chloride and titanium nitride nanopowders. The mixture was then separated by ammonia extraction. The nanopowders were heated under vacuum up to 1200 °C and were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET) surface area measurement, and chemical analysis. The results show that the product is nanocrystalline cubic phase TiN with Ti/N atomic ratio performed 1:1, and the surface area is from 20 to 50 m2 ·g−1 depending on the heating temperature. The particle sizes estimated by the TEM analysis correspond well with the results of the surface area measurements. The XRD pattern indicates that the crystal size grows with an increase in heating temperature.

Screen Printing Fine Pitch Stretchable Silver Inks onto a Flexible Substrate for Wearable Applications

2018 ◽  
Vol 2018 (1) ◽  
pp. 000665-000671
Author(s):  
Jianbiao Pan ◽  
Malcolm Keif ◽  
Joshua Ledgerwood ◽  
Xiaoying Rong ◽  
Xuan Wang
Keyword(s):  
Sheet Resistance ◽  
Flexible Electronics ◽  
Screen Printing ◽  
Flexible Substrate ◽  
Thermoplastic Polyurethane ◽  
Organic Substrate ◽  
Printing Process ◽  
Silver Ink ◽  
Fine Pitch

Abstract The lightweight and bendable features of printed flexible electronics are increasingly attractive. Currently stretchable silver inks are formulated for wide traces, typically larger than 2 mm. To attach ultra-thin silicon chips that have fine pitch onto printed organic substrate, it is necessary to print fine trace width/space that matches the pitch of the chips, which may be less than 200 microns. This paper presents the development and optimization of the screen printing process for printing stretchable silver ink onto stretchable thermoplastic polyurethane (TPU) substrate. A test vehicle was designed including 50 μm/5 mm (line width/line length) to 350 μm/35 mm lines (at 4 biases). The stretchable ink selected was DuPont PE 873 and Dupont's PE 5025 ink (non-stretchable conductive flake silver) was used as a “control” to baseline the printing process. The substrate used was Bemis TPU ST604. The experiment was done on a DEK Horizon 03i printer. A DEK squeegee 200 (Blue) and a DEK 265 flood bar (200 mm) were used. A 2-level factorial design with three replicates was selected to investigate the effect of process parameters on the quality of prints. The quality of the prints is characterized by 1) resistance of traces, 2) sheet resistance, 3) z-axis height, and 4) trace width/spacing. We observed significant noise in the z-axis printed silver ink height measured by profilometry and concluded z-axis height is not a good response variable for characterizing screen printing stretchable silver ink onto TPU substrate, mainly due to high roughness of the TPU substrate. We proposed calculated sheet resistance based on the measured resistance value, trace width, and trace length, which can replace trace height measurements on rough profile substrates. We found that squeegee pressure and emulsion thickness have statistically significant effects on calculated sheet resistance of print traces while print speed does not have statistically significant effects. In our experiment setting levels, the lower the squeegee pressure, the lower the calculated sheet resistance that is achieved. The emulsion with higher emulsion over mesh (EOM) is better than the emulsion with lower EOM since it can achieve lower sheet resistance. After optimizing the screen printing process, we were able to print 100 μm (4 mils) trace width and spacing with high consistency.

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