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Deyang Ji, Tao Li, Wenping Hu, Harald Fuchs
Polymeric dielectrics play a key role in the realization of flexible organic electronics, especially for the fabrication of scalable device arrays and integrated circuits. Among a wide variety of polymeric dielectric materials, aromatic polyimides (PIs) are flexible, lightweight, and strongly resistant to high-temperature processing and corrosive etchants and, therefore, have become promising candidates as gate dielectrics with good feasibility in manufacturing organic electronic devices. More significantly, the characteristics of PIs can be conveniently modulated by the design of their chemical structures...
February 14, 2019: Advanced Materials
Haiyan Duan, Pengbo Lyu, Jingjing Liu, Yanli Zhao, Yuxi Xu
The efficient synthesis of crystalline two-dimensional polymers (2DPs) with designed structures and properties is highly desired but remains a considerable challenge. Herein we report the synthesis of two-dimensional polyimide (2DPI) nanosheets via hydrogen bond induced preorganization and subsequent imidization reaction. The formed intermolecular hydrogen bonds can significantly benefit the internal order and in-plane periodicity of 2DPI. The crystalline few-layer 2DPI nanosheets are micrometer-size, solvent dispersible, and thermally stable...
February 12, 2019: ACS Nano
Fereshteh Chekin, Vladyslav Myshin, Ran Ye, Sorin Melinte, Santosh K Singh, Sreekumar Kurungot, Rabah Boukherroub, Sabine Szunerits
Doxorubicin (DOX), an anthracycline molecule, is currently one of the most widely used anticancer drugs in clinics. Systematic treatment of patients with DOX is known to be accompanied by several unpleasant side effects due to the toxicity of the drug. Thus, monitoring of DOX concentration in serum samples has become increasingly important to avoid side effects and ensure therapeutic efficiency. In this study, we discuss the construction of a disposable electrochemical sensor for the direct monitoring of DOX in clinical blood samples...
February 9, 2019: Analytical and Bioanalytical Chemistry
Hong Liu, Qi Wang, Wenjie Sheng, Xubo Wang, Kaidi Zhang, Lin Du, Jia Zhou
Recently, humidity sensors have been investigated extensively due to their broad applications in chip fabrication, health care, agriculture, amongst others. We propose a capacitive humidity sensor with a shielding electrode under the interdigitated electrode (SIDE) based on polyimide (PI). Thanks to the shielding electrode, this humidity sensor combines the high sensitivity of parallel plate capacitive sensors and the fast response of interdigitated electrode capacitive sensors. We use COMSOL Multiphysics to design and optimize the SIDE structure...
February 6, 2019: Sensors
Silvia Muceli, Wigand Poppendieck, Klaus-Peter Hoffmann, Strahinja Dosen, Julián Benito León, Filipe O Barroso, José Luis Pons, Dario Farina
OBJECTIVE: We propose, design and test a novel thin-film multichannel electrode that can be used for both recording from and stimulating a muscle in acute implants. APPROACH: The system is built on a substrate of polyimide and contains 12 recording and 3 stimulation sites made of platinum. The structure is 420 µm wide, 20 µm thick and embeds the recording and stimulation contacts on the two sides of the polyimide over an approximate length of 2 cm. We show representative applications in healthy individuals as well as tremor patients...
February 5, 2019: Journal of Neural Engineering
Zia Saadatnia, Shahriar Ghaffari Mosanenzadeh, Ebrahim Esmailzadeh, Hani E Naguib
This paper presents a novel aerogel-based Triboelectric Nanogenerator (TENG) which shows a superior performance for energy harvesting and sensing applications. Polyimide-based aerogel film with varying open-cell content level is developed to be used as the main contact material for the TENG. The fabricated aerogel film is fully characterized to reveal the chemical and mechanical properties of the developed material. It is shown the use of Polyimide aerogel film remarkably enhances the performance of the TENG compared to a TENG with fully dense Polyimide layer with no porosity...
February 4, 2019: Scientific Reports
Wei Zhou, Yikun Liu, Xiaoyan Liao, Zilin Chen
Nonaqueous capillary electrophoresis (CE) and organic-aqueous CE using high content of organic solvents are common techniques in capillary electrophoresis-mass spectrometry (CE-MS) due to various advantages. However, the long-term stability of commonly used polyimide coated fused silica capillary remains a major problem that polyimide coating is prone to swelling in organic solvents and aminolysis in alkaline buffer, which cause serious problems like irregular electrospray, current drop or clogging event. In this work, robust PEEK capillary was used as separation capillary for tolerance to high content of organic solvents in CE-MS system...
January 27, 2019: Journal of Chromatography. A
Ismail Laarossi, María Ángeles Quintela-Incera, José Miguel López-Higuera
An experimental study of a high temperature distributed optical fiber sensor based on Raman Optical-Time-Domain-Reflectometry (ROTDR) (up to 450 °C) and optical fibers with different coatings (polyimide/carbon, copper, aluminum and gold) is presented. Analysis of the distributed temperature sensor (DTS) measurements determined the most appropriate optical fiber to be used in high temperature industrial environment over long periods of time. To demonstrate the feasibility of this DTS for an industrial application, an optical cable was designed with the appropriate optical fiber and it was hermetically sealed to provide the required mechanical resistance and isolate the fiber from environmental degradations...
January 30, 2019: Sensors
Zhi Zhang, Er Liu, Wen Zhang, Ping Kwan Johnny Wong, Zhan Xu, Fang Hu, Xia Li, Jiaxuan Tang, Andrew T S Wee, Feng Xu
As a key effect in spintronic devices, exchange bias has attracted tremendous attention. Various approaches have been attempted for optimizing this effect, among which the application of strain in flexible exchange-biased systems is promising but little significant improvement has been reported. Here, we demonstrate encouraging progress in this field. With a pure mechanical compressive strain of -6.26‰ applied to the flexible polyimide (PI) substrate, distinct enhancement of ~900% in the bias field (from 20 Oe to 200 Oe) is achieved for the exchange-biased (FeCo/IrMn)3/Ta multilayers grown on top of a flexible polyimide substrate, accompanied by a notable decrease in the Gilbert damping parameter from 0...
January 30, 2019: ACS Applied Materials & Interfaces
Jung-Woo T Seo, Jian Zhu, Vinod K Sangwan, Ethan B Secor, Shay G Wallace, Mark C Hersam
Solution-processed two-dimensional materials offer a scalable route towards next-generation printed devices. In this report, we demonstrate fully inkjet-printed photodetectors using molybdenum disulfide (MoS2) nanosheets as the active material and graphene as the electrodes. Percolating films of semiconducting MoS2 with high electrical conductivity are achieved with an ethyl cellulose-based ink formulation. Two classes of photodetectors are fabricated, including thermally annealed devices on glass with fast photoresponse of 150 µs and photonically annealed devices on flexible polyimide with high photoresponsivity exceeding 50 mA/W...
January 29, 2019: ACS Applied Materials & Interfaces
Wu-Ji Sun, Yong-Yan Zhao, Jin Zhou, Xue-Feng Cheng, Jing-Hui He, Jian-Mei Lu
Recently, resistance random access memories (RRAMs) have been studied extensively arising from the increasing demand for information. However, its flexible device remains challenging because the active materials involved need to be nontoxic, non-polluting, distortion-tolerable, and bio-degradable as well adhesive to diverse flexible substrates. In this paper, we employed tannic acid (TA) and iron ion (Fe (III)) coordination complex as the active layer in sandwich-like (Al/active layer/substrate) device to achieve memory performance...
January 28, 2019: Chemistry: a European Journal
Tilo H Yang, C Robert Kao, Akitsu Shigetou
Organic-inorganic material hybridization at the solid-state level is indispensable for the integration of IoT applications, but still remains a challenging issue. Existing bonding strategies in the field of electronic packaging tend to employ vacuum or ultrahigh temperature; however, these can cause process complications and material deterioration. Here we report an easy-to-tune method to achieve hybrid bonding at the solid-state level and under the ambient atmosphere. Vacuum-ultraviolet (VUV)-induced reorganization with ethanol was used to develop hydroxyl-carrying alkyl chains through coordinatively-bonded carboxylate onto aluminum, whereas numerous hydroxyl-carrying alkyls were created on polyimide...
January 24, 2019: Scientific Reports
Dongyan Shao, Changhai Xu, Hongbo Wang, Jinmei Du
Polyimide (PI) fibers have outstanding thermal stability and mechanical properties, but are difficult to dye with disperse and basic dyes. In this work, it was proposed to use N-methylformanilide (MFA), phenoxyisopropanol (PIP), and acetophenone (AP) as swelling agents to enhance the dyeability of PI fibers. The PI fibers treated with swelling agents were characterized by thermal gravimetric analysis, scanning electronic microscopy, tensile testing, and crystalline analysis. It was found that the swelling agents penetrated into the PI fibers in amounts greater than 10% (pertaining to the weight of PI fibers)...
January 22, 2019: Materials
Dongliang Ding, Haitao Wang, Zhiqiang Wu, Yanhui Chen, Qiuyu Zhang
Easy and high efficient methods are in great demand to obtain polyimide (PI) composites with high thermal conductivity in the electronic packaging field. In this work, PI/boron nitride (BN) composites with high thermal conductivity are easily fabricated. Tightly connected and well-arranged BN platelets construct effective 3D thermally conductive networks in the PI matrix upon hot pressing, after BN platelets are coated on the surface of PI granules by the help of a kind of PI adhesive. The thermal conductivity of the PI/BN composites reaches as high as 4...
January 23, 2019: Macromolecular Rapid Communications
Hongyin Chen, Jinhan Mo, Ru Xiao, Enze Tian
Formaldehyde is one of the most common indoor air pollutants in Chinese residences. This study introduces a novel laminated plate with adjustable surface temperature to remove gaseous formaldehyde. The plate is fabricated with activated carbon, polyimide and copper foil via thermal compression. The plate can be regenerated in-situ by applying a direct current to the copper foil. Adsorption-regeneration cycle tests were conducted to evaluate the plate's formaldehyde removal performance. The overall removal efficiency of the fabricated laminated plate with glue mass fraction of 25% and thickness of 1...
January 22, 2019: Indoor Air
Yanyang Liu, Haijian Ou, Shangqing Li, Qingliang You, Huixian Liu, Guiying Liao, Dongsheng Wang
A novel polyimide-inlaid amine-rich porous organic block copolymer (PI-b-ARPOP) was prepared via one-step polymerization by using different molar ratios of melamine (MA)/terephthalaldehyde (TA)/pyromellitic dianhydride (PMDA), at molar ratios of 4/3/1, 4/2/2 and 4/1/3. The copolymer contained both aminal groups belonging to ARPOP and imide groups belonging to PI, and the bonding styles of the monomers and growth orientations of the polymeric chains were diversiform, forming an excellent porous structure. Notably, MA/TA/PMDA (4/2/2) had a surface area and pore volume of 487...
April 2019: Journal of Environmental Sciences (China)
Arijana Susa, Anton Mordvinkin, Kay Saalwächter, Sybrand van der Zwaag, Santiago J Garcia
We present a systematic study of the role of the aromatic dianhydride structure on the self-healing behavior of dimer diamine-based polyimides. By means of solid-state NMR and rheology, we studied the molecular and microscale dynamics of four polyimides comprising the same aliphatic branched diamine yet with variable dianhydride rigidities and correlated these to their macroscopic healing kinetics measured by tensile testing. Following the two-step kinetics of the healing process, we were able to differentiate and quantify the extent of mechanical strength recovery in each of the healing stages separately...
November 13, 2018: Macromolecules
Nicholas Teo, Sadhan C Jana
This work focuses on fabrication of polyimide aerogel microparticles of diameter 200-1000 µm from a surfactant-free, two-phase, silicone oil/dimethylformamide (DMF) oil-in-oil (O/O) system using a simple microfluidic device. The polyimide sol prepared in DMF is turned into droplets suspended in silicone oil in the microfluidic device. The droplets are guided to a heated silicone oil bath to accelerate sol-gel transition and imidization reactions, thereby yielding spherical, discrete gel microparticles that do not undergo coalescence...
January 16, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Matthew N Julian, David G MacDonnell, Mool C Gupta
Over the past several decades, the need for high-resolution, high-efficiency, lightweight, high-contrast focusing optics has continued to increase due to their applications in fields such as astronomy, spectroscopy, free-space optical communications, defense, and remote sensing. In recent years, photon sieve planar diffractive optics, which are essentially Fresnel zone plates with the rings broken into individual "pinhole" apertures, have been developed on flexible, lightweight polyimide substrates...
January 1, 2019: Applied Optics
Rajratan Basu, Lukas J Atwood
The planar-alignment agent in an electro-optic liquid crystal (LC) device plays an essential role for the LC's electro-optical characteristics. Rubbed polyimide (PI) layers are conventionally used as the planar-alignment agent in traditional liquid crystal displays (LCDs). Here we experimentally demonstrate that the 2D hexagonal boron nitride (h-BN) nanosheet can serve as the planar-alignment agent in an LC cell. This h-BN has higher chemical stability and more optical transparency than the PI layer. Two h-BN-covered indium tin oxide (ITO) glass slides (without any conventional PI layers) are placed together to fabricate an LC cell...
January 7, 2019: Optics Express
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