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A dc superconducting fault current limiting device can effectively limit the fast rising dc fault current and ensure the safety and reliability of the power grid. However, during the limiting period, the superconducting unit withstands the high voltage. Polymer film, kapton, and polytetrafluoroethylene (PTFE) have an excellent insulation performance at low temperature, which can solve the insulation problem. Quench and recovery is important characteristic, especially for the fault current limiting device. In this work, we measured the resistance development in YBCO tape with three insulation modes. In this work, a new insolating method for YBCO tape is investigated. We measured the resistance development in YBCO tape with three insulation modes. The experiment results show that the PTFE can be used, which can decrease the recovery time 30% ~ 50% than the naked one. As to the high-voltage superconducting fault current limiting device, the PTFE film can be put in the first layer, then twined the kapton film outside, which reduce recovery time about 20% ~ 40%.

The results of the performance tests of a three-layer foil separator for a high-current electron gun of an ELA excimer laser are presented. The separator consisted of two layers of thin titanium foil with a polyimide film between them. Such a composition withstood 5630 electron beam pulses with duration of 80 ns and an energy density per pulse of about 9 J/cm2. In this case, the polyimide film (Dupont Kapton polyimide film) with a thickness of 38 μm was irradiated with a dose of 1 GGy. The initial and induced absorption of this film was measured in the range from 20 to 0.4 μm. The mechanical tensile strength of the irradiated film decreased by 17 times.

Use of thin folded membranes for deployable structures are becoming increasingly popular especially in aerospace applications such as a deployable solar array, sun shields, and solar sails. The folding and compaction process of thin membranes, which introduces permanent, nonrecoverable, localized plastic deformation, changes the geometric shape and material properties. The underlying mechanics in the deployment of creased membrane structures are self-opening and then forced-opening beyond a stable stress-free state. The focus of the previous studies was limited to the characterisation of crease behaviour during force opening. This paper presents an experimental study to characterise the crease mechanics of a single creased membrane during self-opening behaviour which is crucial in the design of gossamer structures. A simple analytical study was performed to predict the moment-rotation response of the crease and hence shows a good qualitative agreement with physical experiment results. It is shown that the moment-rotation response of a single crease can be idealized to a linear rotational spring in virtual simulation and the spring stiffness depends on the thickness of the membrane.

Ultrathin BiOx and FeOx layers were obtained by Atomic Layer Deposition (ALD) on the surface of a flexible Kapton substrate (poly (4,4’-oxydiphenylene-pyromellitimide)) at a temperature of 250 °C. The layer thickness was 50 - 100 nm. Surface morphology, electrical polarization, and mechanical properties were investigated by Atomic Force Microscope, Piezoelectric Force Microscopy and Force Modulation Microscopy. Chemical analysis was performed by X-ray Photoelectron Spectroscopy, where the formation of Bi2O3 and Fe2O3 phases, as well as intermediate phases in the Bi-Fe-O system, was observed. With a small increase in the Bi content of the film, the BFO / Kapton structure becomes more crack resistant. Modification of the Kapton surface with bismuth and iron oxides showed that such a composition exhibits multiferroic behavior.

Experimental study of current-voltage (I-V) characteristics and frequency dependences of impedance in copper-Kapton-copper structures in the temperature range 240 – 300 K were carried out. Concentration and mobility of charge carriers thermally excited from traps with exponential distribution by energy in Kapton bulk and metal-Kapton interface and injected from copper electrodes into Kapton were estimated from the fitting of experimental I-V curves within the frame of the model of the space charge limited current (SCLC). Concentration and the width of energy of localized states, arising from the disorder of the Kapton structure, are additionally estimated from the I-V characteristics.

Free chlorine is commonly used for disinfecting water for various purposes including drinking water, recreational water etc. The free chlorine concentration should remain within a range of 0.5 -2 ppm for an effective disinfection specially for drinking water. Therefore, a low-cost sensor is required to measure free chlorine concentration at different position of the water distribution channels to ensure safe and healthy water for public. Here, we demonstrate a low cost, flexible and solid state chemiresistive sensor fabricated on a Kapton tape with Graphene like Carbon as the sensing film and xurographically patterned gold leaf as the contact electrode. The fabrication process is simple, quick and robust to manufacture reproducible electrodes. The chemiresistive sensor was able to measure free chlorine concentration from 0.05 -1.75 ppm.

Polyimide and PDMS are the most common materials used in the packaging of flexible electronics. Silicon dioxide being photolithographically patternable, can be used to selectively bond polyimide (PI) to PDMS to realize flexible microsystems integrating fluidic and electronic components. In this work, we characterize the plasma bond strength of polyimide (Kapton) to PDMS with thin-film SiO 2 as an intermediate bonding layer. Peel strengths of samples prepared with different types of deposition methods – sputtering, plasma-enhanced chemical vapor deposition (PECVD), and atomic layer deposition (ALD) were evaluated. The measured forces (normalized to the width of the bonded area), required to separate the PDMS and Kapton films, either due to adhesive or cohesive failures, were 174-860 N/m, 79-179 N/m, and 7-12 N/m for samples bonded with sputtered, PECVD and ALD oxide, respectively. The strength of the sputtered oxide bond is comparable to the strength of the best chemical adhesive method available.

Electromagnetic metamaterial-based sensors are promising for wide-range of applications due to their high quality factors and their simple structure designs. On the other hand, surface acoustic wave (SAW)-based actuators have been studied for their capabilities in manipulating microfluids. In this paper, we propose a single flexible structure that can act as a metamaterial-based sensor in microwave frequencies, as well as a SAW actuator in radio frequencies. This feature makes our proposed design suitable for an integrated platform for both sensing and acoustofluidic manipulation purposes.

In this work, a flexible printed potassium ion (K+) sensor with good sensitivity is developed. The sensor is a two-electrode structure potentiometric sensor. It is fabricated by printing the working and reference electrode on a flexible Kapton film, followed by drop casting of an ion-sensitive membrane (ISM) on the working electrode. For the ISM, ion exchangers are deliberately doped into ionophores to obtain a stable and reproducible response and reduce the effects of interfering ions. The sensor has achieved a sensitivity of 50.0mV/log[K+] with an accuracy of 0.19 log[K+] and resolution of 0.17 log[K+] over 10-5 to 1 M K+ concentration range. The interfering ions over the range present in saliva do not significantly affect the sensor’s measurement. The sensor can be used to detect the concentration of K+ accurately from the human saliva in order to achieve quick and non-invasive health diagnostics.

This work presents a soft capacitive pressure sensor fabricated by sandwiching a porous elastomeric dielectric layer between two electrodes on flexible polyimide (Kapton) substrate. The fabricated sensor was tested over a wide pressure sensing range (0-300 kPa), similar to pressures experienced up to approx. 30m below the sea level. In this range, the sensor presented a near-linear response (94.5%) and a sensitivity of 0.0007 kPa−1. The sensor also featured fast response and recovery times (0.8 s and 1.2 s, respectively), as well as good repeatability and stability - thus proving its applicability for a wide range of pressure sensing applications, particularly underwater robotics for real-time monitoring and surveillance operations.

Inductive wireless power transfer has been recognized as a feasible solution to expand the lifespan of wearable and implants. Apparently, these devices have to be mechanically flexible. In this paper, we propose a novel flexible inductive wireless power transfer system with an onboard temperature sensor. We use the flexible Kapton (polyimide) film and printed silver traces to create the circuit layout of the system. The fully flexible and bendable wireless power transfer system occupies an area of 1 cm × 4 cm. Experimental results indicate that the system can deliver 3.3 V DC voltage to the load at the operational frequency of 3.5 MHz when the receiving unit is at a distance of 4 mm. Furthermore, we demonstrate the capability of the proposed system to power up the embedded temperature sensor in two mediums, i.e., air and water. It was observed that the temperature sensor has a linear response in both mediums, which clearly confirms the reliability and stability of the scavenged power by our proposed system.

Measuring surface infrared radiation (IR), thermal infrared detectors can accurately measure surface temperatures with the advantage of non-contact detection. However, IR thermal measurements can only be applied in limited applications due to the limitation that only infrared transparent objects can be placed between the device under test (DUT) and thermal infrared detectors. In this paper, the thermal measurement impact from an IR transparent film has been investigated. The testing setup was built with an IR detector, IR transparent film, and thermocouple instrumented heating element as the device under test. Most of the DUT's metal surface has been prepared with black electric tape, white electric tape, and Kapton thermal tape. Thermocouples were attached to these surfaces as well as areas that were not covered with any material. Thermocouple readings were compared with the results from the IR detectors with and without the IR transparent film. Results show an increasing thermal impact to the measurements as temperatures rose when using the IR transparent film. A minor impact from the various applied surface films was also observed. Correlations between the actual and IR detector measured temperatures when using the IR transparent film were generated, enabling more accurate thermal measurements when using these materials in the future.

This paper presents an ultra-wideband graphene antenna with tapered coplanar-waveguide feed. The proposed antenna covers the 2.7-8.2 GHz bandwidth (2.6-10 GHz measured), with two main resonance frequencies at 3.1 and 5.5 gigahertz (3.1 and 5.8 measured). Simulations show a radiation pattern that looks quasi-omnidirectional with a maximum gain limited to 3.15 dBi and efficiency above 84.7%. In order to post-process the graphene ink and to provide flexibility, Kapton Polyimide is used as a substrate. The flexibility, as well as the lightweight and ease in the fabrication of accurate designs, turns this antenna into a suitable candidate for wearable and flexible wireless applications.

Digital microfluidics (DMF) devices enable precise manipulation of small liquid volumes in point-of-care testing. A printed circuit board (PCB) substrate is commonly utilized to build DMF devices. However, inkjet printing can be used to fabricate DMF circuits, providing a less expensive alternative to PCB-based DMF designs while enabling more rapid design iteration cycles. We demonstrate the cleanroom-free fabrication process of a low-cost inkjet-printed DMF circuit. We compare Kapton and polymethyl methacrylate (PMMA) as dielectric coatings by measuring the minimal droplet actuation voltage for a range of actuation frequencies. A minimum actuation voltage of 5.6 V was required for droplet movement with the PMMA layer thickness of 0.2 μm and a hydrophobic layer of 0.17 μm. Significant issues with PMMA dielectric breakdown were observed at actuation voltages above 10 V. In comparison, devices that utilized Kapton were found to be more robust, even at an actuation voltage up to 100 V.

The inkjet printing of metal electrodes on polymer films is a desirable manufacturing process due to its simplicity but is limited by the lack of thermal stability and serious delaminating flaws in various aqueous and organic solutions. Kapton, adopted worldwide due to its superior thermal durability, allows the high-temperature sintering of nanoparticle-based metal inks. By carefully selecting inks (Ag and Au) and Kapton substrates (Kapton HN films with a thickness of 135 μm and a thermal resistance of up to 400 °C) with optimal printing parameters and simplified post-treatments (sintering), outstanding film integrity, thermal stability, and antidelaminating features were obtained in both aqueous and organic solutions without any pretreatment strategy (surface modification). These films were applied in four novel devices: a solid-state ion-selective (IS) nitrate (NO3-) sensor, a single-stranded DNA (ssDNA)-based mercury (Hg2+) aptasensor, a low-cost protein printed circuit board (PCB) sensor, and a long-lasting organic thin-film transistor (OTFT). The IS NO3- sensor displayed a linear sensitivity range between 10-4.5 and 10-1 M (r2 = 0.9912), with a limit of detection of 2 ppm for NO3-. The Hg2+ sensor exhibited a linear correlation (r2 = 0.8806) between the change in the transfer resistance (RCT) and the increasing concentration of Hg2+. The protein PCB sensor provided a label-free method for protein detection. Finally, the OTFT demonstrated stable performance, with mobility values in the linear (μlin) and saturation (μsat) regimes of 0.0083 ± 0.0026 and 0.0237 ± 0.0079 cm2 V-1 S-1, respectively, and a threshold voltage (Vth) of -6.75 ± 3.89 V.

Naturally occurring radionuclide $^{210}$Pb ($T_{1/2}$=22.2 y) is an important source of background in rare event searches, such as neutrinoless double-$\beta$ decay and dark matter direct detection experiments. When a sample mass of hundreds of grams is available, $\gamma$-counting measurements can be performed. However, there are other cases where only grams of sample can be used. For these cases, better sensitivities are required. In this paper, in collaboration with the Astroparticle Physics group at Carleton University, the capabilities of the A.E. Lalonde AMS Laboratory at the University of Ottawa for $^{210}$Pb measurements are discussed. PbF$_{2}$ and PbO targets were used, selecting in the low energy sector, respectively, (PbF$_{3}$)$^{-}$ or (PbO$_{2}$)$^{-}$ ions. For fluoride targets, the blank $^{210}$Pb/$^{206}$Pb ratio was in the 10$^{-14}$ to 10$^{-13}$ range, but current output was lower and less stable. For oxide targets, current output showed better stability, despite a significant difference in current output for commercial PbO and processed samples, and background studies suggested a background not much higher than that of the fluoride targets. Both target materials showed, therefore, good performance for $^{210}$Pb AMS assay. Measurements of Kapton films, an ultra-thin polymer material, where masses available are typically just several grams, were performed. 90% C.L. upper limits for the $^{210}$Pb specific activity in the range of 0.74-2.8 Bq/kg were established for several Kapton HN films., Comment: 16 pages, 2 figures, 7 tables. We have noticed on a mistake in version 1: due to a typo in the spreadsheet used to analyze the data, where we forgot to use the charge state of 206Pb3+ to calculate the 210Pb/206Pb ratio, the uncorrected ratios are 3 times lower. Since this affects also the standards, the final corrected 210Pb/206Pb ratio are not very different from those presented in version 1

Polyvinyl Alcohol (PVA) is a promising polymer due to its high solubility with water, availability in low molecular weight, having short polymer chain, and cost-effectiveness in processing. Printed technology is gaining popularity to utilize processible solution materials at low/room temperature. This work demonstrates the synthesis of PVA solution for 2.5% w/w, 4.5% w/w, 6.5% w/w, 8.5% w/w and 10.5% w/w aqueous solution was formulated. Then the properties of the ink, such as viscosity, contact angle, surface tension, and printability by inkjet and aerosol jet printing, were investigated. The wettability of the ink was investigated on flexible (Kapton) and non-flexible (Silicon) substrates. Both were identified as suitable substrates for all concentrations of PVA. Additionally, we have shown aerosol jet printing (AJP) and inkjet printing (IJP) can produce multi-layer PVA structures. Finally, we have demonstrated the use of PVA as sacrificial material for micro-electro-mechanical-system (MEMS) device fabrication. The dielectric constant of printed PVA is 168 at 100 kHz, which shows an excellent candidate material for printed or traditional transistor fabrication.

In this paper we describe characterization of semi-metallic bismuth thin films. We prepared bismuth thin films by a deposition of bismuth through thermal evaporation onto flexible Kapton substrates and annealing at temperatures close to the melting point of Bi. We studied the morphology and transport properties of these films. Immediately after the deposition we observed competition between vanishing of the grain boundaries and elastic strain energy, which stabilized at larger thicknesses leading to the grain size of 140 nm. This effect was accompanied by a continuous decrease of resistivity which, however, was larger than for the bulk bismuth. The film annealing at temperatures close to the melting point of Bi led to a 300% increase of magnetoresistance at room temperature and in the magnetic field of 7 T. The in situ resistance measurements allowed us to determine the permissible temperature at which the annealing does not cause the loss of film continuity.

Mechanical swing is common in nature, such as sound waves, wingbeat of birds, and heartbeat, which is important to convert input energy into continuous motion. Here, we report a photodriven swing actuator composed of commercially available polyimide (Kapton) and azobenzene-containing liquid-crystalline polymers. The liquid-crystalline polymers act as the photoactive layer, which were synthesized by copolymerization of one benzenecarboxylic acid-containing monomer (M6BCOOH) and one azobenzene-containing monomer (M6ABOC2) with different molar ratios. The Kapton layer with a high elastic modulus is photoinert and functions as the substrate layer. After thermal annealing, the film displays chaotic swing under continuous irradiation of actinic light. Interestingly, the swing amplitude is greatly enhanced by the existence of supramolecular hydrogen bonding in liquid-crystalline polymer films. It is the introduction of M6BCOOH to the copolymer that accelerates the trans-cis photoisomerization rate of azobenzenes. Also, it forms a hydrogen bond as physical crosslinking sites, enabling the polymer film to work as a whole. Thus, it enhances the driving force for photomechanical deformation. Moreover, it improves the elastic modulus of the photoactive layer and modulates the swing behavior of the bilayer strip. More importantly, the formation of a hydrogen bond in the form of acidic dimers has a spatial confinement effect, extending the timescale of photodriven swing. The photomechanical self-vibration of the bilayer film can be ascribed to the combination of the photoisomerization process of azobenzenes with the local photosoftening effect of liquid-crystalline polymers.

Realization of high-performance optoelectronic and gaseous sensing with excellent mechanical flexibility may open up broad multifunctional applications, such as wearable smart sensor systems, robust environmental/infrastructure monitoring, and personal health monitoring with human-friendly interfaces. Here, we proposed a flexible MoS2/Kapton sensor with synergistic optical UV and humidity functionalities. Because of its ultrathin monolayer, the electrical transport of the 2D MoS2 channel tends to be affected by both the surface and interface states. The photogenerated charge transfer plays a synergistic role in both the UV and humidity sensing by utilizing band alignment engineering. On the one hand, the photoabsorbing Kapton substrate forms a photogating heterointerface with the 2D MoS2 monolayer to greatly strengthen the photogenerated charge transfer. Under 325 nm UV photoexcitation, the flexible MoS2/Kapton sensor has achieved a best photocurrent to dark current ratio of 3.87 × 105. On the other hand, the 2D MoS2 monolayer has a large surface area for the effective adsorption of water molecules. The UV photogenerated charge transfer is beneficial to boost up the relative humidity (RH) response range above 105 for humidity sensing. As a result, flexible MoS2/Kapton heterointerfaces enable high-performance multifunctional sensing for promising 2D/3D heterogeneous integration.

The triboelectric nanogenerator (TENG) is a widely used energy-harvesting unit for self-power applications. The electrical output performance of the TENG could be significantly improved by ion implantation and explore new triboelectric materials beyond the conventional triboelectric series. In this present work, the phase pure hydrothermally synthesized ZnO particles, argon ion-implanted Kapton acted as a positive triboelectric layer while pure Kapton behaved as a negative triboelectric layer. The atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM) were performed to investigate the surface roughness and surface potential of the triboelectric materials utilized in vertical contact mode TENG (I-TENG, abbreviated further). The elemental mapping and X-ray photoelectron spectroscopy (XPS) results suggested successful Argon-ion implantation upon Kapton. Finally, the I-TENG device was subjected to various forces to systematically depict its electrical output responses and power up a wrist-watch and calculator.

Elastomers and, in particular, polydimethylsiloxane (PDMS) are widely adopted as biocompatible mechanically compliant substrates for soft and flexible micro-nanosystems in medicine, biology, and engineering. However, several applications require such low thicknesses (e.g.

We measure Kapton, FeBO3 and sapphire in the terahertz region with a time-domain spectrometer and fit the measurement with Lorentz and Debye oscillators as well as scattering to extract the refractive index and absorption under 5 THz.

We present the first comparison of optoelectronic frequency- and time-domain terahertz (THz) systems for thickness measurements on sub-mm single- and multilayer samples using identical setups, samples and evaluation procedures in order to obtain comparable results. We find that single layer PET and Kapton foils with a thickness of 23 μm – 350 μm can be measured with similar accuracy with both systems. Hence, frequency-domain THz systems may replace time-domain systems in future industrial layer thickness measurements.

Energy harvesting systems for low-power devices are increasingly being a requirement within the context of the Internet of Things and, in particular, for self-powered sensors in remote or inaccessible locations. Triboelectric nanogenerators are a suitable approach for harvesting environmental mechanical energy otherwise wasted in nature. This work reports on the evaluation of the output power of different polymer and polymer composites, by using the triboelectric contact-separation systems (10 N of force followed by 5 cm of separation per cycle). Different materials were used as positive (Mica, polyamide (PA66) and styrene/ethylene-butadiene/styrene (SEBS)) and negative (polyvinylidene fluoride (PVDF), polyurethane (PU), polypropylene (PP) and Kapton) charge materials. The obtained output power ranges from 0.2 to 5.9 mW, depending on the pair of materials, for an active area of 46.4 cm2. The highest response was obtained for Mica with PVDF composites with 30 wt.% of barium titanate (BT) and PA66 with PU pairs. A simple application has been developed based on vertical contact-separation mode, able to power up light emission diodes (LEDs) with around 30 cycles to charge a capacitor. Further, the capacitor can be charged in one triboelectric cycle if an area of 0.14 m2 is used., This research was funded by Fundação para a Ciência e Tecnologia under framework of the Strategic Funding UID/FIS/04650/2020 and projects UIDB/05549/2020 and TSSiPRO-NORTE-01-0145-FEDER-000015. The authors also thank the F.C.T. for financial support under grants SFRH/BD/140242/2018 (T.R.M.), SFRH/BPD/98109/2013 (P.C.). Finally, the authors acknowledge funding by Spanish State Research Agency (A.E.I.) and the European Regional Development Fund (ERFD) through the project PID2019-106099RB-C43/AEI/10.13039/501100011033 and from the Basque Government Industry and Education Department under the ELKARTEK, HAZITEK and PIBA (PIBA-2018-06) programs, respectively, are also acknowledged.

The ATLAS Phase-II Upgrade will replace the Inner detector with a new all-silicon Inner Tracker (ITk) to accommodate the radiation damage and track density expected at the High-Luminosity LHC (HL-LHC). The all-silicon ITk for the HL-LHC consists of a pixel detector with 5 barrel layers and multiple forward disks at a small radius, and a strip tracking detector at the outermost part with 4 barrel layers and 6-end-cap disks on each side. This contribution presents the design of the flexible circuit (bus tape) for the local support structures of the end-cap region of the strip detector, called petals. The bus tapes provide the electrical interface to common services for all the on-board subsystems including power, control and data interfaces. Connections to external services outside of the petals are carried out through the End-of-Structure (EoS) card using optical fibres and copper wires. The bus tapes are manufactured as a 2-layer printed circuit board using polyimide and adhesive Kapton films, with a total thickness of 185 $\mu$m and a total length of 60 cm. The layout design has been focused on achieving good signal and power integrity while keeping low mass and low thermal resistance. A total of 768 end-cap bus tapes will be produced between 2021 and 2022 for the assembly of 384 petals with 6,912 modules, where each end-cap disk will consist of 32 petals.

In this article, we present an eye-tracking system for distance ranging, developed for varifocal contact lens applications. The system comprises of a set of four ~150 µm-thick, semi-circular coils, which are patterned on flexible Kapton substrates and can easily conform to the sclera. The object-distance from the eyeballs is determined via triangulation of the eye gaze angles, which is calculated from the induced electromagnetic voltage between the coils. Preliminary experiments with the coil-system, placed on eyeball simulated polymeric spheres resulted in accurate prediction of object distance in the range of 0.1-15 D (Diopter) with an RMS error of 0.1 D and object direction in the range of -15 to 15-degree arc with 0.4 degree RMS error, respectively. Diopter is the reciprocal of the object distance (in meters). The energy required to perform a single range reading was ~ 20 µJ.

A layer of Kapton polyimide with the dielectric constant of 3.5 as substrate and indium tin oxide (ITO) as conductor (10 × 10 × 0. 375 mm3) are used to construct a miniaturized flexible transparent ultrawideband (UWB) antenna. The antenna’s performances are investigated and evaluated using an ITO transparent conductor in both frequency and time domain. The proposed antenna achieves the wide bandwidth (BW) of 3.26-23.37 GHz, more than 65 % radiation efficiency for most of the working BW, and maximum radiation efficiency of 90 percent at 15 GHz. Besides, it depicts a stable radiation pattern at most of the operating band and a maximum gain of 3.87 dBi. The good agreement between the simulation and measurement results, time-domain considerations, and the reconstructed image of the tumor makes the antenna capable of working in many applications, especially for breast and skin cancer detection.

A combination of resistive type superconducting fault current limiters (R-SFCLs) and mechanical-type DC circuit breaker is a reliable way to protect the medium voltage and high voltage DC systems. Using the insulation barrier plays an important role in enhancing the insulation strength of R-SFCL. It promotes the development of R-SFCLs to a higher voltage level. However, the bubbles effect on the DC flashover characteristics of the insulation barrier is unknown. The objective of this paper is to obtain the DC flashover characteristics of insulation film with and without bubbles in liquid nitrogen (LN2). In the experiments, a triangle-plane electrode was put horizontal and immersed in LN2. A 14 W heater was placed right below the gap of two electrodes. Negative flashover characteristics of PTFE and Kapton were studied with different gap distances. The results show that the negative flashover voltage of PTFE film increases with the increase of gap distance both in conditions with and without bubbles. The shorter the gap distance between the triangle and plane electrodes is, the stronger the influence of bubbles on the negative flashover voltage is. The flashover voltage of PTFE is 1.15 times of Kapton both in the conditions with and without bubbles. The results could be used to design the insulation structure of high voltage R-SFCLs.

In this study, a conformal loop antenna at 400 MHz frequency was designed and implemented for capsule endoscopy applications. The performance of the designed antenna has been further tested for the digestive system organs through which the capsule will move. In order to realize the designed antenna, the capsule is pressed with a three-dimensional printer, and the loop antenna printed on the copper plate is wrapped conformally on the outer surface of the capsule with the kapton tape. The results obtained from the measurements carried out in the laboratory were consistent with the simulation results.

An in-situ technique is presented for measuring the individual contact resistance between the pins of an IC package and a flexible substrate used in hybrid electronic systems. As the substrate flexes, the forces that adhere the IC to the substrate change and cause increase to the series contact resistance; sometimes catastrophically. Tracking this resistance is seen to be fundamental to the success of electronic systems mounted on a flexible substrate subjected to various levels of bending throughout its life cycle. The measurement technique exploits the electrostatic discharge protection circuitry in an IC chip to create a circuit loop involving the contact resistance and the series incremental resistance of the ESD circuit via two IC pins, one being the GND or VDD pin. While the series contact resistance between the pins of the IC package and the board can be measured with a four-point Kelvin measurement, it is extremely difficult to perform with small surface-mount IC package devices. The experimental results pertaining to Kapton polyimide substrate subjected to a controlled bending process will be described. The method proposed here will determine the contact resistance with a relative accuracy error of less than 1%.

Direct derivation (DD) is a novel Powder X-ray diffraction quantification method based on intensity–composition equation, which can determine the weight fraction of individual phases in a mixture of components by chemical formulas. The DD method was applied to determine crystallinity degree of binary mixtures containing amorphous hydroxypropyl methylcellulose and crystalline monohydrate α-lactose in weight percentage ≤ 15% w/w. Three different scenarios were considered: a) the unit cell parameters of the crystalline phases are available b) the unit cell parameters are unknown but the patterns of pure crystalline and amorphous references are available and c) only the mixtures’ patterns are available. Relative errors in scenarios a and b were comparable and reasonable (

This work presents the characterization of integrated inductors on a flexible substrate, fabricated through simple and original technology. Kapton was used as the flexible substrate with gold metallization and silicon dioxide as the dielectric. Several inductors were fabricated with a different number of turns, line widths, line spacing, internal diameters, and geometries to verify the influence of such different configurations on the inductor’s performance. It was possible to obtain inductors compatible with voltage-controlled oscillators design and other radio frequency and microwave circuits, enabling the advancement of heterogeneous integration.

A continuously-tunable terahertz (THz) bandpass filter based on the resonant electromagnetic-wave transmission through a metal-hole array featuring a gradually changing period was developed and fabricated on a silicon substrate using optical lithography. A gradient geometry of the metal-hole array yields a wide tunability of the filter transmission, when operating with a focussed THz beam. The filter was studied numerically, using the finite element method, and experimentally, using the THz pulsed spectroscopy. We find that the central wavelength of the filter transmission band can be tuned in the wide range of λc = 400–800 μm with the relative bandwidth of Δλ/λc ≃ ~0.4. Finally, Kapton-based anti-reflection coating was applied to the filter flat side, in order to suppress an interference pattern in the filter transmission spectrum. We believe that the developed filter holds strong potential for multispectral THz imaging and sensing due to its conceptual simplicity and case of operation. Moreover, the presented filter concept can be translated to other spectral ranges, where appropriate technologies are available for the fabrication of gradient sub-wavelength metal-hole arrays.

Here in this research, room temperature ethanol and humidity sensors were prepared based on two dimensional (2D) hybrid nanostructures of tungsten di-sulfide (WS2) nanosheets and graphene oxide nanoribbons (GONRs) as GOWS. The characterization results based on scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (ESD), Raman spectroscopy and X-ray diffraction (XRD) analysis confirmed the hybrid formations. Ethanol sensing of drop-casted GOWS films on SiO2 substrate indicated increasing in gas response up to 5 and 55 times higher compared to pristine GONRs and WS2 films respectively. The sensing performance of GOWS hybrid nanostructures was investigated in different concentrations of WS2, and the highest response was about 126.5 at 1 ppm of ethanol in 40% relative humidity (R.H.) for WS2/GONRs molar ratio of 10. Flexibility of GOWS was studied on Kapton substrate with bending radius of 1 cm, and the gas response decreased less than 10% after 30th bending cycles. The high response and flexibility of the sensors inspired that GOWS are promising materials for fabrication of wearable gas sensing devices.

A high-barrier polyimide (2,7-CPI) was synthesized through the polymerization of pyromellitic dianhydride (PMDA) and a novel diamine (2,7-CDA) containing carbazole moiety. The synthesized diamine and polyimide were fully characterized by elemental analyses, FTIR and NMR. The 2,7-CPI displays very attractive barrier performances, with oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) low to 0.14 cm3&middot, m&minus, 2&middot, day&minus, 1 and 0.05 g&middot, 1, respectively. Meanwhile, 2,7-CPI also exhibits exceptional thermal stability with a glass transition temperature (Tg) of 467 &deg, C, 5% weight-loss temperature (Td5%) of 550 &deg, C under N2 and coefficient of thermal expansion (CTE) of 3.4 ppm/K. The barrier performances of 2,7-CPI are compared with those of a structural analogue (2,7-CPPI) and a typical polyimide (Kapton). Their barrier performances with respect to microstructure were investigated by molecular simulations, wide angle X-ray diffraction (WAXD), and positron annihilation lifetime spectroscopy (PALS). The results show that 2,7-CPI possesses better coplanar structure and more number of intermolecular hydrogen bonds among the three PIs, which result in tight chain packing and thereby high crystallinity, low free volume, and decreased chains mobility. That is, the high crystallinity and low free volume of 2,7-CPI reduce the diffusion and solubility of gases. Meanwhile, the poor chains mobility further decreases the gases diffusion. The reduced diffusion and solubility of gases consequently promote the improvement of barrier properties for 2,7-CPI. The polyimide has a wide application prospect in the field of flexible electronic packaging industries.