Carbon Resistors Research Articles

Highly Sensitive Detection of DNA Fragments by an Inexpensive and Simple Method Fabricated In-House Blue LED Transilluminator

Agarose gel electrophoresis is a routinely employed experimental technique for visualizing nucleic acids, typically combined with ethidium bromide or some other molecular dye staining and a UV transilluminator. However, the utilization of a UV transilluminator is restricted due to high cost and safety considerations. In this study, an inexpensive and simple in-house blue Light Emitting Diode (LED) transilluminator was developed using a high-brightness blue LED, carbon resistor, and smartphone charging cable. Its sensitivity for DNA detection was compared with conventional methods. A detection limit of 4 ng/band was confirmed by observing a 100 bp DNA fragment, which is comparable to ethidium bromide staining and UV transilluminator. Additionally, the in-house blue LED transilluminator can be attached to existing electrophoresis chambers, allowing real-time observation of electrophoresis and offering a superior alternative to conventional methods. In conclusion, the developed in-house blue LED transilluminator demonstrates high sensitivity in detecting DNA fragments and holds potential for advancing low-cost research facilities.

Development and Optimization of 3D-Printed Flexible Electronic Coatings: A New Generation of Smart Heating Fabrics for Automobile Applications.

Textile-based Joule heaters in combination with multifunctional materials, fabrication tactics, and optimized designs have changed the paradigm of futuristic intelligent clothing systems, particularly in the automobile field. In the design of heating systems integrated into a car seat, conductive coatings via 3D printing are expected to have further benefits over conventional rigid electrical elements such as a tailored shape and increased comfort, feasibility, stretchability, and compactness. In this regard, we report on a novel heating technique for car seat fabrics based on the use of smart conductive coatings. For easier processes and integration, an extrusion 3D printer is employed to achieve multilayered thin films coated on the surface of the fabric substrate. The developed heater device consists of two principal copper electrodes (so-called power buses) and three identical heating resistors made of carbon composites. Connections between the copper power bus and the carbon resistors are made by means of sub-divide the electrodes, which is critical for electrical-thermal coupling. Finite element models (FEM) are developed to predict the heating behavior of the tested substrates under different designs. It is pointed out that the most optimized design solves important drawbacks of the initial design in terms of temperature regularity and overheating. Full characterizations of the electrical and thermal properties, together with morphological analyses via SEM images, are conducted on different coated samples, making it possible to identify the relevant physical parameters of the materials as well as confirm the printing quality. It is discovered through a combination of FEM and experimental evaluations that the printed coating patterns have a crucial impact on the energy conversion and heating performance. Our first prototype, thanks to many design optimizations, entirely meets the specifications required by the automobile industry. Accordingly, multifunctional materials together with printing technology could offer an efficient heating method for the smart textile industry with significantly improved comfort for both the designer and user.

Re-calibration of an automatic evaporimeter

A set of pre-programmed sensors and transducers, including 0.71 EAP, carbon resistor, semi-carbon conductor, IN4007, and lighting diode-4v, 60 mm amp, were used to develop and build an automatic evaporimeter for automating/self-recording evaporation rate. 10 ILP values, 8 FLP values, 150.4 and 12.3 refractive values, respectively, were used to design the evaporimeter's operating principle. The results of equipment calibration utilizing various statistical validations of voltage, calibration index, and refractive index values demonstrate high agreement with R2 values of 0.999, 0.869, and 16.4 correspondingly. Every level (0.1 cm) of the instrument's time response to a step change in the water level caused by evaporation in the pan was calibrated. The voltage (v) was 225.6v, the highest evaporation value was 0.3 cm, and the refractive index was 15.0. With R2 = 0.9718 and 0.9635, statistical validation shows that there was a significant correlation between the initial evaporation reading (IER) and the final evaporation reading (FER).

High resolution diagnostic tools for superconducting radio frequency cavities.

Superconducting radio-frequency (SRF) cavities are one of the fundamental building blocks of modern particle accelerators. To achieve the highest quality factors (1010-1011), SRF cavities are operated at liquid helium temperatures. Magnetic flux trapped on the surface of SRF cavities during cool-down below the critical temperature is one of the leading sources of residual RF losses. Instruments capable of detecting the distribution of trapped flux on the cavity surface are in high demand in order to better understand its relation to the cavity material, surface treatments and environmental conditions. We have designed, developed, and commissioned two high-resolution diagnostic tools to measure the distribution of trapped flux at the surface of SRF cavities. One is a magnetic field scanning system, which uses cryogenic Hall probes and anisotropic magnetoresistance sensors that fit the contour of a 1.3GHz cavity. This setup has a spatial resolution of ∼13μm in the azimuthal direction and ∼1 cm along the cavity contour. The second setup is a stationary, combined magnetic and temperature mapping system, which uses anisotropic magnetoresistance sensors and carbon resistor temperature sensors, covering the surface of a 3GHz SRF cavity. This system has a spatial resolution of 5mm close to the iris and 11mm at the equator. Initial results show a non-uniform distribution of trapped flux on the cavities' surfaces, dependent on the magnitude of the applied magnetic field during field-cooling below the critical temperature.

Densification of Ceramic Matrix Composite Preforms by Si2N2O Formed by Reaction of Si with SiO2 under High Nitrogen Pressure. Part 1: Materials Synthesis

Ceramic matrix composites (CMCs) have been designed and developed for extreme operating environments. The aim of the present study is to look for a rapid densification process providing a high level of material performance. The fibrous preform was made of Hi-Nicalon S fibers woven in a 3D interlock weave. The matrix was composed of Si2N2O prepared inside the CMCs by reacting a mixture of Si and SiO2 under high nitrogen pressure (1 to 3 MPa). Silica was either impregnated by slurry or obtained by oxidation of silicon grains inside the preform. The synthesis reaction was initiated by heating the impregnated preform by means of a carbon resistor submitted to Joule effect. Composition, homogeneity and porosity of the formed matrix were studied and interpreted as a function of the experimental parameters (nitrogen pressure, heating rate of the preform) as well as the recorded thermal history of the process. The present results show that the matrix formation is almost completed in less than one minute. Melting of silicon has a major influence on the process. Competition was observed between the formation of Si3N4 and Si2N2O, which could be mainly controlled by the heating rate of the preform and the nitrogen partial pressure.

Idejni projekat generatora analognog diskretnog uniformnog šuma

The paper presents the basic idea of the construction and a practical realization of a novel analog discrete uniform noise generator. The source of noise is a carbon resistor, the noise signal is linearly amplified and its value is limited in the finite small range [xg, xg]. The probability density function (PDF) of the carbon resistor thermal noise in that region is square one. By narrowing the symmetric allowable gap (interval) around zero, PDF of the noise approaches a uniform distribution. The factor of deviation from the uniform distribution is precisely defined and its value is practically negligible. In addition, the paper discusses the application of the proposed dither noise, both in the two-bit and in the multi-bit stochastic digital measurement method (SDMM). It is shown that noise is more suitable for application in multi-bit SDMM, because it is less sensitive to deviations from the uniform distribution.

KVL and KCL verification by cotton conductive yarn resistor instead of carbon resistor fixation with Ag nanoparticles for sustainable e-textiles application

This paper parades the effectiveness of conductive yarn resistor instead of carbon resistor by verifying the Kirchhoff’s voltage (KVL) & current (KCL) law. This research work enlightens about the sustainability of e-textiles on account of presenting characteristics of this conductive yarn resistor. Resistor is one of the most useful materials in the electrical laboratories. Generally resistor is made by carbon. Using carbon resistor is pernicious for our environment, society & cost. It is known that sustainability is the concerned area at present. Sustainable e-textile is one of the major need in material science .This quest indicates that point to boggle sustainable e-textile by inventing conductive yarn resistor verifying with most orthodox theory of Kirchhoff’s voltage & current laws. KVL and KCL are the most prominent theory in electrical science. Summation of KVL and KCL will be zero in any closed loop in this theory. The summation of KVL is also zero here and summation of KCL is also zero here. It can justify Kirchoff’s KVL & KCL theory.

Understanding the Electrical Behavior of Pyrolyzed Three‐Dimensional‐Printed Microdevices

Herein the electrical and microstructural characterization of additively manufactured glassy carbon fabricated via two‐photon polymerization (2PP) is reported. Thermal decomposition at elevated temperatures volatizes much of the 2PP fabricated part, converting the crosslinked photopolymer into a carbon‐rich structure. Upon heating to continued elevated temperatures the carbon material becomes increasingly conductive. The ability to control the conductivity of the pyrolyzed material is done by varying the pyrolysis temperature, with maximum conductivity obtained of roughly 2 × 104 S m−1. Microstructural characterization with Raman spectroscopy and transmission electron microscopy (TEM) confirms that the increase in conductivity comes from the increased sp2 bonding percentage in carbon and increased crystallinity. This knowledge allows for the manufacturing of predictable, well‐controlled glassy carbon resistors that are within 10% of theoretical values.

Printed resistors for flexible electronics—thermal variance mitigation and tolerance improvement via oxide-metal coatings

Manufactured resistors in conventional electronics are classified into tolerance groups ranging from <1% for high stability film types (E192) to 20% (E6) which are often carbon-based and utilised in less critical resistance value contexts such as current limiting or pull-up/down applications [IEC 60063:2015, Preferred number series for resistors and capacitors. One of the major identified challenges in the printed electronics industry currently is the ability to match this manufacturing capability for printed resistors in terms of initial tolerance, stability over time and power capabilities. In this work, a variety of screen-printed carbon resistors were designed and produced. The effects of utilising additional screen-printed ZnO and Ag layers as thermal variance management for the carbon resistors are investigated with the aim of improving the resistors power rating and stability. The introduction of ZnO or ZnO/Ag layers to carbon resistors saw notable improvements in the peak power capability, stability when sustaining 500 mW power dissipation, and stability in varying environmental conditions. Utilizing ZnO and Ag layers also notably improved the initial tolerance groupings when compared to basic uncoated carbon resistors.

Low-Power Organic Light Sensor Array Based on Active-Matrix Common-Gate Transimpedance Amplifier on Foil for Imaging Applications

This article presents a 57.6- $\mu \text{W}$ mechanically flexible active-matrix imaging system based on a $4\times 5$ array of light sensors, each composed of a photodetector (PD) using a light-sensitive organic polymer and a transimpedance amplifier (TIA) based on organic thin-film transistors and integrated thin-film carbon resistors. The PDs and the electronics are fabricated on separate plastic films and integrated into a system. Two different topologies for the TIA are designed, implemented, and characterized. The first topology is a self-biased TIA based on a gain-boosted operational amplifier (op-amp), providing an open-loop dc gain of 41.3 dB. This op-amp-based TIA, with a feedback resistor, provides stable current-to-voltage conversion (0–100 $\mu \text{A}$ and 2.0–3.7 V) at frequencies up to 300 Hz. The second topology is a low-power gain-boosted common-gate (GB CG) TIA that performs current-to-voltage conversion with a nonlinearity as small as ±0.3% within a bandwidth of 1 kHz. The output voltages of the light sensors are read and converted into a $4\times 5$ pixel gray-scale image displayed on a computer monitor to visualize the functionality of the system.

A high sensitivity micro-pressure sensor based on 3D printing and screen-printing technologies

A 3D-printed micro-pressure sensor with high sensitivity is developed in this paper. It is a fully printed pressure sensor fabricated using a combination of digital light processing (DLP)-based printing and screen-printing technologies, with the advantages of high manufacturing efficiency and low cost. The pressure sensor consists of a sensor substrate with a circular diaphragm and a Wheatstone bridge on the surface. First, the pressure sensor was theoretically analyzed and then verified using the finite element method (FEM). During fabrication, the sensor substrate was made from a transparent high-temperature resin, which was printed by a DLP-based 3D printer. The resistors and leads of the Wheatstone bridge were made from carbon paste and silver paste, respectively, and printed by screen-printing technology. Then, the resistors were characterized to find the gauge factor and the print consistency between different resistors. Next, the experimental setup was established for the characterization of the pressure sensor. Three loops of pressurization and depressurization from 0 kPa to 2.4 kPa were applied to the pressure sensor continuously, and the output voltage was recorded. The experimental results show that the gauge factor of the carbon resistor is 17.01 ± 1.85, the sensitivity of the sensor is 4.5522 mV/kPa/5 V, the linearity error is 2.077% FS, the hysteresis error is 6.327% FS and the repeatability error is 5.708% FS. Also, it is very convenient to obtain pressure sensors with different sensitivities and measurement ranges by changing the thickness of the circular diaphragm. All these results prove that the proposed sensor provides a low cost and high sensitivity approach for micro-pressure measurement, and that 3D printing can be applied to the production of personalized sensors.

New Bridge Temperature Sensor for Superconducting Magnets and Other Cryogenic Applications

A few hundred temperature sensors are used to monitor the temperature behavior of the gigantic ATLAS toroid superconducting magnet system during cool down and normal operation. In order to guarantee good sensitivity of temperature measurements in the range from liquid helium to room temperature, two types of sensors are positioned at the same location: platinum resistance thermometers for the range 30–300 K and carbon composition resistors (Allen-Bradley) for the 4–30 K range. Both types are very well known for use in cryogenics and they have performed satisfactorily during 10 year of ATLAS operation. The sensors themselves are easily available and inexpensive and the main cost is for the many kilometers of cold and warm instrumentation cables, connectors, conditioners, and installation work. A reduction of the amount of measurement channels is an important issue and this motivated us to develop a new compact and robust sensor module covering the entire temperature range that would combine advantages of both platinum and carbon resistors. The solution is trivial, elegant, and simple. Two resistors with positive temperature derivative and two resistors with negative temperature derivative are connected in a full-bridge connection. We used two platinum and two carbon resistors. The output signal is a result of the subtraction of voltages across positive and negative temperature derivative resistors that makes this temperature bridge sensor very sensitive for the entire temperature range. Variable temperature characterization tests were performed in the helium gas environment in the CERN Cryogenic Laboratory. Our measurements have demonstrated that the bridge sensors have a full range sensitivity better than 0.1 mV/K at a supply current of 100 μ A. In the meantime, a few other superconducting detector magnets in experiments operating at CERN are equipped with these new, simple, and robust temperature sensors.

Evolution of the frequency-dependent polarization-angle phase-shift in the microwave radiation-induced magnetoresistance oscillations

We report the evolution of the phase shift, θ0, extracted from traces of the diagonal resistance, Rxx, vs. the linear polarization angle, θ, at oscillatory extrema of the microwave radiation induced magnetoresistance oscillations over the 36 ≤ f ≤ 40 GHz band in GaAs/AlGaAs system. A reference phase shift for the linear polarization angle in the vicinity of the specimen is obtained with the help of a sensitive carbon resistor. We fit an empirical cosine square law to the sinusoidal responses of Rxx vs. θ to extract the phase shift θ0. The quasi-continuous variation θ0 vs. f trace suggests a preferable polarization orientation for the specimen, and the f− and B− independence of overall average of θ0.

Design of Fully-Printed Organic Circuits on Plastic Foils for Wireless Systems

This work is dedicated to the design of fully-printed organic circuits on plastic foils. Passive ring mixers, diode-based active envelope detectors and a flash analog to digital converter are presented. The circuits based on N-type and P-type transistors are manufactured using an organic sheet-to-sheet process in ambient air. The fully-printed active envelope detector based on nine transistors and a capacitance shows better performance than the one described in the literature. The detector is able to perform with different waveforms of AM-modulated signals under a +/−20 V supply voltage for a 40 kHz carrier frequency. It still performs correctly for a modulation depth of 10%. The passive ring mixers only use four transistors and are able to mix a 5 Hz modulating wave with carrier frequencies from 100 Hz until 2 kHz. The analog to digital converter is designed with 45 transistors and four screen-printed carbon resistors for a total surface of 760 mm2. The circuit converts a 20 Hz analog input signal into a digital 2-bit output code under a +/−20 V supply voltage. All presented circuits are simulated before the realization and their measurement is performed in ambient air.

Measure of 1/f noise using the sound card of a PC

An experimental setup is described to measure 1/f noise (pink noise) in conductors using a PC equipped with a sound card functioning as a spectrum analyzer. A simple auxiliary analog electronic circuit with three operational amplifiers has been assembled to yield the required amplification, to match the sound card signal levels, and to implement a bridge configuration to improve dynamical range. Test experiments and data analysis have been conducted using commonly available software, together with some custom scripts and C code. The whole setup is technically accessible and economical for both the high school and undergraduate levels. Results are reported for pink noise of vintage carbon resistors spanning seven frequency decades, from 1 mHz to 10 kHz.

태양전지 실리콘 결정 성장용 120kW 3kA PWM 컨버터 시스템 개발

This paper is research result for a development of solar cell silicon ingot glowing(SCSIG) PWM converter system for 120[kW] 3[kA]. The system include 3-phase AC-DC rectifier diode converter of input voltage AC 460[V] and 60[Hz], DC-AC single phase full bridge PWM inverter of high frequency, AC-DC single-phase full wave rectifier using center-tapped of transformer for low voltage 50[V] and large current 3,000[A], carbon resistor load 0.2[mΩ]. PWM switching frequency for IGBT inverter control set 15KHz. The suggested researching contents are designed data sheets of power converter system, PSIM simulation, operating characteristics and analysis results of developed SCSIG system.

Discrete liquid-helium level-meter sensors based on TVO carbon resistors

It is shown that for discrete liquid-helium level-meter sensors, based on TVO resistors with a rated power of 0.125 W and rated resistance value of 1 kΩ, one can attain a helium-level measurement error of ±0.5 mm for the horizontal TVO resistor disposition and ±2 mm for the vertical one.

Programmable System-on-Chip (PSoC) Embedded Readout Designs for Liquid Helium Level Sensors

This article reports the development of programmable system-on-chip (PSoC)-based embedded readout designs for liquid helium level sensors using resistive liquid vapor discriminators. The system has been built for the measurement of liquid helium level in a concave-bottomed, helmet-shaped, fiber-reinforced plastic cryostat for magnetoencephalography. This design incorporates three carbon resistors as cost-effective sensors, which are mounted at desired heights inside the cryostat and were used to infer the liquid helium level by measuring their temperature-dependent resistance. Localized electrical heating of the carbon resistors was used to discriminate whether the resistor is immersed in liquid helium or its vapor by exploiting the difference in the heat transfer rates in the two environments. This report describes a single PSoC chip for the design and development of a constant current source to drive the three carbon resistors, a multiplexer to route the sensor outputs to the analog-to-digital converter (ADC), a buffer to avoid loading of the sensors, an ADC for digitizing the data, and a display using liquid crystal display cum light-emitting diode modules. The level sensor readout designed with a single PSoC chip enables cost-effective and reliable measurement system design.

Thermal Characterization of the Overload Carbon Resistors

In many applications, the electronic component is not continuously but only intermittently overloaded (e.g., inrush current, short circuit, or discharging interference). With this paper, we provide insight into carbon resistors that have to hold out a rarely occurring transient overload. Using simple electrical circuit, the resistor is overheating with higher current than declared, and dissipation is observed by a thermal camera.

A New Type of Carbon Resistance Thermometer with Excellent Thermal Contact at Millikelvin Temperatures

Using a new brand of commercially available carbon resistor we built a cryogenic thermometer with an extremely good thermal contact to its thermal environment. Because of its superior thermal contact the thermometer is insensitive to low levels of spurious radio frequency heating. We calibrated our thermometer down to 5 mK using a quartz tuning fork He-3 viscometer and measured its thermal resistance and thermal response time.