Excellent Linear Characteristics Research Articles

Urine glucose concentration detection biosensor using one-dimensional photonic crystals with periodical and Fibonacci sequences based on Tamm plasmon resonance

This paper presents the design of biosensors utilizing one-dimensional photonic crystals with periodical and Fibonacci sequences for measuring glucose concentration in urine, aimed at facilitating continuous blood glucose monitoring for diabetic patients. Exploiting Tamm plasmon resonance within a photonic band gap in the medium wave infrared band, the biosensor comprises a configuration with a one-dimensional photonic crystal and an Ag layer deposited on an infrared prism, with a urine sample layer in between. Utilizing the transfer matrix method, the reflection spectra for electromagnetic waves are calculated. The wavelength position of the Tamm plasmon resonant dip is influenced by variations in glucose concentration within the urine sample. This is attributed to the distinct refractive indices exhibited by urine samples with different glucose concentrations. Optimizing biosensor performance under various incident angles involves adjusting the Ag layer and urine sample thicknesses while maintaining excellent linear characteristics. The optimal performance of the biosensor with Fibonacci sequence one-dimensional photonic crystal is significantly superior, with a sensitivity of 113,000 nm RIU−1, a figure of merit of 2.05 × 105 RIU−1, and a detection limit of 4.84 × 10−7 RIU. The combination of high performance and a straightforward structure makes the proposed biosensors for detecting urine glucose concentrations promising in biomedical diagnostics.

An axial flux eddy current sensor with perpendicular coils for speed measurement

This paper presents an axial flux eddy current sensor with a compact and simple structure for measuring the rotating speed of iron shafts. The sensor structure is optimized for high sensitivity with a novel configuration of the coils positioned perpendicularly to each other. The sensor comprises two D-shaped excitation coils and two D-shaped pick-up coils in a double-layer structure. A disc-shaped magnetic shield or core shields the coils. Two iron shafts with different material properties are considered. A new cup-shaped configuration of nonmagnetic copper and aluminum caps mounted on iron shafts improves sensitivity and suppresses susceptibility to shaft material properties and airgap variation. 2D and 3D finite element methods are utilized for the performance analysis of the sensor. The measurements are performed at speeds up to ± 3000 rpm and different excitation frequencies from 400 Hz to 4 kHz. The eddy current speed sensor has excellent linearity characteristics with a nonlinearity error of 0.15%. The geometry of the coils is further optimized and improved for maximum sensitivity and compactness. The fault-tolerant capability of the sensor is also evaluated.

All-Digital Integrated Variable-Frequency Variable-Duty-Cycle Modulator With Single-Element Resolution and Single-Cycle Convergence

This paper introduces a new architecture for an all-digital high-resolution variable-frequency variable-duty-cycle modulator for low-power and area-sensitive applications. Constructed through digital standard-cell delay-line and simple combinatorial logic, the modulator produces PWM signals with time-resolution of a single delay-element for both modulation parameters, thus making it a promising candidate for integration in hybrid controllers of high-frequency switched mode power supplies. Since the entire architecture is realized through standard cells, the solution also scales with fabrication technology and is described in HDL which translates onto hardware using automated process. The modulator has been designed on a 0.18μm 5V CMOS process, totaling 0.18mm2 of silicon area as well as on an Altera V FPGA to demonstrate the versatility of the architecture. Experimental results of the FPGA prototype are provided as well as post-layout simulations of the ASIC realization for a variety of mitigation sequences demonstrating single-cycle convergence and time-resolution of 220ps and 200ps, respectively with excellent linearity characteristics.

Determination of Doxycycline as Pure and in Pharmaceutical Preparation (Capsule) Using 4-Aminoantipyrine in Presence of Potassium Periodate

A simple spectrophotometric method for the determination of doxycycline in aqueous medium using oxidative coupling reaction has been described. The method was based on the reaction of doxycycline with 4-aminoantipyrene (4-AAP) which gives soluble and stable red colored product that gives the highest absorption at the wavelength 515 nm, and the linearity of Beer's law was in the concentration range from 5 to 110 µg/ml, and the value of the determination coefficient for the standard curve was 0.9995, which statistically indicates that it has excellent linear characteristics. The molar absorptivity was calculated and found to be 1.387x103 l.mol-1.cm-1. Sandell's sensitivity value, the Limit of detection (LOD), and ‎‏ limit of quantitation (LOQ) were calculated and equal to 0.3334 μg/cm2, 0.114 and 0.38 µg/ml respectively the method was successfully applied for the determination of doxycycline in its pharmaceutical preparation.

Design of a Compact Energy Storage with Rotary Series Elastic Actuator for Lumbar Support Exoskeleton

Lumbar support exoskeletons with active and passive actuators are currently the cutting-edge technology for preventing back injuries in workers while lifting heavy objects. However, many challenges still exist in both types of exoskeletons, including rigid actuators, risks of human–robot interaction, high battery consumption, bulky design, and limited assistance. In this paper, the design of a compact, lightweight energy storage device combined with a rotary series elastic actuator (ES-RSEA) is proposed for use in a lumbar support exoskeleton to increase the level of assistance and exploit the human bioenergy during the two stages of the lifting task. The energy storage device takes the responsibility to store and release passive mechanical energy while RSEA provides excellent compliance and prevents injury from the human body’s undesired movement. The experimental tests on the spiral spring show excellent linear characteristics (above 99%) with an actual spring stiffness of 9.96 Nm/rad. The results demonstrate that ES-RSEA can provide maximum torque assistance in the ascent phase with 66.6 Nm while generating nearly 21 Nm of spring torque during descent without turning on the DC motor. Ultimately, the proposed design can maximize the energy storage of human energy, exploit the biomechanics of lifting tasks, and reduce the burden on human effort to perform lifting tasks.

Highly sensitive open-channels based plasmonic biosensor in visible to near-infrared wavelength

Abstract In this paper, we numerically demonstrate a low-cost plasmonic refractive index sensor using two-sided open-channels that can operate in both visible and near-infrared region. Widely used finite element method (FEM) software is employed to characterize the sensing properties. A thin coating of gold layer is used inside the open channels of the photonic crystal fiber (PCF) to create the plasmons. It is reported that the highest wavelength sensitivity of 5000 nm/RIU with a sensor resolution of 2.0 × 10−5 RIU can be achieved at an analyte refractive of 1.38. Besides, it is also achievable to have the highest amplitude sensitivity of 396 RIU−1. The proposed sensor shows excellent linear characteristics with the highest figure of merit (FOM) of 47 RIU−1 between a refractive index of 1.33 and 1.39. Due to structural simplicity and improved sensitivity, the proposed plasmonic sensor is highly applicable in biological and biochemical analyte detections.

A single-pole nine-throw antenna switch using radio-frequency microelectromechanical systems technology for broadband multi-mode and multi-band front-ends

In this paper, a generic single-pole nine-throw (SP9T) switch is demonstrated using radio-frequency (RF) microelectromechanical systems (MEMS) technology for broadband multi-mode and multi-band front-ends. In order to improve uniformity and yield required for complex switches, ‘stress-free’ single-crystalline-silicon series dc-contact MEMS switches have been employed instead of metal membrane switches. When tested according to the third-generation partnership project (3GPP) specifications, the antenna switch in this work shows loss, isolation and linearity characteristics better than the conventional semiconductor switches. Measured results showed insertion losses for all nine paths less than 0.5 dB and 2 dB from dc to 2.17 GHz and 21.6 GHz, respectively. Isolations for all input–output and output–output ports are higher than 49 dB at 2.17 GHz. Nonlinearities generated by the MEMS switch were well below the measurement limit of our system setup. The broadband RF performance, together with excellent linearity characteristics, makes this type of MEMS switch a promising candidate for an antenna switch for multi-band and multi-mode front-end applications.

Power and Linearity Characteristics of Field-Plated Recessed-Gate AlGaN–GaN HEMTs

Record power density and high-efficiency operation with AlGaN-GaN high-electron mobility transistor (HEMT) devices have been achieved by adopting a field-plated gate-recessed structure. Devices grown on SiC substrate yielded very high power density (18.8 W/mm with 43% power-added efficiency (PAE) as well as high efficiency (74% with 6 W/mm) under single-tone continuous-wave testing at 4 GHz. Devices also showed excellent linearity characteristics when measured under two-tone continuous-wave signals at 4 GHz. When biased in deep-class AB (33 mA/mm, 3% I/sub max/) device maintained a carrier to third-order intermodulation ratio of 30 dBc up to a power level of 2.4 W/mm with 53% PAE; increasing bias current to 66 mA/mm (6% I/sub max/) allowed high linear operation (45 dBc) up to a power level of 1.4 W/mm with 38% PAE.

Electrical Properties of Woodceramics

Woodceramics have recently attracted much attention as ecomaterials at low cost. Electrical properties of the woodceramics (WCM hereafter) have been characterized in the range 10–70% relative humidity and for temperatures from −20 to 100°C. The WCM bulk has been prepared by burning MDF board impregnated with phenolic resin at 650 and 750°C. Electrical resistance decreased linearly with increasing temperature, indicating the negative temperature coefficient like semiconductor. Relative humidity dependence of the resistance also indicated excellent linear characteristics between 10 and 70% RH measured here. Activation energies of 0.21, 0.15, 0.05, and 0.01 eV have been revealed from van der Pauw method. The excellent linearity for humidity and temperature is prominent advantages of WCM which may be useful as a new humidity and also temperature sensor.

Development of a novel electrochemically active membrane and 'smart' material based vibration sensor/damper

Vibration control has been achieved using state-of-the-art 'smart' materials. A 'smart' material has been developed from a metallized ionomer membrane called Nafion. This electroded material can sense mechanical vibrations and generate a voltage response. Electroded Nafion has a unique vibrational damping property. Damping with this material is achieved by dissipating the electrical energy generated as heat. This can be done using an external resistance or optimally by creating an internal conductive path. A prototype accelerometer cell has been developed which shows excellent linear characteristics and high sensitivity. It is found that the most critical element in both of the applications is the sum of the internal and the contact resistances of the electroded Nafion hydrogen pressure cell. Accordingly, a study of the resistance of these Nafion-based cells has been made and the results are included and discussed.

One-bit A/D D/A converters IC for audio delay

A single-chip IC that provides all the functions for surround decoding of movies by using a novel digital delay system with excellent performance is described. A BiCMOS process with excellent linear characteristics was developed and applied to the new IC. It is noted that the development of this IC can help reduce the size of surround systems, while improving system performance. >

A New Class of FM Subcarrier Oscillators

This paper describes a new class of millivolt-controlled subcarrier oscillators developed especially for operation in the rugged environments of orbital programs. The oscillators cover all the standard IRIG channels. The full IRIG signal-frequency response is achieved at a modulation index equal to five. A less-than-unity-gain, long-tailed pair, silicon-transistor, dc amplifier and a greater-than-unity-gain RC network are combined to form a sine-wave oscillator. The center frequency is deviated ± 15 per cent by a ± 10 millivolt control signal. Excellent linearity characteristics are achieved. A unique feature of the circuit is the inherent deviation limiting. Inductors are avoided in the oscillator design. The passive RC network synthesis procedure is developed to realize 1) a voltage gain greater than unity, 2) the proper percentage of deviation with excellent linearity characteristics, and 3) inherent deviation limiting to contain the FM signal spectra within their assigned channels. The center frequency is deviated by controlling the relative gain of the long-tailed pair type of differential dc amplifier. A pure sine wave is generated without additional filtering. The balanced nature of the circuit yields excellent center frequency stability from 0°C to + 85°C. Center frequency time drift provides an improvement of at least one order of magnitude over present state-of-the-art millivolt-controlled oscillators. Measured data is presented to support the procedures used in the design. The oscillator and associated circuitry are contained in a 4?-cubic-inch package that weighs 4 ounces.

A differentiator for A-C computers

This paper describes an electronic circuit which differentiates, with respect to time, information represented by the amplitude modulation of an a-c carrier wave. A circuit of this type is useful in a-c fire-control computing systems where rate information must be obtained from positional input data. In any fire-control computer, the choice of the particular type of differentiator to be used depends upon the form of the input data. If these data are in the form of d-c signals, accurate electronic differentiating circuits are available. If they are in the form of a-c signals a positional servo coupled to an a-c tachometer is usually used1 (especially for rectangular co-ordinate fire-control systems). The accuracy of servo differentiators, however, is inadequate for many applications. The electronic circuit to be described offers a means of obtaining, for an a-c fire-control computing system, more accurate differentiation than has so far been obtained using servo differentiators. Basically, the circuit described is a modification of a well-known d-c differentiator circuit which utilizes a Miller integrator in a feedback path, achieving differentiation by the implicit function technique.2 A magnetically keyed demodulator3,4 has been incorporated into the design so that the d-c circuit can be used in an a-c computing system. This demodulator circuit has excellent linearity characteristics and a wide operating range, making the electronic differentiator design feasible for many applications.