Graphene Functionalization towards Developing Superior Supercapacitors Performance

Graphene is known as the miracle material of the 21st century for the wide band of participating applications and epic properties. Unlike the CVD monolayer graphene, Reduced graphene oxide (RGO) is a commercial form with mass production accessibility via numerous numbers of methods in preparation and reduction terms. Such RGO form showed exceptional combability in supercapacitors (SCs) where RGO is participated to promote flexibility, lifetime and performance. The chapter will illustrate 4 critical milestones of using graphene derivatives for achieving SC’s superior performance. The first is using oxidized graphene (GO) blind with polymer for super dielectric spacer. The other three types are dealing with electrolytic SCs based on RGO. Polyaniline (PANI) was grown on GO for exceptionally stable SCs of 100% retention. Silver decoration of RGO was used for all-solid-state printable device. The solid-state gel electrolyte was developed by adding GO to promote current rating. Finally, laser reduced graphene is presented as a one-step and versatile technique for micropatterning processing. The RGO reduction was demonstrated from a laser GO interaction perspective according to two selected key parameters; wavelength and pulse duration

Multiband Dual-Meander Line Antenna for Body-Centric Networks’ Biomedical Applications by Using UMC 180 nm

A new, compact, on-chip antenna architecture for 5G body-centric networks’ (BCNs) applications is presented in this paper. The integrated antenna combines two turns of dual-meander lines (DML) on two stacked layers and a metal ground layer. The proposed DML antenna structure operated at resonant bands 22 GHz, 34 GHz, 44 GHz, and 58 GHz with an operating bandwidth up to 2 GHz at impedance bandwidth ≤−7.5 dB (VSWR—Voltage Standing Wave Ratio ≤ 2.5) and antenna gain about −20 dBi, −15 dBi, −10 dBi, and −1 dBi, respectively. Then it was compared with conventional single-meander line antenna. The proposed structure decreased the resonant frequency by 22%, increased number of tuning bands, and broadened the operating bandwidth by 25%, 15%, 10%, and 20% for the tuning bands to be a suitable choice for high-data -ate biomedical applications. Furthermore, the proposed antenna was simulated and studied for its performance on and inside the human body to test the integration effect in wearable equipment. The results showed that the antenna had acceptable performance in both locations. All simulations of the proposed antenna were done were done by using Ansys HFSS (high-frequency structure simulator) v.15 (Ansys, Canonsburg, PA, USA). The DML (Digital Microwave Links) antenna was fabricated by using UMC (United Microelectronics Corporation) 180 nm CMOS (Complementary Metal–Oxidesemi–Conductor) technology with a total area of 1150 µm × 200 µm and the results showed a good agreement between measured and simulated results

A 750 μW 3.5–4.5 GHz FM-UWB transmitter

This paper presents an ultra-low power frequency modulated ultra-wideband (FM-UWB) transmitter implemented in standard 130 nm CMOS technology. The transmitter operates in the range of 3.5–4.5 GHz with 4 GHz RF carrier frequency. The transmitter can accept input data rates up to 250 kbps. A relaxation oscillator is used to generate the subcarrier signal and a VCO for RF carrier generation. The center frequency of the VCO is periodically calibrated to avoid out of band operation. An integer-N phase-locked loop (PLL) is used for both subcarrier generation and RF VCO calibration, which needs only 500 ns to complete the calibration. A class-AB power amplifier is used to output the power under the FCC mask. The proposed FM-UWB transmitter consumes 750 μW from a 1.2 V supply

ULP Super Regenerative Transmitter with Digital Quenching Signal Controller

This paper demonstrates an on–off keying (OOK) super-regenerative quenching transmitter operating in 402–405 MHz MICs band applications. To reduce power consumption, the transmitter is controlled by a novel digital quenching signal controller that generates a digital control signal to start transmitter operation when a baseband signal is input to the transmitter. The digital signal controller consists of an envelope detector, a comparator, and a quench timer designed using a state machine to synchronize the operation between the digital controller and the input baseband signal. The transmitter consists of a Colpitts oscillator operating in double operating frequency followed by a frequency divider by 2; this configuration reduces system area and improves phase noise and signal spectrum. The proposed transmitter is implemented using UMC 130 nm CMOS technology and a 1.2 V supply. Simulation shows that the proposed transmitter can meet MICS band mask specifications with data rates up to 1 Mbps and total power dissipation of 537 uW

Anomalous dielectric constant value of graphene oxide/Polyvinyl alcohol thin film

International audienceGraphene oxide/polyvinyl alcohol (GO/PVA) composites have been developed using facile colloidal processing technique to form a super dielectric spacer of 10(6) order. The dielectric characteristics of GO/PVA composite were investigated at a frequency range from 20 Hz to 1 M Hz. The electrical analysis showed a complex interaction that is quite different than Debye but could be explained using Bruggeman and Maxwell-Garnett assumptions in the high-frequency range and Percolation theory in the low range. Due to the ageing effect and the observed high imaginary part, an investigation of GO film dielectric properties were investigated. The results incorporate a crucial role of water contents on corresponding GO and GO/PVA electromagnetic interaction besides the well-established functional group's theory. Transmission electron microscopy, X-ray diffraction, dispersive Raman, potentiostat/galvanostat and LCR meter were utilized to perform microscopic, structure and electrical characterizations

Successive Approximation Register Analog-to-Digital Converter (SAR ADC) for Biomedical Applications

This study presents a survey of the most promising reported SAR ADC designs for biomedical applications, stressing advantages, disadvantages, and limitations, and concludes with a quantitative comparison. Recent progress in the development of a single SAR ADC architecture is reviewed. In wearable and biosensor systems, a very small amount of total power must be devoured by portable batteries or energy-harvesting circuits in order to function correctly. During the past decade, implementation of the high energy efficiency of SAR ADC has become the most necessary. So, several different implementation schemes for the main components of the SAR ADC have been proposed. In this review study, the various circuit architectures have been explained, beginning with the sample and hold (S/H) switching circuits, the dynamic comparator, the internal digital-to-analog converter (DAC), and the SAR control logic. In order to achieve low power consumption, numerous different configurations of dynamic comparator circuits are revealed. At the end of this overview, the evolutions of DAC architecture in distinct biomedical applications today can make a tradeoff between resolution, speed, and linearity, which represent the challenges of a single SAR ADC. For high resolution, the dual split capacitive DAC (CDAC) array technique and hybrid capacitor technique can be used. Also, for ultralow power consumption, various voltage switching schemes are achieved to reduce the number of switches. These schemes can save switching energy and reduce capacitor array area with high linearity. Additionally, to increase the speed of the conversion process, a prediction-based ADC design is employed. Therefore, SAR ADC is considered the ideal solution for biomedical applications