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10 pages, 3379 KiB

Open AccessArticle

A Simple Capillary Blood Cell Flow Monitoring System using Magnetic Micro-Sensor: A Simulation Study

by Seonghoon Jo and Kyungsik Eom

Electronics 2020, 9(4), 618; https://doi.org/10.3390/electronics9040618 - 6 Apr 2020

Viewed by 3009

Abstract

Since blood flow is a physiologically important parameter in determining the state of the tissue (e.g., viability and activity), various blood flow measurement techniques have been developed. However, existing blood flow measurement methods require complex equipment to generate external energy sources to be [...] Read more.

Since blood flow is a physiologically important parameter in determining the state of the tissue (e.g., viability and activity), various blood flow measurement techniques have been developed. However, existing blood flow measurement methods require complex equipment to generate external energy sources to be applied onto the tissue. This paper describes a magnetic method for the simple and external source-free measurement of blood flowing throughout the capillary. A microcoil located near to the capillary captures the intrinsic magnetic field produced by flowing negatively charged blood cells (e.g., red blood cells and white blood cells) to induce the electromotive force (EMF). The velocity of blood cells is estimated using the time interval between adjacent peaks and the slope of the induced EMF. The direction of blood flow can also be determined based on the frequency shift of the induced EMF. When moving the microcoil in the same direction of the blood flow, the frequency of induced EMF decreases, whereas an increased frequency is observed when moving the microcoil in the opposite direction to the blood flow. Moreover, this method could detect and distinguish streams of red blood cells and white blood cells. These results support the feasibility of a non-invasive magnetic blood flow monitoring system that does not require any external power source applied to the blood stream and thereby alleviates the complexity of conventional blood flow monitoring systems. Full article

(This article belongs to the Special Issue Energy-Harvesting Technology for Stand-Alone Self-Sustainable Sensor System)

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10 pages, 516 KiB

Open AccessArticle

Analysis and Design of Harmonic Rejection Low Noise Amplifier with an Embedded Notch Filter

by Raymond Gyaang, Dong-Ho Lee and Jusung Kim

Electronics 2020, 9(4), 596; https://doi.org/10.3390/electronics9040596 - 31 Mar 2020

Cited by 6 | Viewed by 4654

Abstract

This paper presents the analysis and design of the harmonic rejection (HR) low-noise amplifier (LNA) with the fully passive source degeneration notch filter. The proposed HR LNA provides the rejection for the strong harmonics (

3_{r d}

) of the local oscillator [...] Read more.

This paper presents the analysis and design of the harmonic rejection (HR) low-noise amplifier (LNA) with the fully passive source degeneration notch filter. The proposed HR LNA provides the rejection for the strong harmonics (

3_{r d}

) of the local oscillator (LO) frequencies, where the HR mixer does not provide sufficient HR performance. The proposed

3_{r d}

harmonic notch filter modulates the source degeneration factor and the impedance matching performance thereafter. This effect further helps the blocking of the harmonic signal. The proposed LNA provides 11 dB gain at the fundamental frequency (2.1 GHz) while rejecting the 3rd harmonic component by 37 dBc. Compared to the conventional LNA, the 3rd harmonic notch performance is improved by 23 dB. Additionally, the LNA achieves a minimum noise figure of 3.1 dB, third order input intercept point (

I I P_{3}

) of 0.5 dBm, input reflection (S

_{11}

) below −10 dB from 1.8 GHz–2.3 GHz operational frequency range, and consumed 19 mW of power from a 1.2 V supply. Full article

(This article belongs to the Special Issue Energy-Harvesting Technology for Stand-Alone Self-Sustainable Sensor System)

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19 pages, 6066 KiB

Open AccessFeature PaperArticle

A K_u-Band RF Front-End Employing Broadband Impedance Matching with 3.5 dB NF and 21 dB Conversion Gain in 45-nm CMOS Technology

by Hafiz Usman Mahmood, Dzuhri Radityo Utomo, Seok-Kyun Han, Jusung Kim and Sang-Gug Lee

Electronics 2020, 9(3), 539; https://doi.org/10.3390/electronics9030539 - 24 Mar 2020

Cited by 3 | Viewed by 4542

Abstract

This paper presents a

K_{u}

-band RF receiver front-end with broadband impedance matching and amplification. The major building blocks of the proposed receiver front-end include a wideband low-noise amplifier (LNA) employing a cascade of resistive feedback inverter (RFI) and transformer-loaded common source [...] Read more.

This paper presents a

K_{u}

-band RF receiver front-end with broadband impedance matching and amplification. The major building blocks of the proposed receiver front-end include a wideband low-noise amplifier (LNA) employing a cascade of resistive feedback inverter (RFI) and transformer-loaded common source amplifier, a down-conversion mixer with push–pull transconductor and complementary LO switching stage, and an output buffer. Push–pull architecture is employed extensively to maximize the power efficiency, bandwidth, and linearity. The proposed two-stage LNA employs the stagger-tuned frequency response in order to extend the RF bandwidth coverage. The input impedance of RFI is carefully analyzed, and a wideband input matching circuit incorporating only a single inductor is presented along with useful equivalent impedance matching models and detailed design analysis. The prototype chip was fabricated in 45-nm CMOS technology and dissipates 78 mW from a 1.2-V supply while occupying chip area of 0.29 mm

^{2}

. The proposed receiver front-end provides 21 dB conversion gain with 7 GHz IF bandwidth, 3.5 dB NF, −15.7 dBm IIP

_{3}

while satisfying <−10 dB input matching over the whole input band. Full article

(This article belongs to the Special Issue Energy-Harvesting Technology for Stand-Alone Self-Sustainable Sensor System)

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11 pages, 996 KiB

Open AccessArticle

An Energy Logger for Kinetic-Powered Wrist-Wearable Systems

by Jose Manjarres and Mauricio Pardo

Electronics 2020, 9(3), 487; https://doi.org/10.3390/electronics9030487 - 15 Mar 2020

Cited by 5 | Viewed by 3749

Abstract

Kinetic energy harvesting is a promising technology towards the development of alternative battery-charging schemes or even self-powered wearable devices that obtain their power supply from human motion. Although there are many developments with schemes that leverage piezoelectric materials and human motion to power [...] Read more.

Kinetic energy harvesting is a promising technology towards the development of alternative battery-charging schemes or even self-powered wearable devices that obtain their power supply from human motion. Although there are many developments with schemes that leverage piezoelectric materials and human motion to power devices especially from footsteps, some other body locations like the wrist still need assessment with piezoelectric generators to evaluate their potential of limitations. In this work, we present the results of logging the energy transference from a wrist-worn piezoelectric harvester to a battery in a wearable device. This system is the continuation of our previous work where we implemented the harvester with a resistive load previously tuned to obtain maximum power and assessed the energy harvested during physical activities. Now, we replace the linear load with a charge controller and a Li-ion battery in the same wearable set-up. These new conditions are not optimal for the piezoelectric generator but present a more realistic environment for the kinetic harvester and allows a more precise study of the feasibility of a self-powered system. Tests show that five minutes of activities that involve arm motion can provide between 1.75 mJ and 2.98 mJ of energy, which can represent between 3.6 seconds and 6.2 seconds of additional battery duration. Hence, these results provide an insight of the limitations and challenges remaining in the piezoelectric-based kinetic harvesting field for wearable devices. Full article

(This article belongs to the Special Issue Energy-Harvesting Technology for Stand-Alone Self-Sustainable Sensor System)

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8 pages, 482 KiB

Open AccessArticle

Energy Rate Maximization with Sum-Rate Constraint for SWIPT in Multiple-Access Channels

by Yeonggyu Shim and Wonjae Shin

Electronics 2019, 8(12), 1525; https://doi.org/10.3390/electronics8121525 - 11 Dec 2019

Cited by 1 | Viewed by 2323

Abstract

This paper considers simultaneous wireless information and power transfer (SWIPT) systems in the two-user Gaussian multiple access channel (G-MAC). In SWIPT systems, for a transmit signal each transmitter consists of an information-carrying signal and energy-carrying signal. By controlling a different set of the [...] Read more.

This paper considers simultaneous wireless information and power transfer (SWIPT) systems in the two-user Gaussian multiple access channel (G-MAC). In SWIPT systems, for a transmit signal each transmitter consists of an information-carrying signal and energy-carrying signal. By controlling a different set of the power for the information transmission and power for the energy transmission under a total power constraint, the information sum-rate and energy transmission rate can be achieved. As the information carrying-to-transmit power ratio at transmitters and the information sum-rate increases, however, the energy transmission rate decreases. In other words, there is a fundamental trade-off between the information sum-rate and the energy transmission rate according to the power-splitting ratio at each transmitter. Motivated by this, this paper proposes an optimal power-splitting scheme that maximizes the energy transmission rate subject to a minimum sum-rate constraint. In particular, a closed-form expression of the power-splitting coefficient is presented for the two-user G-MAC under a minimum sum-rate constraint. Numerical results show that the energy rate of the proposed optimal power-splitting scheme is greater than that of the fixed power-splitting scheme. Full article

(This article belongs to the Special Issue Energy-Harvesting Technology for Stand-Alone Self-Sustainable Sensor System)

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12 pages, 358 KiB

Open AccessArticle

A Low-Complexity Resource Allocation for Multiple Access Passive IoT System

by Shiying Han and Zixiong Wang

Electronics 2019, 8(12), 1421; https://doi.org/10.3390/electronics8121421 - 28 Nov 2019

Cited by 1 | Viewed by 2031

Abstract

An ambient backscatter communication (AmBC) system with multiple backscatter devices (BDs) is investigated in this work. The cooperative reader receives the information from the primary transmitter (PT) and the multiple BDs simultaneously. With the asymptotic signal-to-noise-plus-interference ratio (SINR) of the BDs, an optimization [...] Read more.

An ambient backscatter communication (AmBC) system with multiple backscatter devices (BDs) is investigated in this work. The cooperative reader receives the information from the primary transmitter (PT) and the multiple BDs simultaneously. With the asymptotic signal-to-noise-plus-interference ratio (SINR) of the BDs, an optimization problem that jointly optimizes the reflection coefficients of BDs and the primary transmit power is formulated. Considering that the adaptive optimization of reflection coefficients according to the instantaneous primary channel state information (CSI) is unaffordable in practice, we propose a low-complexity resource allocation scheme, which results in a long-term configuration of the BD reflection coefficients before the primary transmit power is allocated. With the long-term reflection coefficients, the transmit power of the primary system is optimized by solving the transformed two cascaded optimization problems which have closed-form solutions. Simulation results are provided to demonstrate the effectiveness of the proposed scheme. Full article

(This article belongs to the Special Issue Energy-Harvesting Technology for Stand-Alone Self-Sustainable Sensor System)

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10 pages, 1848 KiB

Open AccessArticle

Novel L-Slot Matching Circuit Integrated with Circularly Polarized Rectenna for Wireless Energy Harvesting

by Mohamed M. Mansour and Haruichi Kanaya

Electronics 2019, 8(6), 651; https://doi.org/10.3390/electronics8060651 - 10 Jun 2019

Cited by 30 | Viewed by 4475

Abstract

Radio frequency (RF) power harvesting allows wireless power delivery concurrently to several remote RF devices. This manuscript presents the implementation of a compact, reliable, effective, and flexible energy harvesting (EH) rectenna design. It integrates a simple rectifier circuit with a circularly polarized one-sided [...] Read more.

Radio frequency (RF) power harvesting allows wireless power delivery concurrently to several remote RF devices. This manuscript presents the implementation of a compact, reliable, effective, and flexible energy harvesting (EH) rectenna design. It integrates a simple rectifier circuit with a circularly polarized one-sided slot dipole antenna at

2.45

GHz Industrial, Scientific, Medical (ISM) frequency band for wireless charging operation at low incident power densities, from 1 to 95

μ

W/cm

^{2}

. The rectenna structure is printed on a single layer, low cost, commercial FR4 substrate. The integration of the rectifier and antenna produces a low-profile and high performance circularly polarized rectenna. In order to maximize the system efficiency, the matching circuit introduced between the rectifier and antenna is optimized for a minimum number of discrete components and it is constructed using multiple of L-slot defects in the ground plane. For a given input power of

- 6

dBm intercepted by the circularly polarized antenna with 3 dBi gain, the peak RF-DC (radio frequency-direct current) conversion efficiency is

59.5 %

. The rectenna dimensions are 41 × 35.5 mm

^{2}

. It is demonstrated that the output power from the proposed rectenna is higher than the other published designs with a similar antenna size under the same ambient condition. Thanks to its compact size, the proposed rectenna finds a range of potential applications for wireless energy charging. Full article

(This article belongs to the Special Issue Energy-Harvesting Technology for Stand-Alone Self-Sustainable Sensor System)

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Review

Jump to: Research

22 pages, 7674 KiB

Open AccessReview

Inkjet-Printed Electronics on Paper for RF Identification (RFID) and Sensing

by Sangkil Kim

Electronics 2020, 9(10), 1636; https://doi.org/10.3390/electronics9101636 - 4 Oct 2020

Cited by 43 | Viewed by 6057

Abstract

The newly developed research area of inkjet-printed radio frequency (RF) electronics on cellulose-based and synthetic paper substrates is introduced in this paper. This review paper presents the electrical properties of the paper substrates, the printed silver nanoparticle-based thin films, the dielectric layers, and [...] Read more.

The newly developed research area of inkjet-printed radio frequency (RF) electronics on cellulose-based and synthetic paper substrates is introduced in this paper. This review paper presents the electrical properties of the paper substrates, the printed silver nanoparticle-based thin films, the dielectric layers, and the catalyst-based metallization process. Numerous inkjet-printed microwave passive/ative systems on paper, such as a printed radio frequency identification (RFID) tag, an RFID-enabled sensor utilizing carbon nanotubes (CNTs), a substrate-integrated waveguide (SIW), fully printed vias, an autonomous solar-powered beacon oscillator (active antenna), and artificial magnetic conductors (AMC), are discussed. The reported technology could potentially act as the foundation for true “green” low-cost scalable wireless topologies for autonomous Internet-of-Things (IoT), bio-monitoring, and “smart skin” applications. Full article

(This article belongs to the Special Issue Energy-Harvesting Technology for Stand-Alone Self-Sustainable Sensor System)

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