Energy Harvesting Power Sources Research Articles

Boosting the output performance of triboelectric nanogenerators via surface engineering and structure designing.

Triboelectric nanogenerators (TENGs) have been utilized in a wide range of applications, including smart wearable devices, self-powered sensors, energy harvesting, and high-voltage power sources. The surface morphology and structure of TENGs play a critical role in their output performance. In this review, we analyze the working mechanism of TENGs with the aim to improve their output performance and systematically summarize the morphological engineering and structural design strategies for TENGs. Additionally, we present the emerging applications of TENGs with specific structures and surfaces. Finally, we discuss the potential future development and industrial application of TENGs. By deeply exploring the surface and structural design strategy of high-performance TENGs, it is conducive to further promote the application of TENGs in actual production. We hope that this review provides insights and guidance for the morphological and structural design of TENGs in the future.

Three-dimensional graphene foam based triboelectric nanogenerators for energy systems and autonomous sensors

In this work we investigate the potential of three-dimensional graphene (3DG) foam as an active layer in triboelectric nanogenerators (TENGs) and as an energy harvesting power source for autonomous sensors. A series of comprehensive measurements have been carried out to test the output characteristics of 3DG-TENG under cyclic mechanical stimulus, capable of operating TENG in contact-separation mode at different frequencies, gap distances between electrodes, and applied pressures. The triboelectric response of 3DG-TENG (with an effective surface of 16 cm2) showed maximum open-circuit voltage (Voc) and short-circuit current (Isc) of 400 V and 105.7 μA respectively when stimulated at 3 Hz (contact-separation frequency) and 70 mm (optimum gap distance). Under the same conditions, a maximum output power (Pout) of around 10.37 W/m2 is produced using an external load resistance of 40 MΩ; this is an order of magnitude lower resistance than that needed with other graphene based TENG variants. 3DG-TENG exhibited great stability in the output characteristics with 15,000 cyclic mechanical stimuli and a retention percentage in Pout above 95%. This is a significant improvement with respect to other carbon based TENG`s, which show enhanced deterioration of TENG performance due to material transfer between electrodes and plastic deformation of triboelectric materials. Simulations of TENG Voc using distance dependent model determined high triboelectric charge densities in the range of mC/m2. Here, we also demonstrate the potential of 3DG-TENG as an energy supply for energy storage devices, and as an active layer in an autonomous pressure sensing platform for anonymous room occupancy monitoring in smart buildings.

Dielectric Modulated Glass Fiber Fabric‐Based Single Electrode Triboelectric Nanogenerator for Efficient Biomechanical Energy Harvesting

AbstractSingle‐electrode triboelectric nanogenerators (SE‐TENGs) are versatile tools for energy harvesting with simple structures and great practicability. However, low output performance hinders SE‐TENGs in applications as portable power sources. Herein, a novel SE‐TENG that utilizes glass fiber fabric (GFF) as tribo‐materials, along with an inorganic ferroelectric film for the dielectric layer is proposed. The GFF is first shown to be a promising tribo‐material for its highly positive tribo‐polarity and unique chemical/mechanical/durable properties. Meanwhile, an inorganic dielectric film with high dielectric constant is introduced between the GFF and Al electrode for enhancing the charge trapping capability. Owing to the synergistic effect of optimized triboelectrification and dielectric properties, the specific designed SE‐TENG delivers an open‐circuit voltage of 1640 V and a short‐circuit current density of 59.05 mA m−2, which are superior to most reported SE‐TENGs. With a maximum instantaneous power of 11.30 mW, the device can light up 1350 light‐emitting diodes, charge a 47 µF capacitor into 10 V in 421 s, and power up a digital watch even without additional control circuits. This work provides new insights in designing high‐performance SE‐TENGs and facilitates their application in biomechanical energy harvesting and portable power sources.

Self-powered ultraflexible photonic skin for continuous bio-signal detection via air-operation-stable polymer light-emitting diodes

Ultraflexible optical devices have been used extensively in next-generation wearable electronics owing to their excellent conformability to human skins. Long-term health monitoring also requires the integration of ultraflexible optical devices with an energy-harvesting power source; to make devices self-powered. However, system-level integration of ultraflexible optical sensors with power sources is challenging because of insufficient air operational stability of ultraflexible polymer light-emitting diodes. Here we develop an ultraflexible self-powered organic optical system for photoplethysmogram monitoring by combining air-operation-stable polymer light-emitting diodes, organic solar cells, and organic photodetectors. Adopting an inverted structure and a doped polyethylenimine ethoxylated layer, ultraflexible polymer light-emitting diodes retain 70% of the initial luminance even after 11.3 h of operation under air. Also, integrated optical sensors exhibit a high linearity with the light intensity exponent of 0.98 by polymer light-emitting diode. Such self-powered, ultraflexible photoplethysmogram sensors perform monitoring of blood pulse signals as 77 beats per minute.

Self‐Powered Smart Shoes with Tension‐Type Ribbon Harvesters and Sensors

AbstractThis study aims to develop self‐powered smart shoes that can monitor the changes in the bodyweight of a user. A tension‐type energy harvester and strain sensor are fabricated using polyvinylidene fluoride‐based ribbons and nanopowder containing piezoresistive ribbons, respectively. Two different conducting nanopowders (carbon black and multi‐walled carbon nanotubes) are used as stretchable sensors, and the most appropriate mixing ratio of the nanopowders is determined. The energy harvesting performance of the tension‐type ribbon harvesters is experimentally investigated based on the combination patterns of ribbons and gait patterns, and a method is introduced to apply the harvesting ribbon to shoes. Tension‐type ribbon sensors that detect bodyweight are installed in an acrylic insole with four rectangular holes. The connecting method between the sensors, which guarantees the stability and high sensitivity of the sensor signals, is investigated. Finally, electronic circuits are designed for energy harvesting, data communication, and switching power sources. These designed circuits are implemented in smart shoes.

Energy consumption index minimized resource allocation in hybrid energy multiuser OFDM system with distributed antennas

Energy harvesting is one of the promising option for realization of green communication and has been a growing concern recently. In this paper, we address the downlink resource allocation in OFDM system with distributed antennas with hybrid power supply base station, where energy harvesting and non-renewable power sources are used complementarily. A joint subcarrier and power allocation problem is formulated for minimizing the net Energy Consumption Index (ECI) with system Quality of Service (QoS) and bit error rates constraint. The problem is a 0-1 mixed integer nonlinear programming problem due to the binary subcarrier allocation variable. To solve the problem, we design an algorithm based on Lagrange relaxation method and fraction programming which optimizes the power allocation and subcarrier allocation iteratively in two nests. Simulation results show that the proposed algorithm converges in a small number of iterations and can improve net ECI of system greatly.

(Invited) Electrochemical Impedance Analysis of Printable Porous Carbon Electrode for Realization of High-Power Biofuel Cell and Wearable Self-Powered Biosensor

A paper-based biofuel cell (PBFC) have been attracted as a potential application as energy harvesting power sources in the Internet of Things (IoT) field [1-3]. To use the PBFC for practical application, the cell power density of PBFC, generally limited by the biocathode performance, should be improved. The distance between the redox site of the enzyme and the electrode material surface is one of the key factors for biocathode development. By entrapping enzymes in a mesopore of a porous carbon material, the redox center can approach the electrode material surface with high probability. In addition, the stability of the enzyme may be improved. A branch structure (double pore structure) porous carbon material is a suitable porous material for biosensors and biofuel cell electrodes, because the branch structure porous carbon material such as MgO-templated mesoporous carbon (MgOC) has large specific surface areas and mesopores whose size can be easily controlled. In the present study, we formed the branch structure porous carbon electrodes for biofuel cathode by screen-printing technique, and the electrode performance was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) to improve the electrode structure for biofuel cell cathode. In the present paper, we discuss the experimental result in detail and introduce our wearable PBFC performance using the printed porous carbon electrodes. [1] I. Shitanda et al., Chem. Commun. 49 (2013) 11110. [2] Claudia W. Narváez Villarrubia et al., Electrochem. Commun, 45 (2014) 44. [3] Carolin Lau et al., Int. J. Hydrogen. Energy, 42 (2015) 14661.

(Invited) Printable Paper-Based Wearable Diaper-Type and Adhesive Bandage-Type Biofuel Cells for Urine Sugar and Sweat Lactate Monitoring

Printable Electrochemistry has attracted attention for the development field of a disposable biosensor and biofuel cell. A printable paper-based biofuel cell (PBFC) is useful for energy harvesting power sources in the Internet of Things (IoT) field [1-3]. In addition, PBFC is suitable for an application as a self-powered wearable sensor. In the present study, I introduce two paper-based wearable biofuel cells fabricated by screen-printing technique (Fig. 1). One is used as a self-powered diaper sensor (right side in Fig. 1). The biofuel cell can generate electric power from glucose in urine. The maximum output power increase along with increase of glucose concentration. Thus, we can monitor the glucose concentration by measuring the maximum output power. The paper-based biofuel cell exhibited a maximum power density of 0.7 mW in 100 mM glucose solution. Our group also developed an adhesive bandage-type biofuel cell, which get a power from lactate in sweat (left side in Fig. 1). In the present study, we discuss the characteristics of the wearable biofuel cells in detail. Acknowledgement This work was supported by JST-ASTEP Grant Number AS272S004a.

Flexible hybrid eu3+ doped P(VDF-HFP) nanocomposite film possess hypersensitive electronic transitions and piezoelectric throughput

A novel red light-emitter made of Eu3+ doped self-poled electroactive poly(vinylidene fluoride–hexafluoropropylene) [P(VDF-HFP)] hybrid nanocomposite film possesses piezoelectric throughput that is suitable for flexible piezoelectric nanogenerator (PNG) fabrication. We observed that PNG is enabled to generate an open-circuit voltage of 5 V and 0.35 μA of short-circuit current under an applied pressure amplitude of ∼10.4 kPa. By simple mechanical energy scavenging, PNG demonstrates an ability to light more than ten blue commercial light emitting diodes instantly, without using an energy-storage device. Additionally, it successfully charges up capacitors by simple repeating finger touch motion, which indicates its potency as an efficient energy harvesting power source. The high performance of PNG is due to well-coated Eu3+ with P(VDF-HFP) in a hybrid nanocomposite so it displays improved dielectric permittivity and energy storage capacity. This flexible composite film also possesses a hypersensitive electronic transition as it responds by an intense red light-emission confirmed by the CIE 1931 chart. This enables applications in piezo-photonics as a high-performance, energy-saving, flexible solid-state red light emitter. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2335–2345.

Paper-Based Biofuel Array for Self-Powered Wearable Biosensors

We name the Printable Electrochemistry for the development field of printable electrochemical devices [1,2]. Recently, we focus on several paper-based fully-printable electrochemical devices such as biofuel cell [3], biosensor [4] and reference electrode [5]. Paper-based biofuel cell have been attracted as a potential application as energy harvesting power sources in Internet of things (IoT) field [6,7]. In the present study, we newly developed paper-based wearable biofuel cell array fabricated by screen-printing. Figure 1 shows a schematic illustration of one of our wearable biofuel cell array. The paper-based biofuel cell array exhibited a maximum power density of 1 mW. The present flexible paper-based biofuel cell is highly applicable to the development of low cost, flexible, ubiquitous energy devices. In the present study, we discuss the characteristics of the wearable biofuel cells in detail. [1] I. Shitanda et al., Electrochim. Acta 54 (2009) 4933. [2] I. Shitanda et al., Sens. Actu. B: Chem. 160 (2011) 1606. [3] I. Shitanda et al., Chem. Commun. 49 (2013) 11110. [4] I. Shitanda et al., Chem. Lett. 42 (2013) 1369. [5] I.Shitanda et al., Analyst, 140 (2015) 6481. [6] Claudia W. Narváez Villarrubia et al., Electrochem. Commun, 45 (2014) 44. [7] Carolin Lau et al., Int. J. Hydrogen. Energy, 42 (2015) 14661. Figure 1

The charge push-through electronics design for fully implantable artificial cochlea powered by energy harvesting technologies

An implant of artificial cochlea is the only way how to recover lost hearing in some cases. Fully implantable artificial cochlea in comparison with recent approaches including partially implantable devices is proposed and discussed in this work. The proposed implant consists of subcircuits which are designed in close context to reach optimal performance and the lowest power consumption. Power consumption of the device is decreased to a value which allows designing the device as a zero-powered system using energy harvesting. A combination of micro-mechanized diaphragm filter bank, energy harvesting power source and especially ultra-low power processing electronics is presented in this article. A new technique of output signal generation for nerve stimulation is described. This new technique named charge push-through uses the major part of energy generated by energy harvesting subcircuit for output useful signal generation with minimal undesirable current. Thermal and mechanical parts were investigated using complex electro-mechanical simulations. The real energy harvesting power source (human motion, temperature) was experimentally measured. Signal processing circuits powered by energy harvesting power source were designed and simulated. The new signal processing circuits were simulated in relation to the results of complex electro mechanical diaphragm and SPICE energy harvesting power source simulation.

Circuits for the Charge Push-through Electronics: Power Efficient Signal Processing Inside the Artificial Cochlear Implant

This work deals with the new technique called Charge Push-Through technology which is more energy efficient than the currently used approaches. The new energy efficient design regarding utilization of emerging technology such as Energy harvesting (EH) power sources is very promising for future development of energy independent (zero-power) and nonobtrusive cochlear implant. This work presents the solution of Charge Push-Through circuits using the component level design of artificial cochlea.

Lead-free ZnSnO3/MWCNTs-based self-poled flexible hybrid nanogenerator for piezoelectric power generation

A high-performance flexible piezoelectric hybrid nanogenerator (HNG) based on lead-free perovskite zinc stannate (ZnSnO3) nanocubes and polydimethylsiloxane (PDMS) composite with multiwall carbon nanotubes (MWCNTs) as supplement filling material is demonstrated. Even without any electrical poling treatment, the HNG possesses an open-circuit voltage of 40 V and a short-circuit current of 0.4 μA, respectively, under repeated human finger impact. It has been demonstrated that the output volume power density of 10.8 μW cm−3 from a HNG can drive several colour light emitting diodes (LEDs) and a charge capacitor that powers up a calculator, indicating an effective means of energy harvesting power source with high energy conversion efficiency (∼1.17%) for portable electronic devices.

An Ultra-Low Voltage Analog Front End for Strain Gauge Sensory System Application in 0.18µm CMOS

SUMMARY This paper presents analysis and design of a new ultra-low voltage analog front end (AFE) dedicated to strain sensor applications. The AFE, designed in 0.18 μm CMOS process, features a chopper-stabilized instrumentation amplifier (IA), a balanced active MOSFET-C 2nd order low pass filter (LPF), a clock generator and a voltage booster which operate at supply voltage (Vdd) of 0.6 V. The designed IA achieves 30 dB of closedloop gain, 101 dB of common-mode rejection ratio (CMRR) at 50 Hz, 80 dB of power-supply rejection ratio (PSRR) at 50 Hz, thermal noise floor of 53.4 nV/ √ Hz, current consumption of 14 μA, and noise efficiency factor (NEF) of 9.7. The high CMRR and rail-to-rail output swing capability is attributed to a new low voltage realization of the active-bootstrapped technique using a pseudo-differential gain-boosting operational transconductance amplifier (OTA) and proposed current-driven bulk (CDB) biasing technique. An output capacitor-less low-dropout regulator (LDO), with a new fast start-up LPF technique, is used to regulate this 0.6 V supply from a 0.8–1.0 V energy harvesting power source. It achieves power supply rejection (PSR) of 42 dB at frequency of 1 MHz. A cascode compensated pseudo differential amplifier is used as the filter’s building block for low power design. The filter’s single-ended-to-balanced converter is implemented using a new low voltage amplifier with two-stage common-mode cancellation. The overall AFE was simulated to have 65.6 dB of signalto-noise ratio (SNR), total harmonic distortion (THD) of less than 0.9% for a 100 Hz sinusoidal maximum input signal, bandwidth of 2 kHz, and power consumption of 51.2 μW. Spectre RF simulations were performed to validate the design using BSIM3V3 transistor models provided by GLOBALFOUNDRIES 0.18 μm CMOS process.

Wireless sensor node powered by aircraft specific thermoelectric energy harvesting

An energy autonomous wireless sensor system consisting of an energy harvesting power source, an energy management unit and a low power wireless sensor node is tested for aircraft applications. The autonomous power source combines aircraft specific outside temperature changes with a thermoelectric generator (TEG) and a heat storage unit. The temperature difference generated with the latter component artificially at the TEG is used to power the sensor node by thermoelectricity. Additionally, a high efficient low input voltage power management circuit is necessary to store the generated energy and to convert it to higher voltage levels needed to operate the sensor. The experimental data are compared with results from numerical simulation models to predict the energy conversion in the heat storage – TEG system. A new TEG prototype is tested and the energy output is improved by 14%. The power management storage capacitors are adapted to the available energy, thereby increasing storage voltage and conversion efficiency. Doing so, the efficiency of the complete system can be increased by around 50%.

Energy harvesting for autonomous wireless sensor nodes in aircraft

An energy autonomous wireless sensor system consisting of an energy harvesting power source, an energy management unit and a low power wireless sensor node is tested for aircraft applications. The autonomous power source combines aircraft specific outside temperature changes with a thermoelectric generator (TEG) and a heat storage unit. The temperature difference generated with the latter component artificially at the TEG is used to power the sensor node. Additionally, a high efficient low input voltage power management circuit is necessary to store the generated energy and to convert it to higher voltage levels needed to operate the sensor. The experimental data are compared with results from numerical simulation models to predict the energy conversion in the heat storage - TEG system. A new TEG prototype is tested and it is expected that the energy output is improved up to 15%. The power management storage capacitors are adapted to the available energy, thereby increasing storage voltage and conversion efficiency. Doing so, the efficiency of the complete system can be increased by ∼50%.

Energy-harvesting power sources for a wide range of applications

Energy-harvesting power sources for a wide range of applications