Power Microelectronic Devices Research Articles

Vibrational coupling-based multilayer flexible triboelectric nanogenerator for wide-amplitude omnidirectional wave energy harvesting

Wave energy harvesters are viewed as potential foundations for self-powered wireless sensor devices. In this study, a multilayer flexible triboelectric nanogenerator (MFLU-TENG) is proposed and evaluated, which combines the stretching properties of springs and the deformation properties of flexible materials to enable wide-wavelength energy harvesting. It captures wave energy even at very low amplitudes, requiring a minimum wave amplitude of 5 cm for energy recovery. The study explores how geometric parameters of the MFLU-TENG affect vibration behavior and output performance. Optimal performance is achieved when varying the thickness of the PETG cushioning layer, resulting in a peak power density of up to 7.7 mW/m2. Three MFLU-TENGs connected in parallel successfully power 15 LEDs. And four parallel groups of MFLU-TENGs charged a 100µF capacitor to 5.3 V in 198 s and successfully powered the temperature and humidity sensor. And the MFLU-TENGs charge the 100uf capacitor to 4.0v and power the clock in 153 s. These findings underscore the MFLU-TENG’s potential as a cost-effective and efficient wave energy harvesting device, using renewable wave energy to power sensors or microelectronic devices in the Internet of Things.

Regulating the interfacial structure in percolating graphite nanoplate/PVDF composites via TiO2 as an interlayer towards meliorative dielectric performances

Polymer nanocomposites combining large dielectric permittivity (ε′) but low loss along with high breakdown strength (Eb) have garnered significant attention in the fields of electronic devices and power systems. To concurrently accomplish these desirable performances in pristine graphite nanoplates (GNP)/poly(vinylidene fluoride, PVDF) composites, the GNP were initially encased by a layer of anatase-type titanium dioxide (TiO2) shell, and then incorporated into PVDF to investigate the effect of TiO2 interlayer on the dielectric properties of the nanocomposites, specifically in relation to the thickness of the TiO2 shell and the nanofiller concentration. The TiO2 shell acts as a barrier layer prohibiting the electronic percolating, thus significantly reducing the dielectric loss and leakage conductivity of the GNP@TiO2/PVDF. Moreover, it not only alleviates the strong dielectric mismatch between GNP and PVDF, which restrains local electric field distortion, but also introduces charge traps, raising the energy barrier height for captured charge detrapping and preventing the growth of electric trees and subsequently promoting the Eb. For example, the PVDF with 20 wt% of GNP@TiO2 exhibited good comprehensive dielectric performances: ε′ of 50.63, loss factor of 0.071 (100 Hz) and Eb of 7.89 kV/mm. Additionally, tailoring the TiO2’s thickness can simultaneously modulate the overall dielectric parameters in the GNP@TiO2/PVDF. Theoretical fitting of experimental data via Havriliak-Negami equation uncovers the underlying polarization mechanism and the interlayer’s impact on charge migration. This work provides an efficient method for developing and producing polymeric nanodielectrics that simultaneously incorporate increased Eb with high ε′ but low loss for potential use in power devices and microelectronic devices.

Reliability and Optimization of Wire Bonding in Power Microelectronic Devices

Abstract A numerical investigation of the probabilistic approach in estimating the reliability of wire bonding is presented along with a reliability based design optimization methodology for microelectronic devices structures.

Enhanced ultra-high efficiency in high-energy–density PbHfO3-based antiferroelectric ceramics through synergistic effect design

PbHfO3-based antiferroelectric materials with the giant power density and ultrafast charge–discharge performance have exhibited the potential application in advanced pulsed power microelectronic devices. Nevertheless, the huge challenge of the large driving field of the AFE-FE phase transition (EAFE-FE) accompanied by the poor breakdown electric strength (Eb) still exists up to now and further becomes a key bottleneck restricting the simultaneous realization of high energy storage density and efficiency. Hence, we report the synergistic effect to combine the tailor ABO3 perovskite structure for minimizing the electric hysteresis and increasing bandgap width to obtain the ultrahigh Eb. Rietveld refinements of the XRD patterns and Raman spectra experiments that demonstrate the average electronegativity and a redshift with the elevated Sr content attributable to enhancing bonding energy of cation-O bonds and antipolar ordering in crystalline structure, effectively resulting in stability of the PbHfO3-based antiferroelectric structure. Meanwhile, a ultrahigh Eb of 450 kV/cm is achieved owing to optimizing the average grain size and widening bandgap width. A remarkable energy storage density of 7.29 J/cm3 and record-high energy storage efficiency of 96.40 % are achieved via synergistic effect in (Pb0.93La0.02Sr0.04)(Hf0.475Sn0.475Ti0.05)O3 (PLS4HST) ceramics under respective maximum applied field. In addition, large power density of 173.40 MW/cm3 and excellent discharge energy density of 4.90 J/cm3 as well as fast discharge rate of 166.90 ns and superior frequency stability (1 ∼ 140 Hz), along with outstanding thermal stability (25 ∼ 150°C), have been simultaneously presented in PLS4HST ceramic. These results provide a good paradigm by synergistic effect designing for exploring high-performance dielectrics to meet the demanding requirements of advanced pulsed power electronic devices.

Core-shell engineering of graphite nanosheets reinforced PVDF toward synchronously enhanced dielectric properties and thermal conductivity

Polymer composites integrating high dielectric permittivity (ε′) but low loss, large breakdown strength (Eb) and thermal conductivity (TC), have attracted widespread attention in electronic devices and power systems. To simultaneously achieve these properties in graphite nanosheet (GNS)/poly(vinylidene fluoride, PVDF), the GNS were first encapsulated by a layer of aluminum oxide (Al2O3), and then incorporated into PVDF, and the resulting PVDF nanocomposites’ dielectric properties and TC were explored in terms of the Al2O3 shell thickness and filler loading. The insulating Al2O3 shell serves as a barrier layer for the formation of leakage current and long-distance electron migration thus resulting in much lower dielectric loss and conductivity of the GNS@Al2O3/PVDF. It effectively mitigates the dielectric mismatch between the filler and host matrix, further introduces more traps that can capture charge carriers, and increases the barrier height for electron detrapping subsequently preventing the growth of electric trees and elevating the Eb. Moreover, the Al2O3 interlayer alleviates both the phonon density state and phonon impedance mismatches between the filler and matrix and facilitates the interfacial phonon transport thus leading to improved TC. The dielectric parameters and TC of the GNS@Al2O3/PVDF can be simultaneously modulated by optimizing the Al2O3′s thickness. This work offers an effective approach for designing and fabricating the polymeric nanodielectrics concurrently integrating high ε′ but low loss, enhanced Eb, and TC for prospective applications in power equipment and microelectronic devices.

Gas-driven triboelectric nanogenerator for mechanical energy harvesting and displacement monitoring

Gas as an energy carrier has been widely studied, ranging from small bubble motions to steam strike turbines. Despite the remarkable results, fewer studies have investigated the gas-driven liquid column movement commonly used in hydraulic systems, oil extraction, and other fields. Herein, we proposed a gas-driven triboelectric nanogenerator (GD-TENG) with liquid column motion for mechanical energy harvesting and displacement monitoring. When the gas drives a single liquid column to move inside a polytetrafluoroethylene (PTFE) tube, the solid-liquid interface of the GD-TENG can achieve efficient sliding friction and generate an open-circuit voltage of 15.9 V. Meanwhile, the influence of some critical parameters such as liquid column length, PTFE tube wall thickness and liquid column motion speed on the output performance of the GD-TENG were systematically investigated. Furthermore, the GD-TENG can successfully harvest mechanical energy to power microelectronic devices. A sensing system was designed based on the GD-TENG device for displacement monitoring of moving objects. This work provides a new research path in the field of mechanical energy harvesting and self-powered displacement monitoring.

Research Progress in Intelligent Exercise Monitoring Based on Triboelectric Nanogenerator

The coming of the 5G era in the Internet of Things (IoT) opens progress in cross-sectoral research in multiple disciplines. All physiological indicators of the human body are collected through sensors to provide new ideas for developing innovative sports, wearable devices, and modern intelligent venues for IoT. Conventional sensors require an external power source and have a limited lifespan and maintenance cost. Triboelectric nanogenerators (TENG), a new self-powered sensing technology that collects mechanical energy from bodily motions, can break through these limitations and be used in intelligent sports applications. Firstly, TENG can capture kinematic, biochemical, electrophysiological, and tissue dynamics information from the human body. Secondly, the low-frequency mechanical energy of the human body is not only physiological information but can also be used to power microelectronic devices to transmit big data in sports. In conclusion, we discuss TENG-based wearable sensing systems’ challenges and future opportunities.

Frequency‐tunable resonant hybrid vibration energy harvester using a piezoelectric cantilever with electret‐based electrostatic coupling

AbstractHybrid vibration energy harvesting technology converts vibration energy into electricity using multiple transduction mechanisms to improve output power. A frequency‐tunable resonant hybrid vibration energy harvester using a piezoelectric cantilever with electret‐based electrostatic coupling is proposed in this article. The electrostatic coupling including electrostatic force coupling and electrical damping coupling is introduced by an electret film placed below the cantilever, where the electrostatic force acting on the cantilever realises a tunable resonant frequency and additional electrical damping boosts power output. A coupling electromechanical model is derived using Euler–Bernoulli beam theory and Kirchhoff's law. By investigating the static and dynamic stability of cantilever, the maximum electret surface potential is defined to prevent the pull‐in phenomenon. The damping of the device is evaluated, and the optimal electret surface potential is determined to obtain the matching of the electrical and mechanical damping for maximum power output. The resonant frequency of hybrid vibration energy harvester can be adjusted in range of 176.1 rad/s by changing the electret surface potential and resistive load. The experimental output power of hybrid vibration energy harvester was 5.2 μW, 27.4 times higher than that of the individual piezoelectric generator. The proposed hybrid vibration energy harvester exhibits a promising potential to power microelectronic devices and wireless sensor network node.

Micro-Energy Harvesting From Automotive Dynamics

Abstract Most modern vehicles feature some level of automation that contributes to the overall feeling of comfort and safety. Traditional designs are, however, more difficult to apply. In fact, it is a growing consumer of wires for power and communication use, which increases the weight and cost. As a result, new micro-electronics development aims to create systems that do not require external power sources. The automotive systems are exposed to disturbances, which exhibit a vibrational response. This may be harvested into electrical energy. Therefore, the generated energy may be a potential power source for devices, applied to the vehicle. To this end, a micropower generator based on a piezo-electric device is attached to the front suspension arm, an unusual solution in the automotive industry, for extracting energy from vehicle dynamics to power micro-electronic devices and sensors. A numerical simulation from a three degrees-of-freedom model and an experimental vehicular test in different road types were applied to map the energy generated in the harvesting process. The results show that the possibility of generating micro-energy on good quality roads; is low when the International Roughness Index (IRI) is less than 4, and the micro-energy is less than 0.1 mW. However, significant performance is achieved on uneven roads (IRI > 10), that achieve harvested power greater than 0.2 mW. The IRI is a standard method for classifying road roughness. It was found generally that an off-road vehicle is better for harvesting micro-energy because of the high acceleration in the suspension.

Electrostatic Interfacial Cross-Linking and Structurally Oriented Fiber Constructed by Surface-Modified 2D MXene for High-Performance Flexible Pseudocapacitive Storage.

Fiber supercapacitors are promising power supplies suitable for wearable electronics, but the internally insufficient cross-linking and random structure of fiber electrodes restrict their performance. This study describes how interfacial cross-linking and oriented structure can fabricate an MXene fiber with high flexibility and electrochemical performance. The continuous and highly oriented macroscopic fibers were constructed by 2D MXene sheets via a liquid-crystalline wet-spinning assembly. The oxyanion-enriched terminations of surface-modified MXene in situ could reinforce the interfacial cross-linking by electrostatic interactions while mediating the sheet-to-sheet lamellar structure within the fiber. The resultant MXene fiber exhibits high electrical conductivity (3545 S cm-1) and mechanical strength (205.5 MPa) and high pseudocapacitance charge storage capability up to 1570.5 F cm-3. Notably, the assembled fiber supercapacitor delivers an energy density of 77.6 mWh cm-3 at 401.9 mW cm-3, exceptional flexibility and stability exhibiting ∼99.5% capacitance retention under mechanical deformation, and can be integrated into commercial textiles to power microelectronic devices. This work provides insight into the fabrication of an advanced MXene fiber and the development of high-performance flexible fiber supercapacitors.

Polyoxometalate Accelerated Cationic Migration for Reservoir Computing

AbstractMemristor‐based reservoir computing systems represent an attractive approach in processing the time‐series information with a low training cost, in a range of fields from finance to engineering. Previous investigations have identified the charming potential of organic devices for next‐generation memory devices. However, the structural inhomogeneity and wide energy bandgap of most organic polymers usually lead to low‐yield and high operation power microelectronic devices, that permit their further application in neuromorphic computing. Herein, an organic‐inorganic hybrid memristor that can be conveniently processed into crossbar devices with tolerable yield via spin‐coating is shown. The doped inorganic polyoxometalate (POM) clusters via supramolecular assembly strategy not only act as the charge trapping modules but also assist the formation of conductive filaments due to their delocalized electrostatic adsorption property. With the dynamic short‐term memory property, the designed memristor devices can be used as a reservoir framework to process temporal information directly. A smaller reservoir with 100 memristors can be used for the recognition of emotion patterns efficiently. This strategy demonstrates the unique role of POM in developing low‐power and repeated memristors, which provides a new material platform to design advanced function memristors for neuromorphic computing.

Efficient bio-assembled nanogenerator fabricated from chicken bone epidermis

Using biological self-powered materials as a new energy source to replace traditional batteries to power micro-electronic devices is a current research hotspot. We herein fabricate a piezoelectric bio-nanogenerator from chicken bones. The nanogenerator can output a voltage of 1.25 V and a current of 9 nA after being subjected to a pressure of 30 N. This research facilitates an in-depth understanding of bio-nanogenerators and provides a new strategy for reusing bio-waste.

An Overview of High-Performance Indoor Organic Photovoltaics.

In recent years, indoor organic photovoltaics (IOPVs) have attracted increasing attention because of their ability to power microelectronic devices and sensors, especially for the internet of things (IoT). In contrast with silicon-based indoor PV, the IOPVs exhibit better performance due to their tunable bandgap via molecular design, which could achieve a better spectrum matched with the lighting sources. Based on the simulated power conversion efficiency (PCE) in theory, the maximum value can achieve over 50 % under the white LED illumination, which is much higher than the practical top PCE of 31 %, indicating there is room further to improve the performance of IOPVs by various optimization methods. Based on these benefits, the recent progress in IOPVs with different methods was summarizes, and light was shed on the remaining challenges for achieving practical applications in the future. In the end, some guidelines for the development of IOPVs were proposed.

Optimisation of energy harvesting for stiffened composite shells with application to the aircraft wing at structural flight frequency

The conversion of structural dynamic strain into electric power using piezoelectric transducers to power microelectronic devices and wireless sensor nodes for structure health monitoring has been receiving growing attention from academic researchers and industry. Harvesting electric energy from vibration and storing it in an external infinite life-span capacitor is a proposed technique to eliminate the drawbacks of using conventional finite life-span batteries. Optimisation of the harvested power is an important research topic to ensure an endless power source with sufficient flow of electricity.This paper concerns optimisation of energy harvesting for composite shells stiffened by beams, with discrete flexible composite piezoelectric sensors bonded to the surface and located optimally. A homogenous composite shell stiffened by beams with a bonded piezoelectric transducer connected to an external resistive load is modelled using three-dimensional solid finite elements. An efficient and effective placement methodology is proposed to find the optimal locations of piezoelectric sensors based on the maximisation of average percentage sensor effectiveness as an objective function. This study is firstly verified against published work for a cantilever flat plate and beam, and then implemented to optimise the energy harvesting for a composite aircraft wing at structural frequencies during flight. The results show a high reduction in computational effort and improved effectiveness of the methodology to optimise energy harvesting for complex and large-scale structures compared with alternative methods. Furthermore, the harvesting power obtained from optimal sensor distribution shows promise to be sufficient to activate wireless sensor nodes for health monitoring.

Optimization of Non-Uniform Deformation on Piezoelectric Circular Diaphragm Energy Harvester with a Ring-Shaped Ceramic Disk.

Piezoelectric energy harvesting technology using the piezoelectric circular diaphragm (PCD) has drawn much attention because it has great application potential in replacing chemical batteries to power microelectronic devices. In this article, we have found a non-uniform strain distribution inside the PCD energy harvester. From the edge to the center of the ceramic disk, its output voltage first increases and then decreases. This uneven output voltage reduces the output power of the PCD energy harvester. Based on this phenomenon, we reduce the ceramic disk diameter and dig a hole in the center, analyzing the effect of removing the ceramic disk’s low output voltage part on the PCD energy harvester. The experimental results show that removing the ceramic disk’s low output voltage part can improve the output power, reduce the resonance frequency, and increase the optimal impedance of the PCD energy harvester. Under the conditions of 10 g proof mass, 9.8 m/s2 acceleration, the PCD energy harvester with a 19-mm diameter and a 6-mm hole can reach a maximum output power of 8.34 mW.

A New Portable Energy Harvesting Device Mounted on Shoes: Performance and Impact on Wearer

With the rapid development of microelectronic technology, increasing wearable devices are available for us in daily lives. These wearable devices are usually powered by batteries, so the endurance of wearable devices is limited by battery capacity. Biomechanical energy harvesting (EH) is a promising approach to extend the endurance or replace batteries to power microelectronic devices. In this paper, we would first review the different types of EH devices and analyze the key technologies. Secondly, to compare the advantages and disadvantages of different EH devices, the design guidelines of the EH device is proposed. According to the design guidelines, an EH device with a weight of only 110 g is designed, which is lighter than the suspended-load backpack (38 kg) and the knee harvester (1.6 kg). Our EH device is able to convert the vibrations energy generated by the motion of lower limbs into electrical energy. Finally, to verify whether our EH device meets the design guidelines, three sets of experiment are conducted to evaluate the performance of the EH device. Experiment A is used to monitor the metabolic energy and electricity energy. According to experiment data, we calculate the COH and TCOH of EH device. The lowest COH and TCOH are 58 and 59, respectively. The TCOH of our EH device is higher than suspended-load backpack (30.7) and the knee harvester (13.6). Experiment B is used to test the adaptability of the EH device under the different conditions of terrains and walking speeds. The EH device is able to harvest energy in different terrains (up and down stair, at the treadmill with a slope of 0°, 5° and 10°) and at different speeds(4 km/h~8 km/h). The converted electrical power is up to 7.71 mW during walking at the speed of 8 km/h and is up to 5.28 mW when going up stairs. Experiment C is conducted to investigate the influence of the EH device on human motion by measuring the torque of the ankle, knee, and hip joints. When comparing the curves of torque, the EH device does not influence the biological moment of joints, indicating the EH device does not interfere with the movement. At the same time, another method to calculate the TCOH by calculating the net work done by the muscle in a gait cycle is proposed. When comparing the TCOH calculated by the metabolic energy with the TCOH calculated by the additional work done by the muscle, the results are basically the same. Meanwhile, the variation of the latter calculation result is smaller, indicating the method proposed by us is more precise.

Natural wood-based triboelectric nanogenerator as self-powered sensing for smart homes and floors

Abstract With the rapid development of Internet of things (IoTs), big data collection and analysis based on distributed sensing is particularly important. Here, we report a natural biodegradable wood-based triboelectric nanogenerator (W-TENG), which not only can produce high electric output to power microelectronic devices, but also can be used as a self-powered sensor. A pure natural biodegradable and pollution-free wood is used as the triboelectric material. The output voltage and current of the W-TENG (8 cm × 8 cm) is 220 ± 20 V and 5.8 ± 0.5 μA at a frequency of 2 Hz. The maximum output power density could be as high as 158.2 mW/m2 at a resistance of 50 MΩ. On this basis, The W-TENG can be widely used as self-powered light switch, self-powered doorbell which can realize the intelligent control of the lights and contribute to the energy conservation to a great extent. In addition, it can be designed as a smart floor and installed on the stage wooden floor to track and record the dancers' movements. Moreover, dancers can control the lights themselves through the floor under their feet. This W-TENG based self-powered system breaks new ground for wood-based electronics, which will have potential applications in big data analysis, smart home and smart city environments.

Reliability based design optimization of wire bonding in power microelectronic devices

This paper presents a numerical investigation of the probabilistic approach in estimating the reliability of wire bonding, and develops a reliability-based design optimization Methodology (RBDO) for microelectronic device structures. The objective of the RBDO method is to design structures which should be both economical and reliable where the solution reduces the structural weight in uncritical regions. It does not only provide an improved design, but also a higher level of confidence in the design. The Finite element simulation model intends to analyze the sequence of the failure events in power microelectronic devices. This numerical model is used to estimate the probability of failure of power module regarding the wire bonding connection. However, due to time-consuming of the multiphysics finite element simulation, a response surface method is used to approximate the response output of the limit state, in this way the reliability analysis is performed directly to the response surface by using the First and the Second Order Reliability Methods FORM/SORM. Subsequently the reliability analysis is integrated in the optimization process to improve the performance and reliability of structural design of wire bonding. The sequential RBDO algorithm is used to solve this problem and to find the best structural designs which realize the best compromise between cost and safety.

Heat transfer enhancement of microchannel heat sink using transcritical carbon dioxide as the coolant

Microchannel heat sink (MCHS) is regarded as a promising cooling scheme for high power microelectronic devices. To further enhance its cooling capacity and improve the temperature uniformity, the investigation of the MCHS employing transcritical CO2 as coolant was conducted in this work for the first time. A three-dimensional solid–fluid conjugated model is developed to investigate the performance of CO2-cooled MCHS. Sufficiently changed thermophysical properties of the transcritical CO2 is taken into account in the model. The results demonstrate that, with the same pumping power of 0.03W, the thermal resistance (R) of the CO2-cooled MCHS is reduced by 23.34–34.62% in the inlet temperature range of 285–305K, as compared with the water-cooled MCHS. Likewise, the maximum temperature drop (ΔTb,max) on the bottom surface is decreased by 24.18–48.75%. The improved performance is attributed to the lower viscosity and higher specific heat of the transcritical CO2. Moreover, as compared with the water-cooled MCHS, R and ΔTb,max for the CO2-cooled MCHS exhibit a more significant reduction when the MCHS has a larger number of channels, a larger channel aspect ratio, or a smaller channel width to pitch ratio. For a given inlet pressure pin of CO2, the optimal inlet temperature should be appropriately lower than the pseudocritical temperature at the given pin to ensure the larger specific heat for CO2 flowing in microchannels.

Microstructure and mechanical properties of W/Cu vacuum diffusion bonding joints using amorphous Fe–W alloy as interlayer

W/Cu Functionally Graded Materials (FGM) are promising materials to be used as plasma facing materials (PFM) for a fusion reactor as well as a heat sink material for high power microelectronic devices. The immiscible properties in W and Cu, however, make it difficult to join each other without introduction of active metals like iron group elements. In this paper, pulse electro-deposited Fe–W amorphous alloy forming on a copper sheet was proposed as interlayer to join W and Cu via vacuum diffusion bonding. It was found that an improvement in bonding strength and a decrease in bonding residual stresses was obtained by the bidirectional diffusion of Fe, in the form of highly active amorphous state, in W and Cu at the weld temperature. The diffusion transition regions were formed near the W/Cu interface which is consisted of a solid solution zone and various phases between the Fe–W and Fe–Cu binary systems and two different fracture phenomena was observed on the basis of the microstructural characteristics. With the introduction of this new kind amorphous coating as interlayer, the vacuum diffusion bonding joint of W and Cu heating at 950 °C for an hour with a load of 30 MPa showed a maximum tensile strength of about 146 MPa.