Low-power Electronic Devices Research Articles

Triboelectric nanogenerator based on silane-coupled LTA/PDMS for physiological monitoring and biomechanical energy harvesting

Energy harvesting from ambient sources present in the environment is essential to replace traditional energy sources. These strategies can diversify the energy sources, reduce maintenance, lower costs, and provide near-perpetual operation of the devices. In this work, a triboelectric nanogenerator (TENG) based on silane-coupled Linde type A/polydimethylsiloxane (LTA/PDMS) is developed for harsh environmental conditions. The silane-coupled LTA/PDMS-based TENG can produce a high output power density of 42.6 µW/cm2 at a load resistance of 10 MΩ and operates at an open-circuit voltage of 120 V and a short-circuit current of 15 µA under a damping frequency of 14 Hz. Furthermore, the device shows ultra-robust and stable cyclic repeatability for more than 30 k cycles. The fabricated TENG is used for the physiological monitoring and charging of commercial capacitors to drive low-power electronic devices. Hence, these results suggest that the silane-coupled LTA/PDMS approach can be used to fabricate ultra-robust TENGs for harsh environmental conditions and also provides an effective path toward wearable self-powered microelectronic devices.

Strain-Engineered Ferroelectricity in 2H Bilayer MoS2.

The exploration of two-dimensional (2D) materials exhibiting out-of-plane ferroelectric and piezoelectric properties through interlayer twist/translation or strain, known as sliding ferroelectricity, has become a focal point in the quest for low-power electronic devices, capitalizing on weak van der Waals interactions. Herein, we delve into the behavior of strained bilayer molybdenum disulfide (2L-MoS2) transferred onto a nanocone-patterned substrate. An intriguing observation is the emergence of unexpected vertical ferroelectricity in MoS2, irrespective of whether it was prepared using chemical vapor deposition or mechanical exfoliation from the bulk crystal. Such an observation underscores the versatility and reproducibility of the emerging ferroelectricity across different preparation methods. Furthermore, the piezoelectric coefficients recorded are exceptionally high, with the values of 37.54 and 24.80 pm V-1 for monolayer and bilayer MoS2, respectively, outperforming most currently discovered 2D piezoelectrics. The presence of room-temperature out-of-plane ferroelectricity in strained 2L-MoS2 is confirmed through first-principles calculations and piezoresponse force microscopy. This ferroelectric behavior can be attributed to the symmetry breaking and interlayer sliding within the strained 2L-MoS2 structure. Our findings not only deepen the understanding of ferroelectricity in 2D materials but also offer insights for the design of 2D ferroelectrics, thereby enabling diverse functionalities and applications in ferroelectricity.

Upgrading Sustainable Pipeline Monitoring with Piezoelectric Energy Harvesting

This study presents the design and implementation of a piezoelectric power harvesting device to capture vibrational energy from pipelines to self-powered IoT devices. The device utilizes key components along with the PPA-1001 piezoelectric sensor, the STM32F103C8T6 microcontroller, and LTC-3588 energy harvesting power supply. Experimental results verified the system’s performance in harvesting power within a specific frequency range of 10 Hz to 50 Hz, with the foremost overall performance at 30 Hz. The device generated the highest voltage of 3.3 V, delivering a power output of 2.18 mW, which is sufficient to power low-power electronic devices. The device maintained solid performance across a temperature range of 40 °C to 50 °C, underscoring its robustness in various environmental situations. The findings highlight the capacity of this form of generation to offer a sustainable power source for remote pipeline tracking, contributing to stronger protection and operational efficiency.

Self-powered human movement measurement with a unidirectional ratchet driven wearable energy harvester

A large amount of energy is generated during human movement which is mostly not effectively utilized. To collect human movement energy and utilize it rationally, a wearable piezoelectric-electromagnetic energy harvester (WPEEH) driven by a unidirectional ratchet is proposed, which adopts the principle of up-conversion to convert mechanical energy into electrical energy. The electromagnetic power generator unit is used to obtain energy to power the sensing circuit, while piezoelectric generator unit can be used for both energy generation and self-powered sensing. A spring push rod and a ratchet structure are used to convert the swinging of the human limb into the unidirectional rotation of the device to enhance its energy harvesting efficiency. The theoretical model of the WPEEH is established, and the experimental test platform is built. The results show that the WPEEH is able to generate a maximum power of 17.2 mW at an oscillation frequency of 1.5 Hz. In the actual wearable test, the proposed energy harvester is able to supply the harvested energy to the low-power electronic devices through capacitors, and it enables to light up 42 LEDs as well as to drive the digital thermo-hygrometer to work continuously and stably. Apart from having excellent properties of a high output power and low drive frequency, the proposed energy harvester also exhibits a high energy density (7.1 × 10–5 W/cm3). What’s more, the speed of human movement can be predicted and calculated for different individuals by testing the results of the swing frequency with a maximum error of 2.71 %. The investigation proves that the proposed WPEEH can measure human movement and has great potential in the field of power supply for low-power electronic devices.

Towards Integrating Pressure-Sound Piezo Energy Generator in Sports Facility Energy Mix

The paper examines the evolving landscape of energy sources within sports facilities. Traditionally reliant on electrical power and other forms of power from non-renewable resources such as coal, petroleum, and natural gas, these facilities face the inevitability of resource depletion and environmental repercussions. In response, this paper advocates for the adoption of new avenues, including energy conservation, emission reduction, energy recovery, and embracing renewable energy sources. A pioneering focus is on the implementation of a piezoelectric power generation system, tapping into typically wasted sources such as sound and human locomotion. An experimental approach explored the feasibility of such a system in order to ascertain its reliability, efficiency, and sustainability. With applications ranging from powering low-power electronic devices to environmental monitoring sensors, the successful integration of this technology promises a substantial advancement in the use of other renewable energy sources, diminishing reliance on non-renewable sources albeit on a small scale. The paper endeavours to shed light on the potential application of piezoelectric power generation in the electricity production field, aligning with the overarching objective of harvesting energy from unconventional sources and converting it into usable electrical energy. Moreover, it aims to shed light on the potential integration of piezoelectric and audio-electric generators in the energy or renewable energy mix of sports facilities, and address emerging technologies, societal impacts, and strategies to overcome barriers to adoption.

A systematic corrosion failure analysis of Li-ion powered hearing aids from various markets

Hearing aids (HA) are low-power electronic devices used worldwide. The ongoing trend in the HA industry has been to move towards Li-ion battery technology replacing conventional zinc-air batteries. The corrosion reliability of HA devices is a critical issue, due to their exposure to harsh user environments including body fluid contact, high humidity, and temperature. The combined effect of higher operating voltage (4.3 V) and design miniaturisation poses new risks for corrosion reliability. To fully understand the environmental reliability issues of the Li-ion powered HA, it is crucial to investigate field performance by conducting root cause failure analysis on the field-returned failed devices. This study investigated two different HA models (open vs. glued model). The analysis used a systematic FMEA-based approach to identify and understand failure modes, mechanisms, and potential causes using various analysis techniques (e.g., LOM, SEM&EDS, and ICP-OES). Furthermore, statistical analysis was conducted based on the repair data created by the global service centre to reveal the failure percentage, and time to failure of different components. Passive components, solder connections, and galvanic charging contact showed the highest failure percentages. The most common causes of corrosion failures were high levels of chloride ions, high humidity, flux residues, and insufficient coating protection.

Polymer Dielectric-Based Emerging Devices: Advancements in Memory, Field-Effect Transistor, and Nanogenerator Technologies.

Polymer dielectric materials have recently attracted attention for their versatile applications in emerging electronic devices such as memory, field-effect transistors (FETs), and triboelectric nanogenerators (TENGs). This review highlights the advances in polymer dielectric materials and their integration into these devices, emphasizing their unique electrical, mechanical, and thermal properties that enable high performance and flexibility. By exploring their roles in self-sustaining technologies (e.g., artificial intelligence (AI) and Internet of Everything (IoE)), this review emphasizes the importance of polymer dielectric materials in enabling low-power, flexible, and sustainable electronic devices. The discussion covers design strategies to improve the dielectric constant, charge trapping, and overall device stability. Specific challenges, such as optimizing electrical properties, ensuring process scalability, and enhancing environmental stability, are also addressed. In addition, the review explores the synergistic integration of memory devices, FETs, and TENGs, focusing on their potential in flexible and wearable electronics, self-powered systems, and sustainable technologies. This review provides a comprehensive overview of the current state and prospects of polymer dielectric-based devices in advanced electronic applications by examining recent research breakthroughs and identifying future opportunities.

(Invited) Non-Fullerene Acceptor in Organic Solar Cells Toward Improving Performance as Indoor Light Energy Harvester

Research in organic solar cells aims to develop new materials that improve efficiency. The inception of emerging non-fullerene acceptors (NFAs) by replacing the fullerene counterpart in organic solar cells (OSCs) has pushed the bulk-heterojunction based photovoltaics to achieve efficiencies around 18% [1-6]. In order to produce efficient OSCs, it is required to have donor and acceptor materials with matching absorption bands in the Vis-NIR range, high charge-carrier mobility, and a small energy offset to minimize voltage losses. Mainly, the development of Y7 NFA molecule has improved power conversion efficiencies by pairing selected polymer donors, such as PM6 [7, 8]. Nowadays, OSCs have attracted great attention for being used as indoor light energy harvesters. The organic materials in the active layer can have tuned optical band gaps, providing an absorption spectrum that matches with emission spectra of several indoor lights, e.g., halogen lights, LED (light-emitting diodes), and FLs (fluorescent lamp), which have different emitting spectra [9, 10].The use of OSCs for indoor light harvesting applications is promising for integration into low-power indoor electronic devices from microwatts to milliwatts, such as data transfer systems, alarm systems and distributed controls. Moreover, the OSCs have the possibility to be used with power wireless sensor nodes connected to the Internet of Things. At present, LEDs are the most popular low-light level sources which can be found in offices and homes. The intensity of the light emitted by an artificial light source, per unit area of a surface is called illuminance and measured in units of lux (lx). A level 500 lx is typically recommended for office environments and 200 lx for living room environments.In this research, we have been aiming at the performance and stability over time of organic solar cells under LED illumination using fullerene and non-fullerene acceptors. We have chosen as the indoor illumination source an LED lamp with a color temperature of 3000 K and color rendering index (CRI) > 80 following the protocols ISOS [11]. The LED lamp output illuminances were varied in the range from 200 to 1500 lx. We have used PM6 as polymer donor material due to their absorption spectrum and energy band gaps well-matched to the incident LED spectrum. In order to research the improvement of the performance of OSCs under indoor illumination we have compared PC70BM fullerene acceptor with ITIC-M, Y6-O, and Y7 non-fullerene acceptors. As a result, under 1000 lx illumination we achieved PCEs from ~ 12% using Y6-O, ~ 15% using PC70BM, ~16% using Y7 up to more than 18% efficiency using ITIC-M. The study is performed including optical and electrical characterization with the purpose of understanding the behavior and the transport processes taking place in the device. In future work, we focus on the stability of the encapsulated OSCs under continuous LED illumination following the agreed stability testing protocols to study which active layer turns out to be more stable under these conditions. Acknowledgements: This work was supported by the Ministerio de Ciencia, Innovación y Universidades (MICINN/FEDER) PDI2021-128342OB-I00, by the Agency for Management of University and Research Grants (AGAUR) ref. 2021-SGR-00739, and by the Catalan Institution for Research and Advanced Studies (ICREA) under the ICREA Academia Award. M. Ramírez-Como acknowledge to CONAHCYT ref. BPPA-20220624083033039-2364083.

Liquid phase exfoliation of few-layer borophene with high hole mobility for low-power electronic devices

Borophene, the two-dimensional allotrope of boron, has garnered significant interest in recent years due to its exceptional electronic, mechanical, and optical properties. In this work, an environment-friendly green approach has been utilized to synthesize p-type borophene, which consists of few layers as evidenced by electron and atomic force microscopic images. The Raman analysis indicated that these borophene layers possess β12 and χ3 phases. The photoemission spectra of these samples exhibit single exponential decay with a long lifetime of 7.2 µsec, showcasing its potential as a phosphorescent material in optoelectronics and quantum technologies. The photo-sensing capability of borophene was investigated by fabricating a Si/SiO2/Borophene/Ti/Pt photo-detector, which achieved an external quantum efficiency of 31 %, maximum photo responsivity of 200 mAW−1 and detectivity of 8.7x1011 Jones. Hall effect van der Pauw measurements revealed the p-type conductivity of the borophene film, along with a high hole mobility of 931.44 cm2V-1s−1 and a charge carrier density of 2 x 1012 cm−3, rendering these layers suitable for high-speed and low power electronic devices. This work emphasizes the importance of novel 2D materials like borophene with exceptional optoelectronic characteristics for developing future low-power electronic devices with remarkable performance.

Energy Harvesting System

Abstract: This paper presents a novel energy harvesting system designed to harness ambient mechanical energy using piezoelectric sensors, with the Arduino Uno microcontroller serving as the central processing unit. The system's primary objective is to convert mechanical vibrations into electrical energy, storing it for potential use in powering low-energy electronic devices. The proposed setup incorporates piezoelectric materials strategically positioned to capture mechanical vibrations from various sources. The core of the system is an Arduino Uno microcontroller, programmed to efficiently manage the energy harvesting process. The harvested energy is stored in a rechargeable battery, ensuring a consistent power supply for applications with intermittent energy demands. To validate the effectiveness of the system, a light bulb is employed as a demonstrative load, allowing for real-time observation of the energy harvesting capabilities. The paper details the experimental setup, including the placement and configuration of piezoelectric sensors, the Arduino Uno programming logic, and the integration of a light bulb for visual confirmation of the generated current. Performance metrics such as voltage output, current production, and power generation efficiency are thoroughly analyzed under varying environmental conditions and mechanical vibrations. Results demonstrate the feasibility of the proposed energy harvesting system, showcasing its potential as a sustainable power source for low-power electronic devices. The combination of piezoelectric materials, Arduino Uno control, and a practical load application illustrates a promising approach to energy harvesting, paving the way for advancements in self-sufficient and ecofriendly power solutions

A low-frequency piezoelectric wave energy harvester based on segmental beam and double magnetic excitation

Wave energy is a source of clean energy with huge reserves, but its application is limited owing to the low frequency of the waves. This paper proposes a low-frequency piezoelectric wave energy harvester (L-PWEH) based on segmental beam and double magnetic excitation. The L-PWEH uses a combination of mechanical and magnetic frequency tuning to achieve an improved output performance in low-frequency wave environments. The natural frequency of the segmental beam is effectively reduced by using the mechanical tuning method of the segmental beam structure. With the introduction of the tuning magnet, a double magnetic excitation of the segmental beam is formed to make it more susceptible to deformation. Multiple magnets on the rotor for excitation can obtain a better broadband effect. Through theoretical and simulation analysis, the primary variables influencing the output performance of the L-PWEH are discovered. Under ideal testing conditions, the L-PWEH can produce a peak power of 31.21 mW when the external resistance is 30 kΩ. The thermohygrometer can function effectively and be illuminated by 142 light-emitting diodes (LEDs) thanks to the L-PWEH. These findings confirm that the L-PWEH can supply low-power electronic devices with electricity.

Polar Bloch points in strained ferroelectric films

Topological domain structures have drawn great attention as they have potential applications in future electronic devices. As an important concept linking the quantum and classical magnetism, a magnetic Bloch point, predicted in 1960s but not observed directly so far, is a singular point around which magnetization vectors orient to nearly all directions. Here we show polar Bloch points in tensile-strained ultrathin ferroelectric PbTiO3 films, which are alternatively visualized by phase-field simulations and aberration-corrected scanning transmission electron microscopic imaging. The phase-field simulations indicate local steady-state negative capacitance around the Bloch points. The observation of polar Bloch points and their emergent properties consequently implies novel applications in future integrated circuits and low power electronic devices.

Multiplier Design Based on Booth and Sequential Algorithm

Research on cellular networks and low-power electronic devices has ramped up in recent years, thanks to the proliferation of portable and mobile systems. There are many portable applications in the present day that require low power (smaller and more efficient batteries) and more milli ampere hours than before. As a result, designing low-power devices has grown in importance as a performance criterion. Multipliers arrangement (it is an organized set of adders) and delay make up the basic construction of a infinite impulse response filter. This paper deals with analytic procedure for performance evaluation to reduce time and RAM usage throughout the computation process. The Booth and Sequential multipliers have been used to simulate, and implement in this article. Using the Sequential and Booth Algorithms, respectively. Comparative study is carried out utilising Xilinx 14.7 with the virtex 5 family, devices for bit lengths 4, 8, 16, and 32.

Scalable Synthesis of High-Quality Ultrathin Ferroelectric Magnesium Molybdenum Oxide.

The development of ultrathin, stable ferroelectric materials is crucial for advancing high-density, low-power electronic devices. Nonetheless, ultrathin ferroelectric materials are rare due to the critical size effect. Here, a novel ferroelectric material, magnesium molybdenum oxide (Mg2Mo3O8) is presented. High-quality ultrathin Mg2Mo3O8 crystals are synthesized using chemical vapor deposition (CVD). Ultrathin Mg2Mo3O8 has a wide bandgap (≈4.4eV) and nonlinear optical response. Mg2Mo3O8 crystals of varying thicknesses exhibit out-of-plane ferroelectric properties at room temperature, with ferroelectricity retained even at a 2nm thickness. The Mg2Mo3O8 exhibits a relatively large remanent polarization ranging from 33 to 52µCcm- 2, which is tunable by changing its thickness. Notably, Mg2Mo3O8 possesses a high Curie temperature (>980°C) across various thicknesses. Moreover, the as-grown Mg2Mo3O8 crystals display remarkable stability under harsh environments. This work introduces nolanites-type crystal into ultrathin ferroelectrics. The scalable synthesis of stable ultrathin ferroelectric Mg2Mo3O8 expands the scope of ferroelectric materials and may prosper applications of ferroelectrics.

One fell swoop strategized bipolar energy device for triboelectric energy harvesting and electrochemical energy storage

Bipolar energy devices are an essential feature due to the enlargement of intelligent and portable electronics in the present decade. In this work, we demonstrated a bipolar energy device using binder-free MnO2 deposited on carbon cloth (CC) by a one-step electrochemical deposition process (EDP), which was employed for solid-state supercapacitor device (SSCD) and another side of CC with Kapton (KP) as TENG device. The efficiency of the bare CC electrode was boosted by growing uniform porous MnO2 nanoballs on the surface of CC, the standalone CC electrode was aided as a positive tribo-layer, and the Kapton film as the negative tribo-layer in the TENG device. The constructed CC-KP TENG device generated a maximum peak power of 15.11 μW, whereas the MnO2 SSCD delivered energy/power density of 37.41 Wh kg−1/10000 W kg−1, respectively. Overall, the results conclude that these types of bipolar energy devices were splendid and could be used in miniatured low-power electronic devices.

Planar-type SiGe thermoelectric generator with double cavity structure

Thermoelectric power generation is a promising technology that can directly convert thermal energy into electrical energy and is expected to be applied as power supplies for low-power electronic devices, such as sensors. In particular, planar-type devices fabricated based on lithography processes not only enable significant device miniaturization and lower cost but also take advantage of materials with smaller dimensions, such as thin films and nanowires, which have attracted much attention in recent years. Silicon germanium (SiGe) is a promising thermoelectric material due to its relatively high power factor, low thermal conductivity, and compatibility with standard top-down fabrication process. We design and fabricate a planar-type thermoelectric generator with a double cavity structure using a 240 nm thick Si0.8Ge0.2 thin film and report its performance improvement. When the temperature difference is applied to the device, the measured power density of 100 μWcm−2 was achieved at ΔT = 15 K, namely, the performance normalized by the applied temperature was 0.43 μWcm−2K−2. Finally, the dependence of the device performance on the SiGe film thickness is discussed. The results from our simulation show that a maximum performance of 1.75 μWcm−2K−2 can be achieved by the current device structure, indicating the potential for future applications as thermoelectric energy harvesters.

Enhanced Indoor Conversion Efficiency of Dye-Sensitized Solar Cells by Optimizing Ball-Milling Process of TiO2 Paste

The rapid spread of the Internet of Things (IoT) along with the development of innovative low-power electronic devices has also driven the development of indoor photovoltaics. In this paper, we propose a simple and economically feasible solution that can improve the efficiency of dye-sensitized solar cells (DSSCs) under indoor light conditions by ~112%, without requiring a complex TiO2 photoanode architecture or the design of new dyes. The ball milling process of the TiO2 paste was optimized for indoor light conditions for the first time, both in terms of efficiency and production costs, by developing a rapid preparation method that can be used industrially for the application of DSSCs. A simple use of 12 mm diameter balls caused beneficial structural modifications, decreasing the size of the crystallites, and leading to a high OH generation on the TiO2 surface responsible for the improvement of energy conversion efficiency.

Performance analysis of electromagnetic vibration energy harvester under square excitation

Harvesting energy from surrounding vibrations is an effective method for powering various low-power electronic devices. The energy output performance of vibration energy harvesters under some special excitations remains to be investigated. In this paper, a vibration energy harvester (VEH) system based on a rack and pinion mechanism and a bevel gear set is proposed, and a detailed electromechanical coupling modeling of the system under general excitation and square wave excitation is carried out. The energy output characteristics of the proposed system under square wave excitation are explored through simulation and experiment. When the energy output is the target, the priority of adjusting the constituent parameters in the equivalent mass parameter, equivalent damping parameter and equivalent stiffness parameter of the system can be obtained based on the simulation results. The experimental results under periodic square wave excitation force show that the maximum output power of the proposed system is 2.7 W at an amplitude of 4 kN and a frequency of 3 Hz. This is a 55 % increase in the maximum power compared to the sinusoidal excitation under the same conditions. It is demonstrated that the proposed system has great potential to power various low-power electronic devices.

Buckling-driven piezoelectric defect-induced energy localization and harvesting using a Rubik’s cube-inspired phononic crystal structure

Wireless sensor networks that enable advanced internet of things (IoT) applications have experienced significant development. However, low-power electronics are limited by battery lifetime. Energy harvesting presents a solution for self-powered technologies. Vibration-based energy harvesting technology is one of the effective approaches to convert ambient mechanical energy into electrical energy. Various dynamic oscillating systems have been proposed to investigate the effectiveness of energizing low-power electronic sensor devices for supporting various IoT applications across engineering disciplines. Phononic crystal structures have been implemented in vibrational energy harvesters due to their unique bandgap and wave propagation properties. This work proposes a Rubik’s cube-inspired defective-state locally resonant three-dimensional (3D) phononic crystal with a 5 × 5 × 5 perfect supercell that contains 3D piezoelectric energy harvesting units. The advantage of defect-induced energy localization is utilized to harness vibrational energy. The 3D piezoelectric energy harvesting units are constructed by the buckling-driven assembling principle. Adapting to the low-frequency and broadband characteristics of ambient vibration sources, soft silicone gel is used to encapsulate the buckled 3D piezoelectric units, which are embedded in the 3D cubic phononic crystal to assemble an entire system. The energy harvesting performance of various defective layouts and their defect modes is discussed. The results demonstrate that the harvester functions well under multidirectional, multimodal, and low-frequency conditions. The proposed methodology also offers a new perspective on vibrational energy harvesters for defective phononic crystals with superior working performance.

Improved Design of PCB Coil for Magnetically Coupled Wireless Power Transfer

In recent years, wireless power transfer (WPT) has progressed rapidly in both theory and commercialization. However, existing research into WPT coil design for low-power devices to mitigate the coil offset is limited. A dual-layer printed circuit board (PCB) structure is proposed in this paper to mitigate the coil offset while retaining manufacturing simplicity for practical uses. Specifically, the impacts of key geometric parameters on the coil quality factor and coupling coefficient are analyzed through models and simulations. Equivalent PCB coils were formed for mutual inductance models, and four basic compensation circuits were analyzed. The impacts of changes in coil thickness, line width, turn spacing, and number of turns on the quality factor of PCB coils were analyzed with a fixed outer diameter of the coil. Eleven types of PCB coils were manufactured to verify the simulation results. The offset transmission efficiency can reach 46.6% with an output power of 14.4 W. The PCB coil with improved design could offer remarkable improvements in the WPT system for low-power electronic devices.