Self-powered Microsystems Research Articles

High-performance omnidirectional-sliding hybrid nanogenerator for self-powered wireless nodes

Energy-autonomous smart electronics have been the focus of the next generation of the Internet of Things. Recently, advanced power technology with sustainable energy supply and pollution-free characteristics has become a research hotspot. Herein, to realize a reliable and unattended power unit, we propose a high-performance omnidirectional-sliding triboelectric-electromagnetic hybrid nanogenerator (OS-TEHNG) to convert the mechanical energy into electricity. The free-standing triboelectric nanogenerator (TENG) achieves a charge transfer of 24.4 μC in one cycle and a short-circuit current of 0.36 mA after optimizing the electrode structure. The TENG with 130 kΩ impedance allows efficient charging of energy storage units without complex power management modules (PMMs). The electromagnetic part achieves an open-circuit voltage of 300 V after optimization. OS-TEHNG achieves a peak power density of 1568.4 W/m3 and an average power density of 352.3 W/m3 at 2 Hz. As a result, OS-TEHNG charges a 1 mF capacitor to 46 V within 8 s. The strong power supply capability allows OS-TEHNG to charge smartwatches and phones. Furthermore, a completely self-powered wireless keyboard with a PMM and an energy storage unit based on OS-TEHNG is developed. The wireless self-powered keyboard sends data 213 times after only sliding the OS-TEHNG once. Finally, OS-TEHNG is successfully demonstrated to drive a 40 mW wireless sensor node with a 1.3-inch OLED screen in continuous operation. This work represents a significant advance toward self-powered microsystems and practical power sources.

Silicone Rubber Based-Conductive Composites for Stretchable “All-in-One” Microsystems

Wearable electronics with development trends such as miniaturization, multifunction, and smart integration have become an important part of the Internet of Things (IoT) and have penetrated various sectors of modern society. To meet the increasing demands of wearable electronics in terms of deformability and conformability, many efforts have been devoted to overcoming the nonstretchable and poor conformal properties of traditional functional materials and endowing devices with outstanding mechanical properties. One of the promising approaches is composite engineering in which traditional functional materials are incorporated into the various polymer matrices to develop different kinds of functional composites and construct different functions of stretchable electronics. Herein, we focus on the approach of composite engineering and the polymer matrix of silicone rubber (SR), and we summarize the state-of-the-art details of silicone rubber-based conductive composites (SRCCs), including a summary of their conductivity mechanisms and synthesis methods and SRCC applications for stretchable electronics. For conductivity mechanisms, two conductivity mechanisms of SRCC are emphasized: percolation theory and the quantum tunneling mechanism. For synthesis methods of SRCCs, four typical approaches to synthesize different kinds of SRCCs are investigated: mixing/blending, infiltration, ion implantation, and in situ formation. For SRCC applications, different functions of stretchable electronics based on SRCCs for interconnecting, sensing, powering, actuating, and transmitting are summarized, including stretchable interconnects, sensors, nanogenerators, antennas, and transistors. These functions reveal the feasibility of constructing a stretchable all-in-one self-powered microsystem based on SRCC-based stretchable electronics. As a prospect, this microsystem is expected to integrate the functional sensing modulus, the energy harvesting modulus, and the process and response modulus together to sense and respond to environmental stimulations and human physiological signals.

Laser-Induced Interdigital Structured Graphene Electrodes Based Flexible Micro-Supercapacitor for Efficient Peak Energy Storage.

The rapidly developing demand for lightweight portable electronics has accelerated advanced research on self-powered microsystems (SPMs) for peak power energy storage (ESs). In recent years, there has been, in this regard, a huge research interest in micro-supercapacitors for microelectronics application over micro-batteries due to their advantages of fast charge–discharge rate, high power density and long cycle-life. In this work, the optimization and fabrication of micro-supercapacitors (MSCs) by means of laser-induced interdigital structured graphene electrodes (LIG) has been reported. The flexible and scalable MSCs are fabricated by CO2-laser structuring of polyimide-based Kapton ® HN foils at ambient temperature yielding interdigital LIG-electrodes and using polymer gel electrolyte (PGE) produced by polypropylene carbonate (PPC) embedded ionic liquid of 1-ethyl-3-methyl-imidazolium-trifluoromethansulphonate [EMIM][OTf]. This MSC exhibits a wide stable potential window up to 2.0 V, offering an areal capacitance of 1.75 mF/cm2 at a scan rate of 5.0 mV/s resulting in an energy density (Ea) of 0.256 µWh/cm2 @ 0.03 mA/cm2 and power density (Pa) of 0.11 mW/cm2 @0.1 mA/cm2. Overall electrochemical performance of this LIG/PGE-MSC is rounded with a good cyclic stability up to 10,000 cycles demonstrating its potential in terms of peak energy storage ability compared to the current thin film micro-supercapacitors.

A High-Sensitivity Wide Input-Power-Range Ultra-Low-Power RF Energy Harvester for IoT Applications

Radio frequency energy harvesting (RFEH) is very attractive for the Internet of things (IoT) and self-powered micro-systems such as wearable biomedical devices and wireless sensor networks. This paper proposes, analyzes, and implements a new RF-DC converter in standard 130 nm CMOS technology. The developed converter is designed and optimized for ultra-low-power IoT and wearable biomedical applications using the 900 MHz ISM band. The proposed 10-stage cross-connected rectifier compensates the transistors threshold voltage by using both dynamic and static bias compensation techniques. An analytical model of the rectifier based on the MOSFET transistor equations is presented, allowing optimization of the rectifier as a function of the number of stages and transistors sizing, improving the sensitivity and the input power range of the converter. The measurement results demonstrate a sensitivity of &#x2212;25.5 dBm for 1 V output across a 5-<inline-formula> <tex-math notation="LaTeX">$\text{M}\Omega $ </tex-math></inline-formula> resistive load and &#x2212;29 dBm for a 100 <inline-formula> <tex-math notation="LaTeX">$\text{M}\Omega $ </tex-math></inline-formula> load, which is better than the best previously reported results. The measured peak end-to-end efficiency of the proposed harvester is 42.4&#x0025; at &#x2212;16 dBm input power, delivering 2.19 V to a 450 <inline-formula> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> load.

On-chip higher-order topological micromechanical metamaterials

Metamaterials with higher-order topological band gaps that exhibit topological physics beyond the bulk-edge correspondence provide unique application values due to their ability of integrating topological boundary states at multiple dimensions in a single chip. On the other hand, in the past decade, micromechanical metamaterials are developing rapidly for various applications such as micro-piezoelectric-generators, intelligent micro-systems, on-chip sensing and self-powered micro-systems. To empower these cutting-edge applications with topological manipulations of elastic waves, higher-order topological mechanical systems working at high frequencies (MHz) with high quality-factors are demanded. The current realizations of higher-order topological mechanical systems, however, are still limited to systems with large scales (centimetres) and low frequencies (kHz). Here, we report the first experimental realization of an on-chip micromechanical metamaterial as the higher-order topological insulator for elastic waves at MHz. The higher-order topological phononic band gap is induced by the band inversion at the Brillouin zone corner which is achieved by configuring the orientations of the elliptic pillars etched on the silicon chip. With consistent experiments, theory and simulations, we demonstrate the emergence of coexisting topological edge and corner states in a single silicon chip as induced by the higher-order band topology. The experimental realization of on-chip micromechanical metamaterials with higher-order topology opens a new regime for materials and applications based on topological elastic waves.

Low Temperature Deposition of Highly Cyclable Porous Prussian Blue Cathode for Lithium-Ion Microbattery.

Small dimension Li-ion microbatteries are of great interest for embedded microsystems and on-chip electronics. However, the deposition of fully crystallized cathode thin film generally requires high temperature synthesis or annealing, incompatible with microfabrication processes of integrated Si devices. In this work, a low temperature deposition process of a porous Prussian blue-based cathode on Si wafers is reported. The active material is electrodeposited under aqueous conditions using a pulsed deposition protocol on a porous dendritic metallic current collector that ensures good electronic conductivity of the composite. The high voltage cathodes exhibit a huge areal capacity of ≈650 μAh cm-2 and are able to withstand more than 2000 cycles at 0.25mA cm-2 rate. The application of these electrode composites with porous Sn based alloying anodes is also demonstrated for the first time in full cell configuration, with high areal energy of 3.1 J cm-2 and more than 95% reversible capacity. This outstanding performance can be attributed to uniform deposition of Prussian blue materials on conductive matrix, which maintains electronic conductivity while simultaneously providing mechanical integrity to the electrode. This finding opens new horizons in the monolithic integration of energy storage components compatible with the semiconductor industry for self-powered microsystems.

The Interface between Nanoenergy and Self-Powered Electronics.

In recent decades, nanogenerators based on several techniques such as triboelectric effects, piezoelectric effects, or other mechanisms have experienced great developments. The nanoenergy generated by nanogenerators is supposed to be used to overcome the problem of energy supply problems for portable electronics and to be applied to self-powered microsystems including sensors, actuators, integrated circuits, power sources, and so on. Researchers made many attempts to achieve a good solution and have performed many explorations. Massive efforts have been devoted to developing self-powered electronics, such as self-powered communication devices, self-powered human–machine interfaces, and self-powered sensors. To take full advantage of nanoenergy, we need to review the existing applications, look for similarities and differences, and then explore the ways of achieving various self-powered systems with better performance. In this review, the methods of applying nanogenerators in specific circumstances are studied. The applications of nanogenerators are classified into two categories, direct utilization and indirect utilization, according to whether a treatment process is needed. We expect to offer a line of thought for future research on self-powered electronics.

Textile-Based Triboelectric Nanogenerators for Wearable Self-Powered Microsystems.

In recent years, wearable electronic devices have made considerable progress thanks to the rapid development of the Internet of Things. However, even though some of them have preliminarily achieved miniaturization and wearability, the drawbacks of frequent charging and physical rigidity of conventional lithium batteries, which are currently the most commonly used power source of wearable electronic devices, have become technical bottlenecks that need to be broken through urgently. In order to address the above challenges, the technology based on triboelectric effect, i.e., triboelectric nanogenerator (TENG), is proposed to harvest energy from ambient environment and considered as one of the most promising methods to integrate with functional electronic devices to form wearable self-powered microsystems. Benefited from excellent flexibility, high output performance, no materials limitation, and a quantitative relationship between environmental stimulation inputs and corresponding electrical outputs, TENGs present great advantages in wearable energy harvesting, active sensing, and driving actuators. Furthermore, combined with the superiorities of TENGs and fabrics, textile-based TENGs (T-TENGs) possess remarkable breathability and better non-planar surface adaptability, which are more conducive to the integrated wearable electronic devices and attract considerable attention. Herein, for the purpose of advancing the development of wearable electronic devices, this article reviews the recent development in materials for the construction of T-TENGs and methods for the enhancement of electrical output performance. More importantly, this article mainly focuses on the recent representative work, in which T-TENGs-based active sensors, T-TENGs-based self-driven actuators, and T-TENGs-based self-powered microsystems are studied. In addition, this paper summarizes the critical challenges and future opportunities of T-TENG-based wearable integrated microsystems.

Wearable multi-sensing double-chain thermoelectric generator

Wearable electronics play a crucial role in advancing the rapid development of artificial intelligence, and as an attractive future vision, all-in-one wearable microsystems integrating powering, sensing, actuating and other functional components on a single chip have become an appealing tendency. Herein, we propose a wearable thermoelectric generator (ThEG) with a novel double-chain configuration to simultaneously realize sustainable energy harvesting and multi-functional sensing. In contrast to traditional single-chain ThEGs with the sole function of thermal energy harvesting, each individual chain of the developed double-chain thermoelectric generator (DC-ThEG) can be utilized to scavenge heat energy, and moreover, the combination of the two chains can be employed as functional sensing electrodes at the same time. The mature mass-fabrication technology of screen printing was successfully introduced to print n-type and p-type thermoelectric inks atop a polymeric substrate to form thermocouples to construct two independent chains, which makes this DC-ThEG flexible, high-performance and cost-efficient. The emerging material of silk fibroin was employed to cover the gap of the fabricated two chains to serve as a functional layer for sensing the existence of liquid water molecules in the air and the temperature. The powering and sensing functions of the developed DC-ThEG and their interactions were systematically studied via experimental measurements, which proved the DC-ThEG to be a robust multi-functional power source with a 151 mV open-circuit voltage. In addition, it was successfully demonstrated that this DC-ThEG can convert heat energy to achieve a 3.3 V output, matching common power demands of wearable electronics, and harvest biothermal energy to drive commercial electronics (i.e., a calculator). The integration approach of powering and multi-functional sensing based on this new double-chain configuration might open a new chapter in advanced thermoelectric generators, especially in the applications of all-in-one self-powered microsystems.

High Areal Capacity Porous Sn-Au Alloys with Long Cycle Life for Li-ion Microbatteries

Long-term stability is one of the most desired functionalities of energy storage microdevices for wearable electronics, wireless sensor networks and the upcoming Internet of Things. Although Li-ion microbatteries have become the dominant energy-storage technology for on-chip electronics, the extension of lifetime of these components remains a fundamental hurdle to overcome. Here, we develop an ultra-stable porous anode based on SnAu alloys able to withstand a high specific capacity exceeding 100 µAh cm−2 at 3 C rate for more than 6000 cycles of charge/discharge. Also, this new anode material exhibits low potential (0.2 V versus lithium) and one of the highest specific capacity ever reported at low C-rates (7.3 mAh cm−2 at 0.1 C). We show that the outstanding cyclability is the result of a combination of many factors, including limited volume expansion, as supported by density functional theory calculations. This finding opens new opportunities in design of long-lasting integrated energy storage for self-powered microsystems.

Unidirectional-current triboelectric nanogenerator based on periodical lateral-cantilevers

Abstract In view of sustainable energy sources to power the Internet of Things, recently an emerging mechanism of environmental energy harvesting has been developed and named triboelectric nanogenerator (TENG), which has been proven to be clean and robust. However, the intrinsic feature of alternating-current (AC) output of TENG greatly limits its further real-life applications, since an extra rectifier circuit must be employed to convert it to be unidirectional-current output, which increases the complexity and cost of self-powered microsystem integration. Herein, we proposed a new unidirectional-current triboelectric nanogenerator (UC-TENG) based on an innovative design of periodical lateral-cantilevers. With the help of the combination of specially-patterned conductive networks (i.e., inner and outer connections) and lateral-cantilevers placed on the comb bars of their comb-shaped structures, the motion of charges is controlled in a sole direction to form a unidirectional-current flow. The operation mechanism of the proposed UC-TENG was systematically investigated by FEA (finite-element analysis) simulation and electrical measurements, and the uniformly stably unidirectional feature of electric waveforms was proven. The maximum open-circuit voltage, short-circuit current and power density achieved 300 V, 1.4 μA and 15.68 mW/m2, respectively. Moreover, the fabricated UC-TENG was successfully demonstrated to power capacitors and low-power-consumption electronic devices (i.e., thermometer and calculator) directly and continuously. This novel UC-TENG based on lateral-cantilevers simplifies the power management circuit of traditional TENG by avoiding the rectifier circuit, which significantly broadens the attractive potentials of TENG by improving the integration of self-powered microsystems.

Evaluation of vibration energy harvesting using a magnetostrictive iron–cobalt/nickel-clad plate

The design of miniaturized, long-lasting power supplies for portable internet of things (IoT) equipment has been identified as a critical problem constraining further development of the IoT. A promising methodology is able to resolve the problem by harvesting dissipated energy such as vibration in the environment or in a system to form self-powered microsystems. In this work, the performance of vibration energy harvesting using a magnetostrictive iron–cobalt/nickel (FeCo/Ni)-clad plate cantilever was examined both theoretically and experimentally. The experimental results indicate that the output power of the FeCo/Ni-clad plate cantilever shows significant improvement in comparison to a single FeCo plate, as a result of the inverse magnetostrictive properties of the FeCo and Ni layers in response to tension or compression. Finite element analysis illustrates how the unidirectional and identical magnetic induction in the upper and lower sides (i.e. the FeCo and Ni layers) gives rise to this enhanced output. The analysis also demonstrates the cancellation of the positive and negative magnetic induction within the interior of the single FeCo plate. This study not only provides insights into the magnetic features of a FeCo/Ni-clad plate but also proposes a feasible method for realizing industrial applications.

Review and Prospect of Triboelectric Nanogenerators in Self-powered Microsystems

Review and Prospect of Triboelectric Nanogenerators in Self-powered Microsystems

Frequency band widening technique for cantilever-based vibration energy harvesters through dynamics of fluid motion

Vibration energy harvesting has evoked great interests for a wide variety of self-powered microsystems. Vibration energy harvesters typically have a narrow bandwidth, which causes infeasibility for real-life applications. This issue has been addressed by incorporating frequency band widening technique with the help of fluid filled tip mass. It is based on the principle of center of gravity shifts due to the mass change caused by the dynamic motion of the fluid. This concept has been validated through simulations and experimentation carried out for piezoelectric patches from MIDE™, MEAS™ and our fabricated device. Performance evaluation of piezoelectric energy harvester has been carried with solid, and fluid filled tip mass. Open circuit electric potential of 7.4 V with 10 Hz bandwidth has been recorded for fluid (honey-motor oil mixture) tip mass in contrast with 4 Hz bandwidth for solid tip mass. It is found that fluid-filled tip mass has broadened frequency band by 250% without affecting harvested power.

Medlay: A Reconfigurable Micro-Power Management to Investigate Self-Powered Systems.

In self-powered microsystems, a power management is essential to extract, transfer and regulate power from energy harvesting sources to loads such as sensors. The challenge is to consider all of the different structures and components available and build the optimal power management on a microscale. The purpose of this paper is to streamline the design process by creating a novel reconfigurable testbed called Medlay. First, we propose a uniform interface for management functions e.g., power conversion, energy storing and power routing. This interface results in a clear layout because power and status pins are strictly separated, and inputs and outputs have fixed positions. Medlay is the ready-to-use and open-hardware platform based on the interface. It consists of a base board and small modules incorporating e.g., dc-dc converters, power switches and supercapacitors. Measurements confirm that Medlay represents a system on one circuit board, as parasitic effects of the interconnections are negligible. The versatility regarding different setups on the testbed is determined to over 250,000 combinations by layout graph grammar. Lastly, we underline the applicability by recreating three state-of-the-art systems with the testbed. In conclusion, Medlay facilitates building and testing power management in a very compact, clear and extensible fashion.

A Review on Piezoelectric Energy Harvesting: Materials, Methods, and Circuits

Abstract Piezoelectric microelectromechanical systems (PiezoMEMS) are attractive for developing next generation self-powered microsystems. PiezoMEMS promises to eliminate the costly assembly for microsensors/microsystems and provide various mechanisms for recharging the batteries, thereby, moving us closer towards batteryless wireless sensors systems and networks. In order to achieve practical implementation of this technology, a fully assembled energy harvester on the order of a quarter size dollar coin (diameter=24.26 mm, thickness=1.75 mm) should be able to generate about 100 μW continuous power from low frequency ambient vibrations (below 100 Hz). This paper reviews the state-of-the-art in microscale piezoelectric energy harvesting, summarizing key metrics such as power density and bandwidth of reported structures at low frequency input. This paper also describes the recent advancements in piezoelectric materials and resonator structures. Epitaxial growth and grain texturing of piezoelectric materials is being developed to achieve much higher energy conversion efficiency. For embedded medical systems, lead-free piezoelectric thin films are being developed and MEMS processes for these new classes of materials are being investigated. Non-linear resonating beams for wide bandwidth resonance are also reviewed as they would enable wide bandwidth and low frequency operation of energy harvesters. Particle/granule spray deposition techniques such as aerosol-deposition (AD) and granule spray in vacuum (GSV) are being matured to realize the meso-scale structures in a rapid manner. Another important element of an energy harvester is a power management circuit, which should maximize the net energy harvested. Towards this objective, it is essential for the power management circuit of a small-scale energy harvester to dissipate minimal power, and thus it requires special circuit design techniques and a simple maximum power point tracking scheme. Overall, the progress made by the research and industrial community has brought the energy harvesting technology closer to the practical applications in near future.

Twenty-Eight Orders of Parametric Resonance in a Microelectromechanical Device for Multi-band Vibration Energy Harvesting.

This paper contends to be the first to report the experimental observation of up to 28 orders of parametric resonance, which has thus far only been envisioned in the theoretical realm. While theory has long predicted the onset of n orders of parametric resonance, previously reported experimental observations have been limited up to about the first 5 orders. This is due to the rapid narrowing nature of the frequency bandwidth of the higher instability intervals, making practical accessibility increasingly more difficult. Here, the authors have experimentally confirmed up to 28 orders of parametric resonance in a micromachined membrane resonator when electrically undamped. While the implication of this finding spans across the vibration dynamics and transducer application spectrum, the particular significance of this work is to broaden the accumulative operational frequency bandwidth of vibration energy harvesting for enabling self-powered microsystems. Up to 5 orders were recorded when driven at 1.0 g of acceleration across a matched load of 70 kΩ. With a natural frequency of 980 Hz, the fundamental mode direct resonance had a −3 dB bandwidth of 55 Hz, in contrast to the 314 Hz for the first order parametric resonance; furthermore, the half power bands of all 5 orders accumulated to 478 Hz.

Exploring Next Generation Energy Harvesters with PPE and IDE Electrodes: A Review

Next generation harvesters promises environment friendly material suitable for medical field also. This paper reviews recent energy harvester for self-powered Microsystems and propose ZnO piezoelectric material for next generation harvesters. In addition to this, Vibration-powered generators are typically subjected to various design related issues which are addressed in this paper.Power can be generated from various environmental sources such as ambient heat, light, acoustic noise, radio waves, and vibration. Piezoelectric based harvester extract energy from the freely available ambient sources i.e. vibration or motion energy. The vibration energy can be converted to electrical energy by the use of piezoelectric PZT, ZnO, AlNGaAs cemented to micro cantilever. Piezoelectric electrodes play a vital role in energy extraction with higher efficiency .Piezoelectric-type harvesters have the highest reported energy density per volume. Furthermore, piezoelectric materials have an inherent capability of converting the mechanical energy into electrical energy, eliminating the need for external magnetic fields, complicated switching systems, and architectural design complexities. In this paper we have reviewed the work carried out by researchers during last few years. This review paper helps to new comers to decide best structure, material and approach to carry out their research work. Results obtained show a good scope for MEMS harvesters in numerous fields including medical field was far away because of poisonous piezoelectric material.

Nanostructured Membranes for MEMS Energy Harvester

The development of embedded systems and autonomous microsystems requires significant progress in the research of MEMS energy converters. Converting mechanical vibrations into electricity is an efficient way to collect environmental energy by using MEMS. Our contribution to this hot topic is based on the study of piezoelectric converters on silicon membranes. Due to the nature of the energy sources such as motorized machines, miniaturized devices working at low frequencies (few hundred hertz) with efficient coupling coefficient are needed and make essential the emergence of innovative solutions. In this work we propose an improved approach based on the insertion of nanostructured porous zones in circular monocrystalline silicon membranes used as resonating structures of piezoelectric converters. We have shown (in previous work) that nanostructured porous silicon exhibits an unexpected low rigidity due to the disordered interconnections of the crystallites in the porous zones (the Young modulus is divided by a factor of 10 for porosities around 50%). Using such porous silicon properties, ring-shaped nanostructured zones allowing the creation of low rigidity membranes combined with central seismic masses were realized and tested. Interesting potentialities for the development of high quality factor devices at low resonant frequencies have been then demonstrated. The effect of the position, the shape and the size of the nanostructured zones on the resonant frequency and the quality factor of the membrane were experimentally investigated. Complementary numerical simulations were performed using ANSYS software on same modelled structures. Keywords: MEMS on silicon, piezoelectric micro generator, porous silicon, self-powered microsystem

Designing the 3D electrostatic microgenerator

Abstract This paper discusses the design and simulation of a 3D electrostatic generator, one part of power supply component of the self-powered microsystem [1] , which is able to provide enough energy to power up smart sensor chains. In this case the most suitable method to gather enough electrical energy is so-called energy harvesting principle [2] , [3] . The designed generator is based on electrostatic converter and uses the principle of conversion of non-electric energy into electrical energy by periodical modification of gap between electrodes of a capacitor [4] . The structure is designed and modeled as three-dimensional silicon based MEMS. Innovative approach involving the achievement of very low resonant frequency of the structure (around 100 Hz) using the modified long cantilever design, minimal area of the chip, the ability to work in all 3 axes of coordinate system and the ability to be tuned to reach desired parameters shows further development.