Low-power Wireless Sensor Nodes Research Articles

A study on the renewable power generation capacity of microalgae microbial fuel cells for powering GIoT sensor nodes

Microalgae-Microbial Fuel Cell (mMFC) is a novel and attractive green renewable energy source for bio-electricity generation. Its capacity to generate energy is of particular interest for the design of sustainable green internet of things (GIoT) sensor networks. However, this capacity needs to be assessed due to critical limitations in their low-level output voltage and possible bioelectrochemical disturbances. This study investigates the renewable energy generation capacity of an mMFC-harvester system for powering low-power wireless sensor nodes. A two-chamber mMFC prototype is designed as a proof of concept using the CMI7000 membrane and the BQ25570 circuit to harvest the energy. A sensor node based on Nordic nRF52840 ultra-low-power microcontroller implements a uniform power management strategy and the energy capacity is analyzed in terms of the number of Bluetooth low energy (BLE) transmissions. Experimental results show that after an initial cold-start period in the harvester circuit, the system stores the energy in a 0.1 F supercapacitor in 6.25 h, representing 3.26 J. The maximum power density generation is 80.10 mW/m2, and the energy harvested is suitable to perform up to 9 continuous transmissions using BLE.

A hybrid vibration energy harvester with integrated piezoelectric and electrostatic devices

In recent years, energy harvesting technology has become a promising power supply method for low-power wireless sensor nodes. According to the application requirements of energy acquisition, a piezoelectric and electrostatic hybrid vibration energy harvester (HVEH) is proposed in this paper. Compared with other vibration energy harvesters, the proposed hybrid harvester is easier to miniaturize and integrate into a MEMS. The electromechanical coupling model of the hybrid harvester is established. The optimal design of the proposed harvester is carried out based on numerical simulation. The optimal matching impedance of piezoelectric and electrostatic modules are calculated based on numerical simulation and validated through experiments, which are 80–90 kΩ and 15–20 MΩ, respectively. The output power of the HVEH is increased by 0.04%, 0.08%, 0.102%, and 0.097%, when the excitation acceleration is 0.1 g, 0.15 g, 0.2 g, and 0.25 g, respectively, compared with the single piezoelectric module.

Aerosense: A Self-Sustainable and Long-Range Bluetooth Wireless Sensor Node for Aerodynamic and Aeroacoustic Monitoring on Wind Turbines

This paper presents a low-power, self-sustainable, and modular wireless sensor node for aerodynamic and acoustic measurements on wind turbines and other industrial structures. It includes 40 high-accuracy barometers, 10 microphones, 5 differential pressure sensors, and implements a lossy and a lossless on-board data compression algorithm to decrease the transmission energy cost. The wireless transmitter is based on Bluetooth Low Energy 5.1 tuned for long-range and high throughput while maintaining adequate per bit energy efficiency (80 nJ). Moreover, we fieldassessed the node capability to collect precise and accurate aerodynamic data. Outdoor experimental tests revealed that the system can acquire and sustain a data rate of 850 kbps over 438 m. The power consumption while collecting and streaming all measured data is 120 mW, enabling self-sustainability and long-term <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-situ</i> monitoring with a 111 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> photovoltaic panel.

A Concertina-Shaped Vibration Energy Harvester-Assisted NFC Sensor With Improved Wireless Communication Range

The explosive growth of wireless sensor platforms and their emerging wide range of application areas make the development of a sustainable and robust power source, an essential requirement to enable widespread deployment of these wireless devices. As a solution to this cardinal issue, this article reports the design and fabrication of a resonant vibration energy harvester (VEH) that comprises interleaved springs, manifesting a concertina-shaped structure that can enable large mechanical amplitudes of oscillation. Within a relatively small footprint (9 cm3), this concertina-VEH yields a large power density of 455.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> /cm3g2 while operating at a resonant frequency of 75 Hz. Additionally, the feasibility of the implemented VEH to support near field communication (NFC)-based wireless sensor platform, that is yet uncharted, is also investigated in this work. A very low-power consumption NFC wireless sensor node has been designed and developed for this purpose. The developed concertina VEH has been employed to power the electronics interface of this NFC sensor. Using mechanical energy derived from as low as 0.2-g excitation, our study shows that the VEH can enhance the electromagnetic interaction between the transmitting antenna and the reader, resulting in a 120% increase in wireless communication range for the NFC sensor node. Such a high-performance energy harvester-assisted NFC sensor node has the potential to be used in a wide range of Internet of Things (IoT) platforms as a reliable and sustainable power solution.

Dynamic Voltage and Frequency Scaling and Duty-Cycling for Ultra Low-Power Wireless Sensor Nodes

Energy efficiency presents a significant challenge to the reliability of Internet of Things (IoT) services. Wireless Sensor Networks (WSNs) present as an elementary technology of IoT, which has limited resources. Appropriate energy management techniques can perform increasing energy efficiency under variable workload conditions. Therefore, this paper aims to experimentally implement a hybrid energy management solution, combining Dynamic Voltage and Frequency Scaling (DVFS) and Duty-Cycling. The DVFS technique is implemented as an effective power management scheme to optimize the operating conditions during data processing. Moreover, the duty-cycling method is applied to reduce the energy consumption of the transceiver. Hardware optimization is performed by selecting the low-power microcontroller, MSP430, using experimental estimation and characterization. Another contribution is evaluating the energy-saving design by defining the normalized power as a metric to measure the consumed power of the proposed model per throughput. Extensive simulations and real-world implementations indicate that normalized power can be significantly reduced while sustaining performance levels in high-data IoT use cases.

Dual-band ambient energy harvesting systems based on metamaterials for self-powered indoorwireless sensor nodes

AbstractIn this study, we present a comprehensive dual-band ambient radio-frequency (RF) energy harvesting system, consisting of rectenna and power management circuit, to harvest energy from 2.45 and 5.8 GHz Wi-Fi. The rectenna employs a metamaterial antenna based on a split-ring resonator, which possesses omni-directional radiation pattern at both frequencies and compact size (0.18λ × 0.25λ at 2.45 GHz). The dual-band rectifier yields the highest efficiency of 42% at 2.45 GHz and 1 dBm input power, 30% at 5.8 GHz and − 7 dBm input power. The maximum RF-DC efficiency for each band is 72% at − 5 dBm and 27% at − 2 dBm, respectively. The power management circuit, consisting of a storing capacitor and a boost converter, is integrated to produce a stable, sufficient output voltage. The energy harvesting system, with its comprehensiveness, is suitable for supplying low-power wireless sensor nodes for indoor applications.

An ultra-low frequency vibration energy harvester with zigzag piezoelectric spring actuated by rolling ball

This paper presents an ultra-low frequency vibration energy harvester using a zigzag piezoelectric spring oscillator, which consists of two piezoelectric zigzag springs and a rolling metal ball. The metal ball rolls and drives the piezoelectric springs to deform to harvest energy when a slight vibration occurs in the external environment. The natural frequency of zigzag spring oscillator piezoelectric energy harvester (ZSO-PEH) is related to the length of the spring and the weight of the ball, correlation analysis is carried out by theoretical derivation and ANSYS simulation. It is found experimentally that the proposed device offers efficient energy output in ultra-low frequency excitation. A maximum output power of 5.68 mW is achieved under the best matching resistance of 5.1 kΩ at the excitation frequency of 3 Hz. The performance of energy harvester can be optimized by adjusting the length of the spring and the mass of the ball. The results show that the proposed piezoelectric energy harvester has the potential to power low-power electronic devices and wireless sensor nodes.

Theoretical modeling and experimental verification of rotational variable reluctance energy harvesters

Energy harvesting has great potential for powering low-power wireless sensor nodes by converting environmental energies into the electricity. It can be widely used for real-time online industrial monitoring. Among different transducers, the variable reluctance energy harvester (VREH) has attracted much attention due to the great performance for the low-speed rotations. However, there is a lack of precise models for performance prediction. In this paper, a new modeling method for VREH is proposed to predict the output voltage. A combined Substituting Angle - Magnetic Field Division modeling method is presented to accurately model the magnetic permeance of the air–gap for the VREH. Then, the magnetic flux change in the magnetic circuit is derived to calculate the voltage response of the coil. The numerical and experimental results of voltage responses verify the effectiveness of proposed model with the maximum error of 4%. The influence of some key factors on voltage response is investigated, including the thickness of air–gap and tooth height. Moreover, power analysis demonstrates that the output power increases from 5.06 mW to 46.7 mW with the rotational speed from 100 rpm to 300 rpm.

Design and Field Validation of a Low Power Wireless Sensor Node for Structural Health Monitoring

Smart monitoring systems are currently gaining more attention and are being employed in several technological areas. These devices are particularly appreciated in the structural field, where the collected data are used with purposes of real time alarm generation and remaining fatigue life estimation. Furthermore, monitoring systems allow one to take advantage of predictive maintenance logics that are nowadays essential tools for mechanical and civil structures. In this context, a smart wireless node has been designed and developed. The sensor node main tasks are to carry out accelerometric measurements, to process data on-board, and to send wirelessly synthetic information. A deep analysis of the design stage is carried out, both in terms of hardware and software development. A key role is played by energy harvesting integrated in the device, which represents a peculiar feature and it is thanks to this solution and to the adoption of low power components that the node is essentially autonomous from an energy point of view. Some prototypes have been assembled and tested in a laboratory in order to check the design features. Finally, a field test on a real structure under extreme weather conditions has been performed in order to assess the accuracy and reliability of the sensors.

A Wireless Multisensor Node for Long-Term Environmental Parameters Monitoring

Environmental quality is a great concern to everyone, in order to realize the collection, upload, management, and visualization of parameters of atmospheric environment in real time. We propose a cheap, low-power, and fast deployment wireless sensor node for environmental monitoring, consisting of STM32 MCU, ESP8266, light sensor, rain sensor, UV sensor, seven-in-one sensor (including temperature, humidity, PM2.5, PM10, CO2, formaldehyde, and TVOC), and solar automatic tracking module. A customized μC/OS-III runs on the node, which controls the transmission of environment parameters collected by each sensor to the cloud server through the wireless network, and then the server receives, stores, and visualizes the data. In actual test, the node collects data once an hour, and the running power of the node is low and stable. Experimental results show that the node could achieve accurate collection and transmission and display the environmental data, and solar automatic tracking module could meet long-term running of the node in the night and continuous rainy days.

Ultra-Low Frequency Eccentric Pendulum-Based Electromagnetic Vibrational Energy Harvester.

With the development of low-power technology in electronic devices, the wireless sensor network shows great potential in applications in health tracing and ocean monitoring. These scenarios usually contain abundant low-frequency vibration energy, which can be collected through appropriate energy conversion architecture; thus, the common issue of limited battery life in wireless sensor devices could be solved. Traditional energy-converting structures such as the cantilever-beam type or spring-mass type have the problem of high working frequency. In this work, an eccentric pendulum-based electromagnetic vibration energy harvester is designed, analyzed, and verified with the finite element analysis method. The pendulum that contains alternative distributed magnets in the outer side works as a rotor and has the advantages of a simple structure and low center frequency. The structure size is well scalable, and the optimal output performance can be obtained by optimizing the coil thickness and width for a given diameter of the energy harvester. The simulation results show that the energy harvester could work in ultra-low frequencies of 0.2–3.0 Hz. A full-scale prototype of the energy harvester is manufactured and tested. The center working frequency is 2.0 Hz with an average output power of 8.37 mW, which has potential for application in driving low-power wireless sensor nodes.

Vibration‐based piezoelectric, electromagnetic, and hybrid energy harvesters for microsystems applications: A contributed review

Wireless sensor nodes (WSNs) and embedded microsystems have recently gained tremendous traction from researchers due to their vast sensing and monitoring applications in various fields including healthcare, academic, finance, environment, military, agriculture, retail, and consumer electronics. An essential requirement for the sustainable operation of WSN is the presence of an uninterrupted power supply; which is currently obtained from electrochemical batteries that suffer from limited life cycles and are associated with serious environmental hazards. An alternative to replacing batteries of WSNs; either the direct replacement or to facilitate battery regular recharging, is by looking into energy harvesting for its sustainable drive. Energy harvesting is a technique by which ambient energy can be converted into useful electricity, particularly for low-power WSNs and consumer electronics. In particular, vibration-based energy harvesting has been a key focus area, due to the abundant availability of vibration-based energy sources that can be easily harvested. In vibration-based energy harvesters (VEHs), different optimization techniques and design considerations are taken in order to broaden the operation frequency range through multi-resonant states, increase multi-degree-of-freedom, provide nonlinear characteristics, and implement the hybrid conversion. This comprehensive review summarizes recent developments in VEHs with a focus on piezoelectric, electromagnetic, and hybrid piezoelectric-electromagnetic energy harvesters. Various vibration and motion-induced energy harvesting prototypes have been reviewed and discussed in detail with respect to device architecture, conversion mechanism, performance parameters, and implementation. Overall sizes of most of the reported piezoelectric energy harvesters are in the millimeter to centimeter scales, with resonant frequencies in the range of 2-13 900 Hz. Maximum energy conversion for electromagnetic energy harvesters can potentially reach up to 778.01 μW/cm3. The power produced by the reported hybrid energy harvesters (HEHs) is in the range of 35.43-4900 μW. Due to the combined piezoelectric-electromagnetic energy conversion in HEHs, these systems are capable of producing the highest power densities.

A Comparative Study of Wireless Sensor Network Using Cooperative Protocol

In this paper, a novel dispensed energy-efficient clustering strategy for heterogeneous wireless sensor network with fresh cooperative protocol is suggested and assessed. The cluster-heads are chosen by a likelihood issued from the ratio between cooperative energy picks and both Channel State Knowledge (CSK) and Residual Energy Knowledge (REK) consideration of node and the average energy of the network. Matching energy dissipation of Bluetooth low energy, ZigBee and ANT protocols are supplied, in which a particular scope low power wireless sensor node periodically transmits a data packet to base station. Various tests are carried out to test the performance of the CC 2520, CC 2540 and CC 2570 modules. The average network lifetime, the throughput and the packet size calculations are described. It is supposed that the differentiation offered in this paper would interest implementation engineers in choosing a proper protocol.

Study on performance characteristics of thermoelectric generator string

A thermoelectric generator (TEG) converts thermal energy directly into electrical energy. The principle work of this device is known as a Seebeck Effect. The TEG can be used effectively to harvest low thermal energy to power a low power Wireless Sensor Node (WSN). As the same as solar cells, the TEG connection can be a distributed string either in parallel or in series. However, the performance of the TEG string due to the inhomogeneity temperature gradient in each TEG is still not well investigated. This paper presents the effect of the inhomogeneity temperature gradient on the performance characteristics of the TEG string. The test is carried out using a Thermoelectric Cooler (TEC) as a thermal source on the TEG string. The experimental result is provided to verify the performance of the TEG in various cases of this inhomogeneity temperature gradient.

Event Priority Driven Dissemination EPDD management algorithm for low power WSN nodes powered by a dual source energy harvester

This paper proposes a low-power wireless sensor node which is able to deal with energy harvesting mismatches. The hardware incorporates thermoelectric and piezoelectric transducers for a dual energy harvester, energy storage, microcontroller, sensor and wireless transceiver. The software incorporates an energy-aware Event-Priority-Driven-Dissemination algorithm to send data based on priority or event occurrence. This algorithm serves both to detect the availability of the energy source and to control the nodes' sleep mode. The outcomes revealed that the hardware power was 0.16 mW and 2.13 mW in sleep and active modes respectively. Also, energy autonomy was comfortably achieved since the dual harvester energy was 90 mW when both sources were available.

Minimizing power consumption of LoRa® and LoRaWAN for low-power wireless sensor nodes

In this paper we show that RF transmissions using the physical layer of the “Long Range” (LoRa®) interface, and with some limitations also the data link and network layer Long Range Wide Area Network (LoRaWAN), are suitable even for extremely power-restricted devices, like energy-autonomous wireless sensor nodes (WSNs), if configured well. We analyse the most critical parameters and their influence on the power performance. This includes the outer circuitry, software and configuration of the transmitter SX1276 and the new SX1262. Based on that, we give specific advice to lower their power consumption and verify the impact of these measures with evaluations on an own build low power sensor node.

Development of an Energy-Aware Algorithm for Low Power Wireless Sensor Node Powered by Dual Energy Harvesting Sources

A novel self-powered wireless sensor node is proposed and prototyped to overcome the ambient energy lacking in the dual energy harvesting sources by including a secondary energy storage. Moreover, an energy-aware Event-Priority-Driven Dissemination (EPDD) management algorithm has been developed and implemented to control the WSN integrity and reducing the sensor node power consumption as well. EPDD was developed to manage the sensor node operation and to make the sink station able to detect a missing wireless node within the network, which will guarantee the nodes integrity detection. The evaluations revealed that the EPDD shows a good performance in reducing the node power consumption compared to the data push algorithm, whereby, EPDD node was operating 4 hours more than the data push node on the same power source. Regarding the WSN integrity, the EPDD algorithm outpaced the event trigger algorithm, whereby, the EPDD was easily able to detect a node down within the WSN at the contrary of the event trigger.

Delay-Aware MAC Protocol for Wireless Sensor and Actor Networks in Smart Grid

The conventional electric grid is converting in to the new emerging smart grid by utilizing information and communication technologies. The smart grid allows both the utilities and consumers to monitor and manage energy consumption effectively with the help of wireless sensor and actor networks (WSANs). WSANs have large number of low-power, low-cost, and multi-functional wireless sensor and actor nodes. The wireless sensor nodes collect the data from the physical condition of environment, while actor nodes perform different tasks according to the application requirements. For the monitoring and controlling of smart grid assets, WSANs can be considered as potential tools having the capability of low cost, high latency, and flexibility. In smart grid environment, WSANs have the problem of delay in channel access due to packet collisions. In this research work, we compare the performance results of various medium access control protocols in order to analyze which one among them is the best with respect to better throughput and minimum delay for WSANs in the smart grid environment.

Design of a high-speed low-power wireless sensor node and verification for structural health monitoring

Design of a high-speed low-power wireless sensor node and verification for structural health monitoring

Nonlinear dynamics of parametrically excited piezoelectric energy harvester with 1:3 internal resonance

In this work, the nonlinear dynamic analysis of a parametrically base excited cantilever beam based piezoelectric energy harvester is carried. The system consists of a cantilever beam with piezoelectric patches in bimorph configuration and attached mass at an arbitrary position. The attached mass is placed in such a way that the system exhibits 3:1 internal resonance. The governing spatio-temporal equation of motion is discretized to its temporal form by using generalized Galerkin’s method. To obtain the steady state voltage response and stability of the system, Method of multiple scales is used to reduce the resulting equation of motion into a set of first-order differential equations. The response and stability of the system under principal parametric resonance conditions has been studied. The parametric instability regions are shown for variation in different system parameters such as excitation amplitude and frequency, damping and load resistance. Bifurcations such as turning point, pitch-fork and Hopf are observed in the multi-branched non-trivial response. By tuning the attached mass an attempt has been made to harvest the electrical energy for a wider range of frequency. Such kind of smart self-sufficient systems may find application in powering low power wireless sensor nodes or micro electromechanical systems.