Autonomous Wireless Sensor Nodes Research Articles

Efficient Integration of Ultra-low Power Techniques and Energy Harvesting in Self-Sufficient Devices: A Comprehensive Overview of Current Progress and Future Directions.

Compact, energy-efficient, and autonomous wireless sensor nodes offer incredible versatility for various applications across different environments. Although these devices transmit and receive real-time data, efficient energy storage (ES) is crucial for their operation, especially in remote or hard-to-reach locations. Rechargeable batteries are commonly used, although they often have limited storage capacity. To address this, ultra-low-power design techniques (ULPDT) can be implemented to reduce energy consumption and prolong battery life. The Energy Harvesting Technique (EHT) enables perpetual operation in an eco-friendly manner, but may not fully replace batteries due to its intermittent nature and limited power generation. To ensure uninterrupted power supply, devices such as ES and power management unit (PMU) are needed. This review focuses on the importance of minimizing power consumption and maximizing energy efficiency to improve the autonomy and longevity of these sensor nodes. It examines current advancements, challenges, and future direction in ULPDT, ES, PMU, wireless communication protocols, and EHT to develop and implement robust and eco-friendly technology solutions for practical and long-lasting use in real-world scenarios.

A self-powered accelerometer with over-range detection for vibration and shock based on triboelectric-electromagnetic mechanism

Accelerometers based on triboelectric nanogenerators (TENGs) have garnered significant interest in recent years. However, many of these devices lack a self-sustained power supply for autonomous wireless operations and a mechanism for over-range detection. Additionally, theoretical investigations on the sensitivity of TENG-based accelerometers are scarce. In this work, a novel self-powered accelerometer for vibration and shock integrating a freestanding triboelectric-layer-based TENG (FT-TENG), two contact-separation TENGs (CS-TENGs) and an electromagnetic generator (EMG) is proposed and then investigated through both numerical simulations and experimental demonstrations. The EMG is used for vibration energy harvesting, exhibiting an impressive power output of 4.11 mW under a vibration acceleration of 12 m/s2. The FT-TENG and the CS-TENGs work for acceleration sensing and over-range detection respectively. Under vibration, the sensitivity and measurement range are related to the frequency of excitation, and the proposed accelerometer has the maximum sensitivity (0.75 V s2/m) at its natural frequency. For shock events, the sensitivity of the accelerometer is dominated by the shock duration in a short-duration range, which is estimated to be 0.12 V s2/m under a shock duration of 0.03 s. This work not only contributes to the understanding of TENGs adopted for sensing but also creates potential applications of triboelectric and electromagnetic energy harvesting and provides a feasible design for autonomous wireless sensor nodes.

Low-cost IoT-based monitoring system for precision agriculture

The increasing impact of climate change on agriculture necessitates advanced monitoring and management of environmental conditions to ensure sustainable agricultural productivity. This paper introduces a cost-effective, Internet of Things (IoT)-based smart monitoring system designed to provide real-time insights into soil moisture levels and weather conditions across various segments of a single agricultural plot. The system comprises autonomous wireless sensor nodes, a comprehensive weather station, and a centralized base station that collectively capture, process, and relay environmental data to a user-friendly mobile application. Our empirical results demonstrate that this system not only facilitates efficient environmental data monitoring and analysis but also empowers farmers with actionable intelligence for timely decision-making. The proposed model showcases a promising avenue for enhancing agricultural resilience and productivity through technology-driven precision farming.

Microcontroller Unit-Based Wireless Sensor Network Nodes: A Review.

In this paper, a detailed review of microcontroller unit (MCU)-based wireless sensor node platforms from recently published research articles is presented. Despite numerous research efforts in the fast-growing field of wireless sensor devices, energy consumption remains a challenge that limits the lifetime of wireless sensor networks (WSNs). The Internet-of-Things (IoT) technology utilizes WSNs for providing an efficient sensing and communication infrastructure. Thus, a comparison of the existing wireless sensor nodes is crucial. Of particular interest are the advances in the recent MCU-based wireless sensor node platforms, which have become diverse and fairly advanced in relation to the currently available commercial WSN platforms. The recent wireless sensor nodes are compared with commercially available motes. The commercially available motes are selected based on a number of criteria including popularity, published results, interesting characteristics and features. Of particular interest is to understand the trajectory of development of these devices and the technologies so as to inform the research and application directions. The comparison is mainly based on processing and memory specifications, communication capabilities, power supply and consumption, sensor support, potential applications, node programming and hardware security. This paper attempts to provide a clear picture of the progress being made towards the design of autonomous wireless sensor nodes to avoid redundancy in research by industry and academia. This paper is expected to assist developers of wireless sensor nodes to produce improved designs that outperform the existing motes. Besides, this paper will guide researchers and potential users to easily make the best choice of a mote that best suits their specific application scenarios. A discussion on the wireless sensor node platforms is provided, and challenges and future research directions are also outlined.

Energy Autonomous Wireless Sensor Nodes for Freight Train Braking Systems Monitoring.

Nowadays, railway freight transportation is becoming more and more crucial since it represents the best alternative to road transport in terms of sustainability, pollution, and impact on the environment and on public health. Upgrading the potentiality of this kind of transportation, it would be possible to avoid delays in goods deliveries due to road accidents, traffic jams, and other situation occurring on roads. A key factor in this framework is therefore represented by monitoring and maintenance of the train components. Implementing a real time monitoring of the main components and a predictive maintenance approach, it would be possible to avoid unexpected breakdowns and consequently unavailability of wagons for unscheduled repair activities. As highlighted in recent statistical analysis, one of the elements more critical in case of failure is represented by the brake system. In this view, a real time monitoring of pressure values in some specific points of the system would provide significant information on its health status. In addition, since the braking actions are related to the load present on the convoy, thanks to this kind of monitoring, it would be possible to appreciate the different behavior of the system in case of loaded and unloaded trains. This paper presented an innovative wireless monitoring system to perform brake system diagnostics. A low-power system architecture, in terms of energy harvesting and wireless communication, was developed due to the difficulty in applying a wired monitoring system to a freight convoy. The developed system allows acquiring brake pressure data in critical points in order to verify the correct behavior of the brake system. Experimental results collected during a five-month field test were provided to validate the approach.

A Novel Dual-band Ambient RF Energy Harvesting System for Autonomous Wireless Sensor Node Application

This paper presents a novel dual-band ambient Wi-Fi energy harvesting system for an autonomous wireless sensor node (AWSN) which operates independently without other external power source. While conventional wireless sensor nodes employing batteries with limited lifespans, an AWSN is supplied by harvested energy and does not require frequent battery replacement. Due to that reason, research on the energy harvesting aspect of AWSNs has been carried out intensively in recent years. By optimizing the matching network, the proposed ambient Wi-Fi energy harvesting system achieves a relatively good efficiency in dual-band at 2.45 GHz and 5.8 GHz. The efficiency reaches a peak at 47.45 % and 42 % at 2.45 GHz and 5.8 GHz, respectively. The proposed idea is numerically and experimentally demonstrated with the Wi-Fi source in building.

An Autonomous Wireless Sensor Node Based on Hybrid RF Solar Energy Harvesting

The widespread deployment of the Internet of Things (IoT) requires the development of new embedded systems, which will provide a diverse array of different intelligent functionalities. However, these devices must also meet environmental, maintenance, and longevity constraints, while maintaining extremely low-power consumption. In this work, a batteryless, low-power consumption, compact embedded system for IoT applications is presented. This system is capable of using a combination of hybrid solar and radiofrequency power sources and operates in the 900 MHz ISM band. It is capable of receiving OOK or ASK modulated data and measuring environmental data and can transmit information back to the requester using GFSK modulated data. The total consumption of the system during its sleep state is 920 nW. Minimum power required to operate is −15.1 dBm or 70 lux, when using only radiofrequency or solar powering, respectively. The system is fully designed with components off the shelf (COTS).

Design of a solar energy harvesting system for supplying energy to an autonomous wireless sensor node

Introduction: This paper is the product of the research “Generation of a modular electronic platform for the conformation of a WSN” developed in the EAFIT University in 2019.
 Problem: Wireless Sensor Networks (WSNs) are used as a technology of information and communication (TIC) to automate processes. Its implementation is considered non-efficient, because of their high cost concerning to the batteries replacement that the nodes conforming the WSN, require.
 Objective: The objective of the research is to develop more efficient solar energy harvesting systems that can guarantee an average performance of the wireless sensor node at a low cost.
 Methodology: Here we present the design and the implementation of a solar energy harvesting system that integrates a buck converter, a maximum power point tracking (MPPT) control, and a wireless sensor node. Besides, we do measures of voltage at the output of the buck converter and estimation of energy autonomy in the wireless sensor node.
 Results: Autonomous operation with the solar energy harvesting system was rich for the node sending packages each 20 min.
 Conclusion: This article presented a solar energy harvesting system with the implementation of an MPPT control.
 Originality: Through this research, parameters of the MPPT control are formulated for the first time for the solar energy harvesting system design, based on the duty cycle limits.
 Limitations: The availability of the devices used in the implementation of the proposed design.

Tapered nonlinear vibration energy harvester for powering Internet of Things

The lack of a sustainable power source to substitute batteries for long-term applications limits the widespread deployment of wireless sensor nodes in this era of the Internet of Things. Conventional linear Vibration Energy Harvesters are inefficient in converting ambient mechanical energy into usable electrical energy owing to their narrow frequency bandwidth when harnessing mechanical energy that is spread over a wide range of frequencies. In this work, we design, develop and demonstrate high power density nonlinear wideband energy harvesters using novel tapered spring architectures in an autonomous wireless sensor node system. These spring structures exhibit a nonlinear restoring force arising from the atypical stress distribution that can be additionally tuned by changing the taper-ratio in the structure. We investigate different tapering designs in order to achieve optimal spring hardening nonlinearities. This nonlinearity aids in widening the operable bandwidth, making the harvesters suitable for scavenging energy from real-world broadband vibrations. We obtain power densities of the order of 2660 μW/cm3g2 in the nonlinear energy harvester, outpacing most contemporary energy scavengers. We present a modified Perturb and Observe algorithm that allows tracing of the maximum power point in the context of non-stationary vibration conditions. We use the fabricated nonlinear device to power a wireless sensor node that reports on vital physical parameters (humidity, temperature), thereby enabling a resilient remote data acquisition system. This demonstrates the potential of our design to provide a sustainable energy source for platforms within the Internet of Things.

Self-sustained autonomous wireless sensing based on a hybridized TENG and PEG vibration mechanism

Autonomous wireless sensor nodes (WSN) for information acquisition and status monitoring, play an important role in the boom area of the internet of things (IoT) and industry 4.0. Self-sustained power supply is an important pursuit in massive practical applications but yet to be developed. Here we propose a novel hybrid piezoelectric generator (PEG) and triboelectric nanogenerator (TENG) to form a novel self-sustainable WSN. The PEG consisting of a hinged-hinged PZT bimorph and two T shaped proof mass, has an output power of 6.5 mW excited in 25 Hz at 1.0 g. PEG also shows broadband characteristics thanks to the impact of the TENG and tunable frequency due to the axial force. 30 serial LEDs in sine vibration and 20 serial LEDs in shock vibration are lighted up with the proposed double voltage rectifier circuit by PEG, which can serve as alarming signals in vibration and drop monitoring. The triboelectric accelerometer shows good linearity with a sensitivity of 15 V/g in 0–1.5 g with an optimized gap of 1.5 mm. After low power design, Arduino nano and RF transceiver can be sustainably powered by PEG, and send the TENG acceleration signal wirelessly by Zigbee. A VR train monitoring demonstration has been conducted showing the great prospect of the self-sustainable WSN in harsh environments. A novel hybridized piezoelectric generator (PEG) and triboelectric nanogenerator (TENG) vibration mechanism is proposed to achieve self-sustained autonomous wireless sensor node (WSN). A VR train monitoring demonstration has been conducted showing the great prospect of the self-sustainable WSN in harsh environments. • A novel hybridized PEG and TENG vibration mechanism is proposed to achieve a self-sustained autonomous WSN. • Both impact-induced broadband behavior and axial force-induced tunable frequency are achieved in PEG. • A VR train monitoring demonstration shows the great prospect of the self-sustainable WSN in remote and harsh environments.

Self-Powered Autonomous Wireless Sensor Node by Using Silicon-Based 3D Thermoelectric Energy Generator for Environmental Monitoring Application

In this paper, we present the results of a preliminary study on the self-powered autonomous wireless sensor node by using thermoelectric energy generator based on Silicon (Si) thermoelectric legs, energy management integrated circuit (EMIC), Radio Frequency (RF) module with a temperature and humidity sensor, etc. A novel thermoelectric module structure is designed as an energy generator module, which consists of 127 pairs of Silicon legs and this module is fabricated and tested to demonstrate the feasibility of generating electrical power under the temperature gradient of 70K. EMIC has three key features besides high efficiency, which are maximum power point tracking (MPPT), cold start, and complete self-power operation. EMIC achieved a cold start voltage of 200 mV, peak efficiency of 78.7%, MPPT efficiency 99.4%, and an output power of 34 mW through only the Thermoelectric Generator (TEG) source. To assess the capability of the device as a small scale power source for internet of things (IoT) service, we also tested energy conversion and storage experiments. Finally, the proposed sensor node system which can transmit and monitor the information from the temperature and humidity sensor through the RF module in real time demonstrates the feasibility for variable applications.

A novel autonomous wireless sensor node for IoT applications

A novel wireless sensor network node (WSNN) is presented in this paper where the solar energy harvester system is used as an autonomous power solution for endless battery lifetime. In this sensor node, the meander-line Inverted-F-Antenna (MIFA) is proposed and integrated in a single -CC2650 chip of Texas Instrument. The simple structure, low cost, compact size, high efficiency and low power consumption are advantages of this single-chip WSNN. The experimental results show that MIFA antenna is promising solution to enhance communication performance in WSN. In addition, the investigated single-chip WSNN with multi-wireless technologies including Bluetooth Low Energy and Zigbee as well as 6LowPAN is an attractive device for internet of thing (IoT) applications.

Reckoning Network Lifetime Ratio for Wireless Sensor Network

Advanced Technologies such as Internet of Things, Machine Networking give rise to the deployment of autonomous Wireless Sensor Nodes. They are used for various domains namely battlefield monitoring, enemy detection and monitoring the environment change. These Wireless Sensor Nodes have the properties of low cost and high battery life. NL (Network Lifetime) is an important phase of Wireless Sensor Network (WSNs), in which the nodes can maintain sensing for a more amount of time. NL can be improved by use of multiple techniques namely Opportunistic Transmission, Scheduling of Timed Data Packets, Clustering of Nodes, Energy Harvesting and Connectivity. This paper provides the energy consumption computation, life time ratio definition and the overview of NL improvement techniques. The paper also presents brief review of the Destination based and Source based routing algorithm.

Wireless Sensor Network for Distributed Environmental Monitoring

Environmental monitoring is extremely important to ensure a safe and wealthy life of both humans and artifacts. Monitoring requirements are extremely different depending on the environment, leading to ad hoc implementations that lack flexibility. This paper describes an implementation that can be adapted to many different applications and embeds the flexibility required to be deployed and upgraded without the necessity of arranging complex infrastructures. The solution is based on small autonomous wireless sensor nodes, small wireless receivers connected to the Internet, and a cloud architecture which provides data storage and delivery to remote clients. The solution permits supervisors on-site not only to have an immediate idea of the current situation by using their smart-phones but also to monitor remote sites through the Internet. All measurements are redundantly stored at different concentration levels to guarantee a safe back-trace and to provide quality assurance also in case of network failure or unavailability. The sensing nodes have small impact, with dimensions which can be of less than 2.5 cm $\times1.5$ cm when the nodes have to acquire only temperature and relative humidity, and a low cost that enables using them in a set-and-forget way for intervals in excess of one year.

A New Approach to Design Autonomous Wireless Sensor Node Based on RF Energy Harvesting System.

Energy Harvesting techniques are increasingly seen as the solution for freeing the wireless sensor nodes from their battery dependency. However, it remains evident that network performance features, such as network size, packet length, and duty cycle, are influenced by the sum of recovered energy. This paper proposes a new approach to defining the specifications of a stand-alone wireless node based on a Radio-frequency Energy Harvesting System (REHS). To achieve adequate performance regarding the range of the Wireless Sensor Network (WSN), techniques for minimizing the energy consumed by the sensor node are combined with methods for optimizing the performance of the REHS. For more rigor in the design of the autonomous node, a comprehensive energy model of the node in a wireless network is established. For an equitable distribution of network charges between the different nodes that compose it, the Low-Energy Adaptive Clustering Hierarchy (LEACH) protocol is used for this purpose. The model considers five energy-consumption sources, most of which are ignored in recently used models. By using the hardware parameters of commercial off-the-shelf components (Mica2 Motes and CC2520 of Texas Instruments), the energy requirement of a sensor node is quantified. A miniature REHS based on a judicious choice of rectifying diodes is then designed and developed to achieve optimal performance in the Industrial Scientific and Medical (ISM) band centralized at . Due to the mismatch between the REHS and the antenna, a band pass filter is designed to reduce reflection losses. A gradient method search is used to optimize the output characteristics of the adapted REHS. At of input RF power, the REHS provides an output DC power of and a comparison with the energy requirement of the node allows the Base Station (BS) to be located at from the wireless nodes when the Wireless Sensor Network (WSN) has nodes evenly spread over an area of and when each round lasts . The result shows that the range of the autonomous WSN increases when the controlled physical phenomenon varies very slowly. Having taken into account all the dissipation sources coexisting in a sensor node and using actual measurements of an REHS, this work provides the guidelines for the design of autonomous nodes based on REHS.

A Novel High-Performance Energy Harvester Based on Nonlinear Resonance for Scavenging Power-Frequency Magnetic Energy

Self-powered wireless sensor networks based on autonomous wireless sensor nodes have been increasingly attractive due to the outstanding merits of maintenance-free and self-sustainability. In spite of the explosive growth of the wireless sensor network techniques, the corresponding power supply methods with miniaturized, low-cost, flexible, reliable, and efficient designs are still limited. In this paper, a novel magnetic energy harvester based on nonlinear resonance is presented, which has been verified to be capable of scavenging energy from the power-frequency (50 or 60 Hz) magnetic field distributed around the transmission line. We have theoretically and experimentally demonstrated the greatly enhanced harvesting properties in both power density and enlarged bandwidth, which provides great robustness to frequency fluctuations of magnetic field. A prototype of this brand new design is fabricated and tested. Experimental results show that the prototype is capable of harvesting a power as high as 13.5 mW at merely 2.4 Oe (RMS) power-frequency AC magnetic field. The high power density (0.5625 mW/cm3 at 2.4 Oe) and the wide working bandwidth (2.6 Hz) promise its application prospects as a sufficient and reliable power supply for sensors in the smart grid.

An RF-Powered DLL-Based 2.4-GHz Transmitter for Autonomous Wireless Sensor Nodes

This paper presents the system and circuit design of a compact radio frequency (RF)-powered 2.4-GHz CMOS transmitter (TX) to be used for autonomous wireless sensor nodes (WSNs). The proposed TX utilizes the received dedicated RF signal for both energy harvesting as well as frequency synthesis. A TX RF carrier is derived from the received RF signal by means of a delay locked loop and XOR-based frequency multiplier. The 50- $\Omega $ load is subsequently driven by a tuned switching RF power amplifier (PA) with 25% duty cycle input for high global efficiency. The design is fabricated in 40-nm CMOS technology and occupies a die area of 0.16 mm2. Experimental results show a rectifier with 36.83% peak efficiency and power management circuit with 120-nA current consumption that enables a low start-up power of −18.4 dBm. The TX outputs a continuous 2.44-GHz RF signal at −2.57 dBm with 36.5% PA drain efficiency and 23.9% global efficiency from a 915-MHz RF input and supports ON–OFF keying modulation.

Autonomous Wireless Sensor Node with Thermal Energy Harvesting for Temperature Monitoring of Industrial Devices

The feasibility of using thermal energy harvesting to power a wireless sensor node for temperature monitoring of industrial devices is explored and evaluated in this paper. The thermal energy harvesting equipment and energy conversion circuit have been designed and fabricated. A series of experiments with various sleep periods for the sensor node are undertaken. The experimental results show that the thermal energy harvesting equipment and energy conversion circuit are able to power a commercial wireless node when the sleep period of the node is more than 16s, equating to a duty cycle of 5.4%. The results also indicate that the wireless sensor network based on the proposed autonomous wireless sensor node can monitor the industrial device temperature successfully.

Design and realization of an energy autonomous wireless sensor system for ball screw fault diagnosis

This paper presents the design and realization of an energy autonomous wireless sensor system for monitoring and fault diagnosis of ball screw condition. The proposed system is mainly composed of a wireless sensor node and an energy harvester. The novelty of the proposed system is lying in the point that it can be used with any machines that have a linear actuator and generate a low level of vibrations. The sensor node is used to measure the vibration of the ball screw in a linear actuator, while the energy harvester is used to convert linear kinetic motions of the actuator to electrical energy and powered the system. In this work, the design of wireless sensor node, energy harvester and energy management system are proposed. The electrical characteristics of the sensor node and the harvester are investigated to optimize the performance of the system. Lastly, sixteen energy autonomous wireless sensor nodes are fabricated and installed into the DISCO Automatic Dicing Saw DFD6340 machines for examining their performances. As the results, the proposed system can distinguish the condition of ball screw. The average acceleration level of ball screw showing some damage is significantly higher than the average acceleration level of ball screw with normal condition.

UTBB FDSOI suitability for IoT applications: Investigations at device, design and architectural levels

In this paper, we propose to analyze Ultra Thin Body and Box FDSOI technology suitability and architectural solutions for IoT applications and more specifically for autonomous Wireless Sensor Nodes (WSNs). As IoT applications are extremely diversified there is a strong need for flexible solutions at design, architectural level but also at technological level. Moreover, as most of those systems are recovering their energy from the environment, they are challenged by low voltage supplies and low leakage functionalities. We detail in this paper some Ultra Thin Body and Box FDSOI 28nm characteristics and results demonstrating that this technology could be a perfect option for multidisciplinary IoT devices. Back biasing capabilities and low voltage features are investigated demonstrating efficient high speed/low leakage flexibility. In addition, architectural solutions for WSNs microcontroller are also proposed taking advantage of Ultra Thin Body and Box FDSOI characteristics for full user applicative flexibility. A partitioned architecture between an Always Responsive part with an asynchronous Wake Up Controller (WUC) managing WSN current tasks and an On Demand part with a main processor for application maintenance is presented. First results of the Always Responsive part implemented in Ultra Thin Body and Box FDSOI 28nm are also exposed.