More than a decade of research in the field of thermal, motion, vibration and electromagnetic radiation energy harvesting has yielded increasing power output and smaller embodiments. Power management circuits for rectification and DC-DC conversion are becoming able to efficiently convert the power from these energy harvesters. This paper summarizes recent energy harvesting results and their power management circuits.

Micropower energy harvesting

Modern gas monitoring scenarios for medical diagnostics, environmental surveillance, industrial safety, and other applications demand new sensing capabilities. This Review provides analysis of development of new generation of gas sensors based on the multivariable response principles. Design criteria of these individual sensors involve a sensing material with multiresponse mechanisms to different gases and a multivariable transducer with independent outputs to recognize these different gas responses. These new sensors quantify individual components in mixtures, reject interferences, and offer more stable response over sensor arrays. Such performance is attractive when selectivity advantages of classic gas chromatography, ion mobility, and mass spectrometry instruments are canceled by requirements for no consumables, low power, low cost, and unobtrusive form factors for Internet of Things, Industrial Internet, and other applications. This Review is concluded with a perspective for future needs in fundament...

Multivariable Sensors for Ubiquitous Monitoring of Gases in the Era of Internet of Things and Industrial Internet

Wireless Sensor Networks (WSNs) are crucial in supporting continuous environmental monitoring, where sensor nodes are deployed and must remain operational to collect and transfer data from the environment to a base-station. However, sensor nodes have limited energy in their primary power storage unit, and this energy may be quickly drained if the sensor node remains operational over long periods of time. Therefore, the idea of harvesting ambient energy from the immediate surroundings of the deployed sensors, to recharge the batteries and to directly power the sensor nodes, has recently been proposed. The deployment of energy harvesting in environmental field systems eliminates the dependency of sensor nodes on battery power, drastically reducing the maintenance costs required to replace batteries. In this article, we review the state-of-the-art in energy-harvesting WSNs for environmental monitoring applications, including Animal Tracking, Air Quality Monitoring, Water Quality Monitoring, and Disaster Monitoring to improve the ecosystem and human life. In addition to presenting the technologies for harvesting energy from ambient sources and the protocols that can take advantage of the harvested energy, we present challenges that must be addressed to further advance energy-harvesting-based WSNs, along with some future work directions to address these challenges.

https://dl.acm.org/doi/pdf/10.1145/3183338

Energy-Harvesting Wireless Sensor Networks (EH-WSNs): A Review

Breath sensors can revolutionize medical diagnostics by on-demand detection and monitoring of health parameters in a noninvasive and personalized fashion. Despite extensive research for more than two decades, however, only a few breath sensors have been translated into clinical practice. Actually, most never even left the scientific laboratories. Here, we describe key challenges that currently impede realization of breath sensors and highlight strategies to overcome them. Specifically, we start with breath marker selection (with emphasis on metabolic and inflammatory markers) and breath sampling. Next, the sensitivity, stability, and selectivity requirements for breath sensors are described. Concepts are elaborated to systematically address these requirements by material design (focusing on chemoresistive metal oxides), orthogonal arrays, and filters. Finally, aspects of portable device integration, user communication, and clinical applicability are discussed.

Breath Sensors for Health Monitoring

With the development of the Internet-of-Things (IoT) technology, the applications of gas sensors in the fields of smart homes, wearable devices, and smart mobile terminals have developed by leaps and bounds. In such complex sensing scenarios, the gas sensor shows the defects of cross sensitivity and low selectivity. Therefore, smart gas sensing methods have been proposed to address these issues by adding sensor arrays, signal processing, and machine learning techniques to traditional gas sensing technologies. This review introduces the reader to the overall framework of smart gas sensing technology, including three key points; gas sensor arrays made of different materials, signal processing for drift compensation and feature extraction, and gas pattern recognition including Support Vector Machine (SVM), Artificial Neural Network (ANN), and other techniques. The implementation, evaluation, and comparison of the proposed solutions in each step have been summarized covering most of the relevant recently published studies. This review also highlights the challenges facing smart gas sensing technology represented by repeatability and reusability, circuit integration and miniaturization, and real-time sensing. Besides, the proposed solutions, which show the future directions of smart gas sensing, are explored. Finally, the recommendations for smart gas sensing based on brain-like sensing are provided in this paper.

https://www.mdpi.com/1424-8220/19/17/3760/pdf

Review on Smart Gas Sensing Technology.

The Wireless Sensor Network (WSN) technology has recently been used, rather successfully, in a huge number of monitoring applications. However, the monitoring of combustible gases with WSN stands out from typical applications where the wireless communications function is much more power hungry than the sensing one. The reason behind this “dissonance” is in using catalytic or semiconductor sensors that ensure a trade-off among the safety requirements, performance and power consumption. This work provides a survey of intrinsic power optimization techniques with a special focus on recent advances in power management, sensor fabrication, sensing circuits, and measurement procedures. The paper concludes with providing a future outlook in the area.

Optimization of power consumption for gas sensor nodes: A survey

With the widespread use of wireless sensors, the management of their energy resources has become a topic of research. Wireless sensors usually use batteries as their power supply but in some applications battery replacement can be cumbersome and require considerable amount of time which can affect the process being monitored. It is possible to harvest energy from the sources in nature for wireless sensors. In this article, a review of current alternative energy sources has been demonstrated in order to address the feasibility of their integration with wireless sensor networks.

/pdf/energy-harvesting-for-wireless-sensor-networks-review-pty3mbdx23.pdf

Energy harvesting for wireless sensor networks review

Wireless sensor networks (WSNs) have recently been applied for the detection of a number of hazardous gases. Gas monitoring is of significance, for gas leakage and the resultant penetration of gases into the environment can lead to grave or sometimes fatal consequences. In this work, we propose a sensor node architecture for a wireless outdoor CO monitoring unit with an emphasis on the energy efficiency of measurements and optimal power supply mechanism. To guarantee the ‘perpetual’ operation, the sensor node is supported by a hybrid power supply, which takes advantage of both wind and solar ambient energy sources to power the node and to charge the high capacity super capacitors that act as energy buffers. Using an electrochemical CO sensor, we secure the low power consumption of the node without degrading the sensing capabilities. We demonstrate our experience of operating the developed wireless sensor node in real conditions. Our solution can be applied for CO monitoring in urban areas and outdoor industrial facilities.

POCO: ‘Perpetual’ operation of CO wireless sensor node with hybrid power supply

Wireless Sensor Network (WSN) paradigm has been applied to a high number of monitoring and control applications. However, the scarcity of WSN energy resources imposes restrictions on its truly ubiquitous and long-term deployments. We address the problem of long-term autonomous operation of a wireless gas sensor by employing the far-field RF energy harvesting technology at 900 MHz in the power range from −20 dBm to 10 dBm. The node conducts regular CH4 or CO measurements and communicates the data to a wireless network coordinator at 2.4 GHz. Experimental results demonstrate that the optimized energy consumption of WSN, as well as energy harvesting of at least 1 mW (0 dBm) from ambient RF signal, ensure the ‘perpetual’ operation of WSN.

Feasibility of RF energy harvesting for wireless gas sensor nodes

Nowadays, the safety standards for industrial plants are tougher with respect to employee state monitoring and monitoring of working environmental conditions. Combining wireless sensor with wearable technology is possible to significantly improve safety delivery capability of such systems and add new functionality to them. Since wireless sensors use batteries as the sole energy source, the energy efficiency becomes critical. One of the solutions to reduce the energy consumption of the wireless sensor nodes is to use appropriate control for radio data transmission. In this paper, we have developed a wireless sensor system which can be attached to a uniform and used for working condition monitoring in places which could be prone to gas leakage. The main feature of the system is the possibility to be activated remotely by an RF control signal at a frequency of 866 MHz. It performs various functions of wearable sensor system, such as switching the system from sleep, measurement, and data transmission modes when external RF signal is available and its power is greater than an appropriate level. The experimental data demonstrate that the activation distance is about 2.75 m from an RF-generator that has a power of 30 dBm. The wearable sensor system is able to signalize about employee presence in relation to working facilities and to monitor temperature and combustible gases concentration. It consists of light-weight distributed parts attached to clothes and has low power consumption.

Saba Akbari

Papers

Optimization of power consumption for gas sensor nodes: A survey

Energy harvesting for wireless sensor networks review

POCO: ‘Perpetual’ operation of CO wireless sensor node with hybrid power supply

Feasibility of RF energy harvesting for wireless gas sensor nodes

Wearable Wireless Sensor System With RF Remote Activation for Gas Monitoring Applications