Textiles have been concomitant of human civilization for thousands of years. With the advances in chemistry and materials, integrating textiles with energy harvesters will provide a sustainable, environmentally friendly, pervasive, and wearable energy solution for distributed on-body electronics in the era of Internet of Things. This article comprehensively and thoughtfully reviews research activities regarding the utilization of smart textiles for harvesting energy from renewable energy sources on the human body and its surroundings. Specifically, we start with a brief introduction to contextualize the significance of smart textiles in light of the emerging energy crisis, environmental pollution, and public health. Next, we systematically review smart textiles according to their abilities to harvest biomechanical energy, body heat energy, biochemical energy, solar energy as well as hybrid forms of energy. Finally, we provide a critical analysis of smart textiles and insights into remaining challenges and future directions. With worldwide efforts, innovations in chemistry and materials elaborated in this review will push forward the frontiers of smart textiles, which will soon revolutionize our lives in the era of Internet of Things.

Smart Textiles for Electricity Generation.

The advanced electrochemical properties, such as high energy density, fast charge–discharge rates, excellent cyclic stability, and specific capacitance, make supercapacitor a fascinating electronic device. During recent decades, a significant amount of research has been dedicated to enhancing the electrochemical performance of the supercapacitors through the development of novel electrode materials. In addition to highlighting the charge storage mechanism of the three main categories of supercapacitors, including the electric double-layer capacitors (EDLCs), pseudocapacitors, and the hybrid supercapacitors, this review describes the insights of the recent electrode materials (including, carbon-based materials, metal oxide/hydroxide-based materials, and conducting polymer-based materials, 2D materials). The nanocomposites offer larger SSA, shorter ion/electron diffusion paths, thus improving the specific capacitance of supercapacitors (SCs). Besides, the incorporation of the redox-active small molecules and bio-derived functional groups displayed a significant effect on the electrochemical properties of electrode materials. These advanced properties provide a vast range of potential for the electrode materials to be utilized in different applications such as in wearable/portable/electronic devices such as all-solid-state supercapacitors, transparent/flexible supercapacitors, and asymmetric hybrid supercapacitors.

Electrode Materials for Supercapacitors: A Review of Recent Advances

A survey on cybersecurity, data privacy, and policy issues in cyber-physical system deployments in smart cities

The operational efficiency of remote environmental wireless sensor networks (EWSNs) has improved tremendously with the advent of Internet of Things (IoT) technologies over the past few years. EWSNs require elaborate device composition and advanced control to attain long-term operation with minimal maintenance. This article is focused on power supplies that provide energy to run the wireless sensor nodes in environmental applications. In this context, EWSNs have two distinct features that set them apart from monitoring systems in other application domains. They are often deployed in remote areas, preventing the use of mains power and precluding regular visits to exchange batteries. At the same time, their surroundings usually provide opportunities to harvest ambient energy and use it to (partially) power the sensor nodes. This review provides a comprehensive account of energy harvesting sources, energy storage devices, and corresponding topologies of energy harvesting systems, focusing on studies published within the last 10 years. Current trends and future directions in these areas are also covered.

Energy Harvesting Sources, Storage Devices and System Topologies for Environmental Wireless Sensor Networks: A Review.

The internet of things (IoT) manages a large infrastructure of web-enabled smart devices, small devices that use embedded systems, such as processors, sensors, and communication hardware to collect, send, and elaborate on data acquired from their environment. Thus, from a practical point of view, such devices are composed of power-efficient storage, scalable, and lightweight nodes needing power and batteries to operate. From the above reason, it appears clear that energy harvesting plays an important role in increasing the efficiency and lifetime of IoT devices. Moreover, from acquiring energy by the surrounding operational environment, energy harvesting is important to make the IoT device network more sustainable from the environmental point of view. Different state-of-the-art energy harvesters based on mechanical, aeroelastic, wind, solar, radiofrequency, and pyroelectric mechanisms are discussed in this review article. To reduce the power consumption of the batteries, a vital role is played by power management integrated circuits (PMICs), which help to enhance the system’s life span. Moreover, PMICs from different manufacturers that provide power management to IoT devices have been discussed in this paper. Furthermore, the energy harvesting networks can expose themselves to prominent security issues putting the secrecy of the system to risk. These possible attacks are also discussed in this review article.

Energy Harvesting towards Self-Powered IoT Devices

To enable off-grid deployments of autonomous systems for extended operational durations, robust energy harvesting in the medium power range (1-10 W) is essential. Supercapacitor-based solar energy harvesters have emerged as a popular alternative due to their long lifetime under repeated charge-discharge cycles, low maintenance, environmental friendliness, and energy predictability and scalability. Despite their advantages, such systems are not well matched with applications that require power continuously over their operational lifetime because solar power is unavailable during nights and severely reduced on cloudy days. For such applications, it is beneficial to combine solar power with another power source-such as wind-that exhibits complementary availability. In this paper, we present multiple solar/wind (hybrid) supercapacitor-based harvesters, leveraging existing open-source solar-only harvester designs. Our designs center around three main categories that i) add wind harvesting capability to create a wind-only harvesting system, ii) use multiple harvesters for utilizing hybrid sources of power and for providing fault tolerance, or iii) use a single harvester in a time multiplexed configuration to simultaneously harvest from multiple power sources. We provide extensive experimental results to document the functionality and operational performance of a representative set of these designs.

Hybrid Solar-Wind Energy Harvesting for Embedded Applications: Supercapacitor-Based System Architectures and Design Tradeoffs

Significant recent research activities and initiatives by local governments to establish resilient smart city infrastructures signal that time is right for smart cities in the near future. For example, sensors deployed within a city could monitor traffic patterns, perform environmental measurements and determine optimum traffic routing, when deployed in areas that have a power infrastructure. In this paper, we conceptualize the deployment of such nodes, which we term Smart Boxes, in a part of the city where there is no existing or currently functional energy and communication infrastructure. We envision our proposed smart boxes incorporating a multi-source energy harvester (e. g., wind/solar). Eliminating the infrastructure requirement allows our smart box to act as an emergency cell phone network in any part of the city, thereby forming an emergency subinfrastructure. To improve scalability, we use a Software Defined Radio (SDR) within the box. The contribution of this paper is to provide an architectural map of the box and a proof-of-concept experimental demonstration of its LTE network capabilities. Our experiments show that the box is capable of serving three cellular users and can be powered from a 50–100 W solar panel and a 50–100 W wind turbine, thereby confirming its feasibility as a Smart City node.

Smart city sensing and communication sub-infrastructure

For autonomous medium power (1–10 W) field systems deployed in off-grid applications without established power infrastructure, two system design criteria are crucially important: i) continuous availability of power, ii) robust and low-maintenance operation. In this paper, we provide circuit and system designs for energy harvesters that address both issues by utilizing supercapacitors as their energy buffer and hybrid solar and wind power sources for their power supply. By utilizing the complimentary nature of solar and wind power sources, the necessity for large supercapacitor buffers is eliminated. Although a rich body of solar-only designs exist in the literature, in our knowledge, this is the first paper that demonstrates a hybrid harvester design for the medium power range. We experimentally demonstrate the functionality of our harvester designs.

Solar/wind hybrid energy harvesting for supercapacitor-based embedded systems

Off-grid medium-power (1–10 W) systems require either battery-or supercapacitor-based ambient energy harvesting for sustaining their operation. Supercapacitor-based harvesters are advantageous in autonomous field systems due to their extended lifetime, easy power management, and low maintenance requirement; however, they can reach only up to 10% of the energy density of rechargeable batteries. To overcome this energy density challenge, hybrid power sources, such as solar or wind, can be advantageously utilized in harvesting systems. The complementary power supply characteristics of solar and wind can substantially reduce the required supercapacitor buffer size compared with solar-only or wind-only systems. In the literature, no supercapacitor-based hybrid harvesting system design exists for 1–10 W range. In this paper, we develop and experimentally validate three different categories of supercapacitor-based harvesting systems that are capable of simultaneously harvesting solar/wind (hybrid) power sources.

Mohamadhadi Habibzadeh

Papers

Hybrid Solar-Wind Energy Harvesting for Embedded Applications: Supercapacitor-Based System Architectures and Design Tradeoffs

Smart city sensing and communication sub-infrastructure

Solar/wind hybrid energy harvesting for supercapacitor-based embedded systems

Supercapacitor-based embedded hybrid solar/wind harvesting system architectures