The development of flexible piezoelectric nanogenerators has experienced rapid progress in the past decade and is serving as the technological foundation of future state-of-the-art personalized healthcare. Due to their highly efficient mechanical-to-electrical energy conversion, easy implementation, and self-powering nature, these devices permit a plethora of innovative healthcare applications in the space of active sensing, electrical stimulation therapy, as well as passive human biomechanical energy harvesting to third party power on-body devices. This article gives a comprehensive review of the piezoelectric nanogenerators for personalized healthcare. After a brief introduction to the fundamental physical science of the piezoelectric effect, material engineering strategies, device structural designs, and human-body centered energy harvesting, sensing, and therapeutics applications are also systematically discussed. In addition, the challenges and opportunities of utilizing piezoelectric nanogenerators for self-powered bioelectronics and personalized healthcare are outlined in detail.

Piezoelectric nanogenerators for personalized healthcare.

The development of wearable electronics has emphasized user-comfort, convenience, security, and improved medical functionality. Several previous research studies transformed various types of sensors into a wearable form to more closely monitor body signals and enable real-time, continuous sensing. In order to realize these wearable sensing platforms, it is essential to integrate wireless power supplies and data communication systems with the wearable sensors. This review article discusses recent progress in wireless technologies and various types of wearable sensors. Also, state-of-the-art research related to the application of wearable sensor systems with wireless functionality is discussed, including electronic skin, smart contact lenses, neural interfaces, and retinal prostheses. Current challenges and prospects of wireless sensor systems are discussed.

https://www.mdpi.com/1424-8220/19/20/4353/pdf

Recent Progress in Wireless Sensors for Wearable Electronics.

Diversiform sensors and sensing systems driven by triboelectric and piezoelectric nanogenerators

Sensors play a crucial role in factory automation in making the system intellectual. Different types of sensors are available as per the suitability and applications; some of them are produced in mass and available in the market at affordable costs. The standard sensor types available are position sensors, pressure sensors, flow sensors, temperature sensors, and force sensors. They are used in many sectors, such as motorsport, medical, industry, aerospace, agriculture, and daily life. The objective of Industry 4.0 is to increase efficiency through automation. Sensors are vital components of Industry 4.0, allowing several transitions such as changes in positions, length, height, external and dislocations in industrial production facilities to be detected, measured, analysed, and processed. Smart factories will also enhance sustainability by tracking real-time output, and automated control systems will minimise potential factory maintenance costs. It can also be seen that digitalisation can improve production mobility, which gives advanced manufacturing firms a competitive advantage. This paper discusses sensors and their various types, along with significant capabilities for manufacturing. The step-by-step working Blocks and Quality Services of Sensors during implementation in Industry 4.0 are elaborated diagrammatically. Finally, we identified thirteen significant applications of sensors for Industry 4.0. Industry 4.0 provides an excellent opportunity for the development of the sensor market across the globe. In Industry 4.0, sensors will enjoy higher acceptance rates and benefit from a fully enabled connecting and data exchange and logistics integration. In the coming years, sensor installations may grow in process management, automated production lines, and digital supply chains.

Significance of sensors for industry 4.0: Roles, capabilities, and applications

Stretchable Freezing-tolerant Triboelectric Nanogenerator and Strain Sensor Based on Transparent, Long-term Stable, and Highly Conductive Gelatin-based Organohydrogel

Tactile electronic skin to simultaneously detect and distinguish between temperature and pressure based on a triboelectric nanogenerator

Self-powered skin sensors have attracted significant attention in recent years due to their great potential in medical care, robotics, prosthetics, and sports. More importantly, self-powered skin sensors do not need any energy-supply components like batteries, which allows them to work sustainably and saves them the trouble of replacement of batteries. The self-powered skin sensors are mainly based on energy harvesters, with the device itself generating electrical signals when triggered by the detected stimulus or analyte, such as body motion, touch/pressure, acoustic sound, and chemicals in sweat. Herein, the recent research achievements of self-powered skin sensors are comprehensively and systematically reviewed. According to the different monitoring signals, the self-powered skin sensors are summarized and discussed with a focus on the working mechanism, device structure, and the sensing principle. Based on the recent progress, the key challenges that exist and the opportunities that lie ahead are also discussed.

Recent Progress in Self-Powered Skin Sensors

Flexible temperature sensors can be attached to the surface of human skin or curved surfaces directly for continuous and stable data measurements, and have attracted extensive attention in myriad areas. Carbon nanomaterials possess great potential for temperature sensing, and flexible temperature sensors based on carbon nanomaterials have demonstrated unique advantages such as high sensitivity, fast response, good mechanical adaptability, low-cost fabrication processes, high cycling stability and reliability. In this review, the working mechanisms, device structures, material compositions, fabrication technologies, temperature sensing properties, the crucial roles of carbon nanomaterials, specific advantages and existing limitations of different types of flexible temperature sensors based on carbon nanomaterials are comprehensively elaborated and discussed. Based on recent advances, conclusions are made and challenges as well as future perspectives are systematically outlined and discussed.

Jihong Rao

Papers

Tactile electronic skin to simultaneously detect and distinguish between temperature and pressure based on a triboelectric nanogenerator

Recent Progress in Self-Powered Skin Sensors

Flexible temperature sensors based on carbon nanomaterials.