This article identifies energy-saving potential of the fifth generation (5G) Radio Access Network, and describes main energy-saving principles and technologies. It explores how to use network energy saving technologies, such as carrier shutdown, channel shutdown, and symbol shutdown in 5G network, that have been inherited from 4G. Some enhanced technologies for 5G like equipment deep sleep and symbol aggregation have also been introduced in this article. However, it is far from enough and an innovative energy-saving solution should be considered. To meet the requirements and development of intelligent and self-adaptive energy-saving solution, Artificial Intelligence (AI) and big data analysis are introduced to form a more precise energy-saving strategy based on site-specific traffic and site-related conditions, thus improving the efficiency and reducing the manpower. Finally, two commercial application practices of AI-based energy-saving solution are elaborated. One is the practice of AI-based service awareness energy saving for 4G/5G collaborative networks, the energy benefits can be improved up to 20%; The other practice is the adoption of a new architecture Active Antenna Unit (AAU) with beam pattern optimization, its energy benefits can be promoted by 30%. These two practices could help mobile network operators (MNOs) to achieve the most energy-efficient network with good network performance and lower Operating Expense (OPEX).

Piezoelectric nanogenerators (PENGs) not only are able to harvest mechanical energy from the ambient environment or body and convert mechanical signals into electricity but can also inform us about pathophysiological changes and communicate this information using electrical signals, thus acting as medical sensors to provide personalized medical solutions to patients. In this review, we aim to present the latest advances in PENG-based non-invasive sensors for clinical diagnosis and medical treatment. While we begin with the basic principles of PENGs and their applications in energy harvesting, this review focuses on the medical sensing applications of PENGs, including detection mechanisms, material selection, and adaptive design, which are oriented toward disease diagnosis. Considering the non-invasive in vitro application scenario, discussions about the individualized designs that are intended to balance a high performance, durability, comfortability, and skin-friendliness are mainly divided into two types: mechanical sensors and biosensors, according to the key role of piezoelectric effects in disease diagnosis. The shortcomings, challenges, and possible corresponding solutions of PENG-based medical sensing devices are also highlighted, promoting the development of robust, reliable, scalable, and cost-effective medical systems that are helpful for the public.

In advancing the transition of the energy sector toward heightened sustainability and environmental friendliness, biopolymers have emerged as key elements in the construction of triboelectric nanogenerators (TENGs) due to their renewable sources and excellent biodegradability. The development of these TENG devices is of significant importance to the next generation of renewable and sustainable energy technologies based on carbon-neutral materials. This paper introduces the working principles, material sources, and wide-ranging applications of biopolymer-based triboelectric nanogenerators (BP-TENGs). It focuses on the various categories of biopolymers, ranging from natural sources to microbial and chemical synthesis, showcasing their significant potential in enhancing TENG performance and expanding their application scope, while emphasizing their notable advantages in biocompatibility and environmental sustainability. To gain deeper insights into future trends, we discuss the practical applications of BP-TENG in different fields, categorizing them into energy harvesting, healthcare, and environmental monitoring. Finally, the paper reveals the shortcomings, challenges, and possible solutions of BP-TENG, aiming to promote the advancement and application of biopolymer-based TENG technology. We hope this review will inspire the further development of BP-TENG towards more efficient energy conversion and broader applications.

Nowadays, self-powered wearable biosensors that are based on triboelectric nanogenerators (TENGs) are playing an important role in the continuous efforts towards the miniaturization, energy saving, and intelligence of healthcare devices and Internets of Things (IoTs). In this review, we cover the remarkable developments in TENG−based biosensors developed from various polymer materials and their functionalities, with a focus on wearable and implantable self-powered sensors for health monitoring and therapeutic devices. The functions of TENGs as power sources for third-party biosensors are also discussed, and their applications in a number of related fields are concisely illustrated. Finally, we conclude the review with a discussion of the challenges and problems of leveraging TENG−based intelligent biosensors.

Nowadays, magnetic materials are also drawing considerable attention in the development of innovative energy converters such as triboelectric nanogenerators (TENGs), where the introduction of magnetic materials at the triboelectric interface not only significantly enhances the energy harvesting efficiency but also promotes TENG entry into the era of intelligence and multifunction. In this review, we begin from the basic operating principle of TENGs and then summarize the recent progress in applications of magnetic materials in the design of TENG magnetic materials by categorizing them into soft ferrites and amorphous and nanocrystalline alloys. While highlighting key role of magnetic materials in and future opportunities for improving their performance in energy conversion, we also discuss the most promising choices available today and describe emerging approaches to create even better magnetic TENGs and TENG-based sensors as far as intelligence and multifunctionality are concerned. In addition, the paper also discusses the integration of magnetic TENGs as a power source for third-party sensors and briefly explains the self-powered applications in a wide range of related fields. Finally, the paper discusses the challenges and prospects of magnetic TENGs.

The ever-growing interest in wearable electronic devices has unleashed a strong demand for sustainable and flexible power sources that are represented by the combination of flexible energy harvesting with storage devices/technologies. Triboelectric nanogenerators (TENG), which harvest mechanical energy and charge their matching supercapacitors (SCs), may form a distributed power system with flexibility to tap their potential applications in powering wearable electronic devices. This review aims to cover the recent progress in the integration of TENG with flexible SC in terms of operation principle, material selection, device configuration and power management, with an accent on the application scenario in flexible wearable electronics. Further, the current shortcomings, challenges and new prospects for future developments in the emerging field of integrated flexible TENG-SCs for self-powered wearable electronics are discussed.