The long-standing popularity of thermoelectric materials has contributed to the creation of various thermoelectric devices and stimulated the development of strategies to improve their thermoelectric performance. In this review, we aim to comprehensively summarize the state-of-the-art strategies for the realization of high-performance thermoelectric materials and devices by establishing the links between synthesis, structural characteristics, properties, underlying chemistry and physics, including structural design (point defects, dislocations, interfaces, inclusions, and pores), multidimensional design (quantum dots/wires, nanoparticles, nanowires, nano- or microbelts, few-layered nanosheets, nano- or microplates, thin films, single crystals, and polycrystalline bulks), and advanced device design (thermoelectric modules, miniature generators and coolers, and flexible thermoelectric generators). The outline of each strategy starts with a concise presentation of their fundamentals and carefully selected examples. In the end, we point out the controversies, challenges, and outlooks toward the future development of thermoelectric materials and devices. Overall, this review will serve to help materials scientists, chemists, and physicists, particularly students and young researchers, in selecting suitable strategies for the improvement of thermoelectrics and potentially other relevant energy conversion technologies.

Advanced Thermoelectric Design: From Materials and Structures to Devices

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 urgent need for ecofriendly, stable, long-lifetime power sources is driving the booming market for miniaturized and integrated electronics, including wearable and medical implantable devices. Flexible thermoelectric materials and devices are receiving increasing attention, due to their capability to convert heat into electricity directly by conformably attaching them onto heat sources. Polymer-based flexible thermoelectric materials are particularly fascinating because of their intrinsic flexibility, affordability, and low toxicity. There are other promising alternatives including inorganic-based flexible thermoelectrics that have high energy-conversion efficiency, large power output, and stability at relatively high temperature. Herein, the state-of-the-art in the development of flexible thermoelectric materials and devices is summarized, including exploring the fundamentals behind the performance of flexible thermoelectric materials and devices by relating materials chemistry and physics to properties. By taking insights from carrier and phonon transport, the limitations of high-performance flexible thermoelectric materials and the underlying mechanisms associated with each optimization strategy are highlighted. Finally, the remaining challenges in flexible thermoelectric materials are discussed in conclusion, and suggestions and a framework to guide future development are provided, which may pave the way for a bright future for flexible thermoelectric devices in the energy market.

Flexible Thermoelectric Materials and Generators: Challenges and Innovations.

The programmable nature of smart textiles makes them an indispensable part of an emerging new technology field. Smart textile-integrated microelectronic systems (STIMES), which combine microelectronics and technology such as artificial intelligence and augmented or virtual reality, have been intensively explored. A vast range of research activities have been reported. Many promising applications in healthcare, the internet of things (IoT), smart city management, robotics, etc., have been demonstrated around the world. A timely overview and comprehensive review of progress of this field in the last five years are provided. Several main aspects are covered: functional materials, major fabrication processes of smart textile components, functional devices, system architectures and heterogeneous integration, wearable applications in human and nonhuman-related areas, and the safety and security of STIMES. The major types of textile-integrated nonconventional functional devices are discussed in detail: sensors, actuators, displays, antennas, energy harvesters and their hybrids, batteries and supercapacitors, circuit boards, and memory devices.

Smart Textile-Integrated Microelectronic Systems for Wearable Applications

Review of wearable thermoelectric energy harvesting: From body temperature to electronic systems

Fiber-based flexible thermoelectric energy generators are 3D deformable, lightweight, and desirable for applications in large-area waste heat recovery, and as energy suppliers for wearable or mobile electronic systems in which large mechanical deformations, high energy conversion efficiency, and electrical stability are greatly demanded These devices can be manufactured at low or room temperature under ambient conditions by established industrial processes, offering cost-effective and reliable products in mass quantity This article presents a critical overview and review of state-of-the-art fiber-based thermoelectric generators, covering their operational principle, materials, device structures, fabrication methods, characterization, and potential applications Scientific and practical challenges along with critical issues and opportunities are also discussed

Fiber‐Based Thermoelectric Generators: Materials, Device Structures, Fabrication, Characterization, and Applications

The immunosuppression and immune escape of current immunotherapy result in low efficacy, and ferroptosis is greatly restricted by the low reactive oxygen species (ROS) production efficiency. Here, for the first time a “closed-loop” therapy based on photothermal enhancement of ferroptosis and immunotherapy stimulated by each other on a multifunctional nanoplatform is reported. This platform is composed of copper silicate and iron silicate mesoporous hollow nanospheres, followed by in situ growth of Au nanoparticles and loading of an immune adjuvant resiquimod R848. The laser irradiation-mediated heat and the introduction of copper ions significantly enhance ROS generation, leading to the simultaneous depletion of glutathione peroxidase 4 (GPX4) and glutathione (GSH). The onset of ferroptosis in tumor cells is thus enhanced and an immune response with immunogenic cell death (ICD) is triggered, promoting the dendritic cells (DCs) maturation and T cell infiltration. Interferon γ (IFN-γ) released from CD8+ T cells downregulates the expression of SLC7A11 and GPX4, which in turn enhances ferroptosis expression, thus constituting a “closed-Loop” therapy. Importantly, this system is effective in both killing the primary tumor and inhibiting tumor metastasis. The proposed “closed-loop” therapeutic strategy may provide a guidance for the design of future antitumor nanoplatforms. 

A “Closed‐Loop” Therapeutic Strategy Based on Mutually Reinforced Ferroptosis and Immunotherapy

Currently, the incidence of acute liver injury (ALI) is increasing year by year, and infection with coronavirus disease 2019 (COVID‐19) can also induce ALI, but there are still no targeted therapeutic drugs. ZnO–NiO particles is mainly used to clean up reactive oxygen species (ROS) in industrial wastewater, and it is insoluble in water. Its excellent properties are discovered and improved by adding shuttle‐based bonds to make it more water‐soluble. ZnO‐NiO@COOH particles are synthetically applied to treat ALI. The p‐n junction in ZnO–NiO@COOH increases the surface area and active sites, thereby creating large numbers of oxygen vacancies, which can quickly adsorb ROS. The content in tissues and serum levels of L‐glutathione (GSH) and the GSH/oxidized GSH ratio are measured to assess the capacity of ZnO–NiO@COOH particles to absorb ROS. The ZnO–NiO@COOH particles significantly reduce the expression levels of inflammatory factors (i.e., IL‐1, IL‐6, and TNF‐α), macrophage infiltration, and granulocyte activation. ZnO‐NiO@COOH rapidly adsorb ROS in a short period of time to block the generation of inflammatory storms and gain time for the follow‐up treatment of ALI, which has important clinical significance.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/advs.202103982

Scavenging ROS to Alleviate Acute Liver Injury by ZnO‐NiO@COOH

A method for suppressing noise in capillary tubes was developed with aerating techniques. The refrigerant R600a was added to the outlet of a throttling capillary from the end of a transition tube between the capillary and evaporator. To investigate the flow characteristic of R600a in the transition tube, a two-phase flow quasi-steady simulation was performed using the mixture model. The Schnerr–Sauer cavitation model was used, and the turbulence model was realizable k − ɛ. Numerical results show that the local pressure and negative mass transfer rate can both be reduced at the downstream of the capillary where bubbles collapse, when bypass capillaries are used in the aerating model. An experimental system was built to measure the noise in a transition tube with/without a bypass capillary. Results show that the noise sound pressure level decreased by 2 dB on average when aerating techniques were used. This research describes the complex mechanism of the throttling flashing process and provides an effective method to suppress the noise in capillary tubes, which will be beneficial to improve occasional sharp noise in a household refrigerator. 

Shiri Liu

Papers

Fiber‐Based Thermoelectric Generators: Materials, Device Structures, Fabrication, Characterization, and Applications

A “Closed‐Loop” Therapeutic Strategy Based on Mutually Reinforced Ferroptosis and Immunotherapy

Scavenging ROS to Alleviate Acute Liver Injury by ZnO‐NiO@COOH

Application of aerating techniques for noise suppression in capillary tubes

Research and Application on Optimization of Drainage Gas Recovery Methods in Linxing Block