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

Chatter is a self-excited vibration that can occur during machining operations and become a common limitation to productivity and part quality. For this reason, it has been a topic of industrial and academic interest in the manufacturing sector for many years. A great deal of research has been carried out since the late 1950s to solve the chatter problem. Researchers have studied how to detect, identify, avoid, prevent, reduce, control, or suppress chatter. This paper reviews the state of research on the chatter problem and classifies the existing methods developed to ensure stable cutting into those that use the lobbing effect, out-of-process or in-process, and those that, passively or actively, modify the system behaviour.

Chatter in machining processes: A review

Successful materials design for bone-tissue engineering requires an understanding of the composition and structure of native bone tissue, as well as appropriate selection of biomimetic natural or tunable synthetic materials (biomaterials), such as polymers, bioceramics, metals and composites. Scalable fabrication technologies that enable control over construct architecture at multiple length scales, including three-dimensional printing and electric-field-assisted techniques, can then be employed to process these biomaterials into suitable forms for bone-tissue engineering. In this Review, we provide an overview of materials-design considerations for bone-tissue-engineering applications in both disease modelling and treatment of injuries and disease in humans. We outline the materials-design pathway from implementation strategy through selection of materials and fabrication methods to evaluation. Finally, we discuss unmet needs and current challenges in the development of ideal materials for bone-tissue regeneration and highlight emerging strategies in the field. Design of bone-tissue-engineering materials involves consideration of multiple, often conflicting, requirements. This Review discusses these considerations and highlights scalable technologies that can fabricate natural and synthetic biomaterials (polymers, bioceramics, metals and composites) into forms suitable for bone-tissue-engineering applications in human therapies and disease models.

Materials design for bone-tissue engineering

Chatter suppression techniques in metal cutting

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.

On-line chatter detection and identification based on wavelet and support vector machine

Acoustic softening and residual hardening in aluminum: Modeling and experiments

Wearable thermoelectric generator to harvest body heat for powering a miniaturized accelerometer

Photo-crosslinkable gelatin methacrylate (GelMA) has become an attractive ink in 3D printing due to its excellent biological performance. However, limited by low viscosity and long cross-linking time, it is still a challenge to directly print GelMA by extrusion-based 3D printing. Here, to balance the printability and biocompatibility, biomaterial ink composed of GelMA and nanoclay was specially designed. Using this ink, complex scaffolds with high shape fidelity can be easily printed based on the thixotropic property of nanoclay. In this study, we tried to answer some basic printing-required questions of this ink, including the printability window, general properties (porosity, mechanical strength, et al), and biocompatibility. We found that the GelMA/Nanoclay ink enabled printing complex 3D scaffolds, such as a bionic ear and a branched vessel. Furthermore, the addition of nanoclay improved the porosity, increased the mechanical strength, reduced the degradation ratio, and maintained a good biocompatibility of the printed scaffolds. Therefore, this method offers an easy way to print complex scaffolds with good shape fidelity and biological performance, and it might open up new potential applications for the customized therapy of tissue defects.

https://iopscience.iop.org/article/10.1088/1758-5090/ab0cf6/pdf

Zichen Chen

Papers

On-line chatter detection and identification based on wavelet and support vector machine

Acoustic softening and residual hardening in aluminum: Modeling and experiments

Wearable thermoelectric generator to harvest body heat for powering a miniaturized accelerometer

3D printing of complex GelMA-based scaffolds with nanoclay.

Effects of superimposed high-frequency vibration on deformation of aluminum in micro/meso-scale upsetting