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Summary Thermoelectric generator, which converts heat into electrical energy, has great potential to power portable devices. Nevertheless, the efficiency of a thermoelectric generator suffers due to inefficient thermoelectric material performance. In the last two decades, the performance of inorganic thermoelectric materials has been significantly advanced through rigorous efforts and novel techniques. In this review, major issues and recent advancements that are associated with the efficiency of inorganic thermoelectric materials are encapsulated. In addition, miscellaneous optimization strategies, such as band engineering, energy filtering, modulation doping, and low dimensional materials to improve the performance of inorganic thermoelectric materials are reported. The methodological reviews and analyses showed that all these techniques have significantly enhanced the Seebeck coefficient, electrical conductivity, and reduced the thermal conductivity, consequently, improved ZT value to 2.42, 2.6, and 1.85 for near‐room, medium, and high temperature inorganic thermoelectric material, respectively. Moreover, this review also focuses on the performance of silicon nanowires and their common fabrication techniques, which have the potential for thermoelectric power generation. Finally, the key outcomes along with future directions from this review are discussed at the end of this article.

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Micro-electromechanical-system (MEMS) based actuators, which transduce certain domains of energy into mechanical movements in the microscopic scale, are increasingly contributing to the areas of biomedical engineering and healthcare applications. They are enabling new functionalities in biomedical devices through their unique miniaturized features. An effective selection of a particular actuator, among a wide range of actuator types available in the MEMS field, needs to be made through the assessment of many factors involved in both the actuator itself and the target application. This paper presents an overview of the state-of-the-art MEMS actuators that have been developed for biomedical applications. The actuation methods, working principle, and imperative features of these actuators are discussed along with their specific applications. An emphasis of this review is placed on temperature-responsive, electromagnetic, piezoelectric, and fluid-driven actuators towards various application areas including lab-on-a-chip, drug delivery systems, cardiac devices and surgical tools. It also highlights the key issues of MEMS actuators in light of biomedical applications.

Wearable sensors and biomedical devices have attracted a great deal of attention among users. Despite technological advancements in this field, a mixture of both progress and setbacks has been witnessed. The limited battery life of these devices for long‐term operation remains a major challenge. In this context, thermoelectric generators have emerged as potential candidates for harvesting energy from temperature gradients to power wearable sensors and devices. This review focuses on the working mechanism of a thermoelectric generator, as well as the current progress of a variety of promising and widely used inorganic and organic thermoelectric materials. Encouragingly, the highest ZT values of 2.27, 2.5, 2.8, 2.3, and 1.85 are obtained for bismuth telluride, lead telluride, tin selenide, copper selenide, and magnesium antimonide, respectively, at various temperature ranges. Meanwhile, organic materials such as poly (3,4‐ethylenedioxythiophene) polystyrene sulfonate, polyaniline composite, and graphdiyne showed the highest ZT values of 0.75, 0.74, and 4.8, respectively, at near‐room temperature. Furthermore, numerous novel thermoelectric generator‐powered wearable health monitoring sensors and Internet of Things devices are also presented. Finally, the current challenges and perspectives on the future development of thermoelectric generator, in particular for efficient materials and self‐powered devices, are also discussed.