The recent success of additive manufacturing processes (also called, 3D printing) in the manufacturing sector has led to a shift in the focus from simple prototyping to real production-grade technology. The enhanced capabilities of 3D printing processes to build intricate geometric shapes with high precision and resolution have led to their increased use in fabrication of microelectromechanical systems (MEMS). The 3D printing technology has offered tremendous flexibility to users for fabricating custom-built components. Over the past few decades, different types of 3D printing technologies have been developed. This article provides a comprehensive review of the recent developments and significant achievements in most widely used 3D printing technologies for MEMS fabrication, their working methodology, advantages, limitations, and potential applications. Furthermore, some of the emerging hybrid 3D printing technologies are discussed, and the current challenges associated with the 3D printing processes are addressed. Finally, future directions for process improvements in 3D printing techniques are presented.

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Li and S compounds are currently exploited for their applications in battery industry. Here, we discovered that Li-S compounds exhibit supercapacitor like properties in a context-dependent manner viz., when Li and S atoms are entrapped in a conductivity cage of N-doped reduced graphene oxide (ND-RGO) supercapacitor derived from silk cocoon, it resulted in the formation of a superior hybrid Li-S-silk (ND-RGO-Li-S) supercapacitor. Interestingly, ND-RGO-Li-S proves to be a better supercapacitor than ND-RGO alone. Electrochemical properties of ND-RGO versus ND-RGO-Li-S indicated that the later has higher capacitance (~ 10.72%), lower resistance (~ 2.98%), and higher time constant or relaxation time (~ 7.52%). Thus, in one of the first attempts, caging Li and S in ND-RGO supercapacitor matrix offers a new role for Li-S, as an improved supercapacitor, unlike its current application as a battery.

Nanomaterials have already contributed to many innovative products in the consumer markets. Constant efforts are directed at attaining unique morphologies and reduction in size. Exponential growth in research is thus involved in the synthesis of the novel nanomaterials. Boron and its compounds with distinct functional and structural properties find extensive usage in a variety of fields ranging from nuclear technology to electronics, ceramics, etc. Also, due to their non-toxicity, they are considered an attractive intermediate in the healthcare and cosmetic industry. The majority of reviews on boron and its compounds are focused on morphologies and the structure of the boron compound obtained. Here, we offer a comprehensive review of the unique properties of the major boron compounds: boron carbide (B4C), boron nitride (BN), and heterostructures with metals and organic compounds. In each section, we also describe the subsequent synthesis routes and the challenges associated with them. We have also summarized the various morphologies and shapes reported to be associated with boron and its compounds. In recent years, however, primary research on boron nanoparticle (BNP) has focused on non-toxic/greener and energy-efficient synthesis routes. The usage and production of pure BNPs in the industry are very scarce and are often associated with nanoclusters of boron and other elements. The intricate structural design and low purity of the nanoproducts formed make BNP synthesis challenging. Thus, in the last section, we summarize the challenges and outlook of the current research with future prospects in the area of BNP research.

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