Bhargav Akkinepally

People with physical disabilities face significant mobility challenges while climbing uneven surfaces and staircases. In these circumstances, traditional wheelchairs do not provide stable, safely controlled mobility, underscoring the importance of building superior stair‐climbing wheelchairs for both medical and infrastructure purposes. In this study, a review is proposed that provides a comprehensive summary of wheelchair types, developments, compares and evaluates existing stair‐climbing wheelchair technologies, and highlights major design gaps, performance limitations, and future research directions. The review examines four fundamental categories of existing systems: tracked‐based mechanisms, wheel‐leg hybrid mechanisms, tri‐wheel mechanisms, and automatic stair‐climbing systems. These mechanisms are evaluated based on critical performance metrics, including safety and stability, ergonomics, ease of use, energy efficiency, load‐carrying capacity, cost, effectiveness, adaptability to variable terrain, stair‐climbing mobility performance, and control methodologies ranging from manual to AI‐enabled modes. The key findings indicate that although significant advancements in stair‐climbing wheelchairs have been made, current systems still face challenges in portability, weight, cost, and comfort, while recent trends highlight the growing adoption of lightweight materials, hybrid locomotion, and AI‐based navigation frameworks. The proposed review has identified research gaps, including insufficient user‐centric design, high demand for low‐cost, reliable real‐world solutions, and the need for standardized safety testing methods for stair‐climbing systems. Overall, this review will provide an overview of the different technologies and a comprehensive comparison, highlight the major design trade‐offs, and suggest future research directions to advance the design and support designers, rehabilitation engineers, policymakers, and the mobility assistance technology research community in developing user‐friendly, comfortable stair‐climbing wheelchairs.

Flexible perovskite solar cells will transform clean, sustainable, and affordable energy, driving innovation on indoor and outdoor energy markets.

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The global transition toward sustainable and efficient energy storage solutions has placed research on electrolytes and energy storage materials at the heart of scientific and technological innovation

We examines the prospects of solar and hydrogen-based propulsion technologies as transformative solutions for achieving zero-emission aviation. With the aviation sector facing mounting pressure to address its rapidly growing contribution to global greenhouse gas emissions, projected to triple by 2050 without intervention, the paper first outlines the historical evolution of sustainable aviation from biofuels through to fully electrified, solar, and hydrogen-powered systems. Focusing on solar-powered aircraft, the review highlights both technical advances and inherent limitations: while high-efficiency photovoltaic systems have enabled groundbreaking demonstration flights and persistent high-altitude unmanned operations, constraints in power density, weight, and intermittency restrict scalability for large-scale commercial aviation. The discussion then turns to hydrogen technologies, contrasting the gravimetric advantages of hydrogen fuel with the engineering challenges of storage, safety, and infrastructure needs. Both hydrogen fuel cells and direct hydrogen combustion are assessed, with attention to recent demonstrators and ongoing research into mitigating issues such as NOx emissions and material durability. The paper further explores hybrid architectures combining batteries, solar, and hydrogen systems, evaluating their potential to optimize power density, efficiency, and operational flexibility across varying aviation use cases. Comparative lifecycle assessments, sustainability metrics, and economic feasibility analyses are presented to frame the real-world adoption pathways for these technologies. The review concludes by mapping integration challenges, future directions, and policy requirements needed to accelerate the transition toward net-zero aviation, emphasizing the essential interplay between disruptive technology, resilient infrastructure, and supportive regulation in the journey to clean air transport.

The rapid growth of urbanization and increasing congestion in metropolitan areas have spurred the development of Advanced Air Mobility (AAM) systems, with electric and hybrid air taxis emerging as a promising solution for sustainable urban transport. Central to the viability of AAM is the selection and integration of suitable energy storage and conversion technologies, which directly impact safety, endurance, cost, and scalability. This paper provides a comprehensive review of the current state and future prospects of batteries, supercapacitors, and fuel cells in the context of AAM applications. Batteries, particularly lithium-ion chemistries, are currently the most mature technology, enabling near-term demonstrations and certification efforts. However, their limitations in energy density, charging time, and thermal management restrict endurance and necessitate innovations in solid-state and lithium–sulfur variants. Supercapacitors, though limited in energy capacity, offer unparalleled power density and rapid response, making them ideal for handling transient loads during take-off, landing, and regenerative braking. Fuel cells present a promising long-term solution, providing high specific energy and zero carbon emissions at the point of use. Yet, their adoption depends heavily on the establishment of scalable hydrogen production, storage, and refueling infrastructure. The review further highlights hybrid architectures that combine these technologies, such as battery–supercapacitor and battery–fuel cell systems, to exploit complementary advantages. Integration challenges, including thermal management, power electronics, and intelligent energy management systems, are analyzed alongside safety considerations and certification requirements. Case studies of ongoing demonstrators illustrate the diverse strategies being pursued globally. Finally, the paper identifies key challenges and future directions, emphasizing material innovations, infrastructure readiness, supportive policy frameworks, and a roadmap for next-generation AAM energy systems. The findings underscore that while battery-powered air taxis are poised for near-term deployment, the long-term sustainability of AAM will rely on hybrid solutions and breakthroughs in advanced materials and hydrogen technologies.