1. Introduction

The rapid delivery of emergency medical supplies is crucial for saving lives in disaster-stricken areas and remote locations where traditional transportation methods are often inadequate. Natural disasters, such as earthquakes, floods, and hurricanes, can severely disrupt infrastructure, making it extremely difficult to reach affected populations with essential medical items such as blood, vaccines, and medications [1, 2]. In these critical situations, timely access to medical supplies can mean the difference between life and death.

Unmanned Aerial Vehicles (UAVs), commonly known as drones, offer a promising solution to this challenge by enabling swift and direct delivery of medical supplies [3]. UAVs can bypass obstructed roads and reach remote or inaccessible areas quickly, providing immediate relief to those in need. This technology leverages advancements in robotics, aerodynamics, and artificial intelligence to deliver payloads efficiently and safely [4]. Despite the potential benefits, the implementation of UAV-based emergency medical supply delivery systems faces several challenges. These include technical limitations such as flight duration and payload capacity, regulatory frameworks governing airspace usage, and public acceptance and safety concerns [5, 6]. Addressing these challenges is essential for the widespread adoption and integration of UAVs into emergency response strategies [7-10]. The practical applications and empirical evidence from field trials and real-world deployments have been discussed by many studies [11-15]. Therefore, continued research and collaboration between government agencies, healthcare providers, and technology developers is crucial for overcoming the current limitations and realizing the full potential of UAVs in emergency medical supply delivery.

This paper offers a comprehensive review of UAV-based emergency medical supply delivery systems, emphasizing key technological advancements, ongoing challenges, and future opportunities. It begins by exploring foundational technologies such as power sources, payload management, and communication systems, essential for developing reliable UAV platforms. The review then delves into recent improvements in drone design, navigation systems, and regulatory frameworks, highlighting innovations that have enhanced UAV efficiency and safety. Practical case studies from countries like Nepal and rural Africa underscore the impact of UAVs on reducing emergency response times and improving patient outcomes. Emerging trends, including autonomous drone operations, 5G communication networks, and integrated healthcare platforms, are also examined as potential enhancements to UAV delivery systems. Ultimately, this review aims to guide future research and inform stakeholders about the opportunities and challenges of integrating UAVs into emergency medical logistics.

2. Key Development Areas of UAV Technology

UAV technology is currently advancing rapidly, particularly in the fields of lightweight materials, power system optimization, modular design, and multifunctional applications. Progress in these areas has significantly enhanced UAV performance and broadened their potential applications across various sectors. Advancements in lightweight materials, power system optimization, modular design, and multifunctional capabilities have driven the rapid evolution of UAV technology. These innovations have expanded the range of UAV applications and laid a solid foundation for future developments. As technology continues to evolve, drones are expected to demonstrate unique value across a growing number of sectors [16,17,18].

2.1. Lightweight Materials

The use of lightweight materials is crucial for improving UAV efficiency. Carbon fiber composites, known for their high specific strength and low density, have emerged as an ideal choice for UAV structural components. Studies show that integrating carbon fiber materials into UAV designs can significantly reduce weight, enhance load capacity, and maintain structural integrity. Moreover, advanced structural design techniques, such as topological optimization, allow for reduced material usage while meeting strength and stiffness requirements, further improving UAV performance and energy efficiency.

2.2. Power System Optimization

Optimizing UAV power systems is key to improving endurance and operational efficiency. Recent advancements in battery technology, combined with refined motor designs, have increased the efficiency of electric propulsion systems, enabling longer flight durations and greater thrust-to-weight ratios. By selecting energy-efficient battery packs and optimizing the interaction between motors and propellers, UAVs can achieve extended flight times. Additionally, research into hybrid propulsion systems and alternative energy sources, such as hydrogen fuel cells, is paving the way for longer-range missions and improved endurance for future UAV applications.

2.3. Modular Design

Modular design is a significant innovation in UAV technology, addressing challenges related to maintenance, upgrades, and mission-specific adaptability. This design approach enables quick replacement of faulty components and easy reconfiguration of UAVs to meet varying mission requirements. For example, sensors, batteries, and communication modules can be assembled as interchangeable units, simplifying both maintenance and customization. This modularity enhances the flexibility and scalability of UAV systems, ensuring that drones can be adapted quickly for diverse operational scenarios.

2.4. Multifunctional Applications

The multifunctional capabilities of UAVs represent another major area of development. As UAV platforms mature, their utility is no longer limited to single-purpose operations, such as aerial photography or mapping. Modern UAVs are deployed across various fields, including agricultural plant protection, environmental monitoring, and logistics. With modular payloads like high-definition cameras, infrared sensors, and crop-spraying systems, UAVs can be customized to meet specific mission objectives. Additionally, the integration of advanced navigation systems and autonomous flight algorithms enables UAVs to autonomously plan routes, navigate complex environments, and perform tasks such as real-time obstacle avoidance.

3. Cases of Drone Emergency Medical Delivery

Globally, drones have been increasingly integrated into emergency rescue operations, with numerous countries incorporating them into their disaster response systems. As early as 1996, Israel deployed drones for fire monitoring, and by 2006, the United States was using UAVs for search and rescue operations during hurricane disasters. In 2011, Japan utilized drones equipped with sensors to assess radiation levels following the earthquake and nuclear disaster. In contrast, China's use of drones in emergency rescue began relatively late. During the 2008 Wenchuan earthquake, drones appeared for the first time in Chinese disaster response efforts. Since then, UAVs have played an increasingly significant role in subsequent disaster scenarios, such as the Yushu and Lushan earthquakes. In these instances, remote sensing drones were pivotal in providing rapid aerial imagery of affected areas, allowing real-time coordination and damage assessment.

Drones have demonstrated multiple advantages in emergency situations, including low operational costs, ease of deployment, and rapid response capabilities. Their ability to swiftly enter disaster zones, capture aerial imagery, and relay real-time data provides critical insights to disaster management teams. This rapid assessment capability allows experts to evaluate damage remotely, making drones uniquely suited for large-scale disaster analysis. For example, following major earthquakes, drones have been used to survey extensive areas quickly and efficiently, supporting more informed decision-making and resource allocation during the critical early stages of disaster relief.

In China, drones are gradually becoming a core component of emergency rescue operations (Table 1). DJI, a leading drone manufacturer, has actively promoted the use of UAVs in emergency scenarios and established an emergency rescue alliance. During the COVID-19 pandemic in 2020, drones played a vital role in epidemic prevention and control, with 780 drones from 99 companies participating in missions. These drones accounted for 85% of all aerial assets, including helicopters, utilized during the crisis. This data highlights the growing prominence of UAVs in China's emergency rescue efforts and underscores their potential to revolutionize disaster response strategies worldwide.

Table 1. The use of drones in disaster relief in China in recent years

4. Innovation in drone delivery systems

Recent innovations in drone delivery systems, from autonomous operation to advanced communication networks and integrated healthcare platforms, are significantly enhancing the efficiency, reliability, and safety of drone deliveries across various sectors. Innovations in autonomous operations, advanced communication networks, and integrated healthcare platforms are not only transforming the operational efficiency of drone deliveries but also broadening their applications, making them indispensable in fields such as logistics, disaster response, and healthcare.

4.1. Autonomous Operation

Advances in autonomous operation technology have enabled drones to operate in complex environments with minimal or no human intervention. Utilizing a combination of GPS navigation, inertial measurement units (IMUs), vision sensors, and machine learning algorithms, drones are now capable of autonomously taking off, cruising, avoiding obstacles, and landing with precision. Some drones are further equipped with sophisticated Collision Sensing and Avoidance (CSA) systems, which detect and avoid obstacles during flight, ensuring operational safety. These technologies allow drones to function effectively in diverse weather conditions, enhancing their utility in logistics, emergency response, and medical supply delivery. Autonomous operation minimizes human error and increases the reliability of drone missions, further expanding their application potential [19].

4.2. Advanced Communication Networks

Drone delivery systems depend on robust communication networks for remote control, data transmission, and real-time monitoring. The widespread deployment of 5G networks has provided drones with a high-speed, low-latency communication environment, essential for real-time data transmission, remote monitoring, and video streaming. 5G technology enables drones to transmit real-time video, ensure high-precision positioning, and report flight status instantaneously. Additionally, satellite communication systems offer an alternative for drone operations in remote or underserved areas, ensuring global connectivity and expanding the operational reach of drones beyond the limits of terrestrial networks [19]. These advanced communication networks are critical for ensuring the reliability and safety of drone delivery systems, especially in time-sensitive applications like healthcare logistics.

4.3. Integrated Healthcare Platforms

In the healthcare sector, drone delivery systems are being integrated with existing medical infrastructures, forming a streamlined supply chain for essential medical supplies. A notable example is Zipline, a company that has successfully implemented drone-based medical delivery services in Rwanda, delivering blood and other critical medical supplies to remote hospitals. This model drastically reduces delivery times, improving access to life-saving medical resources, especially in underserved regions. By integrating drone delivery systems with hospital information systems (HIS), these platforms can automatically receive orders, prepare goods, and calculate optimal delivery routes, ensuring a seamless and efficient delivery process. Such integration helps address healthcare delivery challenges in remote areas, enhancing the responsiveness and coverage of emergency medical services [20].

5. Summary

UAVs offer a transformative solution for delivering medical supplies in disaster-stricken and remote areas, bypassing infrastructure disruptions. Key advancements in lightweight materials, power optimization, and modular designs have enhanced UAV efficiency and versatility. Globally, UAVs have been integrated into emergency rescue systems, proving their value in rapid response and disaster assessment. In China, drones have played a crucial role in post-earthquake recovery and COVID-19 response. Recent innovations such as autonomous operation, advanced communication networks, and integration with healthcare platforms are further enhancing UAV delivery systems, making them indispensable in logistics and healthcare. These technological strides are setting the stage for more widespread adoption and improved emergency response capabilities.