Results

The number of publications for the period 2020 to April 2023 totaled 236, accounting for 82% of the total research sample. It showed that there had been an explosion of scientific research results during the last 3 years of the COVID-19 pandemic. The global COVID-19 had greatly triggered knowledge innovation in the novel field of emergency manufacturing.

From the analysis of the document co-citation network and its clusters (Figure 1-①), the surge in demand for emergency supplies and supply chain disruptions caused by the pandemic ^{Reference Ranney, Griffeth and Jha1} laid the foundation for current emergency manufacturing innovation. Disaster information and virus characteristics ^{Reference Balachandar, Mahalaxmi and Kaavya4} provided the research direction for this field (Figure 2-①), which in turn gave rise to subsequent research hotspots in the era of pandemics such as 3-dimensional printing technology, supply chain management, and medical textiles (see Figure 2-②).

Figure 1. The document co-citation network and keywords co-occurrence network and their clusters map.

Figure 2. The evolution process of the topics.

The keywords co-occurrence network and its clusters (see Figure 1-②) showed that the field research hotspots focused on pandemic-triggered emergency manufacturing technology innovations, pandemic-triggered emergency manufacturing material innovations, and pandemic-triggered emergency manufacturing management innovations. Emerging technologies such as additive manufacturing technology, the digital twin, and the Internet of things are widely used in the emergency manufacturing process during major epidemics. The research covers various aspects such as some specific aspects of printing emergency supplies, using additive manufacturing technologies (including printed materials, model design files, the expansion of the types of emergency materials printed, and quality testing of the finished printed products); crisis simulation using computer simulation technology to mimic scenarios after an epidemic, achieving better control over resources in the manufacturing process; remote collaboration using cloud computing to maintain efficiency and productivity even when working remotely under an epidemic; and using blockchain technology for source identification and anti-counterfeiting of raw materials for emergency supplies. ^{Reference Pour, Nazzal and Darras5} Emergency manufacturing material innovations include the application of novel materials such as silicone rubber, stainless steel wheeled structures, and protein receptors in the manufacturing process of respirators ^{Reference Rebelo, Neutel and Alves6} and vaccines. In the aspect of emergency manufacturing management innovations, supply chain responsiveness, supply chain resilience, and supply chain transparency have become research hotspots, and scholars have used technologies such as block chain to provide traceability solution of emergency supply chains ^{Reference Ilhaam, Mazin and Raja7} (see Figure 2-②).

The high-burst keywords indicated that research trends in the post-pandemic era mainly focus on the application innovation of additive manufacturing and new information and communication technology (ICT), innovation of emergency manufacturing materials, and construction of an emergency supply chain system (see Table 1 and Figure 2-③). To meet the technological innovation of emergency manufacturing, additive manufacturing technology in the future will develop in the direction of higher precision, more convenience, safety, standardization, and networking. ^{Reference Clifton, Damon and Martin8} New ICT will further need to be deeply integrated with the emergency manufacturing industry so as to strengthen the stress capacity of manufacturing application scenario transformation, and realize the supply chain collaborative arrangement from offline to online. ^{Reference Alcock, Boutilier and Siddiq9} In terms of material innovation, in the future, during the design process of innovative personal protective equipment (PPE), attention should be given to providing optional alternatives to raw materials and processes to match those alternatives. This conceptualized design idea can be built into a knowledge database and shared on the web to guide people to use local materials and processes for more efficient emergency manufacturing and reduced reliance on global supply chains. In addition, there is also a trend to explore easily disposable and reusable raw materials to produce PPE. In the aspect of management innovation, the use of information and network technology, the collection and analysis of information flow within the supply chain, big data analysis, manufacturing intelligence, and control of logistics processes have all become future research targets for the management optimization of emergency supply chains. In addition, multilateral and regional entities and governments need to act together to create vaccine information platforms and portals and develop financial incentives and policies to attract all types of companies to share information related to the pandemic. ^{Reference Sodhi, Tang and Willenson10}

Table 1. Top 25 keywords with strongest bursts