Figure . Annual publication trends for different biomedical applications of 3D printing Next, we look at the trends of publications related to different biomedical applications of 3D printing. The publications of tissues/organs, orthopedics/prosthetics, pharmaceuticals, and others were examined from our database (Figure ). The analysis displays that the 3D printing technique has mainly been applied to tissues/organs-related fields since 2014. In 2021, 3D printing contributed to tissues/organs by 46.0%, followed by pharmaceuticals (25.9%), others (16.8%), and orthopedics/prosthetics (11.2%). Figure provides more details for each application. Journal publication counts are considerably higher than the patent. This may indicate that the commercialization of inventions in journals and that the patent issuing process is usually time-consuming. In orthopedics/prosthetics (Figure ), the annual patent to journal publication ratio is higher than other three applications. It may correlate to the mature techniques and applications in this field. In Figure , powder bed fusion's annual patent ratio is also relatively higher than other techniques. Powder bed fusion is often used for orthopedic/prosthetic application and inorganic substances are the primary feeding materials (Figure ). Figure reveals the growth of hydroxylapatite in 3D printing earlier than 2013. These publication trends demonstrates that the relative maturity of powder bed fusion (technique), inorganic substances (material), and orthopedics/prosthetics (application). We further analyzed a sub-field of tissues/organs-bioprinting. Figure shows the total publication counts in 2021 are 1014, around 42% of the tissues/organs publication volume. Bioprinting has become one of the emerging fields in tissues/organs application of 3D printing techniques. The top substances occurring in documents related to tissues/organs and orthopedics/prosthetics applications are shown in Figures and, respectively. 3D printing applications in tissues/organs mostly use natural polymers (in hydrogel form) like gelatin, collagen, alginic acid, and chitosan, while synthetic polymers like polycaprolactone and poly(lactic acid) are also used. HAp, TCP, and cellulose are also applied to the tissues/organs to form hybrid materials. However, in this application, journal publication counts are considerably higher than the patents. This may represent the potential for development of the commercialized application using these substances. Figure shows the top substances occurring in documents concerning bioprinting. In general, natural polymers like alginic acid, sodium alginate, gelatins, and collagens as well as synthetic polymers like polycaprolactone, polyethylene glycol diacrylate, and methacrylic anhydride primarily resulted in journal publications. Alginic acid and sodium alginate have been extensively utilized as materials for 3D bioprinting applications. HAp also got involved in this area as an inorganic filler with other natural or synthetic polymers to form modified biopolymers for bioprinting. The top 15 concepts indexed from documents related to tissues/organs and orthopedics/prosthetics are shown in Figures and, respectively. Concepts that frequently appeared in tissues/organs application include bioprinting, biocompatibility, bone formation/bone, pharmaceutical hydrogels, etc. For orthopedics/prosthetics applications, concepts such as dental implants, bone formation, and artificial bone frequently appeared. This indicates that dental/bone-related innovation is the mainstream in orthopedics/prosthetics applications.