Tensile strength test

Each specimen for the tensile strength test was composed of 6 tracheal rings (n=5), and all were subjected to an axial elongation test. A fixture was placed in parallel with the load cell and was used to actively pull the specimen. The other end, which was at the bottom, pulled the other end of the specimen. The outermost membrane regions on both ends of the trachea were sutured to the fixture with a 4-0 Mersilk suture (braided silk, Ethicon, Somerville, NJ, USA) (Figure 1C). The original length before stretching was measured using electronic digital display calipers (LINKS 0–150 mm, HMCT Group, Harbin, China), and the specimen was stretched at a speed of 5 mm/min. When the trachea was stretched to 150% of the original length (50% displacement), the measurement was stopped (Figure 1D). The tensile load (N) of each tracheal specimen at 50% displacement was calculated using a spreadsheet.