One of the biggest moments for China's booming robotics industry this year was the catwalk performance by carmaker Xpeng's new humanoid robot: it was so lifelike that founder He Xiaopeng had to unzip its back to prove there was no person inside. The reveal exposed what was under the covers: bionic "muscles" that enable such uncanny lifelikeness, made possible by the 3D printing technology and high-performance materials from Chinese start-up PollyPolymer. Wang Wenbin, founder and chairman of PollyPolymer ...