The material revolution of flat-chested sex dolls continues, and the integration of silicone and smart materials indicates a new direction. "Active silicone" developed by a laboratory in the United States implants microfluidic channels in the chest of the life size sex doll to simulate the skin flushing caused by hormonal changes. The more advanced 4D printed silicone can automatically adjust its softness according to the ambient humidity. This technology enables the tactile realism of the flat chested sex doll to break through physical limitations and open a new era of hyper-realistic experience.