A 4D-printed programmable soft network with fractal design and adjustable hydrophobic performance

The concept of creating novel structures by drawing inspiration from the natural world has broad prospects in bio-integrated electronics. Auxetic mechanical metamaterials have wide applications in flexible sensors, implantable medical devices, and soft robots. Here, by combining 4D-printed fractal-inspired metamaterials with microlevel biomimetic electrodes, we propose a shape memory sensor with functional and structural reconfiguration, enhanced sensitivity, and high flexibility. First, we propose the design conception and mechanical model of the 4D-printed metamaterials. Then, the metamaterial skeleton is integrated with shape memory biomimetic electrodes, which prove to possess adjustable hydrophobic and electrical performance. The derived health-monitoring sensor proves to possess reconfiguration ability in electrical and mechanical properties according to the external stimulus and high sensitivity to signal feedback with high flexibility and compliance to the human body. This work demonstrates potential applications of 4D-printed reconfigurable sensors in the fields of wearable electronics and human-computer interaction.