4D-Printed micro-tentacles exhibiting wide-spectrum deformability

It has been widely reported that untethered micro-robots can access hard-to-reach regions within the body to perform a range of medical procedures. However, the narrow operating space limits the ability of such micro-robots to interact with the external environment. Here, inspired by chameleons, we propose a prehensile micro-tentacle with wide-spectral deformability using the micro four-dimensional (4D)-printing technology. The design procedure includes programmable design material distribution and the integration of pH-responsive hydrogels and photoresists via the two-photon polymerization (TPP) process to build pH-responsive actuated joints . The resulting micro-tentacles were able to wrap objects located within a range of >12 times their own volume, wherein the theoretical size range of these entangled objects was found to range from 6.5 to 40 µm. Furthermore, we demonstrate the cell-capturing characteristics of micro-tentacles and confirm their ability to anchor onto specific objects. Such micro-tentacles with a large graspable space and an excellent shape adaptability could be easily integrated into untethered micro-robots in the future, paving the way for their medical application in complex biological environments.