Magnetoactive Janus Particle Swarms for Information Display, Memory and Encryption

Magnetic microrobots have drawn attention due to their untethered actuation, fast response, easy to miniaturize and flexible control mechanisms. While actuation of a single magnetic robot is relatively straightforward, the design and control of robotic swarms to achieve programmed synchronized and asynchronous motions remains a challenge. Here, we develop a microrobotic swarm system based on responsive magnetoactive Janus particle (MAJP) with programmable magnetization that can rotate individually with external magnetic fields to present different color states at the surface for multiple programmable functions. MAJP microrobots were designed with tunable structure and properties, i.e., encoded swarming behavior and fully reversible switching mechanisms, to enable programmable dynamic display, non-volatile and semi-volatile memory, Boolean logic, and information encryption functions in soft, wearable devices. MAJPs and their unique swarming behaviors open new functions for the design of multifunctional and reconfigurable display devices, and constitute a promising building block to develop the next generation of soft physical computing devices and responsive metamaterials.