Magnetoresponsive Photonic Micromotors and Wireless Sensing Microdevices Based on Robust Magnetic Photonic Microspheres

Magnetic photonic crystal microspheres (MPCMs), featuring the optical performances of photonic crystals (PCs) and magnetic properties of magnetic materials, have attracted increasing interest in biomedical separation and detection, micro-/nano-motors, magnetic displays, and so forth. Herein, we present a robust strategy for the fabrication of new generation MPCMs with angle-independent structural color and extraordinary mechanical stability, by chemically growing an inorganic PC shell onto a strongly magnetic micro inner core. The magnetic micro inner core introduces strong magnetism, allowing the assembly and motion of the MPCMs for magnetoresponsive photonic micromotors. Furthermore, by virtue of the unique pyroelectric and photoelectric effects of a ZnO layer compositing a PC shell, the MPCMs can be used to construct a multifunctional microsensor with quadruple sensing capabilities, including ultraviolet light, heating, infrared light, and an alternating magnetic field. Such a microsensor is further integrated with a Bluetooth transmitter to construct a wireless sensing microdevice, achieving the remote transmission of the stimulus to a mobile device. This work not only provides a novel strategy for fabricating robust, magnetic photonic microspheres but also opens a new avenue for their use as magnetoresponsive photonic micromotors and multifunctional sensing platforms.