Light On The Move: ME Researchers Create Microscopic Particles That Steer Light

Researchers in the Department of Mechanical Engineering within the University of Minnesota College of Science and Engineering have developed a new class of microscopic particles that can swim through liquid and redirect light on command, combining mobility and sophisticated optical control in a single device.

The work, led by Professor Ognjen Ilic with research scientist Seung Yeol Lee and PhD student Yujie Luo, was published in Advanced Materials, a leading multidisciplinary materials journal.

The researchers call the devices magneto-photonic metaparticles. Each particle pairs a magnetic core, which allows researchers to guide its movement, with a nanostructured surface engineered to control light precisely. The result functions like a microscopic smart mirror: it can travel through a liquid and redirect light toward a chosen location.

The combination represents a fundamental advance. Until now, researchers typically had to choose between sophisticated optical components that stayed fixed in place or mobile particles with limited ability to manipulate light. To the team’s knowledge, this is the first particle to combine controlled movement with advanced optical functionality.

The clearest applications are in medicine. Many medical technologies rely on delivering light precisely inside the body, whether to image tissue, stimulate neurons, or activate therapies. Conventional optical systems often require a clear line of sight, limiting their effectiveness inside complex, dynamic environments such as the human body.

Mobile optical devices could navigate those environments and deliver light exactly where it is needed with minimizing invasive procedures. Potential applications include targeted light delivery for imaging, phototherapy, biosensing, optogenetics, and lab-on-a-chip systems.

The particles are also designed with future production in mind. The team’s fabrication method is compatible with scalable nanoimprint manufacturing, offering a potential path toward producing large numbers of devices as the technology develops.

The team describes the work as an early proof of concept. Next, they plan on making the particles smaller, adapting them for use in biological environments, and expanding their optical capabilities so they can focus light or control properties such as color and polarization.

The longer-term vision is a new generation of microscopic photonic agents that can travel through complex environments, carrying sophisticated optical functions directly to where they are needed for applications in medicine, sensing, and integrated photonic systems.