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Professor Jaeyoung Yoo’s team, in collaboration with Professor John Rogers' group at Northwestern University, has developed a groundbreaking wireless, skin-attachable haptic interface that mimics the complexity of human touch. This research introduces the "Full Freedom-of-Motion (FOM) Actuator," a compact device capable of delivering multidirectional tactile stimuli—including pressure, vibration, stretching, sliding, and twisting—by precisely engaging various mechanoreceptors in the skin.

Unlike conventional haptic technologies that primarily rely on unidirectional vibrations, the FOM actuator employs a nested configuration of electromagnetic coils and magnets to generate dynamic, programmable forces in all directions. This design enables the device to produce complex tactile sensations, offering a more realistic and immersive user experience in extended reality (XR) applications.

The research team demonstrated the device's versatility through various applications. For instance, by attaching the haptic interface to different body parts such as the back of the hand, fingers, or arms, visually impaired users could receive navigation cues through tactile feedback, facilitating precise hand movements and object detection without visual input. Additionally, the device successfully replicated the textures of materials like fabric and metal, enhancing the realism of virtual object interactions. Notably, the team converted sound frequency information from musical instruments into distinct vibration patterns, allowing users to perceive musical components through touch alone, thereby offering a novel sensory substitution method for individuals with hearing impairments.

The haptic platform is designed to be compact, lightweight, and capable of delivering high-resolution tactile feedback. It ensures a high data transmission rate per device and features wireless control via Bluetooth, along with a flexible material structure optimized for skin contact. These attributes make it a promising tool for various applications, including XR-based gaming, medical training, rehabilitation, and sensory assistive devices.

Professor Jaeyoung Yoo remarked, “This research demonstrates the potential of advanced actuator technology capable of physically stimulating diverse tactile receptors. It offers promising applications not only as assistive technology for individuals with sensory impairments but also as a core interface for more immersive XR experiences.”

The study, titled “Full freedom-of-motion actuators as advanced haptic interfaces,” was published in the March 28, 2025, issue of the journal Science. This international collaboration was supported by the National Research Foundation of Korea (Global Research Laboratory Program) and the Ministry of Trade, Industry and Energy (Core Technology Development for Robot Industry Program). 

▲ Flexible haptic electronic system for omnidirectional tactile stimulation on skin

▲ Omnidirectional tactile stimulation technology utilizing a stimulation mechanism that takes into account human skin sensory receptors

▲ Auditory stimulation through omnidirectional tactile feedback (top), tactile navigation via object tracking in real-time smart glasses footage (bottom left), and texture reproduction in virtual reality environments (bottom right).