#South Korea #Seoul #wearable technology #Tactile Sensors #SEOULTECH

SEOULTECH's Groundbreaking Tactile Sensor Technology

In a significant advancement for wearable technology, researchers from the Seoul National University of Science and Technology (SEOULTECH) have unveiled a pioneering tactile sensing platform utilizing 3D-printed auxetic metamaterials. This innovative work holds great potential in the realms of robotics, prosthetics, and health monitoring, particularly in enhancing the performance of pressure sensors commonly found in wearables.

The Inspiration Behind the Technology

Tactile sensors play a crucial role in detecting and converting external stimuli like pressure and force into electrical signals, which are integral for effective environmental interactions. Despite extensive research efforts aimed at improving the sensitivity and range of these sensors, many existing technologies still face challenges in their applications. The introduction of auxetic mechanical metamaterials (AMMs)—materials that exhibit a negative Poisson's ratio—has opened up new avenues for sensor design. Unlike conventional materials, AMMs contract inward when compressed, allowing for localized strain concentration, which can enhance the performance of sensors and actuators.

A Bold New Approach

Under the guidance of Associate Professor Soonjae Pyo, Mr. Mingyu Kang, a Master's student from SEOULTECH's Department of Mechanical Design and Robot Engineering, led the charge in developing a novel tactile sensing platform. The researchers fabricated this platform using a cubic lattice structure embedded with spherical voids through digital light processing (DLP)-based 3D printing. This technique not only simplifies the manufacturing process but also allows for the fine-tuning of structural performance without altering the material's base properties.

The findings were significant enough to be published in the journal Advanced Functional Materials on July 6, 2025. In their study, SEOULTECH researchers explored the potential of 3D-printed auxetic metamaterials in two main sensing modes—capacitive and piezoresistive. In the capacitive mode, sensor performance varies with the spacing of electrodes and dielectric distribution. Conversely, in the piezoresistive mode, a network of conformally coated carbon nanotubes adjusts its resistance based on the applied load. This dual approach significantly enhances the sensors' responsiveness and versatility.

Key Advantages of the New Technology

Mr. Kang explains that the unique negative Poisson's ratio behavior of the technology results in pronounced inward contraction during compression, which amplifies sensitivity by concentrating strain at the sensing points. The design has several undeniable advantages:

• - Enhanced Sensitivity: By focusing strain at specific points, the sensors can detect subtle changes in pressure, crucial for applications in health monitoring and robotic systems.
• - Stability in Confinement: Unlike traditional porous structures, the auxetic design maintains its sensitivity and performance even when integrated into rigid containment systems, such as those found in smart wearables or robotic devices.
• - Minimized Crosstalk: The design significantly reduces interference between adjacent sensing units, allowing for more accurate readings in multi-sensor setups.

Real-World Applications

The team showcased two significant proof-of-concept applications: a tactile array that maps spatial pressure and classifies objects, and a wearable insole system capable of monitoring gait patterns and identifying pronation types. "The proposed sensor platform can seamlessly integrate into smart insoles for effective gait monitoring, robotic hands for object manipulation, and health monitoring systems that aim for unobtrusive sensing, thereby supporting everyday life activities effortlessly," noted Dr. Pyo.

By overcoming the limitations of current technologies, this platform is engineered for a range of applications, from rehabilitation devices to pressure-sensing surfaces that require high sensitivity and mechanical robustness. The scalable nature and compatibility with various transduction modes widen its utility to various fields, including specialized healthcare solutions and human-robot interfaces.

Future Prospects

Looking ahead, the potential for auxetic-structured 3D-printed tactile sensors appears boundless. In the coming decade, these advanced pressure sensors could become foundational components of next-generation wearable electronics, providing continuous, high-fidelity data on human movement, posture, and physiological metrics. Their adaptability and independence from materials could lead to the development of bespoke, application-driven sensors tailored for personalized medicine, enhanced prosthetics, and immersive haptic feedback systems.

This remarkable innovation from SEOULTECH not only emphasizes the university's commitment to cutting-edge research but also signals a transformative step toward a future where wearables provide deeper insights into our health and interactions with technology.