Representative image of 3D printing. Getty Images
Tactile sensors have become essential in robotics, prosthetics, wearable devices, and healthcare monitoring.
By detecting and converting pressure or force into electrical signals, these devices allow machines and medical tools to respond more accurately to the environment.
For years, researchers have worked to expand the sensing range and boost sensitivity. One promising route has been mechanical metamaterials, which exhibit unique properties not found in conventional materials.
Among them, auxetic mechanical metamaterials (AMMs) stand out. They feature a negative Poisson’s ratio, which enables inward contraction and localized strain concentration when compressed, a counterintuitive trait that makes them highly attractive for advanced sensing applications.
Despite their potential, AMMs have faced practical obstacles. Existing technologies struggle with fabrication challenges and integration issues that prevent large-scale adoption in real-world systems.
A research team from the Seoul National University of Science and Technology has now taken a major step forward. Led by Mingyu Kang and Dr. Soonjae Pyo, the group developed a novel 3D AMM-based tactile sensing platform.
Their findings demonstrate how a cubic lattice with spherical voids, fabricated using digital light processing (DLP)-based 3D printing, can unlock new design possibilities.
The team tested their 3D-printed auxetic metamaterials in both capacitive and piezoresistive sensing modes. In the first, pressure alters electrode spacing and dielectric distribution. In the second, a carbon nanotube coating changes resistance under load.
Kang explained that the unique negative Poisson’s ratio behavior enables inward contraction under compression, which concentrates strain in the sensing region and boosts sensitivity.
“The auxetic design strengthens sensor performance in three ways—enhancing sensitivity through localized strain concentration, maintaining stability in confined structures, and minimizing crosstalk between sensing units,” he said.
He added that, unlike conventional porous structures, the design avoids lateral expansion, making it more wearable and less prone to interference. “With digital light processing-based 3D printing, we can precisely program structural performance and customize geometry without changing the base material,” Mr. Kang noted.
The team validated the concept with two demonstrations: a tactile array for spatial pressure mapping and object classification, and a wearable insole system capable of monitoring gait patterns and detecting pronation types.
According to Dr. Pyo, the proposed sensor platform can be applied across diverse fields, from smart insoles for gait monitoring to robotic hands for precise object manipulation and wearable systems that track health comfortably without disrupting daily activities.
“The auxetic structure preserves its sensitivity and stability even when confined within rigid housings, such as insole layers, where conventional porous lattices typically lose performance,” he said.
He further noted that the design’s scalability and compatibility with multiple transduction modes make it “suitable for pressure mapping surfaces, rehabilitation devices, and human-robot interaction interfaces that require high sensitivity and mechanical robustness.”
Looking ahead, these auxetic-structured 3D-printed tactile sensors could reshape wearable electronics. They offer the promise of continuous, high-fidelity monitoring of human movement, posture, and health metrics.
Their adaptability and independence from specific materials also open doors to personalized sensors for prosthetics, medical applications, and immersive haptic systems.
As additive manufacturing technology becomes more widespread, the researchers believe customizable tactile interfaces may soon become standard across consumer products, healthcare devices, and robotics, paving the way for the next generation of smart, responsive systems.
The findings have been published in Advanced Functional Materials.
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