Tactile sensors—devices that detect touch, pressure, and force—are at the heart of many modern technologies.
They help robots grip objects, allow prosthetics to sense pressure, and power wearable devices that monitor health.
But to keep up with the growing demand for accurate, flexible, and comfortable sensing, researchers have been looking for ways to make these devices more sensitive and reliable.
One promising solution comes from a special type of engineered material known as auxetic mechanical metamaterials (AMMs).
Unlike most materials that expand outward when squeezed, AMMs behave in the opposite way: they contract inward, focusing strain in a small region. This unusual property makes them excellent candidates for improving sensors.
However, until now, building these materials into practical devices has been a big challenge.
A research team from the Seoul National University of Science and Technology has taken a major step forward.
Led by Master’s student Mingyu Kang and Associate Professor Soonjae Pyo, the group developed a new tactile sensor platform made with 3D-printed auxetic structures.
Using a cubic lattice design with tiny spherical holes, they were able to fabricate these advanced materials with a digital light processing (DLP) 3D printer, which allows very precise control of structure.
The team tested their design in two types of sensors.
In the first, called capacitive mode, pressure changes were detected by shifts in electrode spacing and dielectric distribution.
In the second, piezoresistive mode, a coating of carbon nanotubes changed its resistance under pressure. In both cases, the auxetic design made the sensors more sensitive and stable.
According to Kang, the inward-contracting behavior of their design concentrates strain in the sensing area, boosting sensitivity.
The researchers also found three key advantages: improved sensitivity, consistent performance even when built into confined structures like shoe insoles, and reduced interference between sensing units. Unlike traditional porous designs, these 3D-printed structures don’t expand sideways, making them more comfortable and reliable for wearable use.
To show the potential, the team built two examples: a tactile sensor array that could map pressure and identify objects, and a smart insole system capable of monitoring gait patterns and detecting pronation (foot roll). Dr. Pyo explained that the platform could be applied to robotic hands for precise gripping, smart insoles for everyday health tracking, and rehabilitation tools that require accurate, non-intrusive sensing.
Looking ahead, these 3D-printed auxetic sensors could transform wearable electronics and robotics. Because they can be customized through geometry rather than material changes, they are adaptable and scalable. As 3D printing becomes more accessible, this approach may pave the way for mass-produced, personalized tactile devices for healthcare, prosthetics, and immersive virtual experiences.
Source: KSR.
