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Scientists develop a 3D-printed pressure sensor embedded with a temperature sensor from conductive carbon-based composites

Pressure sensors are important tools for accurate sensing of applied forces. However, they can mostly sense forces along only a single direction. In a new study, scientists from South Korea take things to the next level with a multi-directional pressure sensor fabricated using 3D-printed conductive polymer composites and paired with a temperature sensor for resistance calibration. The low cost of such 3D-printed sensors could enable large-scale production of robotic grippers and tactile sensors.

Scientists develop a 3D-printed pressure sensor embedded with a temperature sensor from conductive carbon-based composites
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The treatment of many medical issues like abnormal gait and muscular disorders require an accurate sensing of applied pressure. In this regard, flexible pressure sensors that are simple, lightweight, and low-cost, have garnered considerable attention. These sensors are designed and manufactured through “additive manufacturing,” or what is more commonly called “3D printing,” using conductive polymer composites as their building blocks. 
 
However, all 3D-printed pressure sensors developed so far are limited to sensing applied forces along a single direction only. This is hardly enough for real world applications, which involve situations where forces can be applied along various angles and directions. Moreover, the electrical resistance of most conductive polymers varies with temperature and must be compensated for accurate pressure sensing.

Professor Hoe Joon Kim (left) and his student Mr. Hang-Gyeom Kim (right), who were key members of the research team that conceptualized and conducted the groundbreaking study ⓒDGIST
Professor Hoe Joon Kim (left) and his student Mr. Hang-Gyeom Kim (right), who were key members of the research team that conceptualized and conducted the groundbreaking study ⓒDGIST

In a study published in Composites Part B: Engineering, a group of scientists led by Prof. Hoe Joon Kim from Daegu Gyeongbuk Institute of Science and Technology, South Korea, have addressed this issue with a newly designed multi-axis pressure sensor coupled with a temperature-sensing component that overcomes the limitations of conventional sensors.

Prof. Hoe Joon Kim explains:
“Our multi-axis pressure sensor successfully captures the readings even when tilted forces are applied. Moreover, the temperature-sensing component can calibrate the resistance shift with temperature changes. In addition, the scalable and low-cost fabrication process is fully compatible with commercial 3D printers”

The scientists are thrilled about the future prospects of their 3D-printed sensor.

Scientists first prepared the printable conductive polymer using multi-walled carbon nanotubes (MWCNTs) and polylactic acid (PLA). Next, they built the sensor body with a commercial elastomer and sensing material with MWCNTs/PLA composite filament using 3D printing. The sensor is based on a bumper structure with a hollow trough beneath and employs three pressure-sensing elements for multi-axis pressure detection and a temperature-sensing element for calibration of resistance. The sensor could successfully calibrate both the magnitude and direction of the applied force by evaluating the response of each pressure-sensing element. This bumper structure, when installed in a 3D-printed flip-flop and a hand gripper, enabled clear distinction between distinct human motions and gripping actions.

Prof. Kim comments:
“The proposed 3D printing technology has a wide range of applications in energy, biomedicine, and manufacturing. With the incorporation of the proposed sensing elements in robotic grippers and tactile sensors, the detection of multi-directional forces along with temperature could be achieved, heralding the onset of a new age in robotics”

More information https://scholar.dgist.ac.kr