Scientists from South Korea’s Daegu Gyeongbuk Institute of Science and Technology (DGIST) have developed low-cost multi-directional pressure sensors using 3D printed conductive polymer composites as their building blocks.
The sensor is designed to overcome the current limitations of 3D printed sensors regarding the effect of temperature on electrical resistance and the ability to only sense applied forces along a single direction.
Embedded with a temperature sensing component for resistance calibration, the low-cost 3D printed pressure sensors could reportedly enable large-scale production of a wide range of applications for the energy, biomedicine, and manufacturing sectors, such as robotic grippers and tactile sensors.
“Our multi-axis pressure sensor successfully captures the readings even when titled forces are applied,” said Professor Hoe Joon Kim of DGIST. “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 printers.”
3D printed sensors
Artificial Intelligence (AI) sensors have been named as one of the top emerging technologies to watch in 2021 by Lux Research. Researchers and industry players alike are increasingly leveraging 3D printing to produce a wide array of light, motion, and bacteria-sensitive devices for a whole host of applications within healthcare, robotics, and consumer goods.
Recent research developments in this area include 3D printed biosensors capable of protecting wearers from UV overexposure, flexible wearable motion sensors designed for soft robotics and wound dressing applications, and 3D printed sensors that enable humans to remotely interact with deformable soft robotics systems.
Just last month, scientists based in China, Pakistan and Hong Kong developed novel 3D printed sensors that could be used as a basis for “smart beds” of the future, enabling staff to monitor the wellbeing of patients and track their sleeping patterns.
The potential benefits of 3D printed sensors have also caught the attention of Google’s Advanced Technology and Projects (ATAP) division, which has leveraged 3D printer OEM Stratasys’ PolyJet 3D printing technology to prototype its wearable Jacquard electronic motion sensors.
DGIST’s 3D printed multifunctional sensor
Flexible pressure sensors that are simple, lightweight, and low-cost, have gained increasing attention for their ability to accurately sense applied pressure during the treatment of medical issues such as abnormal gait and muscular disorders.
However, according to the DGIST scientists 3D printed sensors produced thus far have been limited to sensing applied forces along a single direction, falling short of the demands of real-world applications which involve situations where forces can be applied across various angles and directions. Additionally, they identified that the electrical resistance of most conductive polymers varies with temperature, which needs to be addressed to achieve accurate pressure sensing.
In order to overcome the limitations of these sensors, the scientists embarked upon designing a multi-axis pressure sensor coupled with a temperature-sensing component using 3D printing technology.
They began by preparing a printable conductive polymer using multi-walled carbon nanotubes and PLA. The resulting composite filament was then 3D printed alongside a commercial elastomer and sensing material to form the body of the sensor, which is based on a bumper structure with a hollow trough beneath. The 3D printed sensor employs three pressure-sensing elements to allow for multi-axis pressure detection and a temperature-sensing element for calibration of electrical resistance.
During testing, the sensor was installed in a 3D printed flip-flop and a hand gripper, and was able to calibrate both the magnitude and direction of an applied force by evaluating the response of each pressure-sensing element. As such, the sensor was able to detect a clear distinction between human motions and gripping actions.
“The proposed 3D printing technology has a wide range of applications in energy, biomedicine, and manufacturing,” said Kim. “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.”
Further information on the study can be found in the paper titled: “Additive manufacturing of high-performance carbon-composites: An integrated multi-axis pressure and temperature monitoring sensor”, published in Composites Part B: Engineering. The study was co-authored by H. Kim, S. Hajra, D. Oh, N. Kim, and H. J. Kim.
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Featured image shows DGIST scientists have developed a novel, multi-directional pressure sensor using 3D printing technology that is low-cost and scalable to large-scale production of smart robotic systems. Photo via DGIST.