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Shear-Pressure Decoupling and Accurate Perception of Shear Directions in Ionic Sensors 

with Wonjeong Suh, Kanghyun Ki, Taeyeong Kim, Hyeongseok Choi, and Unyong Jeong


In artificial tactile sensing, to emulate the human sense of touch, independent perception of shear force and pressure is important. Decoupling the pressure and shear force is a challenging task for ensuring stable grasping manipulation for both soft and brittle objects. This study introduces a deformable ion gel-based tactile sensor that is capable of distinguishing pressure from shear force when pressurized shear force is applied in any direction. Recognition of the decoupled forces and precise shear directions is enabled by acquiring tactile data at only two frequencies (20 Hz and 10 kHz) based on the frequency-dependent ion dynamics. This study demonstrates monitoring the changes in pressure, shear force, and shear directions while performing practical robotic actions, such as pouring a water bottle, opening a water bottle cap, and picking up a book and placing it on a shelf.

Related publications:

  • Wonjeong Suh, Kanghyun Ki, Taeyeong Kim, Hyeongseok Choi, Anna Lee*, and Unyong Jeong*, "Shear-Pressure Decoupling and Accurate Perception of Shear Directions in Ionic Sensors by Analyzing the Frequency-Dependent Ionic Behavior," ACS Applied Materials & Interfaces, in press.

Sequential Multi-Modal Morphing of Single-Input Pneu-Nets

with Han Bi Jeong, Cheongsan Kim, and Ho-Young Kim


Soft actuators provide an attractive means for locomotion, gripping, and deployment of those machines and robots used in biomedicine, wearable electronics, automated manufacturing, etc. In this study, we focus on the shape-morphing ability of soft actuators made of pneumatic networks (pneu-nets), which are easy to fabricate with inexpensive elastomers and to drive with air pressure. As a conventional pneumatic network system morphs into a single designated state, achieving multimodal morphing has required multiple air inputs, channels, and chambers, making the system highly complex and hard to control. In this study, we develop a pneu-net system that can change its shape into multiple forms as a single input pressure increases. We achieve this single-input and multimorphing by combining pneu-net modules of different materials and geometry, while harnessing the strain-hardening characteristics of elastomers to prevent overinflation. Using theoretical models, we not only predict the shape evolution of pneu-nets with pressure change but also design pneu-nets to sequentially bend, stretch, and twist at distinct pressure points. We show that our design strategy enables a single device to carry out multiple functions, such as grabbing—turning a light bulb and holding—lifting a jar.

Related publications:

  • Han Bi Jeong, Cheongsan Kim, Anna Lee*, and Ho-Young Kim*, "Sequential Multi-Modal Morphing of Single-Input Pneu-Nets," Soft Robotics  (2023).

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