Our lab’s research in origami‐inspired robotics extends into the medical arena through collaborations with the University of Pennsylvania Hospital and the Children’s Hospital of Philadelphia, as well as with faculty like Prof. Jordan Raney (MEAM) and Prof. Flavia Vitale (Penn’s Center for Neuroengineering & Therapeutics). These efforts focus on reconfigurable implants, artificial muscles, and soft actuators for medical devices.

A central goal is to develop origami-inspired soft actuators that function as artificial muscles, leveraging advanced fabrication techniques to enable compact, flexible, and highly robust motion. By incorporating principles such as multistability and bistability from origami, we design actuator systems that can be easily reconfigured yet remain strong enough to perform clinically relevant tasks. Our lab also leads work on mechanical characterization of origami-inspired tubular structures for use as reconfigurable implants, aiming to reduce surgical invasiveness by creating implantable devices (e.g., heart or bile duct stents) that can be adjusted noninvasively.

MORF in Medical Applications
Our MORF (Magnetic Origami Reprogramming and Folding) System—initially developed for general reconfigurable devices—has proven especially promising for medical stents. Recently, in Penn’s Y-Prize competition, the 2025 winners “Stentix” proposed a magnetically reconfigurable biliary stent based on MORF. By using magnetic forces, this stent can be adjusted in position and diameter from outside the body, helping maintain bile flow without repeat endoscopies.

Related Publications

1. C. Kim, L. Yang, A. Anbuchelvan, R. Garg, N. Milbar, F. Vitale, and C. Sung, “Origami-Inspired Bistable Gripper with Self-Sensing Capabilities,” 2024 IEEE-RAS 7th International Conference on Soft Robotics (RoboSoft), San Diego, CA, USA, 2024 (Accepted)
2. B. Leung, G. Unger, S. Escorza, J. Chen, M. Fogel, and C. Sung, “Mechanical Characterization of an Origami-Inspired Multistable Tube for Reconfigurable Implants,” Poster at the Biomedical Engineering Society’s (BMES) Annual Meeting, 2023

Kim, Christopher; Yang, Lele; Anbuchelvan, Ashwath; Garg, Raghav; Milbar, Niv; Vitale, Flavia; Sung, Cynthia Origami-Inspired Bistable Gripper with Self-Sensing Capabilities (Conference) IEEE-RAS International Conference on Soft Robotics (Robosoft), 2024. (Abstract | BibTeX | Links: ) @conference{kim2024origami, title = {Origami-Inspired Bistable Gripper with Self-Sensing Capabilities}, author = {Christopher Kim and Lele Yang and Ashwath Anbuchelvan and Raghav Garg and Niv Milbar and Flavia Vitale and Cynthia Sung}, url = {https://www.youtube.com/watch?v=7BFJBbKCvJU https://repository.upenn.edu/entities/publication/f2892aab-8294-4e97-bd3e-3d77590c5b1e}, doi = {10.1109/RoboSoft60065.2024.10522014}, year = {2024}, date = {2024-04-13}, urldate = {2024-04-13}, booktitle = {IEEE-RAS International Conference on Soft Robotics (Robosoft)}, abstract = {An origami-inspired bistable gripper, featuring a dual-function custom PET linear solenoid actuator that acts both as an actuator and a sensor, is presented. Movements in the permanent magnet plunger, which is directly mounted to the gripper, create induced electromotive force (emf) in the solenoid, and these induced emf measurements are used to detect snap-through actions and light contacts on the gripper. The fabrication methods for the gripper, actuator, and a gel-free soft wearable EMG electrode are outlined, and the actuator’s self-sensing method utilizing the time-integral of the induced emf measurements are explored. Because a self-sensing actuator eliminates the need for extra sensors, it allows for further miniaturization of the robot while maintaining its compactness and lightweight design. The paper also introduces a full human-in-the-loop system, allowing users to open or close the gripper with their biceps via a wearable EMG electrode. This system bridges human intent with robotic action, offering a more intuitive interaction model for robotic control.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } Close An origami-inspired bistable gripper, featuring a dual-function custom PET linear solenoid actuator that acts both as an actuator and a sensor, is presented. Movements in the permanent magnet plunger, which is directly mounted to the gripper, create induced electromotive force (emf) in the solenoid, and these induced emf measurements are used to detect snap-through actions and light contacts on the gripper. The fabrication methods for the gripper, actuator, and a gel-free soft wearable EMG electrode are outlined, and the actuator’s self-sensing method utilizing the time-integral of the induced emf measurements are explored. Because a self-sensing actuator eliminates the need for extra sensors, it allows for further miniaturization of the robot while maintaining its compactness and lightweight design. The paper also introduces a full human-in-the-loop system, allowing users to open or close the gripper with their biceps via a wearable EMG electrode. This system bridges human intent with robotic action, offering a more intuitive interaction model for robotic control. Close

Acknowledgments

This work was supported in part by the Johnson & Johnson WiSTEM2D program, by the Penn Health-Tech program, and by the Penn Center for Undergraduate Research and Fellowships. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of funding source.

Current Personnel

• Christopher Kim (MEAM PhD)
• Gabriel Unger (MEAM PhD)
• Kylie Autullo (MEAM Undergrad)

Biologically inspired underwater robots simulate the swimming motions of marine organisms. Jet propulsion, a locomotion mode in cephalopods and tunicates such as squids, cuttlefish, and salps, serves as a key inspiration for our designs. We aim to develop soft bio-inspired robots to study locomotion mechanisms in marine creatures, with the focus of achieving greater propulsion efficiencies through design optimization and active control strategies.

Design and Characterization of an Origami Swimmer

This project designs a soft underwater robot inspired by cephalopods. Traditional soft robots use flexible materials for shape change but require complex fabrication. To simplify this, we used an origami-inspired design, which allows the robot to fold from flat sheets into 3D shapes, making it easier to store, transport, and assemble in just a few hours. The robot mimics squid locomotion using the origami magic ball pattern, which transforms between an ellipsoid and a sphere. This enables it to expand and contract, pulling in and expelling water to create a jet for propulsion. A tendon mechanism in its spine controls its length. Ongoing effects focus on evaluating different configurations’ effect (e.g. adding a front nozzle) on the performance of the robot and understanding the underlying dynamics of it.

Leveraging Fluid-Structure Interactions for Efficient Control in Geophysical Flows¹

Micro-vehicles are cost-effective platforms for robotics and automation, excelling in maneuverability and adaptability in diverse environments. However, their lightweight and limited computational capacity pose control challenges. This research aims to understand fluid-structure interactions to enhance design and control, resulting in more efficient micro-vehicles with extended lifespans. The interdisciplinary effort focuses on fluid dynamics, control theory, and reconfiguration planning. The project aims to leverage environmental forces for power efficiency, investigating morphological adaptations and passive transport properties. It seeks to synthesize motion control strategies considering inertial effects and fluid-structure interactions while exploring efficiency trade-offs. Ultimately, it aims to enhance micro-autonomous vehicles’ capabilities for long-term operations and future large-scale deploy.

Salp-Inspired Reconfigurable Robot Platform for Long-Term Distributed Sensing

The design of bio-inspired autonomous systems aims to derive the concepts of sensorimotor control, biomechanics, and fluid dynamics of underwater propulsion from aquatic species. The goal of this program is to expand the operational envelope of Navy underwater and amphibious vehicles and enable enhanced underwater manipulation. We are interested in designing a salp-inspired robot to simulate the locomotion of salps and develop a system for distributed sensing. Salps are barrel-shaped marine invertebrates that swim via jet propulsion. They move forward by rapidly changing the volumes of their body cavity, drawing water into their muscular mantle cavity through the front aperture, and then expelling it under high pressure through the rear funnel. We will investigate and compare the performance and efficiency of the salp-inspired robot against the biological salps. Currently, we are studying the locomotion behavior of a multi-jet SALP robot and trying to understand the inherent fluid mechanics involved.

Related Publications

	Yang, Zhiyuan; Zhang, Yipeng; Herbert, Matthew; Hsieh, M. Ani; Sung, Cynthia Effect of Jet Coordination on Underwater Propulsion with the Multi-Robot SALP System (Conference) 8th IEEE-RAS International Conference on Soft Robotics (RoboSoft 2025), Forthcoming. (Abstract | BibTeX | Links: ) @conference{yang2025salp, title = {Effect of Jet Coordination on Underwater Propulsion with the Multi-Robot SALP System}, author = {Zhiyuan Yang and Yipeng Zhang and Matthew Herbert and M. Ani Hsieh and Cynthia Sung}, url = {https://www.youtube.com/watch?v=mzd1QCXssCk https://repository.upenn.edu/handle/20.500.14332/61048}, year = {2025}, date = {2025-04-23}, urldate = {2025-04-23}, booktitle = {8th IEEE-RAS International Conference on Soft Robotics (RoboSoft 2025)}, abstract = {Salps, marine invertebrates known for their collective swimming through coordinated jet propulsion, offer a unique model for efficient underwater movement. Inspired by this biological system, we develop the SALP (Salp-inspired Approach to Low-energy Propulsion) robot, a soft underwater robot that swims via jet propulsion similarly to a biological salp. The SALPs can be physically connected into SALP chains and coordinate their jets to achieve various propulsion modes. In our experiments, we compare the swimming performance of the individual SALP with the two-SALP system, focusing on power, acceleration, velocity, and energy efficiency. Results indicate that two SALPs swimming synchronously exhibit a 9.0% increase in steady-state velocity and a 16.6% improvement in transient acceleration compared to a single SALP. Additionally, our analysis of swimming efficiency implies that asynchronous swimming is potentially more energy efficient than the synchronous mode, as reflected by a decrease in the cost of transport (COT).}, keywords = {}, pubstate = {forthcoming}, tppubtype = {conference} } Close Salps, marine invertebrates known for their collective swimming through coordinated jet propulsion, offer a unique model for efficient underwater movement. Inspired by this biological system, we develop the SALP (Salp-inspired Approach to Low-energy Propulsion) robot, a soft underwater robot that swims via jet propulsion similarly to a biological salp. The SALPs can be physically connected into SALP chains and coordinate their jets to achieve various propulsion modes. In our experiments, we compare the swimming performance of the individual SALP with the two-SALP system, focusing on power, acceleration, velocity, and energy efficiency. Results indicate that two SALPs swimming synchronously exhibit a 9.0% increase in steady-state velocity and a 16.6% improvement in transient acceleration compared to a single SALP. Additionally, our analysis of swimming efficiency implies that asynchronous swimming is potentially more energy efficient than the synchronous mode, as reflected by a decrease in the cost of transport (COT). Close
	Chen, Guanyu; Chen, Dongsheng; Weakly, Jessica; Sung, Cynthia Drag coefficient characterization of the origami magic ball (Proceedings Article) In: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE), pp. DETC2023-117182, 2023. (Abstract | BibTeX | Links: ) @inproceedings{chen2023drag, title = {Drag coefficient characterization of the origami magic ball}, author = {Guanyu Chen and Dongsheng Chen and Jessica Weakly and Cynthia Sung}, url = {https://repository.upenn.edu/grasp_papers/73}, doi = {10.1115/DETC2023-117182}, year = {2023}, date = {2023-08-29}, urldate = {2023-08-29}, booktitle = {ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE)}, pages = {DETC2023-117182}, abstract = {The drag coefficient plays a vital role in the design and optimization of robots that move through fluids. From aircraft to underwater vehicles, their geometries are specially engineered so that the drag coefficients are as low as possible to achieve energy-efficient performances. Origami magic balls are 3-dimensional reconfigurable geometries composed of repeated simple waterbomb units. Their volumes can change as their geometries vary and we have used this concept in a recent underwater robot design. This paper characterizes the drag coefficient of an origami magic ball in a wind tunnel. Through dimensional analysis, the scenario where the robot swims underwater is equivalently transferred to the situation when it is in the wind tunnel. With experiments, we have collected and analyzed the drag force data. It is concluded that the drag coefficient of the magic ball increases from around 0.64 to 1.26 as it transforms from a slim ellipsoidal shape to an oblate spherical shape. Additionally, three different magic balls produce increases in the drag coefficient of between 57% and 86% on average compared to the smooth geometries of the same size and aspect ratio. The results will be useful in future designs of robots using waterbomb origami in fluidic environments.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Close The drag coefficient plays a vital role in the design and optimization of robots that move through fluids. From aircraft to underwater vehicles, their geometries are specially engineered so that the drag coefficients are as low as possible to achieve energy-efficient performances. Origami magic balls are 3-dimensional reconfigurable geometries composed of repeated simple waterbomb units. Their volumes can change as their geometries vary and we have used this concept in a recent underwater robot design. This paper characterizes the drag coefficient of an origami magic ball in a wind tunnel. Through dimensional analysis, the scenario where the robot swims underwater is equivalently transferred to the situation when it is in the wind tunnel. With experiments, we have collected and analyzed the drag force data. It is concluded that the drag coefficient of the magic ball increases from around 0.64 to 1.26 as it transforms from a slim ellipsoidal shape to an oblate spherical shape. Additionally, three different magic balls produce increases in the drag coefficient of between 57% and 86% on average compared to the smooth geometries of the same size and aspect ratio. The results will be useful in future designs of robots using waterbomb origami in fluidic environments. Close
	Yang, Zhiyuan; Chen, Dongsheng; Levine, David J.; Sung, Cynthia Origami-inspired robot that swims via jet propulsion (Journal Article) In: IEEE Robotics and Automation Letters, vol. 6, no. 4, pp. 7145-7152, 2021. (Abstract | BibTeX | Links: ) @article{yang2021origami, title = {Origami-inspired robot that swims via jet propulsion}, author = {Zhiyuan Yang and Dongsheng Chen and David J. Levine and Cynthia Sung}, url = {https://repository.upenn.edu/grasp_papers/68 https://youtu.be/cZ1nx_kOw3w}, doi = {10.1109/LRA.2021.3097757}, year = {2021}, date = {2021-07-19}, urldate = {2021-07-19}, booktitle = {IEEE Robotics and Automation Letters}, journal = {IEEE Robotics and Automation Letters}, volume = {6}, number = {4}, pages = {7145-7152}, abstract = {Underwater swimmers present unique opportunities for using bodily reconfiguration for self propulsion. Origami-inspired designs are low-cost, fast to fabricate, robust, and can be used to create compliant mechanisms useful in energy efficient underwater locomotion. In this paper, we demonstrate an origami-inspired robot that can change its body shape to ingest and expel water, creating a jet that propels it forward similarly to cephalopods. We use the magic ball origami pattern, which can transform between ellipsoidal (low volume) and spherical (high volume) shapes. A custom actuation mechanism contracts the robot to take in fluid, and the inherent mechanics of the magic ball returns the robot to its natural shape upon release. We describe the design and control of this robot and verify its locomotion in a water tank. The resulting robot is able to move forward at 6.7 cm/s (0.2 body lengths/s), with a cost of transport of 2.0. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Underwater swimmers present unique opportunities for using bodily reconfiguration for self propulsion. Origami-inspired designs are low-cost, fast to fabricate, robust, and can be used to create compliant mechanisms useful in energy efficient underwater locomotion. In this paper, we demonstrate an origami-inspired robot that can change its body shape to ingest and expel water, creating a jet that propels it forward similarly to cephalopods. We use the magic ball origami pattern, which can transform between ellipsoidal (low volume) and spherical (high volume) shapes. A custom actuation mechanism contracts the robot to take in fluid, and the inherent mechanics of the magic ball returns the robot to its natural shape upon release. We describe the design and control of this robot and verify its locomotion in a water tank. The resulting robot is able to move forward at 6.7 cm/s (0.2 body lengths/s), with a cost of transport of 2.0. Close

Acknowledgments

The “Leveraging Fluid-Structure Interactions for Efficient Control in Geophysical Flows” project is supported by the NSF Grant No. 2121887. The “Salp-Inspired Reconfigurable Robot Platform for Long-Term Distributed Sensing” project is supported by ONR award #N00014-23-1-2068.

1. This project is in collaboration with Ani Hsieh’s lab from University of Pennsylvania, Eric Forgoston’s lab from Montclair State University, and Philip Yecko’s lab from The Cooper Union. ↩︎

Current Personnel

• Dongsheng Chen (MEAM PhD)
• Zhiyuan (Annie) Yang (MEAM PhD)
• Ryan Stanford (MEAM Undergrad)
• Benedic Onyekwe (ROBO Master's)
• Jingshuo Li (MEAM Master's)
• Neel Mulay (MEAM Master's)
• Yipeng Zhang (MEAM Master's)