Graphical Abstract Figure
The snake-bone in a rigid state provides support for instruments manipulation.
Graphical Abstract Figure
The snake-bone in a rigid state provides support for instruments manipulation.
Abstract
In robot-assisted endoscopic procedure, snake-bone located at distal part of the endoscope is required to flexibly bend for adjusting tip position and passing through the body's winding anatomical pathways. After reaching the target lesion, it should serve as a stable platform to support precise operations. Therefore, it is necessary to develop a snake-bone with both bending and stiffness adjustment capabilities. To address these challenges, this paper proposes a novel snake-bone based on a bioinspired honeycomb pattern and the thermoplastic polymer polycaprolactone (PCL), which achieves structure-function integration. Compared with conventional endoscopic snake-bones, our snake-bone in a rigid state has a greater loading capacity, withstanding a torque of 293 Nmm while providing a maximum bending stiffness of 97,297 Nmm2. In a flexible state, the snake-bone exhibits an excellent 2 degrees-of-freedom (DOF) bending motion performance, with a maximum bending angle of 90 deg. This snake-bone can switch states within 18.37 s (from rigid state to flexible state) and 18.65 s (from flexible state to rigid state). Different from other material-based variable-stiffness snake-bones, our snake-bone incorporates an active cooling mechanism. Moreover, compared with other variable-stiffness snake-bones, our snake-bone can achieve variable stiffness while maintaining a reasonable outer diameter. Through phantom experiments, the snake-bone can support surgical instruments in performing endoscopic tasks, facilitating stable operations. The experimental results have proven the feasibility of the snake-bone, highlighting its significant potential for application in endoscopic procedures.
References
1.
Dupont
, P. E
, Nelson
, B. J.
, Goldfarb
, M.
, Hannaford
, B.
, Menciassi
, A.
, O'Malley
, M. K.
, Simaan
, N.
, Valdastri
, P.
, and Yang
, G. Z.
, 2021
, “A decade retrospective of medical robotics research from 2010 to 2020
,” Sci. Robot.
, 6
(60
), p. 8017
.10.1126/scirobotics.abi80172.
Liu
, B.
, Zhang
, A. Y.
, Liu
, J.
, Han
, Z. M.
, and Xie
, T. Y.
, 2018
, “Design and Evaluation of a Novel Rotatable One-Element Snake Bone for NOTES
,” ASME J. Med. Devices
, 12
(2
), p. 021006
.10.1115/1.40395923.
Liang
, T.
, Zhang
, C.
, Wang
, Y.
Kong
, K
, Chen
, X
, Wei
, B
, Wang
, S
, and Zuo
, S.
, 2024
, “A Novel Miniature Flexible Robotic System for Endoscopic Mucosal Dissection: An Animal Experimental Study
,” J. Robot. Surg.
, 18
, p. 17
.10.1007/s11701-023-01793-74.
Azeem
, N.
, Tabibian
, J. H.
, Baron
, T. H.
, Orhurhu
, V.
, Rosen
, C. B.
, Petersen
, B. T.
, Gostout
, C. J.
, Topazian
, M. D.
, and Levy
, M. J.
, 2013
, “Use of a Single-Balloon Enteroscope Compared With Variable-Stiffness Colonoscopes for Endoscopic Retrograde Cholangiography in Liver Transplant Patients With Roux-en-Y Biliary Anastomosis
,” Gastrointest. Endosc.
, 77
(4
), pp. 568
–577
.10.1016/j.gie.2012.11.0315.
Chen
, X. Y.
, Lai
, W.
, Xiong
, X.
, Wang
, X.
, Wang
, S. M.
, Li
, P.
, Han
, W.
, et al., 2025
, “Robotic Bronchoscopy System With Variable-Stiffness Catheter for Pulmonary Lesion Biopsy
,” IEEE Trans. Med. Robot. Bionics
, 7
(1
), pp. 416
–427
.10.1109/TMRB.2025.35276556.
Chen
, B. J.
, Li
, L. D.
, and Zuo
, S. Y.
, 2025
, “A Novel Cable-Driven Variable-Stiffness Manipulator With Teeth-Engagement Structure for Transoral Surgery
,” IEEE Robot. Autom. Lett.
, 10
(6
), pp. 5241
–5248
.10.1109/LRA.2025.35584527.
Gifari
, M. W.
, Naghibi
, H.
, Stramigioli
, S.
, and Abayazid
, M.
, 2019
, “A Review on Recent Advances in Soft Surgical Robots for Endoscopic Applications
,” Int. J. Med. Robot. Comput. Assisted Surg.
, 5
(15
), p. e2010
.10.1002/rcs.20108.
Wang
, Y. J.
, Hu
, X. B.
, Cui
, L. H.
, Xiao
, X.
, Yang
, K. J.
, Zhu
, Y. J.
, and Jin
, H. R.
, 2024
, “Bioinspired Handheld Time-Share Driven Robot With Expandable DoFs
,” Nat. Commun.
, 15
(1
), pp. 1
–10
.10.1038/s41467-024-44993-x9.
Loeve
, A.
, Breedveld
, P.
, and Dankelman
, J.
, 2010
, “Scopes Too Flexible…and Too Stiff
,” IEEE Pulse
, 1
(3
), pp. 26
–41
.10.1109/MPUL.2010.93917610.
Hwang
, M. H.
, and Kwon
, D. S.
, 2019
, “Strong Continuum Manipulator for Flexible Endoscopic Surgery
,” IEEE-ASME Trans. Mechatron.
, 24
(5
), pp. 2193
–2203
.10.1109/TMECH.2019.293237811.
Zappetti
, D.
, Arandes
, R.
, Ajanic
, E.
, and Floreano
, D.
, 2020
, “Variable-Stiffness Tensegrity Spine
,” Smart Mater. Struct.
, 29
(7
), p. 075013
.10.1088/1361-665X/ab87e012.
Liang
, T
, Kong
, K.
, and Wang
, S.
, 2023
, “A Variable Stiffness Manipulator With Multifunctional Channels for Endoscopic Submucosal Dissection
,” Int. J. Comput. Assisted Radiol. Surg.
, 18
(10
), pp. 1795
–1810
.10.1007/s11548-023-02875-513.
Li
, Y. T
, Chen
, Y. H.
, Yang
, Y.
, and Wei
, Y.
, 2017
, “Passive Particle Jamming and Its Stiffening of Soft Robotic Grippers
,” IEEE Trans. Robot.
, 33
(2
), pp. 446
–455
.10.1109/TRO.2016.263689914.
Ma
, J. L
, Chen
, D. S
, Liu
, Z.
, Li
, J. L.
, Zeng
, Z. H.
, Yin
, Y. T.
, Zhang
, X. L.
, and Shu
, C.
, 2024
, “Muscle-Inspired Stiffness-Tunable Flexible Fiber Jamming Structure for Wearable Robots
,” Smart Mater. Struct.
, 33
(5
), p. 055002
.10.1088/1361-665X/ad37b515.
Sun
, Y.
, and Yang
, Y.
, 2024
, “Parameter Characterization of Variable Bending Stiffness Module With Electrostatic Layer Jamming Based on Giant Electrorheological Fluid
,” Smart Mater. Struct.
, 33
(6
), p. 065032
.10.1088/1361-665X/ad49ee16.
Sun
, T.
, Chen
, Y. L.
, Han
, T. Y.
, Jiao
, C. L.
, Lian
, B. B.
, and Song
, Y. M.
, 2020
, “A Soft Gripper with Variable Stiffness Inspired by Pangolin Scales, Toothed Pneumatic Actuator and Autonomous Controller
,” Robot. Comput.-Int. Manuf.
, 61
, p. 101848
.10.1016/j.rcim.2019.10184817.
Li
, C. S.
, Guo
, X. Y.
, Xiao
, X.
, Lim
, C. W.
, and Ren
, H. L.
, 2020
, “Flexible Robot With Variable Stiffness in Transoral Surgery
,” IEEE-ASME Trans. Mechatron.
, 25
(1
), pp. 1
–10
.10.1109/TMECH.2019.294552518.
Zhao
, B
, Zeng
, L. Y.
, Wu
, Z. H.
, and Xu
, K.
, 2020
, “A Continuum Manipulator for Continuously Variable Stiffness and Its Stiffness Control Formulation
,” Mech. Mach. Theory
, 149
, p. 103746
.10.1016/j.mechmachtheory.2019.10374619.
Brancadoro
, M.
, Manti
, M.
, Grani
, F.
, Tognarelli
, S.
, Menciassi
, A.
, and Cianchetti
, M.
, 2019
, “Toward a Variable Stiffness Surgical Manipulator Based on Fiber Jamming Transition
,” Front. Robot. AI
, 6
, p. 432162
.10.3389/frobt.2019.0001220.
Liu
, J. B.
, Yin
, L. K.
, Chandler
, J. H.
, Chen
, X.
, Valdastri
, P.
, and Zuo
, S. Y.
, 2021
, “A Dual-Bending Endoscope With Shape-lockable Hydraulic Actuation and Water-jet Propulsion for Gastrointestinal Tract Screening
,” Int. J. Med. Robot.
, 17
(1
), pp. 1
–13
.10.1002/rcs.219721.
Zhang
, B. Y.
, 2023
, “A Miniaturized Variable Stiffness Soft Manipulator With a Customizable LMPA Pattern
,” IEEE Robot. Autom. Lett.
, 8
(9
), pp. 5704
–5711
.10.1109/LRA.2023.330024122.
Deng
, H. X.
, Wang
, M. X.
, Han
, G. H.
, Zhang
, J.
, Ma
, M. C.
, Zhong
, X.
, and Yu
, L. D.
, 2017
, “Variable Stiffness Mechanisms of Dual Parameters Changing Magnetorheological Fluid Devices
,” Smart Mater. Struct.
, 26
(12
), p. 125014
.10.1088/1361-665X/aa92d523.
Xiong
, J.
, Sun
, Y. X.
, Zheng
, J.
, Dong
, D. B.
, and Bai
, L.
, 2021
, “Design and Experiment of a SMA-Based Continuous-Stiffness-Adjustment Torsional Elastic Component for Variable Stiffness Actuators
,” Smart Mater. Struct.
, 30
(10
), p. 105021
.10.1088/1361-665X/ac1eae24.
Yang
, Y.
, Wang
, P.
, Liu
, J.
, Fu
, Y. L.
, and Shen
, Y.
, 2024
, “Tunable Stiffness Kirigami Gripper Based on Shape Memory Polymer and Supercoiled Polymer Artificial Muscle for Multi-Mode Grasping
,” Smart Mater. Struct.
, 33
(9
), p. 095033
.10.1088/1361-665X/ad6ed125.
Li
, Y. T.
, Yang
, Y.
, Wang
, P.
, Zhu
, H. H.
, Xia
, K.
, Ren
, T.
, and Shen
, Y.
, 2024
, “A Variable Stiffness Soft Robotic Manipulator Based on Antagonistic Design of Supercoiled Polymer Artificial Muscles and Shape Memory Alloys
,” Sens. Actuators, A
, 366
, p. 114999
.10.1016/j.sna.2023.11499926.
Peters
, J.
, 2019
, “Actuation and Stiffening in Fluid-Driven Soft Robots Using Low-Melting-Point Material
,” 2019 IEEE/RSJ International Conference on Intelligent Robots and Systems
(IROS
), Macao, China, Nov. 3--8, pp. 4692
–4698
.10.1109/IROS40897.201927.
Kitano
, S.
, Komatsuzaki
, T.
, Suzuki
, I.
, Nogawa
, M.
, Naito
, H.
, and Tanaka
, S.
, 2020
, “Development of a Rigidity Tunable Flexible Joint Using Magneto-Rheological Compounds-Toward a Multijoint Manipulator for Laparoscopic Surgery
,” Front. Robot. AI
, 7
, p. 59
.10.3389/frobt.2020.0005928.
Jiang
, S. R.
, Chen
, B.
, Qi
, F.
, Cao
, Y. F.
, Ju
, F.
, Bai
, D. M.
, and Wang
, Y. Y.
, 2021
, “A Variable-Stiffness Continuum Manipulators by an SMA-Based Sheath in Minimally Invasive Surgery
,” Int. J. Med. Robot.
, 16
(2
), p. e2081
.10.1002/rcs.208129.
Li
, X.
, Wang
, H.
, and Zuo
, S. Y.
, 2024
, “A Novel Flexible Catheter With Integrated Magnetic Variable Stiffness and Actuation
,” Smart Mater. Struct.
, 33
(2
), p. 025028
.10.1088/1361-665X/ad1dee30.
IARC Working Group
, 2018
, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 116: Drinking Coffee, Mate, and Very Hot Beverages
, International Agency for Research on Cancer
, Lyon, France
.31.
Babaee
, S.
, Pajovic
, S.
, Kirtane
, A. R.
, Shi
, J.
, Caffarel-Salvador
, E.
, Hess
, K.
, Collins
, J. E.
, et al., 2019
, “Temperatureresponsive Biometamaterials for Gastrointestinal Applications
,” Sci., Transl., Med.
, 11
(488
), p. eaau8581
.10.1126/scitranslmed.aau858132.
Lee
, H.
, and O'Mahony
, M.
, 2006
, “At What Temperatures Do Consumers Like to Drink Coffee?: Mixing Methods
,” J. Food Sci.
, 67
, pp. 2774
–2777
.10.1111/j.1365-2621.2002.tb08814.x33.
De Jong
, U. W.
, Day
, N. E.
, Mounier-Kuhn
, P. L.
, and Haguenauer
, J. P.
, 1972
, “The Relationship Between the Ingestion of Hot Coffee and Intraoesophageal Temperature
,” Gut
, 13
, pp. 24
–30
.10.1136/gut.13.1.2434.
Mattmann
, M.
, Marco
, C. D.
, Briatico
, F.
, Tagliabue
, S.
, Colusso
, A.
, Chen
, X. Z.
, Lussi
, J.
, Chautems
, C.
, Pané
, S.
, and Nelson
, B.
, 2021
, “Thermoset Shape Memory Polymer Variable Stiffness 4D Robotic Catheters
,” Adv. Sci.
, 9
(1
), p. 2103277
.10.1002/advs.20210327735.
Olympus Corporation
, “Endoscope Overview 2022
,”Olympus Medical Systems, Tokyo, Japan, accessed Mar. 2025, https://www.olympus.co.uk/medical/en/Products-and-solutions/Products/Echoendoscopes.html36.
Yeung
, B. P. M.
, and Gourlay
, T.
, 2011
, “A Technical Review of Flexible Endoscopic Multitasking Platforms
,” Int. J. Surg.
, 10
(7
), pp. 345
–354
.10.1016/j.ijsu.2012.05.00937.
Hwang
, M.
, and Kwon
, D. S.
, 2020
, “K-FLEX: A Flexible Robotic Platform for Scar-Free Endoscopic Surgery
,” Int. J. Med. Robot. Comput. Assisted Surg.
, 16
(2
), p. 2078
.10.1002/rcs.207838.
Zhao
, R.
, Yao
, Y.
, and Luo
, Y.
, 2016
, “Development of a Variable Stiffness Over Tube Based on Low-Melting-Point-Alloy for Endoscopic Surgery
,” ASME. J. Med. Devices
, 10
(2
), p. 021002
.10.1115/1.403281339.
Stocchi
, A.
, Colabella
, L.
, Cisilino
, A.
, and Alvarez
, V.
, 2014
, “Manufacturing and Testing of a Sandwich Panel Honeycomb Core Reinforced With Natural-Fiber Fabrics
,” Mater. Design
, 55
, pp. 394
–403
.10.1016/j.matdes.2013.09.05440.
Liu
, A
, Wang
, A
, Jiang
, Q
, Jiao
, Y.
, Wu
, L.
, and Tang
, Y.
, 2024
, “Structure Design and Performance Evaluation of Fibre Reinforced Composite Honeycombs: A Review
,” Appl. Compos. Mater.
, 31
, pp. 1
–27
.10.1007/s10443-024-10281-641.
Li
, D. C. F.
, Wang
, Z.
, Zhou
, J.
, and Liu
, Y. H.
, 2021
, “Honeycomb Jamming: An Enabling Technology of Variable Stiffness Reconfiguration
,” Soft Robot.
, 8
(6
), pp. 720
–734
.10.1089/soro.2019.018842.
Kaur
, M.
, and Kim
, W. S.
, 2019
, “Toward a Smart Compliant Robotic Gripper Equipped With 3D-Designed Cellular Fingers
,” Adv. Intell. Syst.
, 1
(3
), p. 1900019
.10.1002/aisy.20190001943.
Rus
, D.
, and Tolley
, M. T.
, 2015
, “Design, Fabrication and Control of Soft Robots
,” Nature
521
(7553
), pp. 467
–475
.10.1038/nature1454344.
Wang
, Z.
, Wang
, T.
, Zhao
, B.
, Li
, B.
, Zhang
, P.
, and Meng
, M.
, 2021
, “Hybrid Adaptive Control Strategy for Continuum Surgical Robot Under External Load
,” IEEE Robot. Autom. Lett.
, 6
(2
), pp. 1407
–1414
.10.1109/LRA.2021.305755845.
Shintani
, H.
, 2017
, “Ethylene Oxide Gas Sterilization of Medical Devices
,” Biocontrol Sci.
, 22
(1
), pp. 1
–16
.10.4265/bio.22.146.
Zhang
, B. Y.
, Yang
, P. H.
, Gu
, X. M.
, and Liao
, H. E.
, 2021
, “Laser Endoscopic Manipulator Using Spring-Reinforced Multi-DoF Soft Actuator
,” IEEE Robot. Autom. Lett.
, 6
(4
), pp. 7736
–7743
.10.1109/LRA.2021.3100617
