Jonas Lussi’s research while affiliated with Multi Scale Solutions and other places

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Publications (11)


This figure illustrates substantial variations in placental vessels among patients, posing challenges when deploying a model and encountering significant differences between training and inference data
A PGGAN takes a sampled latent variable as input and produces masks. After a structural similarity check, the masks are inputted into the pix2pix network to generate placental images. These image-mask pairs, along with the original dataset used to train the PGGAN and pix2pix networks, were then utilized to train a segmentation network
Examples of generated image pairs. Comparison between the real image and mask pairs and generated image pairs from the GANs, with varying real training dataset sizes
Experimental results. The segmentation performance of the ratio experiment is shown here for different initial dataset sizes as well as for different ratios of artificial and real data. A significant performance improvement was achieved using the generated data, especially for the initial dataset size of 20 images. The improvements range from 8 to 100%. Additionally, the results are shown for the pipeline applied to another dataset (UCL), as well as the results discussed in Sect. 4.4 for inference, without a patient-specific trained PGGAN (no PGGAN)
Patient-specific placental vessel segmentation with limited data
  • Article
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June 2024

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46 Reads

Journal of Robotic Surgery

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Jonas Lussi

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A major obstacle in applying machine learning for medical fields is the disparity between the data distribution of the training images and the data encountered in clinics. This phenomenon can be explained by inconsistent acquisition techniques and large variations across the patient spectrum. The result is poor translation of the trained models to the clinic, which limits their implementation in medical practice. Patient-specific trained networks could provide a potential solution. Although patient-specific approaches are usually infeasible because of the expenses associated with on-the-fly labeling, the use of generative adversarial networks enables this approach. This study proposes a patient-specific approach based on generative adversarial networks. In the presented training pipeline, the user trains a patient-specific segmentation network with extremely limited data which is supplemented with artificial samples generated by generative adversarial models. This approach is demonstrated in endoscopic video data captured during fetoscopic laser coagulation, a procedure used for treating twin-to-twin transfusion syndrome by ablating the placental blood vessels. Compared to a standard deep learning segmentation approach, the pipeline was able to achieve an intersection over union score of 0.60 using only 20 annotated images compared to 100 images using a standard approach. Furthermore, training with 20 annotated images without the use of the pipeline achieves an intersection over union score of 0.30, which, therefore, corresponds to a 100% increase in performance when incorporating the pipeline. A pipeline using GANs was used to generate artificial data which supplements the real data, this allows patient-specific training of a segmentation network. We show that artificial images generated using GANs significantly improve performance in vessel segmentation and that training patient-specific models can be a viable solution to bring automated vessel segmentation to the clinic.

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Autonomous Magnetic Navigation in Endoscopic Image Mosaics

March 2024

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241 Reads

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1 Citation

Endoscopes navigate within the human body to observe anatomical structures with minimal invasiveness. A major shortcoming of their use is their narrow field‐of‐view during navigation in large, hollow anatomical regions. Mosaics of endoscopic images can provide surgeons with a map of the tool's environment. This would facilitate procedures, improve their efficiency, and potentially generate better patient outcomes. The emergence of magnetically steered endoscopes opens the way to safer procedures and creates an opportunity to provide robotic assistance both in the generation of the mosaic map and in navigation within this map. This paper proposes methods to autonomously navigate magnetic endoscopes to 1) generate endoscopic image mosaics and 2) use these mosaics as user interfaces to navigate throughout the explored area. These are the first strategies, which allow autonomous magnetic navigation in large, hollow organs during minimally invasive surgeries. The feasibility of these methods is demonstrated experimentally both in vitro and ex vivo in the context of the treatment of twin‐to‐twin transfusion syndrome. This minimally invasive procedure is performed in utero and necessitates coagulating shared vessels of twin fetuses on the placenta. A mosaic of the vasculature in combination with autonomous navigation has the potential to significantly facilitate this challenging surgery.


Dexterous helical magnetic robot for improved endovascular access

February 2024

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237 Reads

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30 Citations

Science Robotics

Treating vascular diseases in the brain requires access to the affected region inside the body. This is usually accomplished through a minimally invasive technique that involves the use of long, thin devices, such as wires and tubes, that are manually maneuvered by a clinician within the bloodstream. By pushing, pulling, and twisting, these devices are navigated through the tortuous pathways of the blood vessels. The outcome of the procedure heavily relies on the clinician’s skill and the device’s ability to navigate to the affected target region in the bloodstream, which is often inhibited by tortuous blood vessels. Sharp turns require high flexibility, but this flexibility inhibits translation of proximal insertion to distal tip advancement. We present a highly dexterous, magnetically steered continuum robot that overcomes pushability limitations through rotation. A helical protrusion on the device’s surface engages with the vessel wall and translates rotation to forward motion at every point of contact. An articulating magnetic tip allows for active steerability, enabling navigation from the aortic arch to millimeter-sized arteries of the brain. The effectiveness of the magnetic continuum robot has been demonstrated through successful navigation in models of the human vasculature and in blood vessels of a live pig.


Magnetically Guided Laser Surgery for the Treatment of Twin‐to‐Twin Transfusion Syndrome

October 2022

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367 Reads

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13 Citations

Twin‐to‐twin transfusion syndrome (TTTS) is a severe disorder that often leads to the death of monochorionic twin fetuses, if left untreated. Current prenatal interventions to treat the condition involve the use of rigid fetoscopes for targeted laser coagulation of the vascular anastomoses. These tools are limited in their area of operation, making treatment challenging, especially in cases with anterior placentation. Herein, a robotic platform to perform this task using remote magnetic navigation is proposed. In contrast to rigid tools, the presented custom magnetic fetoscope is highly flexible, dexterous, and has considerable advantages, including safety and precision. A visual servoing algorithm that allows the surgeon to navigate in the uterus with submillimeter precision is introduced. The system has been validated on ex vivo human placentas in a setting that mimics the real intraoperative conditions. Twin‐to‐twin transfusion syndrome (TTTS) is a severe disorder that often leads to the death of monochorionic twin fetuses, if left untreated. Herein, a robotic platform to perform TTTS surgery using remote magnetic navigation is presented. In contrast to rigid tools, the custom magnetic fetoscope is highly flexible, dexterous, and has considerable advantages, including safety and precision.


Structure and operating principle of the variable stiffness thread (VST). a) The VST consists of a polytetrafluoroethylene (PTFE) tube with a working channel coated in a conductive shape memory polymer (CSMP) layer, which is further encapsulated in silicone. b) Heating rate of the VST from room temperature (23 °C) for different applied powers. Voltages 7.6, 10.7, 13.1, and 15.1 V were applied to achieve powers of 0.5, 1, 1.5, and 2 W, respectively. Three different samples were tested for each level of applied power. c) The VST can exhibit a change in the stiffness upon direct Joule heating of the CSMP layer. The device undergoes the state change from a rigid state at room temperature (23 °C) to a soft state at 80 °C in 27 s with an applied power of 1.5 W. d) The VST only minimally bends under a weight of 30 g in the rigid state, but freely bends under the same weight when heated to 80 °C in the soft state.
Fabrication process of the variable stiffness threads (VSTs). a) A PTFE tube is prepared and fixed on a metal rod. b) The tube is dipped into a conductive shape memory polymer (CSMP) mixture. c) The tube is hung vertically and cured in an oven. Steps (a–c) can be repeated to achieve the desired thickness of the CSMP layer. d–f) The sample is then dipped into liquid silicone, hung vertically, and cured in an oven, forming an encapsulation layer.
Variable stiffness thread (VST) characterization. The coating thickness of the VSTs was 0.3 mm. a) Thickness and electrical resistance of the conductive shape memory polymer (CSMP) layer as functions of the number of dips. The thickness changes from 84 µm after the first dip to 550 µm after the eighth dip. The resistance decreases from 891 ohms for the first dip to 91 ohms after the eights dip. b) Reaction force of the VST against forced displacement under a three‐point flexural test. c) Electrical resistance of the CSMP layer as a function of the temperature change under indirect Joule heating. The resistance decreases from 115.3 ohms at 23 °C to 106.6 ohms at 80 °C, with a significant drop in the range between 23 and 45 °C due to the change in state from solid to rubbery. d) VST with the CSMP layer heated to 80 °C, reaching a surface temperature of 66 °C in air and 41.5 °C in water at 37 °C without flow. e) The state of the VST can be seen with the resistance drop caused by the temperature difference for the cold and hot states. Direct Joule heating under 1 W of applied power increases the VST temperature from room temperature (23 °C) to 80 °C in 175 s in air. Then, the thread cools back down to room temperature in 107 s. During this heating–cooling cycle, the VST experiences a relative resistance change equal to 5%. f) Resistance change in the VST for 10 heating–cooling cycles under direct Joule heating. The green and red triangles represent the resistance change in the rigid state at 28 °C and soft state at 80 °C, respectively. After passing the first three cycles, the resistance change remains almost constant.
Single‐segment catheter with variable stiffness thread (VST) and characterization results. a) i) The catheter consists of a VST, permanent magnet, base part, and electrode wire wrapped around the conductive shape memory polymer (CSMP) layer. The entire structure is encapsulated in silicone. ii) The catheter has a length of 44 mm and a diameter of 2.0 mm with a working channel of 0.5 mm. b) Bending actuation of the VST catheter. c) Actuation stroke angle as a function of the magnetic field angle and magnitude. The values represent three tested catheters and five cycles per device. The maximum actuation angle in the rigid state under a magnetic field magnitude of 80 mT is 1.5°. In the soft state, the actuation angle exhibits the maximum value of 51° under a magnetic field angle of 90°. d) Actuation stroke angle as a function of the magnetic field angle in the soft state. The values represent three tested catheters and five cycles per device.
Two‐segmented catheter design, performance, and application. a) The catheter consists of two variable stiffness threads (VSTs) and two permanent magnets fastened on the same PTFE tube. The catheter is placed in an electromagnetic navigation system i) when both VSTs are solid and ii–iv) when one of them is sequentially soft. b) An illustration of catheter application in the cardiac ablation procedure. The path of the catheter is shown in blue: it goes through the right femoral vein and inferior vena cava into the right atrium, through which, with a transseptal puncture, it reaches the left atrium. In the left atrium, the catheter reaches one of the four pulmonary veins (i, ii).
A Variable Stiffness Magnetic Catheter Made of a Conductive Phase‐Change Polymer for Minimally Invasive Surgery

February 2022

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456 Reads

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60 Citations

Variable stiffness (VS) is an important feature that significantly enhances the dexterity of magnetic catheters used in minimally invasive surgeries. Existing magnetic catheters with VS consist of sensors, heaters, and tubular structures filled with low melting point alloys, which have a large stiffness change ratio but are toxic to humans. In this paper, a VS magnetic catheter is described for minimally invasive surgery; the catheter is based on a novel variable stiffness thread (VST), which is made of a conductive shape memory polymer (CSMP). The CSMP is nontoxic and simultaneously serves as a heater, a temperature sensor, and a VS substrate. The VST is made through a new scalable fabrication process, which consists of a dipping technique that enables the fabrication of threads with the desired electrical resistance and thickness (with a step size of 70 µm). Selective bending of a multisegmented VST catheter with a diameter of 2.0 mm under an external magnetic field of 20 mT is demonstrated. Compared to existing proof‐of‐concept VS catheters for cardiac ablation, each integrated VST segment has the lowest wall thickness of 0.75 mm and an outer diameter of 2.0 mm. The segment bends up to 51° and exhibits a stiffness change factor of 21. A variable stiffness (VS) catheter made of a conductive shape memory polymer (CSMP) is developed. The CSMP used here is a nontoxic material that simultaneously serves as a heater and a temperature sensor while providing VS. The catheter, fabricated through a scalable process, exhibits a stiffness change factor of 21 and bends up to 51° under an external magnetic field.


Magnetically Assisted Robotic Fetal Surgery for the Treatment of Spina Bifida

February 2022

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133 Reads

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18 Citations

IEEE Transactions on Medical Robotics and Bionics

Spina bifida is a congenital defect that occurs on the vertebral spine of a fetus. The most severe form causes exposure of the spinal cord and spinal nerve and has important repercussions on the life of the newborn child. Current prenatal operative procedures require laparotomy of the abdomen as well as hysterotomy of the uterus, which can result in severe consequences and risks for the mother. Here, we propose a robotically assisted endoscopic procedure based on magnetically steerable catheters to treat spina bifida defects in a minimally invasive way. The procedure can be performed in a fully remote manner using magnetic guidance and a haptic controller. Four custom magnetic catheter designs are presented to image, sever, grasp and close the lesion on the fetus back. We demonstrate our approach in vitro using phantom models of the abdomen, the uterus, and the defected fetus.


Design and manufacturing of the composite variable stiffness catheter. a) Possible applications of a VSC. The VSC can provide increased push‐ability in hard‐to‐reach areas of the body or increase the reachable workspace in open volumes. b) Stiffness properties of state‐of‐the‐art variable stiffness materials (SMA: shape memory alloy, ERF: electrorheological fluids, PP: piezoelectric polymer, PCL: polycaprolactone, MRF: magnetorheological fluid, TP SMP: thermoplastic shape memory polymer, TP: thermoplastic, LCE: liquid crystal elastomer, and LMPA: low melting point alloy). The maximum tensile elastic modulus versus moduli ratio (maximum over minimum) of reported and analyzed variable stiffness materials. Adapted from.[²¹] c) Schematic illustration of the VSC: graphite or neodymium particles are embedded in the VS polymeric body. The lumen provides a working channel for tools or fluid injections, while the permanent magnet on the tip allows for magnetic actuation. The embedded copper wires allow for temperature and stiffness control. d) Fabrication method of the VSC, based on an injection molding process. The PDMS mold is fabricated i) with a PMMA structure, a PTFE wire, and a glass capillary. The mold is ii) filled with a copper wire, coiled around a PTFE wire and iii) NOA injected into the remaining space. UV–A light and heat are used to cure the thermoset material.
Characterization of the variable stiffness SMP composite. a) Variable stiffness catheter without filler showing the embedded control structure. The copper wire was uniformly coiled around the inner lumen over the entire length of the VS segment. b) SEM image of the catheter surface with embedded graphite and c) NdFeB particles. d) Glass transition temperature (Tg) versus concentration of NdFeB and graphite. e) Thermal conductivity of NdFeB and graphite in a polymeric matrix. f) Electrical conductivity of NdFeB and graphite in a polymeric matrix. Stiffness ratio and complex modulus values in the rubbery and glassy state versus g) increasing concentration of graphite and h) NdFeB. i) Hysteresis curves of NdFeB in a polymeric matrix.
Characterization of the variable stiffness catheter. a‐i) Magnetic actuation of a three section VSC allows complex configurations to be reached in an open volume. ii,iii) When S2 was heated, the segment could be easily deformed. In a second step, iv) S2 was locked in position, and v,vi) S3 was heated and deflected. b) Stiffness of a segment as a function of temperature. The stiffness can be accurately controlled allowing for a controlled deflection limitation. c) Transition time as a function of material: the transition speed can be increased with the addition of thermally conductive powders.
Applications of a composite variable stiffness catheter. a) Schematic illustration of an endoscopic procedure performed with a VS endoscope. The VS endoscope is i) magnetically steered and locked in position when the desired configuration is reached. This allows for the ii) insertion and magnetic actuation of the second tool. iii) The second tool is used to perform the desired intervention with a iv) visual feedback given from the endoscopic camera. b) Illustration of an endovascular application of the VS technology. i) A VS guiding catheter in combination with a magnetic micro catheter can be used for the treatment of endovascular diseases. ii) A VS guiding catheter can be used, in the soft state, to reach the desired location and be locked in position to ease the insertion of a micro catheter. iii) A VS micro catheter can be navigated to the targeted position (e.g., aneurysm) for the iv) injection of an embolization agent.
Thermoset Shape Memory Polymer Variable Stiffness 4D Robotic Catheters

October 2021

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805 Reads

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68 Citations

Variable stiffness catheters are typically composed of an encapsulated core. The core is usually composed of a low melting point alloy (LMPA) or a thermoplastic polymer (TP). In both cases, there is a need to encapsulate the core with an elastic material. This imposes a limit to the volume of variable stiffness (VS) material and limits miniaturization. This paper proposes a new approach that relies on the use of thermosetting materials. The variable stiffness catheter (VSC) proposed in this work eliminates the necessity for an encapsulation layer and is made of a unique biocompatible thermoset polymer with an embedded heating system. This significantly reduces the final diameter, improves manufacturability, and increases safety in the event of complications. The device can be scaled to sub‐millimeter dimensions, while maintaining a high stiffness change. In addition, integration into a magnetic actuation system allows for precise actuation of one or multiple tools. In this work, an advanced 4D robotic medical catheter based on a processable thermoset shape‐memory polymer composite, is reported. The developed electrically conductive composite allows for superior processability and further miniaturization maintaining high stiffness variations and fast transition speeds. The capabilities are demonstrated by performing robotic manipulations with multiple magnetic tools.


A Submillimeter Continuous Variable Stiffness Catheter for Compliance Control (Adv. Sci. 18/2021)

September 2021

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134 Reads

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6 Citations

Variable Stiffness Catheter In article number 2101290 by Quentin Boehler, Bradley J. Nelson, and co-workers, a magnetically controlled catheter that is able to continuously change its stiffness is presented. Soft, magnetic tools that are enhanced with the capability to apply and control forces during surgical intervention can significantly improve outcome of the procedure. The capabilities are demonstrated by performing a fully robotic surgery for a challenging ophthalmic intervention. Image designed by Adrián Bago González.


Schematic views of the continuous variable stiffness (CVS) catheter. A) Cross‐section of the catheter: the low melting point alloy (LMPA) core is encapsulated by an isolation layer and surrounds a working channel, and the heating and measurement wires are used for the control of the phase boundary within the LMPA. B) Control of the phase boundary: the radial heat expansion, due to the central heating and peripheral passive cooling from ambient air temperature causes the LMPA to melt from the inside out. Increased heat will shift the phase boundary radially outward. C) Overview of the proposed CVS catheter: the end‐effector tip has an embedded permanent magnet to steer the catheter with external magnetic fields. D) Close‐up view of the catheter: the heating wires are wrapped around the working channel, and the distal measurement wire is attached at the distal end of the LMPA and led back through the outer isolation. E) Non‐encapsulated LMPA cores before and after melting. F) The CVS catheter with a microgripper as an end‐effector. G) Clinical setup for a magnetically‐guided robotic membrane peel surgery: the magnetic navigation system is placed below the patient and allows the CVS catheter to be magnetically steered to the desired location. The compliance capabilities of the tool allow the surgeon to avoid tissue damage, as the catheter can be advanced with a robotic advancer that is placed above the patient. The procedure is monitored through a microscope, commonly used in most ophthalmic surgeries.
Control of the electrical resistance of the continuous variable stiffness (CVS) catheter. A) Signal flow to achieve stiffness changes in the catheter: the black arrows indicate the measurement loop, the red arrows the heating circuit. B) Schematic illustration of the setup for measurements for the temperature‐resistance relationship of CVS catheter. The catheter is immersed in a water tank with a controlled temperature; a magnetic stirrer guarantees a uniform temperature distribution. C) The resistance‐temperature relationship of the CVS catheter with the described measurement setup. Region I: Heating of measurement wires embedded in device; Region II: Phase change of LMPA; Region III: Heating of measurement wires and impurities D) CVS controller response to the desired resistance change from completely rigid to flexible in water (blue line) and air (red line). E) Applied electrical current by the controller to switch the CVS catheter from stiff to flexible in water and air, blue and red lines, respectively.
Characterization of the continuous variable stiffness (CVS) catheter. Dimensions: L = 30 mm, OD = 1 mm, ID = 180 µm. A) Amplitude measurements at different resistance states: a constant oscillating magnetic field of 40 mT was applied to the catheter with a magnetic manipulation system. The resulting oscillating magnetic torque deflects the catheter. Simultaneously, the resistance of the CVS catheter was controlled at discrete resistance levels and the obtained amplitude recorded. B) Oscillation Amplitude for a constant magnetic field and different controlled resistances (n = 10). The standard deviation at each measurement is depicted as an error bar. With the given magnetic field strength, the catheter does not oscillate if none of the low melting point alloy (LMPA) is liquid (Region Ι). As the LMPA liquefies, the amplitude increases nonlinearly (Region ΙΙ). When all of the LMPA has melted (Region ΙΙΙ) only a minor increase in oscillation amplitude was observed. C) Three‐point bending test setup. The catheter was fixed on two supports and a centered force deflected the catheter. From the resulting force–deflection curve, the bending stiffness could be measured for the same discrete controlled input resistances. D) Measured (n = 10) and simulated bending stiffness for different controlled resistances. E) Setup for compliance testing. The catheter was fixed on a linear stage and pushed toward a rigid force‐sensor. F) Force–displacement curves (n = 6) for the same set of discretely controlled input resistances. Due to bending of the catheter, the curves are concave, limiting the maximally applicable forces.
Robotic epiretinal membrane peeling surgery in an eye phantom A) Setup to validate a fully robotic epiretinal membrane peel intervention, consisting of the electromagnetic navigation system, the robotic colinear advancer, the continuous variable stiffness (CVS) catheter, a phantom eye, a light source, and a microscope. B) Custom microgrippers to perform epiretinal membrane peeling. C) The catheter can be moved efficiently in the flexible state to the location of the membrane. D) The intermediate stiffness level limits the forces that are applied to the tissue when making contact. E) To close the gripper, the stiffness is increased to minimize the position change due to the forces applied by the pull‐wire attached to the gripper. F) The membrane can be removed while the gripper remains closed.
Design and Fabrication of the continuous variable stiffness (CVS) catheter. A) Workspace of a rigid and flexible tool: the workspace of a rigid tool is limited by the pivot point at the sclera (green area), a soft, magnetic tool has a potentially greater workspace and dexterity (blue area). B) Surface temperature for different polymer thicknesses. C) CVS catheter manufacturing steps: 1) after the heating wires are coiled around the working channel, 2) the Low Melting Point Alloy (LMPA) is uniformly coated around it. 3) The permanent magnet is then glued to the catheter. 4) Finally the device is coated with a 150 µm Perfluoropolyether (PFPE) layer. D) Mold and temperature controller for the fabrication of the CVS catheter. E) Close‐up of the microfluidic channels in the mold: the microfluidic channels are sealed with a teflon layer that is pressed together with screws.
A Submillimeter Continuous Variable Stiffness Catheter for Compliance Control

July 2021

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740 Reads

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73 Citations

Minimally invasive robotic surgery often requires functional tools that can change their compliance to adapt to the environment and surgical needs. This paper proposes a submillimeter continuous variable stiffness catheter equipped with a phase-change alloy that has a high stiffness variation in its different states, allowing for rapid compliance control. Variable stiffness is achieved through a variable phase boundary in the alloy due to a controlled radial temperature gradient. This catheter can be safely navigated in its soft state and rigidified to the required stiffness during operation to apply a desired force at the tip. The maximal contact force that the catheter applies to tissue can be continuously modified by a factor of 400 (≈20 mN–8 N). The catheter is equipped with a magnet and a micro-gripper to perform a fully robotic ophthalmic minimally invasive surgery on an eye phantom by means of an electromagnetic navigation system.


A Robotic Diathermy System for Automated Capsulotomy

November 2017

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250 Reads

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6 Citations

Journal of Medical Robotics Research

Background: Cataracts are the leading cause of blindness and are treated surgically. Capsulotomy describes the opening of the lens capsule during this surgery and is most commonly performed by manual tearing, thermal cutting, or laser ablation. This work focuses on the development of a flexible instrument for high precision capsulotomy, whose motion is controlled by a hybrid mechanical-magnetic actuation system. Methods: A flexible instrument with a magnetic tip was directed along a circular path with a hybrid mechanical-magnetic actuation system. The system’s motion control and thermal cutting behavior were tested on ex vivo porcine lenses. Results: Position control of the magnetic tip on a circular path with radius of 2.9mm resulted in a relative positioning error of 3% at a motion period of 60s. The instrument’s accuracy improves with decreasing speed. A fully automated capsulotomy is achieved on an ex vivo porcine lens capsule by continuously coagulating the tissue under controlled conditions. Conclusions: Robot assisted capsulotomy can be performed with excellent precision in ex vivo conditions.


Citations (9)


... Novel conceptional design of MSRs has recently emerged to facilitate new requirements for minimally invasive surgery. These new MSRs attempt to modify the structure of the singletube shape configuration of the MSR to enhance the clinically relevant functionality, e.g., multi-section [ 16 ], concentric tube [ 17 ], variable stiffness [ 18 ], and helical shape [ 9 ]. The multisection MSRs have the capability to deform as multi-curvature shapes to traverse through the human body lumen [ 19 ], which shows high potential in adapting to anatomical variabilities. ...

Reference:

Multi-Section Magnetic Soft Robot with Multirobot Navigation System for Vasculature Intervention
Dexterous helical magnetic robot for improved endovascular access
  • Citing Article
  • February 2024

Science Robotics

... Compared to traditional rigid robots, soft robots demonstrate superior properties including high compliance, adaptability, safe human-robot interaction, simple structures, and cost-effectiveness [1][2][3][4][5][6][7][8][9][10][11][12]. These soft robots employ actuation methods such as pneumatic [13][14][15], hydraulic [16,17], shapememory polymer [18,19], shape-memory alloy [20,21], and phase-change alloy [22]. ...

Magnetically Guided Laser Surgery for the Treatment of Twin‐to‐Twin Transfusion Syndrome

... The generation of actuating magnetic fields is possible via systems of electromagnetic coils 22 or the use of manipulated External Permanent Magnets (EPMs) 23,24 . The use of manipulated EPMs comes with the advantage of larger workspace, lower power requirements, but increased control complexity 23 . ...

Magnetically Assisted Robotic Fetal Surgery for the Treatment of Spina Bifida
  • Citing Article
  • February 2022

IEEE Transactions on Medical Robotics and Bionics

... Compared to traditional rigid robots, soft robots demonstrate superior properties including high compliance, adaptability, safe human-robot interaction, simple structures, and cost-effectiveness [1][2][3][4][5][6][7][8][9][10][11][12]. These soft robots employ actuation methods such as pneumatic [13][14][15], hydraulic [16,17], shapememory polymer [18,19], shape-memory alloy [20,21], and phase-change alloy [22]. In recent years, innovative designs of 3 These authors contributed equally to this work. ...

A Variable Stiffness Magnetic Catheter Made of a Conductive Phase‐Change Polymer for Minimally Invasive Surgery

... Active variable stiffness techniques, such as electrical, thermal, magnetically induced, and antagonistic variable stiffness, require additional energy interventions, beyond the robot drive energy [92][93][94][95]. In contrast, passive variable stiffness techniques, such as obstruction and composite variable stiffness, do not require additional energy stimulation to increase the stiffness of soft grippers [99][100][101][102][103][104][105]. ...

Thermoset Shape Memory Polymer Variable Stiffness 4D Robotic Catheters

... The classical challenge of catheter steering is, today, addressed not only by pull-wire systems but also with soft-actuator solutions based on conductive polymer (8) and hydraulic actuators (9) as well as magnetic actuation. The latter is widely explored throughout academia (10,11) and the clinical sector, where it is used in robotic systems for cardiac ablation (12). Other commercial robotic systems, including the Da Vinci Robotic System (13) or Monarch Platform for robotic catheter control (14) provide medical practitioners with superhuman precision and control. ...

A Submillimeter Continuous Variable Stiffness Catheter for Compliance Control (Adv. Sci. 18/2021)

... Among these technologies, variable-stiffness tools based on thermally induced phase transitions has the potential to be miniaturized. For instance, Lussi et al. [21] achieved compliance control of a sub-millimeter continuous variable stiffness catheter through the variable phase change boundary in low melting point alloy, which is controlled by a radial temperature gradient. Similarly, Chautems et al. [22] proposed a magnetic continuum device with variable stiffness, where the tip is precisely shaped and controlled using an external magnetic field. ...

A Submillimeter Continuous Variable Stiffness Catheter for Compliance Control

... Tasks to which surgical robots have been applied include cochlear implantation [14], vascular anastomosis [15], and variocolectomy [16]. In particular, there has been considerable effort to develop robotic surgical tools for ophthalmic surgery [17]- [20], including systems which use magnetic fields to guide the tool [21], [22]. Many of these systems are designed for teleoperation by human surgeons, but there has also been work on automatic motion planning for surgical robotics. ...

A Robotic Diathermy System for Automated Capsulotomy
  • Citing Article
  • November 2017

Journal of Medical Robotics Research

... The range of systems for telemanipulation in surgery places various demands on the user interface in terms of available DOF, workspace, form factor, and, in the case of haptic feedback, stiffness and mechanical bandwidth. While telemanipulation systems for visceral surgery or flexible robots for applications in the gastrointestinal tract must apply and feedback forces in the range of several newtons which are typical for the respective application [6], micromanipulators for more delicate applications such as ophthalmology have to cope with only a few millinewtons [7]. To provide haptic feedback, there are furthermore applications, that require to measure and display small, dynamic forces while others require high, relatively static interaction forces. ...

Perforation Forces of the Intact Porcine Anterior Lens Capsule
  • Citing Article
  • May 2016

Journal of the Mechanical Behavior of Biomedical Materials