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V.G. Kortman

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13 records found

Review (2026) - V.G. Kortman, J. Jovanova, H. Nabae, G. Endo, K. Suzumori, A. Sakes
McKibben artificial muscles (AMs) are known as a prominent class of pneumatic actuators in soft robotics and biomechanical engineering, due to their unique structure and multifunctionality. This paper presents a comprehensive review of recent advancements in McKibben AMs, focusing on their performance, structural variations, and operational principles. A systematic literature search on Scopus identified 146 relevant articles, which were analysed for both performance metrics and design characteristics. Inspired by natural muscle behaviour, McKibben AMs enable complex motions such as bending, linear extension, and twisting. These actuators can be organised as individual or bundled systems: individual units are typically arranged in linear or circular patterns, while bundled systems occur in serial, parallel, braided, convergent, or pennate configurations. Recent innovations in smart actuation methods, braided sleeves and internal bladders have expanded their capabilities, enabling embedded sensing, environmental adaptability and untethered operation. Additionally, alternative manufacturing methods offer promising solutions for developing McKibben muscles with enhanced functionality and tailored properties. ...
Journal article (2025) - V.G. Kortman, J.T. Hompes, A. Sakes, J. Jovanova
In nature, organisms such as the octopus exhibit remarkable adaptability by reconfiguring their bodies into contracting and extending segments. Translating this modularity into robotics, origami-inspired designs have proven effective in creating adaptable building blocks for modular robotic arms. The Kresling cylinder, a bistable cylindrical origami structure, exemplifies this approach by functioning as both a contracting and extending actuator. However, current actuation strategies in origami-inspired structures—such as pneumatic, mechanical, or stimuli-responsive methods—suffer from bulky actuators, slow speed, or inability to provide local actuation. Magnetically-actuated Kresling cylinders offer promising solutions for rapid and localized actuation. However, they typically rely on large external coils, limiting their use in restricted environments. To overcome this limitation, we have embedded coils directly into a modular Kresling cylinder, creating a standalone electromagnetically-actuated system. The finite element analysis was employed to understand the effect of the electromagnets' dimensions on effective contraction and extension, resulting in a weight-efficient actuator. Trends were uncovered for the design of flat, effective electromagnets for embedded electromagnetic actuation. Following these design trends, a prototype was successfully manufactured, demonstrating rapid contraction and extension in both horizontal and vertical orientation. The standalone Kresling actuator is particularly well-suited for use in dynamic, remote or restricted environments. The simple design of the manufactured prototype illustrates the potential for incorporating embodied actuation into functional soft robotic designs. ...
Review (2025) - Vera Gesina Kortman, Barbara Mazzolai, Aimeé Sakes, Jovana Jovanova
Engineers frequently aim to streamline environmental factors to facilitate the effective operation of robots. However, in nature, environmental considerations play a crucial role in shaping the embodiment of organisms. To comply robots with the complexity of real-world environments, embedding similar intelligence is key. In the field of soft robotics, various approaches offer insight into how intelligence can be integrated into artificial agents. A discussed topic is the intricate relationship between the brain and the body at the core of intelligence in robots. The goal of this article is, therefore, to unravel the strategies to implement different types of intelligence currently adopted in soft robots. A classification is made by making a distinction between agents that adapt to their environment by 1) their adaptive shape, 2) their adaptive functionality, and 3) their adaptive mechanics. Additionally, the perspectives on intelligence based on their computational approach are distinguished: centralized computation, decentralized computation, or embedded computation. It is concluded that a tailored robotic design approach attuned to specific environmental demands is needed. To unlock the full potential of soft robots, a fresh perspective on embodied intelligence is described, so-called mechanical intelligence, emphasizing the robot's responsiveness to changing external conditions of a real-world environment. ...

Encoding complex deformation profiles in mckibben artificial muscles

The octopus achieves intricate arm deformations through local muscle interactions rather than centralized coordination. Inspired by this principle, this study aims to develop embodied intelligent McKibben Artificial Muscles (AMs), in which global deformation is encoded directly into their physical structure. The key design parameter explored is the braiding angle, which governs the type and magnitude of motion. By spatially varying this angle along the actuator, we demonstrate embedded capabilities for local extension and contraction within a single AM. Additionally, a mismatch in braiding angles between opposing wire sets generates a twisting motion. To implement these variations, traditional braiding techniques were adapted for localized angle control. Within a single McKibben AM, a maximum strain of +0.06 and minimum strain of −0.19 was measured. A twist angle of 100° was achieved using a 50.4° angle difference at 50 kPa actuation pressure. A final modular prototype demonstrated the integration of multiple motion modes within a single actuator body. These results highlight the potential of mechanically intelligent AMs to simplify actuation systems in soft robotics. Applications include wearable technologies such as exoskeletons and prosthetics, as well as bioinspired systems like artificial hearts or continuum robotic arms, where compact and adaptive actuation is essential. ...
Journal article (2025) - J. Bloemberg, S. van Wees, V.G. Kortman, A. Sakes
Percutaneous pancreatic core biopsy is conclusive but challenging due to large-diameter needles, while smaller-diameter needles used in aspiration methods suffer from buckling and clogging. Inspired by the ovipositor of parasitic wasps, which resists buckling through self-propulsion and prevents clogging via friction-based transport, research has led to the integration of these functionalities into multi-segment needle designs or tissue transport system designs. This study aimed to combine these wasp-inspired functionalities into a single biopsy needle by changing the interconnection of the needle segments. The resulting biopsy needle features six parallel needle segments interconnected by a ring passing through slots along the length of the needle segments, enabling a wasp-inspired reciprocating motion. Actuation employs a cam and follower mechanism for controlled translation of the segments. The needle prototype, constructed from nitinol rods and stainless steel rings, measures 3 mm in outer diameter and 1 mm in inner diameter. Testing in gelatin phantoms demonstrated efficient gelatin core transport (up to 69.9% ± 9.1% transport efficiency) and self-propulsion (0.842 ± 0.042 slip ratio). Future iterations should aim to reduce the outer diameter while maintaining tissue yield. The design offers a promising new avenue for wasp-inspired medical tools, potentially enhancing early pancreatic cancer detection, thus reducing healthcare costs and patient complications. ...
Journal article (2024) - Simona Aracri, Josie Hughes, Cosimo Della Santina, Jovana Jovanova, Sam Hoh, Ditzia Susana Garcia Morales, Yu Jun Tan, Vera G. Kortman, Aimée Sakes, More authors...
Robotics is entering our daily lives. The discipline is increasingly crucial in fields such as agriculture, medicine, and rescue operations, impacting our food, health, and planet. At the same time, it is becoming evident that robotic research must embrace and reflect the diversity of human society to address these broad challenges effectively. In recent years, gender inclusivity has received increasing attention, but it still remains a distant goal. In addition, awareness is rising around other dimensions of diversity, including nationality, religion, and politics. Unfortunately, despite the efforts, empirical evidence shows that the field has still a long way to go before achieving a sufficient level of equality, diversity, and inclusion across these spectra. This study focuses on the soft robotics community?a growing and relatively recent subfield?and it outlines the present state of equality and diversity panorama in this discipline. The article argues that its high interdisciplinary and accessibility make it a particularly welcoming branch of robotics. We discuss the elements that make this subdiscipline an example for the broader robotic field. At the same time, we recognize that the field should still improve in several ways and become more inclusive and diverse. We propose concrete actions that we believe will contribute to achieving this goal, and provide metrics to monitor its evolution. ...
Journal article (2024) - Shibo Zou, Sergio Picella, Jelle de Vries, Vera G. Kortman, Aimée Sakes, Johannes T.B. Overvelde
Soft robots are intrinsically capable of adapting to different environments by changing their shape in response to interaction forces. However, sensory feedback is still required for higher level decisions. Most sensing technologies integrate separate sensing elements in soft actuators, which presents a considerable challenge for both the fabrication and robustness of soft robots. Here we present a versatile sensing strategy that can be retrofitted to existing soft fluidic devices without the need for design changes. We achieve this by measuring the fluidic input that is required to activate a soft actuator during interaction with the environment, and relating this input to its deformed state. We demonstrate the versatility of our strategy by tactile sensing of the size, shape, surface roughness and stiffness of objects. We furthermore retrofit sensing to a range of existing pneumatic soft actuators and grippers. Finally, we show the robustness of our fluidic sensing strategy in closed-loop control of a soft gripper for sorting, fruit picking and ripeness detection. We conclude that as long as the interaction of the actuator with the environment results in a shape change of the interval volume, soft fluidic actuators require no embedded sensors and design modifications to implement useful sensing. ...

Magnetic-Actuated Deployable Suction Gripper for Complex Surface Handling

Suction grippers offer a distinct advantage in their ability to handle a wide range of items. However, attaching these grippers to irregular and rough surfaces presents an ongoing challenge. To address this obstacle, this study explores the integration of magnetic intelligence into a soft suction gripper design, enabling fast external magnetic actuation of the attachment process. Additionally, miniaturization options are enhanced by implementing a compliant deploying mechanism. The resulting design is the first-of-its-kind magnetically-actuated deployable suction gripper featuring a thin magnetic membrane (Ø 50 mm) composed of carbonyl iron particles embedded in a silicone matrix. This membrane is supported by a frame made of superelastic nitinol wires that facilitate deployment. During experiments, the proof-of-principle prototype demonstrates successful attachment on a diverse range of curved surfaces in both dry and wet environments. The gripper achieves attachment on curved surfaces with radii of 50-75 mm, exerting a maximum attachment force of 2.89 ± 0.54 N. The current gripper design achieves a folding percentage of 75%, enabling it to fit into a Ø 12.5 mm tube and access hard-to-reach areas while maintaining sufficient surface area for attachment forces. The proposed prototype serves as a foundational steppingstone for further research in the development of reliable and effective magnetically-actuated suction grippers across various configurations. By addressing the limitations of attachment to irregular surfaces and exploring possibilities for miniaturization and precise control, this study opens new avenues for the practical application of suction grippers in diverse industries and scenarios. ...
Thrombus removal from the human body is facilitated through the utilization of aspiration catheters during minimally invasive thrombectomy procedures, where a pressure differential guides the targeted tissue through a flexible tubular medical instrument. In this paper, we present a patent analysis of thrombectomy aspiration catheter tip designs sourced from the EspaceNet database. Our findings reveal that enhancing the operability of aspiration catheters can be achieved by improving ease of positioning or suction capacity, whether through active or passive means. In terms of the former, both tip shape and flexibility play pivotal roles in maneuvering the distal end effectively. Variations in aspiration port characteristics, either distal-oriented or sideways-oriented, have the potential to enhance suction efficiency. In the active approach, aspects of positioning and suctioning are integrated into a single design, allowing for seamless transitions between configurations. While numerous design characteristics can coexist in a thrombectomy aspiration tip, a balance between flexibility and buckling resistance, as well as between maximizing aspiration lumen diameter and minimizing tip diameter, must be struck. This paper offers an insightful overview of existing thrombectomy aspiration tip designs, providing valuable inspiration for future innovations in this field. ...

Review of Four-Dimensional Printing, Challenges and Opportunities

In the field of Additive Manufacturing, four-dimensional (4D) printing has emerged as a promising technique to fabricate smart structures capable of undergoing shape morphing in response to specific stimuli. Magnetic stimulation offers a safe, remote, and rapid actuation mechanism for magnetically responsive structures. This review provides a comprehensive overview of the various strategies and manufacturing approaches employed in the development of magnetically stimulated shape morphing 4D-printed structures, based on an extensive literature search. The review explores the use of magnetic stimulation either individually or in combination with other stimuli. While most of the literature focuses on single-stimulus responsive structures, a few examples of multistimuli responsive structures are also presented. We investigate the influence of the orientation of magnetic particles in smart material composites, which can be either random or programmed during or after printing. Finally, the similarities and differences among the different strategies and their impact on the resulting shapemorphing behavior are analyzed. This systematic overview functions as a guide for readers in selecting a manufacturing approach to achieve a specific magnetically actuated shape-morphing effect. ...
Conference paper (2023) - V.G. Kortman, J. Jovanova, A. Sakes
In the medical field, it is essential to remove delicate tissues from the body without damaging them or disturbing the surroundings. Current tissue transport mechanisms depend on the tissue composition and shape of the transported tissue, which results in problems such as clogging. This study presents a soft transportation mechanism for tissues inspired by the longitudinal muscles associated with the peristaltic movement of the gastrointestinal tract. The mechanism is designed as a conveying toroid that turns itself inside out in a continuous motion. A fabrication method was developed to manufacture a small-sized silicone toroid, filled with lubricating liquid. Comparable to the peristaltic movement, the silicone toroid adapts its shape to the transported tissue which results in a soft seal around the tissue. The toroid conveys the tissue while locking it at a stationary spot. A prototype was built to evaluate the transport efficiency of the conveying toroid in differently curved pathways. The preliminary experiments showed good transport efficiency, revealing the potential of the proposed soft transport mechanism for medical, and other transport applications. ...
Journal article (2023) - Vera G. Kortman, Aimée Sakes, Gen Endo, Paul Breedveld
Gripping slippery and flexible tissues during minimal invasive surgery (MIS) is often challenging using a conventional tissue gripper. A force grip has to compensate for the low friction coefficient between the gripper’s jaws and the tissue surface. This study focuses on the development of a suction gripper. This device applies a pressure difference to grip the target tissue without the need to enclose it. Inspiration is taken from biological suction discs, as these are able to attach to a wide variety of substrates, varying from soft and slimy surfaces to rigid and rough rocks. Our bio-inspired suction gripper is divided into two main parts: (1) the suction chamber inside the handle where vacuum pressure is generated, and (2) the suction tip that attaches to the target tissue. The suction gripper fits through a ∅ 10 mm trocar and unfolds in a larger suction surface when being extracted. The suction tip is structured in a layered manner. The tip integrates five functions in separate layers to allow for safe and effective tissue handling: (1) foldability, (2) air-tightness, (3) slideability, (4) friction magnification and (5) seal generation. The contact surface of the tip creates an air-tight seal with the tissue and enhances frictional support. The suction tip’s shape grip allows for the gripping of small tissue pieces and enhances its resistance against shear forces. The experiments illustrated that our suction gripper outperforms man-made suction discs, as well as currently described suction grippers in literature in terms of attachment force ( 5.95 ± 0.52 N on muscle tissue) and substrate versatility. Our bio-inspired suction gripper offers the opportunity for a safer alternative to the conventional tissue gripper in MIS. ...
Journal article (2023) - V.G. Kortman, Y.J.M.A. Verberne, J. Jovanova, A. Sakes
Introduction
Tissue extraction plays a crucial role in various medical disciplines, with aspiration catheters serving as the prevailing method. Unfortunately, these catheters face limitations such as clogging and dependence on tissue properties and device dimensions. Therefore, there is a pressing need for an improved tissue extraction device that enables efficient and reliable tissue removal during Minimally Invasive Surgery (MIS).

Methods
In this study, we present a novel tissue transport system that utilizes a cylindrical conveyor belt mechanism for reliable tissue transportation. We conducted experiments using a proof-of-principle prototype to explore the influence of tissue elasticity, rotational velocity, instrument orientation, and tissue shape on the transportation rate, efficiency, and reliability. Tissue phantoms with gelatine concentrations of 3, 9, and 12 wt% were employed to simulate a range of Young’s moduli from 1 to 110 kPa.

Results
The mean transportation rates for these phantoms were 7.75±0.48, 8.43±1.50, and 8.90±0.56 g/min, respectively. Notably, all phantoms were transported successfully. The perfect reliability exhibited underscores the potential of our instrument as an alternative to aspiration catheters.

Conclusion
This research presents a significant step forward in the field of tissue extraction, offering a promising approach for MIS with enhanced efficiency and reliability.
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