This paper presents the concept design of a modular soft manipulator for minimally invasive surge... more This paper presents the concept design of a modular soft manipulator for minimally invasive surgery. Unlike traditional surgical manipulators based on metallic steerable needles, tendon-driven mechanisms, or articulated motorized links, we combine flexible fluidic actuators to obtain multidirectional bending and elongation with a variable stiffness mechanism based on granular jamming. The idea is to develop a manipulator based on a series of modules, each consisting of a silicone matrix with pneumatic chambers for 3-D motion, and one central channel for the integration of granular-jamming-based stiffening mechanism. A bellows-shaped braided structure is used to contain the lateral expansion of the flexible fluidic actuator and to increase its motion range. In this paper, the design and experimental characterization of a single module composed of such a manipulator is presented. Possible applications of the manipulator in the surgical field are discussed.
ABSTRACT This paper presents the design of a single module composing a modular soft variable stif... more ABSTRACT This paper presents the design of a single module composing a modular soft variable stiffness manipulator for minimal access surgery. The module exploits flexible fluidic actuation for obtaining multi directional bending and elongation capabilities. A novel flexible crimped braided sheath is introduced in order to increase the performances of the flexible actuator. Granular jamming based stiffening mechanism is used to tune the stiffness of the module. The fabrication of the module is described and the performances in terms of bending, elongation and stiffening are reported.
Most devices for single-site or natural orifice transluminal surgery are very application specifi... more Most devices for single-site or natural orifice transluminal surgery are very application specific and, hence, capable of effectively carrying out specific surgical tasks only. However, most of these instruments are rigid, lack a sufficient number of degrees of freedom (DOFs), and/or are incapable of modifying their mechanical properties based on the tasks to be performed. The current philosophy in commercial instrument design is mainly focused on creating minimally invasive surgical systems using rigid tools equipped with dexterous tips. Only few research efforts are aimed at developing flexible surgical systems, with many DOFs or even continuum kinematics. The authors propose a radical change in surgical instrument design: away from rigid tools toward a new concept of soft and stiffness-controllable instruments. Inspired by biology, we envision creating such soft and stiffnesscontrollable medical devices using the octopus as a model. The octopus presents all the capabilities requested and can be viewed as a precious source of inspiration. Several soft technologies are suitable for meeting the aforementioned capabilities, and in this article a brief review of the most promising ones is presented. Then we illustrate how specific technologies can be applied in the design of a novel manipulator for flexible surgery by discussing its potential and by presenting feasibility tests of a prototype responding to this new design philosophy. Our aim is to investigate the feasibility of applying these technologies in the field of minimally invasive surgery and at the same time to stimulate the creativeness of others who could take the proposed concepts further to achieve novel solutions and generate specific application scenarios for the devised technologies.
This paper presents the concept design, the fabrication and the experimental characterization of ... more This paper presents the concept design, the fabrication and the experimental characterization of a unit of a modular manipulator for minimal access surgery. Traditional surgical manipulators are usually based on metallic steerable needles, tendon driven mechanisms or articulated motorized links. In this work the main idea is to combine flexible fluidic actuators enabling omnidirectional bending and elongation capability and the granular jamming phenomenon to implement a selective stiffness changing. The proposed manipulator is based on a series of identical modules, each one consisting of a silicone tube with pneumatic chambers for allowing 3D motion and one central channel for the implementation of the granular jamming phenomenon for stiffening. The silicone is covered by a novel bellows-shaped braided structure maximizing the bending still limiting lateral expansion. In this paper one single module is tested in terms of bending range, elongation capability, generated forces and stiffness changing.
Steerable instruments are a promising trend in minimally invasive surgery (MIS), due to their man... more Steerable instruments are a promising trend in minimally invasive surgery (MIS), due to their manoeuvring capabilities enabling reaching over obstacles. Despite the great number of steerable joint designs, currently available steerable tips tend to be vulnerable to external loading, thus featuring low bending stiffness. This work aims to provide empirical evidence that the bending stiffness can be considerably increased by using fully actuated joint constructions, enabling left/right and up/down tip rotations with the minimum of two degrees of freedom (DOF), rather than conventional underactuated constructions enabling these rotations with more than two DOF. A steerable MIS instrument prototype with a fully actuated joint construction was compared to state-of-the-art underactuated steerable instruments in a number of tip deflection experiments. The tip deflections due to loading were measured by means of a universal testing machine in four bending scenarios: straight and bent over 20°, 40° and 60°. The experimental results support the claim that a fully actuated joint construction exhibits a significantly larger bending stiffness than an underactuated joint construction. Furthermore, it was shown that the underactuated instrument tips show a considerable difference between their neutral positions before and after loading, which could also be greatly minimised by full actuation.
Soft robotics for medical, endoscopic applications requires a dexterous and compliant mechanism t... more Soft robotics for medical, endoscopic applications requires a dexterous and compliant mechanism to increase accessibility and decrease patient injury. However, soft structures do not offer the level of image and platform stability provided by rigid structures. Thus, a variable stiffness mechanism is an ideal solution to reconcile the two requirements of compliance and stability; the mechanism explored here is granular jamming. Granular jamming is a phenomenon where particulate matter within a membrane can transition from a fluid-like to a solid-like state, based on the level of applied vacuum pressure. In the solid-like jammed state, the conventional assumption is made that granule-granule contacts dominantly contribute to the system's stiffness. Thus, many works have evaluated the effects of different granule types by experimentally varying the sizes, shapes, and material properties of the particles. However, the role of the membrane in determining the possible range of stiffness or the variability of granular jamming has not been well studied. This paper investigates the effects and significance of membranes for a granular jamming system. Several membranes were experimentally tested and analyzed in order to find the amount of flexibility and stiffness they provide when the system is in an unjammed and jammed state, respectively. This paper presents for the first time that the membrane plays a significant contributing factor in granular jamming stiffness.
This paper introduces a novel, bioinspired manipulator for minimally invasive surgery (MIS). The ... more This paper introduces a novel, bioinspired manipulator for minimally invasive surgery (MIS). The manipulator is entirely composed of soft materials, and it has been designed to provide similar motion capabilities as the octopus's arm in order to reach the surgical target while exploiting its whole length to actively interact with the biological structures. The manipulator is composed of two identical modules (each of them can be controlled independently) with multi-directional bending and stiffening capabilities, like an octopus arm. In the authors' previous works, the design of the single module has been addressed. Here a two-module manipulator is presented, with the final aim of demonstrating the enhanced capabilities that such a structure can have in comparison with rigid surgical tools currently employed in MIS. The performances in terms of workspace, stiffening capabilities, and generated forces are characterized through experimental tests. The combination of stiffening capabilities and manipulation tasks is also addressed to confirm the manipulator potential employment in a real surgical scenario.
This paper presents the concept design of a modular soft manipulator for minimally invasive surge... more This paper presents the concept design of a modular soft manipulator for minimally invasive surgery. Unlike traditional surgical manipulators based on metallic steerable needles, tendon-driven mechanisms, or articulated motorized links, we combine flexible fluidic actuators to obtain multidirectional bending and elongation with a variable stiffness mechanism based on granular jamming. The idea is to develop a manipulator based on a series of modules, each consisting of a silicone matrix with pneumatic chambers for 3-D motion, and one central channel for the integration of granular-jamming-based stiffening mechanism. A bellows-shaped braided structure is used to contain the lateral expansion of the flexible fluidic actuator and to increase its motion range. In this paper, the design and experimental characterization of a single module composed of such a manipulator is presented. Possible applications of the manipulator in the surgical field are discussed.
ABSTRACT This paper presents the design of a single module composing a modular soft variable stif... more ABSTRACT This paper presents the design of a single module composing a modular soft variable stiffness manipulator for minimal access surgery. The module exploits flexible fluidic actuation for obtaining multi directional bending and elongation capabilities. A novel flexible crimped braided sheath is introduced in order to increase the performances of the flexible actuator. Granular jamming based stiffening mechanism is used to tune the stiffness of the module. The fabrication of the module is described and the performances in terms of bending, elongation and stiffening are reported.
Most devices for single-site or natural orifice transluminal surgery are very application specifi... more Most devices for single-site or natural orifice transluminal surgery are very application specific and, hence, capable of effectively carrying out specific surgical tasks only. However, most of these instruments are rigid, lack a sufficient number of degrees of freedom (DOFs), and/or are incapable of modifying their mechanical properties based on the tasks to be performed. The current philosophy in commercial instrument design is mainly focused on creating minimally invasive surgical systems using rigid tools equipped with dexterous tips. Only few research efforts are aimed at developing flexible surgical systems, with many DOFs or even continuum kinematics. The authors propose a radical change in surgical instrument design: away from rigid tools toward a new concept of soft and stiffness-controllable instruments. Inspired by biology, we envision creating such soft and stiffnesscontrollable medical devices using the octopus as a model. The octopus presents all the capabilities requested and can be viewed as a precious source of inspiration. Several soft technologies are suitable for meeting the aforementioned capabilities, and in this article a brief review of the most promising ones is presented. Then we illustrate how specific technologies can be applied in the design of a novel manipulator for flexible surgery by discussing its potential and by presenting feasibility tests of a prototype responding to this new design philosophy. Our aim is to investigate the feasibility of applying these technologies in the field of minimally invasive surgery and at the same time to stimulate the creativeness of others who could take the proposed concepts further to achieve novel solutions and generate specific application scenarios for the devised technologies.
This paper presents the concept design, the fabrication and the experimental characterization of ... more This paper presents the concept design, the fabrication and the experimental characterization of a unit of a modular manipulator for minimal access surgery. Traditional surgical manipulators are usually based on metallic steerable needles, tendon driven mechanisms or articulated motorized links. In this work the main idea is to combine flexible fluidic actuators enabling omnidirectional bending and elongation capability and the granular jamming phenomenon to implement a selective stiffness changing. The proposed manipulator is based on a series of identical modules, each one consisting of a silicone tube with pneumatic chambers for allowing 3D motion and one central channel for the implementation of the granular jamming phenomenon for stiffening. The silicone is covered by a novel bellows-shaped braided structure maximizing the bending still limiting lateral expansion. In this paper one single module is tested in terms of bending range, elongation capability, generated forces and stiffness changing.
Steerable instruments are a promising trend in minimally invasive surgery (MIS), due to their man... more Steerable instruments are a promising trend in minimally invasive surgery (MIS), due to their manoeuvring capabilities enabling reaching over obstacles. Despite the great number of steerable joint designs, currently available steerable tips tend to be vulnerable to external loading, thus featuring low bending stiffness. This work aims to provide empirical evidence that the bending stiffness can be considerably increased by using fully actuated joint constructions, enabling left/right and up/down tip rotations with the minimum of two degrees of freedom (DOF), rather than conventional underactuated constructions enabling these rotations with more than two DOF. A steerable MIS instrument prototype with a fully actuated joint construction was compared to state-of-the-art underactuated steerable instruments in a number of tip deflection experiments. The tip deflections due to loading were measured by means of a universal testing machine in four bending scenarios: straight and bent over 20°, 40° and 60°. The experimental results support the claim that a fully actuated joint construction exhibits a significantly larger bending stiffness than an underactuated joint construction. Furthermore, it was shown that the underactuated instrument tips show a considerable difference between their neutral positions before and after loading, which could also be greatly minimised by full actuation.
Soft robotics for medical, endoscopic applications requires a dexterous and compliant mechanism t... more Soft robotics for medical, endoscopic applications requires a dexterous and compliant mechanism to increase accessibility and decrease patient injury. However, soft structures do not offer the level of image and platform stability provided by rigid structures. Thus, a variable stiffness mechanism is an ideal solution to reconcile the two requirements of compliance and stability; the mechanism explored here is granular jamming. Granular jamming is a phenomenon where particulate matter within a membrane can transition from a fluid-like to a solid-like state, based on the level of applied vacuum pressure. In the solid-like jammed state, the conventional assumption is made that granule-granule contacts dominantly contribute to the system's stiffness. Thus, many works have evaluated the effects of different granule types by experimentally varying the sizes, shapes, and material properties of the particles. However, the role of the membrane in determining the possible range of stiffness or the variability of granular jamming has not been well studied. This paper investigates the effects and significance of membranes for a granular jamming system. Several membranes were experimentally tested and analyzed in order to find the amount of flexibility and stiffness they provide when the system is in an unjammed and jammed state, respectively. This paper presents for the first time that the membrane plays a significant contributing factor in granular jamming stiffness.
This paper introduces a novel, bioinspired manipulator for minimally invasive surgery (MIS). The ... more This paper introduces a novel, bioinspired manipulator for minimally invasive surgery (MIS). The manipulator is entirely composed of soft materials, and it has been designed to provide similar motion capabilities as the octopus's arm in order to reach the surgical target while exploiting its whole length to actively interact with the biological structures. The manipulator is composed of two identical modules (each of them can be controlled independently) with multi-directional bending and stiffening capabilities, like an octopus arm. In the authors' previous works, the design of the single module has been addressed. Here a two-module manipulator is presented, with the final aim of demonstrating the enhanced capabilities that such a structure can have in comparison with rigid surgical tools currently employed in MIS. The performances in terms of workspace, stiffening capabilities, and generated forces are characterized through experimental tests. The combination of stiffening capabilities and manipulation tasks is also addressed to confirm the manipulator potential employment in a real surgical scenario.
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Papers by Giada Gerboni