Surgical Grasper Research Articles

Shape Deposition Manufacturing of a Soft, Atraumatic, and Deployable Surgical Grasper

This paper details the design, analysis, fabrication, and validation of a deployable, atraumatic grasper intended for retraction and manipulation tasks in manual and robotic minimally invasive surgical (MIS) procedures. Fabricated using a combination of shape deposition manufacturing (SDM) and 3D printing, the device (which acts as a deployable end-effector for robotic platforms) has the potential to reduce the risk of intraoperative hemorrhage by providing a soft, compliant interface between delicate tissue structures and the metal laparoscopic forceps and graspers that are currently used to manipulate and retract these structures on an ad hoc basis. This paper introduces a general analytical framework for designing SDM fingers where the desire is to predict the shape and the transmission ratio, and this framework was used to design a multijointed grasper that relies on geometric trapping to manipulate tissue, rather than friction or pinching, to provide a safe, stable, adaptive, and conformable means for manipulation. Passive structural compliance, coupled with active grip force monitoring enabled by embedded pressure sensors, helps to reduce the cognitive load on the surgeon. Initial manipulation tasks in a simulated environment have demonstrated that the device can be deployed though a 15 mm trocar and develop a stable grasp using Intuitive Surgical's daVinci robotic platform to deftly manipulate a tissue analog.

Evaluation of liver tissue damage and grasp stability using finite element analysis

Minimizing tissue damage and maintaining grasp stability are essential considerations in surgical grasper design. Most past and current research analyzing graspers used for tissue manipulation in minimally invasive surgery is based on in vitro experiments. Most previous work assessed tissue injury and grasp security by visual inspection; only a few studies have quantified it. The goal of the present work is to develop a methodology with which to compute tissue damage magnitude and grasp quality that is appropriate for a wide range of grasper–tissue interaction. Using finite element analysis (FEA), four graspers with varying radii of curvature and four graspers with different tooth sizes were analyzed while squeezing and pulling liver tissue. All graspers were treated as surgical steel with linear elastic material properties. Nonlinear material properties of tissue used in the FEA as well as damage evaluation were derived from previously reported in vivo experiments. Computed peak stress, integrated stress, and tissue damage were compared. Applied displacement is vertical and then horizontal to the tissue surface to represent grasp and retraction. A close examination of the contact status of each node within the grasper–tissue interaction surface was carried out to investigate grasp stability. The results indicate less tissue damage with increasing radius of curvature. A smooth wave pattern reduced tissue damage at the cost of inducing higher percentage of slipping area. This methodology may be useful for researchers to develop and test various designs of graspers. Also it could improve surgical simulator performance by reflecting more realistic tissue material properties and predicting tissue damage for the student.

Mastering instruments before operating on a patient: the role of simulation training in tool use skills.

We examined the impact of tool complexity on surgeons' performance and evaluated the value of using a simulation-based program for reducing training cost. Three pairs of surgical graspers with increasing mechanical complexity, which were designed for open, laparoscopic, and endoscopic procedures, were used in performing a simple object transportation task. Task times and mental workload of 17 surgeons were compared using all 3 variations of the graspers to test the impact of tool complexity on surgical performance. Subsequently, 4 of these surgeons decided to enter a 3-week training phase and practiced with these 3 surgical instruments on a daily basis. Learning curves were plotted to examine the value of using simulation for proficiency training with these tools. Task time was significantly prolonged as tool complexity increased. Practice in a simulated environment shortened the task time significantly and moderately reduced mental workloads. However, the difference in task time varied among the 3 types of tools. Between days 1 and 9, task times for each types of grasper were reduced by 55% (endoscopic), 42% (open), and 22% (laparoscopic). Tool complexity may degrade a surgeon's performance. Extensive simulation training programs are important for surgeons to gain proficiency in handling a tool before they practice on patients.

Spring-based tactile array for assistive robotic surgical applications

Tactile sensing is highly desirable for robotic surgery, more specifically minimally invasive surgery, during tissue/organ manipulation. For safe handling and safe grasping of tissues, the two most important aspects are the monitoring and controlling of force and the stiffness information that exists at the sensor-tissue interface. In this study, a spring-based tactile sensing system is used to measure both the interacting forces and stiffness in surgical assistive applications. A differential analysis is performed to obtain the stiffness of a compliant object whilst individual elements of the proposed sensing array experience different deflections when they come in contact with the object. A lumped model formulation for tactile array performance shows that larger differences in stiffness between the force sensing elements provide higher sensitivity in evaluating the object stiffness. For benchmarking of our sensing principle, a macro tactile-sensor array is designed and tested. Different stiffness combinations of the sensing elements show an inverse linear relationship between the stiffness of the object and the output signal magnitude of the stiffness sensing unit. The proposed tactile array based on spring-based stiffness sensing has high potential for safe grasping/handling of the tissues when integrated into the jaws of a surgical grasper during the minimally invasive robotic procedures.

Output control of da Vinci surgical system's surgical graspers

IntroductionThe number of robot-assisted surgeries performed with the da Vinci surgical system has increased significantly over the past decade. The articulating movements of the robotic surgical grasper are controlled by grip controls at the master console. The user interface has been implicated as one contributing factor in surgical grasping errors. The goal of our study was to characterize and evaluate the user interface of the da Vinci surgical system in controlling surgical graspers. Materials and methodsAn angular manipulator with force sensors was used to increment the grip control angle as grasper output angles were measured. Input force at the grip control was simultaneously measured throughout the range of motion. Pressure film was used to assess the maximum grasping force achievable with the endoscopic grasping tool. ResultsThe da Vinci robot's grip control angular input has a nonproportional relationship with the grasper instrument output. The grip control mechanism presents an intrinsic resistant force to the surgeon's fingertips and provides no haptic feedback. The da Vinci Maryland graspers are capable of applying up to 5.1 MPa of local pressure. ConclusionsThe angular and force input at the grip control of the da Vinci robot's surgical graspers is nonproportional to the grasper instrument's output. Understanding the true relationship of the grip control input to grasper instrument output may help surgeons understand how to better control the surgical graspers and promote fewer grasping errors.

Quantifying Forces at the Tool-Tissue Interface of a Surgical Laparoscopic Grasper

Quantifying Forces at the Tool-Tissue Interface of a Surgical Laparoscopic Grasper

Experimental Analysis of Jaw-Tissue Interaction Forces Using a Compliant Surgical Grasper

Experimental Analysis of Jaw-Tissue Interaction Forces Using a Compliant Surgical Grasper

Design of an Atraumatic Compliant Surgical Grasper

Design of an Atraumatic Compliant Surgical Grasper

Determination of tissue properties using microfabricated piezoelectric tactile sensor during minimally invasive surgery

PurposeThe purpose of this paper is to present the design, analysis, fabrication, and assembly of four tooth annular microfabricated tactile sensors integrated with the upper and lower jaws of an endoscopic surgical grasper tool, in order to determine the properties and particularly the compliance of the biological tissues during minimally invasive surgery.Design/methodology/approachA viscoelastic Kelvin model is employed for tissue characterization. A comprehensive closed form and finite element analysis has been carried out to express the relationship between the force ratio, compliance, and the equivalent viscous damping of the tissue. The designed sensor uses a polyvinyledene fluoride film as its sensing element. The sensor consists of arrays of rigid and compliant elements which are mounted on the tip of an endoscopic surgical grasper tool. Relative force between adjacent parts of the contact object is used to measure the viscoelastic properties.FindingsThe tactile sensor is able to characterize different viscoelastic properties of tissues. The experiments validate analytical and finite elements results.Practical implicationsThe sensor is designed to integrate with the actual endoscopic tools to measure the softness of tissues.Originality/valueA novel sensor‐tissue model is presented to characterize the variety of biological tissues.

Using Global Implicit Measurement Strategies to Assess Situation Awareness during the Training of Laparoscopic Surgical Skills

How well does a global implicit measure assess situation awareness in an elementary laparoscopic training scenario? Nine volunteers threaded as many orange, purple, and blue foam rings as possible onto a pegboard during 2-minute trials. They used a pair of 5mm laparoscopic surgical graspers in an endoscopy training simulator to perform the task. Ring sizes were identical for all colors in the first three trials but were of different inner diameters for the remaining six trials. This switch was never mentioned to participants. Workload measures were collected for each trial and included a subjective measure (NASA-TLX) and a secondary-task method (interval productions). Results indicated that interval productions, but not the NASA-TLX, showed evidence of a workload spike at the time that situation awareness was first manifested in performance. These preliminary data suggest that a global implicit measure can be used for evaluating SA in a relatively simple environment.

Design and analysis of a micromachined piezoelectric sensor for measuring the viscoelasticproperties of tissues in minimally invasive surgery

In this paper, the design, analysis and fabrication of a micromachined piezoelectricendoscopic tactile sensor to determine the properties of tissues in minimally invasivesurgery is presented. The viscoelastic Kelvin model is employed for tissue characterization.A closed form expression is derived to express the relationship between the force ratio,compliance and the equivalent viscous damping of the tissue. The designed sensor uses aPVDF film as its sensing element. The sensor consists of rigid and compliant elementswhich are mounted on the tip of an endoscopic surgical grasper tool. The relative forcebetween adjacent parts of the contact object is used to measure the viscoelastic propertiesexperimentally.

The Aperture Illusion can Occur with “3-D” Displays and Active Control: Implications for Minimally-Invasive Surgery

When a moving contour is viewed through a circular aperture, observers misperceive the contour's direction of motion. This aperture illusion is relevant to minimally-invasive surgery because surgeons view anatomical tissues through a reduced field-of-view. In prior studies of the illusion, observers passively viewed simple computer-generated displays of moving lines. Here, it is demonstrated that the illusion can occur with displays created with a 3-D laparoscopic simulator, and when participants actively control the movement of a surgical grasper. However, the illusion was smaller with active control than with passive viewing, and was smaller with a rectangular aperture than with a circle or octagon. The implication is that navigation during MIS may improve when surgeons (rather than assistants) actively control the camera, and when the aperture that frames the laparoscopic image is rectangular. Future studies of this kind will improve the design of image-guided technologies and reduce complications during MIS.

Improving the retention of suturing needles in surgical graspers

Improving the retention of suturing needles in surgical graspers

Improving the retention of suturing needles in surgical graspers

Surgical needles are usually held using dedicated grasping instruments. When the tissue to be penetrated is resilient, or the grasping force is low, the needle can swivel, causing it to deviate from the intended path, resulting in suboptimal tissue approximation. Needle swivel is particularly prevalent when needles are not held transversely in the jaws, but it is difficult to maintain a transverse grasp during surgery. An improved swivel-resistant grasper design is proposed. Conventional and swivel-resistant graspers were tested to quantify the benefits of the swivel-resistant design. Needles secured in the grasper were repeatedly distracted until swiveling occurred. The torque required to swivel the needles was statistically analyzed. The swivel-resistant grasper offers greatly improved resistance to swivel (p = 0.01) when the needle is not held transversely. The four-point contact afforded by the modified needle graspers imparts improved needle retention and resistance to swivel.

Force controlled and teleoperated endoscopic grasper for minimally invasive surgery--experimental performance evaluation.

Minimally invasive surgery generates new user interfaces which create visual and haptic distortion when compared to traditional surgery. In order to regain the tactile and kinesthetic information that is lost, a computerized force feedback endoscopic surgical grasper (FREG) was developed with computer control and a haptic user interface. The system uses standard unmodified grasper shafts and tips. The FREG can control grasping forces either by surgeon teleoperation control, or under software control. The FREG performance was evaluated using an automated palpation function (programmed series of compressions) in which the grasper measures mechanical properties of the grasped materials. The material parameters obtained from measurements showed the ability of the FREG to discriminate between different types of normal soft tissues (small bowel, lung, spleen, liver, colon, and stomach) and different kinds of artificial soft tissue replication materials (latex/silicone) for simulation purposes. In addition, subjective tests of ranking stiffness of silicone materials using the FREG teleoperation mode showed significant improvement in the performance compared to the standard endoscopic grasper. Moreover, the FREG performance was closer to the performance of the human hand than the standard endoscopic grasper. The FREG as a tool incorporating the force feedback teleoperation technology may provide the basis for application in telesurgery, clinical endoscopic surgery, surgical training, and research.

Computerized endoscopic surgical grasper.

We report a computerized endoscopic surgical grasper with computer control and a force feedback (haptic) user interface. The system uses standard unmodified grasper shafts and tips. The device can control grasping forces either by direct surgeon control, via teleoperation, or under software control. In this paper, we test an automated palpation function in which the grasper measures mechanical properties of the grasped tissue by applying a programmed series of squeezes. Experimental results show the ability to discriminate between the normal tissues of small bowel, lung, spleen, liver, colon, and stomach. We anticipate applications in telesurgery, clinical endoscopic surgery, surgical training, and research.