Masakatsu G. Fujie

NeuRobot: Telecontrolled Micromanipulator System for Minimally Invasive Microneurosurgery—Preliminary Results

OBJECTIVE Microneurosurgery can be performed less invasively with the recent advances in neuronavigation and neuroendoscopy. For even less invasive microneurosurgery, we have developed a telecontrolled micromanipulator system. METHODS The NeuRobot telecontrolled micromanipulator system was developed. With the use of this system, surgical simulations were performed with a human cadaveric head. RESULTS The system consists of four main parts, i.e., a micromanipulator (slave manipulator), a manipulator-supporting device, an operation-input device (master manipulator), and a three-dimensional display monitor. Three 1-mm forceps and a three-dimensional endoscope, which could be remotely controlled with three degrees of freedom (rotation, neck swinging, and forward/backward motion), were installed in the slave manipulator. All surgical procedures were accurately performed with this system. CONCLUSION The use of telecontrolled manipulator systems in neurosurgery is very promising, and we are convinced that this system will facilitate more accurate, less invasive microneurosurgery. The details of the NeuRobot system and preliminary results are presented.

Integration of a Miniaturised Triaxial Force Sensor in a Minimally Invasive Surgical Tool

This paper reports preliminary results on design and fabrication of a cutting tool with an integrated triaxial force sensor to be applied in fetal surgery procedures. The outer diameter of the proposed device is 7.4 mm, but a scaled down design can be easily achieved. Linearity and hysteresis tests have been performed for both normal and tangential loadings. A linear transformation relating the sensor output to the external applied force is introduced and discussed. The typical working range for the conceived instrument is around 0.3 N, while 20 N and 1 N are, respectively, maximum normal and tangential forces for which the device robustness has been assessed

Micro Manipulators for Intrauterine Fetal Surgery in an Open MRI

We propose a new surgical robotic system for intrauterine fetal surgery in an Open MRI. The target disease of the fetal surgery is spina bifida or myelomeningocele that is incomplete closure in the spinal column and one of the common fetal diseases. In the proposed surgical process, the abdominal wall and uterine wall would not widely be opened but rather surgical instruments inserted through the small holes in both walls to perform minimally invasive surgery. In this paper, a prototype of the micro manipulator of diameter is 2.4mm and bending radius 2.45 mm is presented. The diameter and bending radius of this manipulator is one of the smallest ever developed among surgical robots to the best of the knowledge of the investigating authors. The mechanism of the manipulator includes two ball joints and is driven using four wires able to bend through 90 degrees in any direction. The features of the mechanism include a small diameter, small bending radius, ease of fabrication, high rigidity and applicability for other surgical applications. Although the manipulator is not yet MRI compatible, the feature of the prototype demonstrated the feasibility of robotic intrauterine fetal surgery.

Physical Properties of the Liver and the Development of an Intelligent Manipulator for Needle Insertion

Medical procedures such as RFA and cryosurgery require the insertion of a needle into the target area within the body. Needle insertion is difficult because it can easily result in organs being deformed and displaced. This research aims to produce an intelligent robot for needle insertion, incorporating the following three techniques, A: visual feedback B: organ-model base control C: force control. This research uses a robot model and a liver for the target object to evaluate organ-model base control. For the purpose of organ-model base control, three experiments were conducted to evaluate the physical properties of the liver for robot control. A dynamic viscoelastic test was then carried out to show the dynamic properties of the liver in the form of a differential equation. The nonlinearity of the liver was supported by the creep test while an axial needle insertion test was also carried out to model the force and the extent of deformation experienced during needle insertion. In addition, an intelligent needle insertion robot was developed for the purpose of the experimentation concerning intelligent control of the needle. The experimental result displayed the margin error between the needle tip and target marker when the needle reaches the target position was around 1[mm] and a result led to positive findings.

Development of an integrated needle insertion system with image guidance and deformation simulation

OBJECTIVE The purpose of our work was to develop an integrated system with image guidance and deformation simulation for the purpose of accurate needle insertion. METHODS We designed an ultrasound-guided needle insertion manipulator and physical model to simulate liver deformation. We carried out an in vivo experiment using a porcine liver to verify the effectiveness of our manipulator and model. RESULTS The results of the in vivo experiment showed that the needle insertion manipulator accurately positions the needle tip into the target. The experimental results also showed that the liver model accurately reproduces the nonlinear increase of force upon the needle during insertion. DISCUSSION Based on these results, it is suggested that the needle insertion manipulator and the physical liver model developed and validated in this work are effective for accurate needle insertion.

Physical properties of the liver for needle insertion control

Medical procedures such as RFA and cryosurgery require inserting a needle into the target location inside the body. Needle insertion is difficult because it is easy for organs to be deformed and displaced. Modeling the target object is essential in analyzing and developing a control system. Thus, a precise model is required to develop an intelligent robot that is able to insert the needle into the target area. This research uses a robot model and a liver for the target object. Four experiments were conducted to show the physical properties of the liver for robot control. A dynamic viscoelastic test was carried out to show the dynamic properties of the liver as a differential equation. The nonlinearity of the liver was supported by the creep test. In addition, the liver model was validated using a constant strain rate test. A needle insertion test was also carried out to validate the model.

A Haptic Interface “Force Blinker 2” for Navigation of the Visually Impaired

In this paper, we develop a new haptic interface called “Force Blinker 2” to navigate the visually impaired. In Force Blinker 2, rotating weights and repulsive magnets are used to reduce the force generated in the opposite direction to the traveling direction, which caused false recognition in the previous system, “Force Blinker 1.” In Force Blinker 2 [diameter: 30 (mm), weight: 365 (g)], based on the balance of the centrifugal force of the weight and repulsive force of permanent magnets, the rotational radius of the weight varies depending on the velocity of the rotational weight. First, from a mechanical and control performance perspective, it has been confirmed using an encoder and high-speed camera that the rotational angle, velocity, and weight position are well controlled. Second, ten visually impaired subjects evaluated Force Blinker 2 by comparing it with Force Blinker 1, a fixed radius type interface. The directions presented by Force Blinker 2 were correctly recognized at a rate of approximately 85%, which is about a 10% improvement over the rate achieved by Force Blinker 1. This means the effect of decreasing the force in the opposite direction to the traveling direction on recognition thereof yields about a 10% improvement in recognition performance. In the future, we intend to integrate a route decision system with a cane containing the built-in haptic interface.

Modeling of friction force based on relative velocity between liver tissue and needle for needle insertion simulation

Needle insertion treatments require accurate placement of the needle tip into the target cancer. However, it is difficult to insert the needle into the cancer because of cancer displacement due to the organ deformation. Then, a path planning using needle insertion simulation to analyze the deformation of the organ is important for the accurate needle insertion. A frictional model for needle insertion simulation is presented in this report. In particular, we focus on a model of frictional force based on the relative velocity between the needle and liver tissue ranging from hyper slow velocity. First, in vitro experiments using hog liver were performed at several relative velocities in order to measure the velocity dependence of the frictional force. Several needle insertion experiments were performed under identical conditions in order to deal with the variance of experimental data. The 60 frictional force data were used to obtain average data at each relative velocity. Second, the model of frictional force was developed using the averages of the experimental results. This model is defined according to the relative velocity ranging from hyper slow velocity. Finally, an evaluation experiment was carried out. The data obtained by the evaluation experiment reveals that the frictional force changes according to the relative velocity between the needle and liver tissue. The experimental results support the validity of proposed model of frictional force.

Bending Laser Manipulator for Intrauterine Surgery and Viscoelastic Model of Fetal Rat Tissue

A bending laser manipulator of 2.4 mm in diameter has been developed for intrauterine fetal surgery. This manipulator deflects a laser fiber in any direction thorough 90 degrees. The results of a positioning test and in vitro/in vivo tests are reported. Meanwhile, creep tests for fetal rat tissue of 16 to 20 days in gestation were performed to evaluate fetal tissue fragility. Unique features of fetal rat tissue compared to other soft organs are discussed and a viscoelastic model of the fetal rat tissue was proposed. The result of the modeling will be used not only for fabricating fetal tissue phantom but also for the force control of robotic application for fetal surgery.

Development of a needle insertion manipulator for central venous catheterization.

Central venous catheterization is a procedure in which a doctor inserts a catheter into a patients vein for transfusions. Risks of this procedure include bleeding from the puncture of blood vessels and pneumothorax caused by pleural puncture. To avoid these and other risks, physicians are required to ensure that the needle is inserted securely and that it stops within the vein.