Fluidic Tip Actuation for Concentric Tubes in MRI Surgery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing surgical interventions for epilepsy, such as Laser Interstitial Thermal Therapy (LITT), face challenges in effectively ablating the naturally curved hippocampus due to the mismatch between the straight trajectory of the procedure and the curved structure, leading to limited ablation coverage and lower seizure freedom rates. Additionally, performing surgeries within MRI scanners is hindered by issues like tube buckling, torsional windup, and increased device length, which are exacerbated by the intense magnetic fields and limited workspace.
Innovation Solution
A robotic surgical system employing a direct drive actuation system for concentric tube manipulators, utilizing flexible fluidic actuators (FFAs) to directly manipulate tubes near their tips, eliminating unsupported lengths and reducing the risk of buckling and torsional windup, while maintaining a compact design suitable for MRI environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional concentric tube actuation units operate on the principle of manipulating tubes at their base, then the device can be simpler in structure, but the unsupported tube length increases leading to greater risk of buckling and torsional windup
Solution Approach 1:
The patent inverts the traditional actuation approach by moving the actuation point from the tube base to the tube tip. The actuator unit is positioned at the distal end of the manipulator and directly manipulates the tube tips, reversing the conventional wisdom and eliminating the unsupported tube length that causes buckling and torsional windup.
Solution Approach 2:
The patent extracts and eliminates the transmission tube component from the system. By directly actuating the tubes at their tips without intermediary transmission structures, the design removes the source of frictional interaction forces and unsupported lengths, thereby reducing buckling risk while maintaining structural simplicity.
2Reliability
If the actuation unit directly manipulates tubes near their tips, then the risk of buckling and torsional windup is reduced, but the device length increases
Solution Approach 1:
The patent employs a nested configuration where the actuator is positioned within the distal end of the manipulator structure, and the tube tips extend through the actuation unit. This nesting allows the actuation functionality to be integrated into the existing manipulator geometry, minimizing additional length while enabling direct tip manipulation.
3Length of moving object
If conventional actuation methods with lead screws and transmission tubes are used, then the device can be more compact, but the unsupported tube length increases leading to increased frictional interaction forces and buckling risk
Solution Approach 1:
The patent removes lead screws and transmission tubes from the actuation system, replacing them with a direct drive mechanism at the tube tips. This extraction eliminates the frictional interaction forces between tubes and transmission structures, reducing the force required for actuation while maintaining compact dimensions.
4Area of stationary object
If MRI scanner workspace constraints are considered, then the device must be more compact, but this limits the ability to implement direct tip actuation
Solution Approach 1:
The actuation unit is nested within the distal portion of the manipulator, with the actuator positioned inside the hollow structure of the manipulator shaft. This nested arrangement minimizes the external footprint and allows the device to fit within the constrained MRI scanner workspace while still enabling direct tip actuation through the distal opening.
Solution Approach 2:
The patent transitions from proximal actuation (along the length of the tubes) to distal actuation (at the tube tips), utilizing the spatial dimension at the distal end of the manipulator. This dimensional shift allows direct tip manipulation without requiring additional proximal space, accommodating the limited MRI workspace.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables minimally invasive, accurate, and effective ablation of the hippocampus under MRI guidance, reducing device length and overcoming space constraints, thereby enhancing seizure freedom rates and improving surgical precision.
Implementation Method 1
The actuator bellows are fluidly actuatable to move the gripper in response to fluid pressure
Data Source
AI summary
A flexible fluidic actuator for robotically imparting translational or rotational motion to a tube of a concentric tube manipulator, the flexible fluidic actuator includes a gripper that is actuatable in response to fluid pressure to grasp the tube, and de-actuatable in response to relieving fluid pressure to release the tube. The flexible fluidic actuator also includes one or more actuator bellows that are actuatable in response to fluid pressure to move the gripper to an actuated position, and de-actuatable in response to releasing fluid pressure to return the gripper to a de-actuated position. The gripper is configured to move to the actuated position in a first translational or rotational direction, and to move to the de-actuated position in a second translational or rotational direction, opposite the first translational or rotational direction. The one or more actuator bellows are arranged on an actuator frame and configured to support the gripper, and wherein the flexible fluidic actuator is configured so that the frame, actuator bellows, and gripper occupy the same axial length.