Hydraulic Surgical Tool Actuation with Fluid-Coupled Branches
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Solution Overview
Problem
Surgical tools used in minimally invasive surgery lack effective force feedback, leading to tissue damage from excessive force and tiring work due to mechanical transmission inefficiencies and complex, costly hydraulic systems with high friction losses.
Innovation Solution
A surgical tool with hydraulically actuatable, pivotally connected branches forming a fluid-tight cavity, where the pivoting position and fluid volume are operatively coupled, allowing direct pressure transmission without gears or levers, using an incompressible fluid for efficient power transfer and minimizing friction losses, and a balloon for sealing and force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical transmission with gears and Bowden cables is used, then force feedback can be provided to the operator, but frictional losses make the instrument stiff and require more operating force
Solution Approach 1:
The patent replaces the mechanical transmission system (gears, Bowden cables) with a hydraulic transmission system. The hydraulic actuator converts electrical signals to hydraulic motion, which directly actuates the surgical tool without mechanical intermediaries. This eliminates frictional losses in mechanical components while maintaining force feedback through the hydraulic fluid's incompressibility and direct force transmission to the actuator.
2Loss of energy
If hydraulic actuation with piston-cylinder arrangement is used, then power transmission losses are reduced, but many lines must be routed through the shaft increasing overall size
Solution Approach 1:
The patent extracts the piston-cylinder arrangement from the instrument shaft and places it in the handle. Only essential hydraulic connections (fluid supply and return lines) need to be routed through the shaft, significantly reducing the number of lines compared to routing multiple control lines for each surgical tool. This reduces the shaft's overall size while maintaining efficient power transmission.
Solution Approach 2:
The patent uses a hydraulic fluid as an intermediary to transmit power from the actuator in the handle to the surgical tool at the distal end. This fluid mediator allows power transmission without requiring multiple mechanical control lines through the shaft, reducing the instrument's overall size while maintaining low power transmission losses.
3Adaptability or versatility
If complex hydraulic systems with multiple connections and piston seals are used, then surgical tools can be hydraulically actuated, but the risk of leaks increases
Solution Approach 1:
The patent extracts the complex piston-seal arrangements and multiple hydraulic connections from the surgical tool and concentrates them in the handle's actuator. The surgical tool itself receives simplified hydraulic actuation with fewer connection points, reducing the overall number of potential leak sources in the system.
Solution Approach 2:
The patent merges multiple hydraulic functions into a single integrated actuator system in the handle. Instead of having separate hydraulic circuits for each surgical tool, the system uses a centralized hydraulic power unit that supplies fluid to multiple tools through a reduced number of connections, thereby reducing the total number of seals and potential leak points.
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
Enables improved force feedback and reduced operating forces, with fewer and less expensive parts, reducing the risk of leaks and tissue damage, while maintaining precise control and sensitivity.
Implementation Method 1
using an incompressible fluid for efficient power transfer and minimizing friction losses
Implementation Method 2
a balloon for sealing and force application
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
The present invention discloses an actuation method for a surgical instrument (14) and the instrument (14) itself, which has a proximal coupling section (145) from which two hydraulically actuated, pivotably connected branches (141') extend. The branches each have an active section (141) at least at their distal ends and form a boundary within the coupling section (145) for at least a portion of a fluid-tight, fluid-fillable cavity (15). A pivot position of the branches (141') and a volume of fluid in the cavity (15) are operationally coupled.Furthermore, an actuation method for a microsurgical tool (1) and the microsurgical tool (1) are disclosed, which has a proximal handle (11) with an actuating device (12) and a distally arranged hydraulically actuated surgical tool (14) according to the invention, which is connected to the handle by a shaft and can be actuated by means of the actuating device (12).