Forceps Construction With Isolated FBG Sensing for Jaw Forces
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Solution Overview
Problem
Existing surgical instruments for minimally invasive surgery face challenges in accurately determining the force exerted on jaw elements due to interference from multiple strain sensors and complex measurement systems, leading to inaccurate force feedback.
Innovation Solution
A forceps construction with a strain element between extensions, featuring a strain sensor isolated from other forces, uses Fibre Bragg Gratings (FBGs) to measure bending-induced strain accurately, eliminating the need for additional sensors and simplifying the measurement process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple strain sensors are mounted on the forceps frame to measure bending forces, then force measurement capability is improved, but measurement precision deteriorates due to interference from other forces
Solution Approach 1:
The patent extracts the force measurement function from multiple distributed strain sensors and concentrates it into a single strain sensor mounted on a specific location (the slot between the first and second extensions). This location was specifically chosen because it experiences minimal interference from other forces, thereby extracting only the relevant bending force information while eliminating measurement interference from actuation forces.
Solution Approach 2:
The slot between the first and second extensions acts as an intermediary structure that isolates the strain measurement location from interfering forces. By mounting the strain sensor on this slot rather than directly on the extensions or jaw elements, the system mediates between the complex force environment and the measurement requirement, allowing accurate force detection without direct exposure to actuation forces.
2Reliability
If strain sensors are mounted at the end of the slot between extensions to measure bending, then force detection capability is improved, but measurement precision deteriorates due to interference from pulling and pushing forces
Solution Approach 1:
The patent converts the potentially harmful effect of force interference into a beneficial measurement location characteristic. By carefully selecting the slot location between extensions, the design ensures that while some forces are present, the specific bending forces of interest are predominantly measured while other forces (pulling/pushing from actuation) are minimized. The slot structure itself becomes advantageous by providing a measurement point that is relatively isolated from the main actuation force paths.
3Measurement precision
If multiple strain sensors are used to compensate for force interference, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the force measurement function from a complex multi-sensor system and concentrates it into a single strain sensor located at the slot between extensions. This extraction eliminates the need for multiple sensors and the complex signal processing required to differentiate between various force components, thereby simplifying the measurement system while maintaining accuracy.
Solution Approach 2:
The single strain sensor mounted on the slot serves multiple functions: it measures bending forces, automatically compensates for actuation forces through its strategic location, and provides reliable force feedback without requiring additional sensors or complex calculation algorithms. This universal measurement point replaces what would otherwise require multiple specialized sensors.
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
This design allows for precise determination of forces on jaw elements, providing reliable and simplified force feedback without interference from other forces, enhancing the accuracy of tissue manipulation in minimally invasive surgery.
Implementation Method 1
uses Fibre Bragg Gratings (FBGs) to measure bending-induced strain accurately
Implementation Method 2
measuring this bending of the first extension and/or the second extension, the force exerted on the first jaw element and/or second jaw element may be measured
Data Source
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AI summary
The invention relates to a surgical instrument, for example a surgical instrument for minimally invasive surgery, comprising: an elongate frame, at least one jaw element mounted movably at a distal end of the elongate frame, a trigger device to operate the at least one jaw element and arranged at a proximal end of the elongate frame, an actuation rod provided between the trigger device and the at least one jaw element, a sensor to provide a sensor signal representative for a force exerted on the at least one jaw element, and an actuator to exert a feedback force on the trigger device on the basis of the sensor signal, wherein the elongate frame comprises a handle part and a shaft, wherein the trigger device and the actuator are mounted on the handle part and the at least one jaw element is mounted on the shaft.