Force Sensor Drum Lever Transmission for Surgical Feedback
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Solution Overview
Problem
Current force sensors for measuring small forces applied to biological tissues, such as those in middle ear surgery, lack objective feedback on displacement, relying on subjective surgeon assessment due to forces and displacements being near human capabilities limits.
Innovation Solution
A sensor system with a frame supporting a force-sensing tip, an input drum, and an output lever connected via a mechanical transmission, allowing precise displacement of the tip to measure resistance, providing objective feedback on force and displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is used to measure small forces applied to biological tissues, then force measurement capability is improved, but displacement measurement information is lost
Solution Approach 1:
The device segments the measurement function into two independent parts: a force sensor for measuring applied forces and a separate displacement sensor (encoder) for measuring drum rotation. This segmentation allows each sensor to optimize for its specific measurement type while providing complete biomechanical data
Solution Approach 2:
The mechanical transmission system acts as an intermediary that couples the drum rotation to the force sensor tip displacement. The encoder measures the intermediary drum rotation parameter, which is then mathematically related to the tip displacement through the known mechanical transmission ratio
2Ease of operation
If manual palpation is used to assess ossicle mobility, then surgical simplicity is maintained, but measurement objectivity deteriorates
Solution Approach 1:
The device provides real-time quantitative feedback through digital display of both force (in mN) and displacement (in µm) measurements during palpation. This objective feedback replaces subjective surgeon perception with precise numerical data, enabling accurate assessment of ossicle mobility while maintaining the simplicity of manual palpation technique
Solution Approach 2:
The patent replaces the purely mechanical/sensory assessment system with an instrumented system that uses sensors and electronic processing. The mechanical palpation action remains simple, but the assessment mechanism is substituted from human sensation to electronic sensing and digital display
3Measurement precision
If displacement range is increased to improve measurement capability, then measurement range is improved, but human perception capability becomes insufficient
Solution Approach 1:
The encoder on the drum serves as an intermediary measurement device that can accurately measure rotations corresponding to very small tip displacements (several microns). This intermediary measurement is then translated to the actual tip displacement through the mechanical transmission ratio, extending measurement capability beyond human perception limits
Data Source
AI summary
Sensor system comprising a frame supporting a force-sensing tip arranged to generate a signal based upon a force applied by said force-sensing tip to a material to be tested, the system further comprising:an input drum mounted in said frame such that it can rotate about an input axis of rotation;an output lever supported by said frame by means of an output revolute joint defining an output axis of rotation;wherein said force-sensing tip is mounted on said output lever such that said force-sensing tip is arranged to be brought into contact with a material to be tested;and wherein said sensor system comprises a mechanical transmission arranged to kinematically link said input drum to said output lever such that a rotation of said input drum about said input axis of rotation causes said output lever to pivot in an oscillatory manner about said output axis of rotation.