Sarrus Linkage Force Sensor for Endoscope Distal Feedback
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Solution Overview
Problem
Developing cost-effective, mm-scale end-effector solutions for surgical robotics that incorporate robust distal sensing modalities is challenging due to limitations in conventional manufacturing approaches and the need for optical fiber-based force sensing systems, which occupy valuable space and require expensive interrogators.
Innovation Solution
A light-intensity-based force sensor using a Sarrus linkage, biasing mechanism, and encapsulated infrared light emitter and detector, which self-assembles into a compact 3 mm orthogonal dimensions, allowing for distal integration in catheters and endoscopes, providing force feedback with mN-level resolution and reduced interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fiber-based force sensing methods are used, then force feedback resolution is improved, but device size and manufacturing complexity increase
Solution Approach 1:
The patent extracts the light transmission function from complex optical fiber systems and implements it using simple free-space optical paths between an LED and photodetector. This eliminates the need for optical fibers and interrogators while maintaining force sensing capability through light intensity modulation caused by Sarrus linkage deformation.
Solution Approach 2:
The patent creates a simplified copy of optical fiber-based sensing functionality using basic optical components (LED and photodetector) instead of complex fiber optic systems. The light intensity modulation principle is copied and implemented in a miniaturized form factor suitable for mm-scale end-effectors.
2Ease of manufacture
If conventional meso- or micro-scale manufacturing approaches are used, then manufacturing capability is improved, but cost-effectiveness and integration at mm-scales deteriorate
Solution Approach 1:
The patent segments the force sensing system into modular components (Sarrus linkage, biasing mechanism, light emitter, light detector) that can be independently manufactured and then assembled. This modular approach enables cost-effective production while achieving full integration at mm-scale dimensions.
Solution Approach 2:
The patent transitions from planar 2D manufacturing constraints to 3D integrated assemblies by stacking components vertically and using z-axis compression sensing. The Sarrus linkage's out-of-plane deformation mode enables force sensing in a dimension perpendicular to the device's lateral footprint, achieving mm-scale integration.
3Measurement precision
If distal sensing modalities are integrated into mm-scale packages, then sensing capability is improved, but manufacturing and assembly difficulty increase
Solution Approach 1:
The patent merges multiple functions (structural support, force sensing, and signal generation) into a single integrated distal module. The Sarrus linkage serves both as the structural element that experiences force and as the transducer that converts force into optical signal modulation, eliminating the need for separate sensing components.
Solution Approach 2:
The biasing mechanism is designed to automatically return the Sarrus linkage to its neutral position after force application, enabling self-resetting operation without external actuation. This self-service capability simplifies the control system and reduces assembly complexity.
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 solution enables sensitive and modular force sensing with reduced production costs, improved sensitivity, and resistance to interference, capable of discerning biologically relevant forces in minimally invasive procedures, while eliminating the need for optical fiber transmission.
Implementation Method 1
The light emitter is an infrared light-emitting diode
Implementation Method 2
the light detector is an infrared phototransistor
Implementation Method 3
The biasing mechanism can include a spring coupled with opposing collapsible linkages
Data Source
AI summary
A light-intensity-based forced sensor comprises a Sarrus linkage, a biasing mechanism, a light emitter, and a light detector includes a first plate, a second plate, and at least one collapsible linkage pivotably coupled to both the first and the second plates. The biasing mechanism biases the collapsible linkage toward an extended configuration. The light emitter is coupled with and displaceable with the first plate; and the light detector is coupled with and displaceable with the second plate and configured to receive light emitted from the light emitter and generate an electrical signal in response to light received from the light emitter, wherein the generated electrical signal provides an indication of the distance between the first plate and the second plate. The sensor can be distally mounted on, e.g., an endoscope to provide haptic feedback at the distal end of the endoscope.