Autoclavable Load Sensing Device for Surgical End Effectors
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Solution Overview
Problem
Conventional strain gauges used in surgical devices and adapters fail during sterilization processes due to delamination and boundary stresses caused by high temperatures, leading to electrical connector failures and short circuits.
Innovation Solution
An autoclavable load sensing device with a tubular design and insulated conductive element, where the conductive element is secured within an annular groove and surrounded by a potting material, eliminating bonded substrate interfaces and ensuring functionality even if the seal is broken.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional strain gauges with bonded substrate interfaces are used in surgical devices, then load sensing capability is provided, but the strain gauges fail during sterilization processes due to delamination and boundary stresses
Solution Approach 1:
The patent removes the substrate interface entirely from the strain gauge design. The strain sensing element is mounted directly to the load-bearing structure without any intermediate substrate, eliminating the bonded interfaces that cause delamination and boundary stresses during sterilization. This extraction of the problematic substrate layer resolves the contradiction between reliability under sterilization and device complexity.
Solution Approach 2:
The strain gauge is segmented into separate functional elements: the sensing element itself, the mounting structure, and the electrical connections. Each segment is designed to withstand sterilization independently, with no bonded interfaces between them that could fail. This segmentation allows each component to be optimized for thermal stability while maintaining load sensing capability.
2Reliability
If strain gauges with multiple solder points and substrate interfaces are used, then electrical connectivity is achieved, but liquid penetration and short circuits occur after sterilization
Solution Approach 1:
The patent eliminates the substrate that requires multiple solder points by mounting the strain sensing element directly to the load-bearing structure. This reduces the electrical connection architecture to essential connections only, removing unnecessary solder joints that could fail or allow liquid penetration during sterilization. The extraction of the substrate layer directly addresses the electrical connector integrity problem.
3Duration of action of stationary object
If conventional strain gauges are used in adapters requiring multiple autoclave cycles, then initial load sensing function is provided, but material property changes at high temperatures cause failure
Solution Approach 1:
The patent changes the material parameters and thermal properties of the strain gauge components. The strain sensing element and mounting structure are selected or designed to maintain dimensional stability and mechanical properties across the temperature range of autoclave sterilization. This parameter optimization ensures the strain gauge survives multiple high-temperature cycles without delamination or boundary stress failure.
Solution Approach 2:
The patent designs the strain gauge mounting structure to accommodate thermal expansion and contraction that occurs during autoclave sterilization. By providing pre-designed compensation mechanisms for thermal stress, the structure prevents boundary stresses from developing to failure levels during temperature cycling. This beforehand cushioning of thermal effects enables multiple autoclave cycles without damage.
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 allows the load sensing device to withstand multiple sterilization cycles without failing, providing reliable mechanical force feedback to surgical devices by converting strain into radial deflection and resistance changes, thus preventing electrical connector failures.
Implementation Method 1
The load sensing device is configured to measure the strain on the shaft
Implementation Method 2
converting strain into radial deflection and resistance changes
Data Source
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AI summary
An adapter for interconnecting a surgical end effector to a surgical device includes: a drive shaft; and a load sensing device disposed about the draft shaft, the load sensing device configured to measure strain imparted on the drive shaft. The load sensing device includes a housing having: a tubular portion having a first end and a second end and defining a cavity therebetween; a first end cap disposed at the first end, the first end cap having a first opening; and a second end cap disposed at the second end, the second end cap having a second opening. The load sensing device also includes a conductive element wrapped at least partially about the tubular portion.