Capacitive Sheath Encoder for Sterilization-Stable Catheter Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional linear encoders used in surgical procedures for determining the location of catheters are prone to inaccuracies due to temperature variance and hardware susceptibility to damage during sterilization, and are costly and difficult to manufacture.
Innovation Solution
A linear encoder system utilizing a substrate with aligned first and second capacitive sensors and pin oscillator connections, which measures coupling capacitance to determine the position of a sheath electrode invariant to temperature changes and resistant to sterilization damage, integrated with a microcontroller for accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional linear encoders use capacitance measurements along capacitive sensors, then position determination is achieved, but measurement precision deteriorates due to temperature variance
Solution Approach 1:
The patent replaces traditional mechanical encoders with capacitive sensing elements integrated into a printed circuit board. The encoder uses capacitive coupling between a movable electrode and fixed capacitive sensors to detect position, eliminating mechanical moving parts that are susceptible to temperature effects. The capacitive measurement system with differential sensing and calibration compensates for temperature variance electronically.
Solution Approach 2:
The patent implements temperature compensation by measuring capacitance values at different temperatures and applying calibration factors. The system changes the measurement parameters by using multiple capacitive sensors with different orientations (first and second capacitive sensors with perpendicular lengths) to detect and compensate for temperature-induced drift in the position measurement.
2Measurement precision
If traditional linear encoders use resistive elements or wiper contact, then position measurement is achieved, but reliability deteriorates due to hardware susceptibility to damage during sterilization
Solution Approach 1:
The patent eliminates mechanical wiper contacts and resistive elements by using a fully capacitive sensing system integrated into a printed circuit board. The capacitive sensors and electrode structure have no sliding contacts or fragile mechanical components, making the entire encoder assembly sterilizable using standard medical sterilization procedures without damage to sensitive hardware.
Solution Approach 2:
The encoder is designed as a disposable or single-use component integrated into the catheter handle, with all capacitive sensing elements fabricated on a sterilizable printed circuit board. This design allows the entire encoder assembly to be sterilized with the catheter, ensuring reliability in medical applications where sterilization is required.
3Measurement precision
If conventional linear encoders are implemented, then position measurement capability is achieved, but device complexity increases making them costly and difficult to manufacture
Solution Approach 1:
The patent merges the encoder functionality directly into the printed circuit board of the device handle by fabricating capacitive sensors and signal traces on the same PCB. This integration eliminates the need for separate encoder assemblies, reducing part count, simplifying manufacturing, and lowering costs while maintaining measurement precision through the capacitive sensing array.
Solution Approach 2:
The printed circuit board serves multiple functions: it provides structural support for the handle, routes electrical signals, and contains the complete capacitive encoder system. The same PCB substrate that carries other circuitry also hosts the capacitive sensors and electrode connections, eliminating the need for dedicated encoder hardware and simplifying the overall device architecture.
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 system provides accurate and reliable catheter location measurement during surgery, requiring no calibration and using robust hardware, ensuring precise positioning and durability.
Implementation Method 1
The substrate may be configured to determine an axial position of the electrode based on a coupling capacitance caused by the electrode overlapping one or more of the first capacitive sensors and one or more of the second capacitive sensors
Data Source
AI summary
A treatment system for treating tissue is disclosed in which a handle with an elongate shaft projecting from the handle, a sheath axially slidable relative to the elongate shaft, and an electrode mounted on a proximal portion of the sheath is provided. A substrate having an elongate portion may be located within the handle. A plurality of first and second capacitive sensors may be positioned along the elongate portion. The electrode may be configured to slide along the elongate portion during movement of the sheath. The electrode may maintain contact with at least one of the first capacitive sensors at least one of the second capacitive sensors during movement of the sheath. The substrate may be configured to determine an axial position of the electrode based on a coupling capacitance caused by an electrode overlapping one or more of the first capacitive sensors and one or more of the second capacitive sensors.