Catheter Digitizing Circuit for Accurate Temperature Measurement
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Solution Overview
Problem
Conventional catheters using thermocouples for temperature measurement face significant measurement errors due to additional junctions of dissimilar metals and thermal junctions at connectors, which are not designed with appropriate TC materials, leading to signal degradation and inaccuracies.
Innovation Solution
Incorporating a thermocouple signal-processing circuit at the catheter handle to digitize the TC voltage signal, reducing the need for TC wires and minimizing material transitions, with a digitizing circuit that includes an isothermal block, low pass filter, amplifier, analog-to-digital converter, and cold-junction compensation to transmit digital data via a digital link.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermocouple wires and connectors are used to transmit temperature signals, then the temperature measurement function is achieved, but measurement errors increase due to additional junctions of dissimilar metals and thermal junctions at connectors
Solution Approach 1:
The patent extracts the temperature measurement function from the physical thermocouple wire and connector system, relocating the measurement capability to an integrated circuit within the handle. This eliminates the need for physical connectors and extension wires that cause measurement errors, while maintaining the temperature sensing function through electronic signal processing.
Solution Approach 2:
The patent introduces a thermocouple signal-processing circuit as an intermediary between the thermocouple sensor and the display system. This intermediary circuit processes the thermocouple signal locally and transmits only digital temperature data, eliminating the need for physical thermocouple wire extensions and connectors that cause measurement errors.
2Measurement precision
If thermocouple signal is transmitted through connectors with dissimilar metals, then the signal can be transmitted to the display, but measurement errors occur due to material transitions creating additional thermal junctions
Solution Approach 1:
The patent replaces the mechanical/electrical thermocouple wire and connector system with an electronic signal processing system. The thermocouple signal is processed locally by an integrated circuit that converts the analog thermocouple output to digital temperature data, which is then transmitted electronically without physical connectors, eliminating signal degradation from material transitions.
3Ease of manufacture
If disposable catheter is connected through off-the-shelf connectors, then the device can be assembled quickly, but measurement errors increase due to lack of TC material compatibility
Solution Approach 1:
The patent extracts the temperature measurement and processing functions from the connector interface, integrating them into the catheter handle as an onboard signal-processing circuit. This eliminates the need for specialized thermocouple-compatible connectors while maintaining measurement accuracy, as the circuit processes the thermocouple signal locally before transmission.
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 solution significantly reduces measurement errors by processing the TC signal locally, eliminating signal degradation through connectors and providing accurate temperature measurements, thus enhancing the catheter's temperature measurement capability.
Implementation Method 1
a first pair of conductors extend through the catheter shaft, and each one of the first pair of conductors has a first end and a second end. The first ends of the first pair of conductors are coupled to each other at the distal end of the catheter shaft to form a first thermocouple
Implementation Method 2
The digitizing circuit may include an isothermal block thermally coupled to the second ends of the first pair of conductors
Implementation Method 3
The digitizing circuit may include a low pass filter for filtering the voltage signal of the first thermocouple
Implementation Method 4
The digitizing circuit may include an amplifier for amplifying the voltage signal of the first thermocouple
Data Source
AI summary
A temperature sensing catheter with improved accuracy is provided. The catheter includes a catheter shaft having a proximal end and a distal end, and a first pair of conductors extending through the catheter shaft. Each one of the first pair of conductors has a first end and a second end, and the first ends of the first pair of conductors are coupled to each other at the distal end of the catheter shaft to form a first thermocouple. A handle is coupled to the proximal end of the catheter shaft and receives the second ends of the first pair of conductors, and the handle includes a digitizing circuit coupled to the second ends of the first pair of conductors for digitizing a voltage signal of the first thermocouple.