PTC Heating Element for Patient Warming System
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Solution Overview
Problem
Conventional patient warming systems, such as forced air convective and fluid conductive warming systems, face issues with temperature consistency, noise, contamination risks, and inadequate control over the patient contact surface temperature, which can lead to detrimental heat loss and surgical site contamination.
Innovation Solution
A patient warming system utilizing a heating element with a resistive layer formed of positive temperature coefficient (PTC) material, which self-regulates by increasing electrical resistance with temperature, ensuring uniform heat distribution and safety, integrated into a warming device like an underbody pad or blanket, along with temperature sensors and a control system for precise temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If forced air convective warming is used, then warming can be provided, but temperature consistency at patient contact surface deteriorates and surgical site contamination risk increases
Solution Approach 1:
The patent replaces forced air convective warming with electrically conductive heating elements that directly transfer thermal energy through conduction. This eliminates mechanical airflow that causes contamination while providing superior temperature consistency at the patient contact surface through direct thermal contact.
Solution Approach 2:
The patent introduces an electrically conductive heating element as an intermediary between the power source and the patient. This heating element serves as a thermal mediator that directly transfers heat to the patient's body through conduction, eliminating the need for convective airflow and its associated contamination risks.
2Temperature
If fluid conductive warming is used, then conductive warming is provided, but temperature control at patient contact surface deteriorates and noise increases
Solution Approach 1:
The patent replaces fluid-based conductive warming with solid electrically conductive heating elements. This eliminates the mechanical fan and fluid circulation systems that generate noise, while providing superior temperature control through direct electrical heating and thermal conduction at the patient contact surface.
Solution Approach 2:
The patent extracts and removes the fan and fluid circulation components from the warming system. By eliminating these noisy mechanical elements and using direct electrical heating, the system achieves noiseless operation while maintaining excellent temperature control through the heating element in direct contact with the patient.
3Temperature
If electrically conductive warming is used, then warming is provided, but temperature uniformity and safety control deteriorate
Solution Approach 1:
The patent incorporates temperature sensors and a control system that provides feedback to regulate the heating element's output. This closed-loop control ensures uniform temperature distribution across the patient contact surface while maintaining safety by preventing overheating, thus improving both temperature uniformity and reliability.
Solution Approach 2:
The patent uses PTC (positive temperature coefficient) material in the heating element, which automatically changes its electrical resistance parameter in response to temperature changes. As the material heats up, its resistance increases, naturally limiting the current and preventing overheating. This intrinsic parameter change provides self-regulating safety without requiring external control systems.
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 PTC heating element provides consistent and controlled warming, reducing the risk of heat loss and contamination, while maintaining thermal uniformity and safety, thereby improving patient care during medical procedures.
Implementation Method 1
a resistive layer formed of a positive temperature coefficient (PTC) material... Using the PTC material provides a self-regulating characteristic for the heating element such that as the heating element is heated, the electrical resistance of the PTC material in the heating element increases to limit the flow of current through the heating element
Implementation Method 2
a resistive layer formed of a positive temperature coefficient (PTC) material... the electrical resistance of the PTC material in the heating element increases to limit the flow of current through the heating element
Implementation Method 3
as the heating element is heated, the electrical resistance of the PTC material in the heating element increases to limit the flow of current through the heating element... provides consistent and controlled warming, reducing the risk of heat loss and contamination, while maintaining thermal uniformity
Data Source
AI summary
A heating element includes an electrically insulating layer; resistive layer formed of a positive temperature coefficient material; and an electrically conductive layer disposed between the electrically insulating layer and the resistive layer and including a first bus and a second bus that is spaced apart from the first bus, the resistive layer electrically connecting the first bus and the second bus. The electrically insulating layer, the electrically conductive layer, and the resistive layer are stacked to form a lamination and the lamination having a thickness and a width and length extending orthogonal to the thickness. The lamination may have slits extending through the thickness thereof and along a portion of the length thereof. Terminals may be connected to the buses and arranged to provide a counter current flow pattern across the lamination. The lamination may be used in a warming device and in connection with a patient warming system.