Infusion fluid warmer comprising printed circuit board heating elements
Inventors
Assignees
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Publication Number
US-10888671-B2
Publication Date
2021-01-12
Expiration Date
Abstract
An infusion fluid warmer including a heat exchanger and first and second printed circuit boards having respective integrally formed electrically resistive patterns acting as heating elements. The integrally formed electrically resistive patterns are heated by supply of electrical power and thermally coupled to a heat exchanger to warm an infusion fluid flowing through a fluid passage of the heat exchanger.
Core Innovation
The invention relates to an infusion fluid warmer that uses a heat exchanger having an upper wall structure and a lower, opposing, wall structure separated by a fluid channel or passage extending between fluid inlets and outlets. A first printed circuit board includes a first surface and an opposing second surface with a first integrally formed electrically resistive pattern, and a second printed circuit board includes a first surface and an opposing second surface with a second integrally formed electrically resistive pattern. The outer surface of the upper wall structure is thermally connected to the first integrally formed electrically resistive pattern, and the outer surface of the lower wall structure is thermally connected to the second integrally formed electrically resistive pattern.
A controller connects a DC power supply input to one or both of the first and second integrally formed electrically resistive patterns during a first time period to dissipate power and thereby serve as a heater or heating element. After the first time period, the controller disconnects the DC power supply input from the one or both of the integrally formed electrically resistive patterns during a predetermined delay time following the first time period. During a second time period following the predetermined delay time, the controller determines a resistance of the first or second integrally formed electrically resistive pattern and determines a temperature of the first or second integrally formed electrically resistive pattern based on the determined resistance.
The document further describes that temperature is determined from resistance and a known temperature coefficient, and that the resistance determination can be performed using an electronic switching circuit with a reference resistor and controllable semiconductor switches. In addition, a secondary invention concept is described in which multiple sequential resistive patterns are selected among a plurality.
Claims Coverage
The partial content identifies one independent claim (clm-00001). The independent claim includes a combination of a heater structure with two PCBs and integrally formed resistive patterns thermally coupled to a heat exchanger, and a control and sensing scheme with timed power dissipation, delayed disconnect, and resistance-based temperature determination.
Infusion fluid warmer with thermally coupled integrally formed resistive patterns
An infusion fluid warmer comprising a DC power supply input, a first printed circuit board with an integrally formed electrically resistive pattern thermally connected to an outer surface of an upper wall structure, and a second printed circuit board with an integrally formed electrically resistive pattern thermally connected to an outer surface of a lower wall structure, wherein the upper and lower wall structures form a heat exchanger separated by a fluid channel or passage extending between fluid inlets and outlets.
Controller timed power dissipation and post-delay resistance-based temperature determination
A controller configured to connect the DC power supply input to one or both of the first or second integrally formed electrically resistive patterns during a first time period to dissipate power, then disconnect the DC power supply input during a predetermined delay time following the first time period, and during a second time period determine a resistance of the first or second integrally formed electrically resistive pattern and determine a temperature of the first or second integrally formed electrically resistive pattern based on the determined resistance.
Across the independent claim, the core claim coverage centers on using integrally formed electrically resistive patterns on first and second PCBs thermally coupled to opposite heat-exchanger walls, together with a controller that alternates power delivery for a first time period with a controlled disconnect after a predetermined delay, then measures resistance and determines temperature from that resistance.
Stated Advantages
More responsive and accurate control versus prior PCB heaters.
Documented Applications
Heating an infusion fluid in an infusion fluid warmer using a heat exchanger with a fluid channel or passage between fluid inlets and outlets.
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