TEMPERATURE SENSOR ASSEMBLIES FOR ELECTRIC WARMING BLANKETS

1 . An electric warming blanket for warming patients during surgery and other medical procedures, comprising:

a flexible heater having a surface area and a substantially uniform watt density output across the surface area when the heater is electrically powered;

a temperature sensor assembly coupled to the heater and providing input of an average temperature over a portion of the surface area of the heater to a temperature controller when the heater and the sensor assembly are coupled to the controller; and

a first layer of water resistant material coupled to a second layer of water resistant material about a perimeter of the heater to form a substantially hermetically sealed space for the heater and the temperature sensor assembly.

2 . The blanket of claim 1 , wherein the heater comprises a conductive fabric.

3 . The blanket of claim 1 , wherein the heater comprises carbon.

4 . The blanket of claim 1 , wherein the heater comprises a nonconductive layer coated with a conductive material.

5 . The blanket of claim 4 , wherein the nonconductive layer comprises a woven polyester and the conductive material comprises polypyrrole.

6 . The blanket of claim 1 , wherein the heater comprises a fabric incorporating closely spaced conductive elements.

7 . The blanket of claim 1 , wherein the portion is disposed along the surface area so at to be in conductive contact with the patient when the blanket is placed over the patient to warm the patient.

8 . The blanket of claim 1 , wherein the temperature sensor assembly includes a temperature sensor coupled to a heat spreader, the heat spreader extending over the portion of the surface area.

9 . The blanket of claim 8 , wherein the portion of the surface area is no greater than approximately four square inches.

10 . The blanket of claim of claim 8 , wherein the heat spreader comprises a metal foil.

11 . The blanket of claim 1 , wherein the temperature sensor assembly includes a distributed temperature sensor comprising a resistance temperature detector (RTD) laid out in a flat plane across the portion of the surface area.

12 . The blanket of claim 1 , wherein the temperature sensor assembly includes an array of temperature sensors spaced apart over the portion of the surface area.

13 . An electric warming blanket for warming patients during surgery and other medical procedures, comprising:

a flexible heater including a first side and a second side, at least one of the first and second sides having a surface area and a substantially uniform watt density output across the surface area when the heater is electrically powered;

a temperature sensor assembly coupled to the first side of the heater;

a first layer of water resistant material disposed over the first side of the heater, being un-adhered thereto, and forming a top surface of the blanket when the blanket is placed over the patient;

a second layer of water resistant material disposed over the second side of the heater, being un-adhered thereto, and forming a bottom surface of the blanket, adjacent to the patient, when the blanket is placed over the patient,

the first layer of water resistant material coupled to the second layer of water resistant material about a perimeter of the heater to form a substantially hermetically sealed space for the heater and the temperature sensor; and

a layer of thermal insulation disposed between the temperature sensor assembly and the first layer of water resistant material.

14 . The blanket of claim 13 , wherein the flexible heater comprises a conductive fabric.

15 . The blanket of claim 13 , wherein the heater comprises carbon.

16 . The blanket of claim 13 , wherein the heater comprises a nonconductive layer coated with a conductive material.

17 . The blanket of claim 16 , wherein the nonconductive layer comprises a woven polyester and the conductive material comprises polypyrrole.

18 . The blanket of claim 13 , wherein the flexible heater comprises a fabric incorporating closely spaced conductive elements.

19 . The blanket of claim 13 , wherein the layer of thermal insulation comprises flexible polymeric foam.

20 . The blanket of claim 13 , wherein the layer of thermal insulation comprises high loft fibrous polymeric non-woven material.

21 . The blanket of claim 13 , wherein the layer of thermal insulation comprises non-woven cellulose material.

22 . The blanket of claim 13 , wherein the layer of thermal insulation comprises air.

23 . An electric warming blanket for warming patients during surgery and other medical procedures, comprising:

a flexible heater having a surface area and a substantially uniform watt density output across the surface area when the heater is electrically powered; and

a temperature sensor assembly coupled to the heater,

the sensor assembly including a temperature sensor and a heat spreader, and

the heat spreader comprising a metal foil disposed between the temperature sensor and the heater.

24 . The blanket of claim 23 , wherein the temperature sensor comprises a surface mount chip thermistor.

25 . The blanket of claim 23 , wherein the heat spreader extends over a portion of the surface area of the heater, the portion being no greater than approximately four square inches.

26 . The blanket of claim 23 wherein the heater spreader has a thickness that is no greater than approximately 0.001 inch.