Thermometer heater and thermistor
View Patent ↗A thermometric apparatus for determining a patient's temperature having a elongated sensing probe that is connected to a base housing. The insertion tip of the probe contains a outer shell and a spaced apart inner shell. The outer surface of the inner shell has a heater that is fabricated of a resistive thick film material and a heat sensor mounted thereon. The heater and the heat sensor are connected to a pair of thick film conductive traces which in turn are electrically attached by a flexible circuit board to leads running back to the base housing. The space between the two shells is filled by a thermally conductive epoxy.
1. A thermometry apparatus for determining a temperature of a body that includes:
a temperature sensing probe that further includes an elongated shaft having a proximal end and a distal end;
a tip member secured to the distal end of said shaft, said tip member containing an inner shell and an outer shell that are separated by a space, said shells being fabricated of a material having a high heat transfer coefficient;
a heating element that is mounted upon the outer surface of the inner shell;
a heat sensor that is also mounted upon the outer surface of the inner shell;
electrical leads connected to said heating element and to said heat sensor;
a thermally conductive material filling said space between said shells; and
wherein said inner shell contains a first pair of thick film electrical traces extending along the outer surface of said inner shell, said first pair of electrical traces being arranged to electrically couple said heater to a first pair of electrical leads.
2. The apparatus of claim 1 wherein said electrical leads pass through said shaft into a base unit secured to the proximal end of said shaft.
3. The apparatus of claim 2 wherein said base unit contains a processor connected to said leads for controlling said heater and for determining said body temperature from said heat sensor data.
4. The apparatus of claim 2 wherein said base unit contains a readout screen that is connected to said processor for providing a visual display of said body's sensed temperature.
5. The apparatus of claim 1 wherein said inner shell contains a second pair of thick film electrical traces extending along the outer surface of said inner shell, said second pair of electrical traces being arranged to electrically couple said heat sensor to a second pair of electrical leads.
6. The apparatus of claim 5 wherein said heat sensor is a thermistor.
7. The apparatus of claim 6 wherein said heat sensor is a ceramic oxide device.
8. The apparatus of claim 7 wherein the heat sensor is a laser etched NTC device.
9. The apparatus of claim 5 wherein said inner shell contains a dielectric layer that is placed beneath said heating element, said heat sensor and said conductive traces.
10. The apparatus of claim 9 wherein said inner shell is fabricated of stainless steel.
11. The apparatus of claim 5 wherein said inner shell is fabricated of a plastic material.
12. The apparatus of claim 5 wherein said inner shell is fabricated of a ceramic material.
13. The apparatus of claim 5 that further includes a flexible circuit board for connecting said electrical leads to each pair of thick film conductive traces.
14. The apparatus of claim 6 wherein said thermistor has a negative thermal coefficient and a linear response in a range of between 85° F. and 110° F.
15. The apparatus of claim 5 wherein said first pair of thick film conductive traces are mounted inside said second pair of thick film conductive traces.