Devices and sensing method for measuring temperature from an ear
An electronic device comprises an enclosure configured for insertion into the ear canal and comprising a distal end configured to extend at least beyond a first bend of the ear canal. A distal temperature sensor is situated at a location of the enclosure that faces a tragus-side of the ear canal between the first and second bends when the enclosure is fully inserted into the ear canal. A proximal temperature sensor is situated on the enclosure at a location spaced apart from a surface of the ear canal and proximal of the distal temperature sensor in an outer ear direction when the enclosure is fully inserted into the ear canal. A processor, coupled to the distal and proximal temperature sensors and to memory, is configured to calculate an absolute core body temperature using a heat balance equation stored in the memory and the first and second temperature signals.
1 . A sound amplification device configured to measure temperature from within an ear canal of an ear comprising a first bend and a second bend, the device comprising:
an enclosure configured for insertion into the ear canal and comprising a distal end configured to extend at least beyond the first bend;
sound amplification circuitry disposed in the enclosure;
a distal temperature sensor situated at a location of the enclosure that faces ear canal tissue distal to the first bend and proximal to the second bend when the enclosure is deployed in the ear canal, the distal temperature sensor configured to sense one or both of conductive heat and convective heat and to produce a first temperature signal;
a proximal temperature sensor situated on the enclosure at a location proximal to the distal temperature sensor location in an outer ear direction when the enclosure is deployed in the ear canal, the proximal temperature sensor configured to sense one or both of conductive heat and convective heat and to produce a second temperature signal;
a memory configured to store a pre-established heat balance equation; and
a processor coupled to the distal and proximal temperature sensors and the memory, the processor configured to calculate a core body temperature using the heat balance equation and the first and second temperature signals;
wherein the heat balance equation is derived by plotting (T(oral)−T(2)) vs. (T(2)−T(faceplate),
wherein the heat balance equation is a linear or logarithmic heat balance equation, and
wherein:
T(2) is measured at or near Location 2 of the ear canal, wherein Location 2 is located on the ventral side of the ear canal just past the first bend and before the second bend;
T(faceplate) is measured at a location more exterior than Location 2; and
T(oral) is measured using an oral reference thermometer.
2 . The device of claim 1 , wherein:
a temperature measured by the distal temperature sensor is closer to the core body temperature than a temperature measured by the proximal temperature sensor; and
the temperature measured by the proximal temperature sensor is closer to an ambient temperature than the temperature measured by the distal temperature sensor.
3 . The device of claim 1 , wherein the pre-established heat balance equation characterizes a temperature gradient of the ear for a population of persons.
4 . The device of claim 1 , wherein the core body temperature calculated by the processor has an error within +/−0.5° C. relative to a reference core body temperature over one or both of a range of ambient temperatures and a range of wind draft conditions.
5 . The device of claim 1 , wherein the distal temperature sensor is situated on the enclosure to establish contact with ear canal tissue.
6 . The device of claim 1 , wherein the distal temperature sensor is recessed into, or situated within, the enclosure and configured to be thermally coupled to ear canal tissue.
7 . The device of claim 1 , wherein at least a portion of the distal temperature sensor is covered with a thermally conductive material.
8 . The device of claim 1 , wherein at least a portion of the distal temperature sensor in contact with or penetrating into the enclosure is surrounded by thermally insulating material.
9 . The device of claim 1 , wherein the first temperature signal is representative of a temperature of blood supplied to a branch of the external carotid artery.
10 . The device of claim 1 , wherein the device is configured as an in-the-ear (ITE) device, an in-the-canal (ITC) device, a completely-in-canal (CIC) device or an invisible-in-the-canal (IIC) device.
11 . A method implemented by a sound amplification device configured for insertion into an ear canal of an ear, the ear canal comprising a first bend and a second bend, the method comprising:
measuring a first temperature indicative of one or both of conductive heat and convective heat at a location of the ear canal between the first and second bends;
measuring a second temperature indicative of one or both of conductive heat and convective heat at a location proximal of an ear canal location where the first temperature is measured in an outer ear direction;
storing, in a memory of the device, a pre-established heat balance equation; and
calculating, using a processor of the device, a core body temperature using the heat balance equation and the first and second temperatures,
wherein the heat balance equation is derived by plotting (T(oral)−T(2)) vs. (T(2)−T(faceplate)),
wherein the heat balance equation is a linear or logarithmic heat balance equation, and
wherein:
T(2) is measured at or near Location 2 of the ear canal, wherein Location 2 is located on the ventral side of the ear canal just past the first bend and before the second bend;
T(faceplate) is measured at a location more exterior than Location 2; and
T(oral) is measured using an oral reference thermometer.
12 . The method of claim 11 , wherein:
the first temperature is closer to the core body temperature than the second temperature; and
the second temperature is closer to an ambient temperature than the first temperature.
13 . The method of claim 11 , wherein the pre-established heat balance equation characterizes a temperature gradient of the ear for a population of persons.
14 . The method of claim 11 , wherein the core body temperature calculated by the processor has an error within +/−0.5° C. relative to a reference core body temperature over one or both of a range of ambient temperatures and a range of wind draft conditions.
15 . The method of claim 11 , wherein the first temperature is measured using a distal temperature sensor situated on an enclosure of the device to establish contact with ear canal tissue.
16 . The method of claim 11 , wherein the first temperature is measured using a distal temperature sensor recessed into, or situated within, an enclosure of the device and thermally coupled to ear canal tissue.
17 . The method of claim 11 , wherein the first temperature is measured using a distal temperature sensor, and at least a portion of the distal temperature sensor is covered with a thermally conductive material.