Surgery – Diagnostic testing – Temperature detection
Reexamination Certificate
2000-02-14
2001-08-28
O'Connor, Cary (Department: 3736)
Surgery
Diagnostic testing
Temperature detection
Reexamination Certificate
active
06280397
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a high speed accurate temperature measuring device which is especially useful for measuring the temperature of a low thermal conductivity cavity hereinafter called “body” (e.g. human body). More specifically the present invention relates to a high speed accurate temperature measuring device wherein the body temperature is calculated according to heat flux measured between the body and a first temperature sensor location and between the first temperature sensor and a second temperature sensor (or sensors) location.
BACKGROUND OF THE INVENTION
Every temperature measuring process involves the transfer of heat from the measured body to the measuring device probe. Heat may be transferred in three ways; by conduction, by convection and by radiation. The method of the present invention measures heat convection as well as heat conduction (such as in streaming air or liquids). Radiation heat meant lacks accuracy since achieving accuracy is dependent on earlier knowledge of constants that are not known with a high certainty.
Most temperature measuring devices using convection or conduction require the temperature measuring sensor to come into thermal equilibrium with the body being measure. When the body being measured is a poor heat conductor, the time to reach equilibrium (with the temperature measuring sensor) may be considerable. This measurement waiting time (to reach equilibrium) is a thermodynamic necessity. Various methods aiming at shortening this waiting time exist. For example DE 3527942 and U.S. Pat. No. 4,183,248 disclose a method comprising two temperature sensors and a heating elements. Shortening of this wait time is always at the expense of the accuracy of measurement.
The device of the present invention eliminates this waiting time. Instead of directly measuring the temperature (which requires waiting for equilibrium), the device of the present invention calculates the temperature by predicting temperature sensor measurements. This prediction relies on a heat transfer equation, and preferably a heat conduction equation whereby the body temperature is calculated according to heat flux measured (a) between the body and a first temperature sensor and (b) between the first temperature sensor and a second temperature sensor (or sensors). Since firstly the heat flux measurements do not require waiting for thermal equilibrium and secondly the calculation per se is performed in real time on a standard micro-processor, the device of the present invention can rapidly display the accurate temperature of the body.
Following is a detailed explanation of deriving the essential equations (embodied within the algorithm used by the data processing limit according to the present invention).
The Conduction Heat Transfer Equation (one dimensional without heat sources, since the heating body of the present device is not operated during the temperature measurement):
ρ
C
P
=
ⅆ
T
ⅆ
t
=
-
ⅆ
ⅆ
x
(
k
ⅆ
T
ⅆ
x
)
This equation represents heat flux differences between the inlet and the outlet of the body under discussion.
ⅆ
T
ⅆ
t
=
1
ρ
C
P
Δ
x
Δ
[
k
ⅆ
T
ⅆ
x
i
n
-
k
ⅆ
T
ⅆ
x
out
]
where one dimensional heat flux (Q) is defined as the constant “k” times the change in temperature dT with regard to a change in position dx:
(
*
)
Q
=
-
k
Δ
T
Δ
X
Using finite differences equation (*) can be written:
T
(
t
+
Δ
t
)
-
T
(
t
)
Δ
t
=
1
ρ
C
P
Δ
x
[
k
T
(
x
+
Δ
x
)
-
T
(
x
)
Δ
x
&LeftBracketingBar;
x
=
x
i
n
-
k
T
(
x
+
Δ
x
)
-
T
(
x
)
Δ
x
&RightBracketingBar;
x
=
x
out
]
If:
ω
i
n
=
k
Δ
t
ρ
C
P
Δ
x
i
n
2
and
ω
out
=
k
Δ
t
ρ
C
p
Δ
x
out
2
Then:
(
**
)
T
(
t
+
Δ
t
)
-
T
(
t
)
&RightBracketingBar;
x
=
1
2
(
x
i
n
+
x
out
)
=
ω
i
n
[
T
(
x
+
Δ
x
)
-
T
(
x
)
]
&RightBracketingBar;
x
=
x
i
n
-
ω
out
[
T
(
x
+
Δ
x
)
-
T
(
x
)
]
&LeftBracketingBar;
x
=
x
out
If there are two heat sensors “S
1
” which is located at x
in
and “S
2
” which is located at x
out
, and these sensors are separated by a finite distance having a known thermal conduction coefficient (e.g a thermal insulation member), and “S
1
” is in thermal contact with the body, and “S
2
” is within a thermal probe, and the body is located at x
in
+&Dgr;x then from (**) it is clearly seen that approximately:
T
(
t
+
Δ
t
)
-
T
(
t
)
&RightBracketingBar;
x
=
1
2
(
x
i
n
+
x
out
)
=
ω
i
n
[
T
body
-
T
s
1
]
&LeftBracketingBar;
-
ω
out
[
T
s
1
-
T
s
2
]
The temperature rise as evaluated at location ½(x
in
+x
out
) is defined as heat in from the body &ohgr;
in
times: [(T
body
) minus (T
s
1
)] minus &ohgr;
out
times heat out from the probe [(T
s
1
) minus (T
2
2
)}.
The device of the present invention solves this equation for the unknown T
body
, &ohgr;
in
, &ohgr;
out
according to measured temperatures representing the heat fluxes, without any need to wait for thermal equilibrium.
SUMMARY OF THE INVENTION
The present invention relates to a high speed accurate temperature measuring device especially useful for measuring human body temperature, comprising (a) an elongated temperate probe, (b) a first temperature sensor located beneath the surface of the probe, (c) at least one second temperature sensor located within the probe and parallel to the first sensor, (d) a thermal insulation member located between the first sensor and the second sensor (or sensors), (e) a data processing unit connected to the first and second temperature sensors calculating the body temperature according to heat flux measured between the body and the first sensor and between the first sensor and the second sensor (or sensors), and (f) a data display connected to the data processing unit.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a high speed accurate temperature measuring device especially useful for measuring the human body temperature. The device of the present invention is likewise useful for measuring animal body temperatures and for measuring the temperature of any low thermal conductivity cavity.
The device of the present invention is comprised of:
(a) An elongated temperature probe. This probe is for insertion into a body cavity (in the present invention, the term “body cavity” also refers to the armpit; mouth cavity and rectum). The probe has a rounded insertion tip to facilitate safe insertion into delicate body cavities.
(b) A first temperature sensor. This first sensor is located beneath the surface of the probe near the insertion tip (to facilitate minimum depth insertion).
(c) At least one second temperature sensor. This second sensor is located within the probe and parallel to the fist sensor.
(d) A thermal insulation member. This member is located between the firs sensor and the second sensor (or sensors). It should be emphasized (as will be described) that the whole structure of the sensors and insulation members is preferably rolled up.
(e) A data processing unit. This data processing unit is connected to the first and second temperature sensors. The data processing unit calculates the body temperature according to heat flux measured (i) between the body and the firs
Teich Sorin T.
Vadal Ilan
Yarden Moshe
Lowe Hauptman & Gilman & Berner LLP
Medism, Ltd.
O'Connor Cary
Wingood Pamela L.
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