U.S. patent application number 10/801496 was filed with the patent office on 2004-12-02 for multi-point polymer encapsulated micro-thermocouple.
Invention is credited to Bernier, Pete, Richetto, Audeen.
Application Number | 20040238023 10/801496 |
Document ID | / |
Family ID | 29406685 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040238023 |
Kind Code |
A1 |
Richetto, Audeen ; et
al. |
December 2, 2004 |
Multi-point polymer encapsulated micro-thermocouple
Abstract
A thermocouple produced by removing insulation from a distal end
of each of at least first and second thermocouple conductors,
forming a thermocouple junction at the distal ends of the at least
first and second thermocouple conductors, placing the thermocouple
junction into the heat shrinkable polymer material by sliding a
second end of the tube of heat shrinkable polymer material over the
thermocouple junction and sealing the thermocouple junction by
heating and melting the polymer material.
Inventors: |
Richetto, Audeen; (Maple
Grove, MN) ; Bernier, Pete; (Minneapolis,
MN) |
Correspondence
Address: |
Schwegman, Lundberg, Woessner & Kluth, P.A.
P.O. Box 2938
Minneapolis
MN
55402
US
|
Family ID: |
29406685 |
Appl. No.: |
10/801496 |
Filed: |
March 16, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10801496 |
Mar 16, 2004 |
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10391531 |
Mar 17, 2003 |
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60366435 |
Mar 21, 2002 |
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60455617 |
Mar 17, 2003 |
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Current U.S.
Class: |
136/224 ;
136/201 |
Current CPC
Class: |
G01K 7/02 20130101 |
Class at
Publication: |
136/224 ;
136/201 |
International
Class: |
H01L 035/28 |
Claims
What is claimed is:
1. A thermocouple produced by the method comprising: removing
insulation from a distal end of each of at least first and second
thermocouple conductors; forming a thermocouple junction at the
distal ends of the at least first and second thermocouple
conductors; placing the thermocouple junction into a heat
shrinkable polymer material by sliding an end of a tube of heat
shrinkable polymer material over the thermocouple junction; and
sealing the thermocouple junction by heating and melting the
polymer material.
2. The thermocouple of claim 1, wherein the sealing the
thermocouple junction provides a reproducible confined shape having
a height less than about 0.008 inches and a width less than about
0.010 inches.
3. The thermocouple of claim 2, wherein a height of the confined
shape falls within a range of about 0.003 to 0.010 inches.
4. The thermocouple of claim 2, wherein a width of the confined
shape falls within a range of about 0.005 to 0.0110 inches.
5. The thermocouple of claim 1, wherein a length of the
thermocouple junction and the polymer seal falls within a range of
about 0.05 to 0.5 inches.
6. The thermocouple of claim 1, wherein the placing the
thermocouple junction into the heat shrinkable polymer material
further comprises: melting a second end of the tube to form the
second end into a sealed dome shape.
7. The thermocouple of claim 1, wherein a second thermocouple
junction is formed.
8. The thermocouple of claim 7, wherein the thermocouple junctions
are formed at different locations along the thermocouple
conductors.
9. The thermocouple of claim 1, wherein forming the thermocouple
junction comprises soldering the distal ends of the thermocouple
conductors.
10. The thermocouple of claim 1, wherein forming the thermocouple
junction comprises welding the distal ends of the thermocouple
conductors.
11. The thermocouple of claim 1, wherein the thermocouple
conductors are conductors of types selected from a set of A.S.T.M.
types T, J, K, E, S, R, and B.
12. The thermocouple of claim 1, wherein the polymer material is
polyethylene terephthalate (PET).
13. The thermocouple of claim 1, wherein the polymer material is
fluorinated ethylene propylene (FEP).
14. The thermocouple of claim 1, wherein the thermocouple is
adapted and sized to fit into a catheter.
15. The thermocouple of claim 1, wherein the thermocouple junction
further comprises a fuse such that the fuse causes the device to
lose the properties of a thermocouple when an electrical rating is
exceeded across the thermocouple junction.
16. The thermocouple of claim 1, wherein the device further
comprises a fuse placed between a proximal end of at least one of
the thermocouple conductors and the thermocouple junction, such
that exceeding an electrical rating of the fuse breaks an
electrical connection between the proximal end of the conductor and
the thermocouple junction.
17. A thermocouple comprising: a thermocouple junction formed by
soldering distal ends of first and second thermocouple conductors,
wherein a length of the junction falls within the range of about
0.03 inches to 0.07 inches; and heat shrinkable polymer material
melted to seal and electrically insulate the thermocouple junction
within a reproducible confined shape, wherein a height of the
confined shape falls within a range of about 0.003 to 0.010 inches,
and wherein a width of the confined shape falls within a range of
about 0.005 to 0.0110 inches.
18. The thermocouple of claim 17, wherein a length of the
thermocouple junction together with the polymer material falls
within a range of about 0.05 to 0.5 inches.
19. A device comprising: a plurality of thermocouple conductors
including at least a first, a second and a third thermocouple
conductor, wherein the first thermocouple conductor is of a first
type, the second thermocouple conductor is of a second type, and
the third conductor is of a type different from the second type; at
least first and second thermocouple junctions, wherein the first
thermocouple junction is formed from the first and second
thermocouple conductors and the second thermocouple junction is
formed from the second and third thermocouple conductors; and heat
shrinkable polymer material melted to seal the at least first and
second thermocouple junctions.
20. The device of claim 19, further comprising a distal end,
wherein the at least first and second thermocouple junctions are
positioned such that a first thermocouple junction is located at
the distal end and the at least second thermocouple junction is
located further from the distal end than the first thermocouple
junction.
21. The thermocouple of claim 19, wherein the sealing the
thermocouple junction provides a reproducible confined shape having
a height less than about 0.008 inches and a width less than about
0.010 inches.
22. The device of claim 19, wherein the device is adapted and sized
to fit into a catheter, and wherein the second end further
comprises at least three terminations of the at least three
thermocouple conductors, and wherein a difference in voltage at the
thermocouple junctions available at the at least three terminations
indicates a difference in temperature along the length of the
catheter.
23. The device of claim 19, wherein the thermocouple conductor
types are selected from a set of A.S.T.M. types T, J, K, E, S, R,
and B.
24. A device comprising: N thermocouple conductors including at
least a first conductor and a second conductor; a range of N/2 to
N--1 thermocouple junctions formed from thermocouple conductor
pairs, wherein a thermocouple junction is comprised of two
thermocouple conductors of different types, and wherein one
thermocouple conductor type may be used in comprising more than one
thermocouple junction; and heat shrinkable polymer material melted
to seal thermocouple junctions.
25. The device of claim 24, wherein the device further comprises a
distal end, and wherein the thermocouple junctions are formed at
different distances from the distal end.
26. The device of claim 24, wherein the thermocouple conductor
types are selected from a set of A.S.T.M. types T, J, K, E, S, R,
and B.
Description
RELATED APPLICATIONS AND CLAIMS OF PRIORITY
[0001] This application is a continuation-in-part of U.S. patent
Ser. No. 10/391,531, filed on Mar. 17, 2003, which claims the
benefit as provided under 35 U.S.C. .sctn. 119(e) to U.S.
Provisional Application No. 60/366,435 filed Mar. 21, 2002, which
is hereby incorporated by reference in its entirety. The
application also claims benefit as provided under 35 U.S.C. .sctn.
119(e) to U.S. Provisional Application No. 60/455,617, filed on
Mar. 17, 2003, which is hereby incorporated by reference in its
entirety.
TECHNICAL FIELD
[0002] This patent application relates to thermocouple devices, and
in particular, to a thermocouple device produced by encapsulating a
thermocouple junction with a heat-shrinkable polymer coating.
BACKGROUND
[0003] A thermocouple is a bimetal junction that provides a voltage
proportional to temperature. Temperature probes are often formed
using thermocouples. Many applications requiring temperature probes
require extremely small size.
[0004] One application for extremely small temperature probes is in
the medical device industry; especially for use in catheters. For
example, ablation catheters are used in non-invasive treatment of
heart abnormalities. The ablation catheter is able to identify
abnormal tissue growth and uses heat to remove the tissue causing
the additional conduction paths. Thermal feedback is required when
removing the tissue to prevent blood clotting or blood boiling
during the procedure. In using a temperature probe to provide this
feedback, the probe must be small enough to get as near an ablation
electrode as possible. Also, when used in catheters, it is
desirable that a temperature probe not rupture a catheter sleeve by
tearing or abrasion. Further, a probe should be electrically
insulated to allow in vivo operation.
[0005] It is apparent that uses for extremely small temperature
probes beyond the medical field are possible. An extremely small
probe would be useful in any field where a measurement of a
localized temperature variation is desired, such as for example,
the field of electronics.
[0006] What is needed is an insulated thermocouple device of
extremely small size.
SUMMARY
[0007] This document discusses an insulated thermocouple device of
extremely small size. The thermocouple is produced by removing
insulation from distal ends of two thermocouple conductors and then
forming a thermocouple junction at the distal ends of the two
thermocouple conductors. A tube of heat shrinkable polymer material
is placed over the thermocouple junction. The entire thermocouple
junction is then sealed by heating and melting the polymer
material.
[0008] The resulting thermocouple and seal fall within a
reproducible confined shape, where the height of the confined shape
falls within a range of about 0.003 to 0.010 inches and the width
of the confined shape falls within a range of about 0.005 to 0.0110
inches.
[0009] This summary is intended to provide an overview of the
subject matter of the present application. It is not intended to
provide an exclusive or exhaustive explanation of the invention.
The detailed description is included to provide further information
about the subject matter of the preset patent application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the drawings like numerals refer to like components
throughout the several views.
[0011] FIG. 1 is a drawing of one embodiment of the
micro-thermocouple.
[0012] FIG. 2 is a flowchart showing one method for forming the
micro-thermocouple.
[0013] FIG. 3 is a drawing showing fused embodiments of the
micro-thermocouple.
[0014] FIG. 4 is a drawing of an embodiment of the
micro-thermocouple that comprises two thermocouple junctions.
[0015] FIG. 5 is a drawing of an embodiment of the
micro-thermocouple that comprises two thermocouple junctions at
different locations along the length of the device.
DETAILED DESCRIPTION
[0016] In the following detailed description, reference is made to
the accompanying drawings which form a part hereof, and specific
embodiments in which the invention may be practiced are shown by
way of illustration. It is to be understood that other embodiments
may be used and structural changes may be made without departing
from the scope of the present invention.
[0017] As stated previously, the present application is concerned
with materials and techniques used to create a sealed thermocouple
of extremely small size. FIG. 1 shows one embodiment of a
micro-thermocouple 100. The thermocouple junction 130 is formed
from joining conductors 120, 122 of dissimilar metals. The metals
comprise any of the standard metal combinations defined by the
American Society of Testing and Materials (A.S.T.M.) for
thermocouples. The size of the thermocouple conductors generally
fall with a range of about 30 awg (0.010 inch diameter) to about 50
awg (0.0009 inch diameter). In one embodiment conductors 120, 122
are joined to form a thermocouple junction 130 by soldering using
lead-free solder 135. In another embodiment, conductors 120, 122
are welded and 135 represents a welded bead or seam. Beyond the
thermocouple junction 130, the conductors 120, 122 are electrically
insulated with commonly used insulating material 140 such as nylon,
polyurethane, or polyimide. A heat shrinkable polymer material is
then used to form an electrically insulating seal 150 over the
micro-thermocouple 100. To create the seal 150, a tube is slid over
the thermocouple junction. In one embodiment, the tube is slid over
the thermocouple junction and the seal 150 is then formed by
heating the tube of polymer material to the point of melting onto
and over the thermocouple joint 130 and onto the insulation 140.
Melting the polymer material onto the thermocouple conductor
insulation 140 provides a seal around the insulation 140. The
melting also forms a domed shape 155 on the end of
micro-thermocouple 100. This domed end 155 is advantageous if the
thermocouple is used in a catheter as it results in the
micro-thermocouple 100 being resistant to abrading or tearing a
catheter sleeve. In another embodiment, the tube of heat shrinkable
polymer material is first sealed on one end by melting the end and
forming the domed end before the tube is slid over the thermocouple
junction. After the tube is slid over the thermocouple junction
130, further heating and melting provides the insulating seal 150.
Other embodiments involve sealing the end while it is placed over
the thermocouple junction 130.
[0018] The length (1) 160 of the resultant seal 150 is within the
range of about 0.05 inches to 0.5 inches. The overall length (L)
165 of the micro-thermocouple 100 is within the range of about 20
inches to 78 inches. One embodiment of the micro-thermocouple 100
uses polyethylene terephthalate (PET) as the polymer material.
Another embodiment uses fluorinated ethylene propylene (FEP). The
seal 150 is moisture resistant and electrically insulating. The
insulation resistance of the seal is greater than 100 Mega-ohms
when measured at 50 Volts(DC).
[0019] FIG. 1 also shows a cross section 110 of micro-thermocouple
100. The width (w) 170 of the micro-thermocouple 100 falls within a
range from about 0.005 inches to 0.011 inches. The height (h) 175
of the micro-thermocouple 100 falls within a range of about 0.003
inches to 0.01 inches. Thus, it can be seen that the
micro-thermocouple can be formed within a reproducible confined
shape having a height 175 less than about 0.01 inches and a width
170 less than about 0.011 inches. The final dimensions of the
confined shape is determined in part by the gauge of the
thermocouple conductors used. Providing the insulation by the
technique described herein adds about 0.0005 inches to the width
and height dimensions of a formed thermocouple junction.
[0020] FIG. 2 shows a flowchart of one embodiment of a method 200
of forming micro-thermocouple 100. At 210, insulation 140 is
removed from a distal end of thermocouple conductors 120, 122. At
220, a thermocouple junction 130 is formed at the distal end of the
conductors 120, 122. At 230, the tube of polymer material is slid
over the thermocouple junction 130. At 240, a seal 150 is formed
over the thermocouple junction 130 by heating and melting the
polymer material.
[0021] FIG. 3 shows fused embodiments of the micro-thermocouple
100. A fused thermocouple prevents the possibility of recycling or
reusing the thermocouple if the micro-thermocouple 100 is used in a
medical device. In one embodiment a fuse 390 is placed in a
thermocouple conductor 120 between a proximal end of the conductor
120 and the thermocouple joint 130. Exceeding the rating of the
fuse breaks the electrical connection between the proximal end of
conductor 120 and the thermocouple joint. In another embodiment, a
fuse 395 is formed by placing within the thermocouple junction 130.
Exceeding the rating of the fuse 395 across the thermocouple
conductors 120 causes the device to lose the properties of a
thermocouple.
[0022] FIG. 4 is a drawing of an embodiment of micro-thermocouple
100 that is comprised of two thermocouple junctions 130. The first
is formed by thermocouple conductors 120 and 122, and the second is
formed by thermocouple conductors 122 and 424. Conductor 122 must
be a different metal than conductors 120 and 424, but conductors
120 and 424 may be the same or different metals.
[0023] FIG. 5 is a drawing of an embodiment of micro-thermocouple
100 that is comprised of two thermocouple junctions in a different
arrangement than the junctions shown in FIG. 4. In FIG. 5 a second
thermocouple junction 530 is at a point further from the end 155 of
the micro-thermocouple 100 than thermocouple junction 130.
Thermocouple junction 130 is comprised of thermocouple conductors
120 and 122, and thermocouple junction 530 is comprised of
thermocouple conductors 122 and 424. As in the embodiment in FIG.
4, conductor 122 must be a different metal than conductors 120 and
424, but conductors 120 and 424 may be the same or different
metals. Thus, thermocouple junctions 130, 530 may be the same type
or may be different types. An electrically insulating seal 550 is
formed over thermocouple junction 530. The arrangement of
thermocouple junction 130, 530 in FIG. 5 provides a measurement of
temperature change at multiple locations along the length of the
micro-thermocouple 100. This concept can be expanded to a
thermocouple device having N thermocouple conductors, where N is an
integer. If all thermocouple conductors are used in only one
thermocouple junction pair, N/2 thermocouple junctions are created
and can be placed at N/2 locations along the thermocouple device to
provide temperature information at the N/2 locations. If a
thermocouple conductor is used in more than one thermocouple
junction it is possible to create N-1 thermocouple junctions from N
thermocouple conductors. Again, the N-1 thermocouple conductors may
be placed at N-1 locations along the thermocouple device to provide
temperature information at the N-1 locations.
[0024] Although specific examples have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that any arrangement calculated to achieve the same
purpose could be substituted for the specific example shown. This
application is intended to cover any adaptations or variations of
the present invention. Therefore, it is intended that this
invention be limited only by the claims and the equivalents
shown.
* * * * *