U.S. patent application number 15/249295 was filed with the patent office on 2017-03-30 for measurement probe with heat cycle event counter.
The applicant listed for this patent is BROADLEY-JAMES CORPORATION. Invention is credited to Scott T. Broadley, Robert Fish, Robert J. Garrahy, Andrew W. Hayward, Jared H. Nathanson, William E. Reynolds, IV.
Application Number | 20170087261 15/249295 |
Document ID | / |
Family ID | 50693968 |
Filed Date | 2017-03-30 |
United States Patent
Application |
20170087261 |
Kind Code |
A1 |
Reynolds, IV; William E. ;
et al. |
March 30, 2017 |
MEASUREMENT PROBE WITH HEAT CYCLE EVENT COUNTER
Abstract
A measurement device is disclosed, embodiments of which are
adapted to withstand, detect, and record detection of heat cycle
events, including autoclave cycles. Embodiments of the measurement
device comprise a sensor for measuring a characteristic of a medium
and a heat cycle detection unit. Embodiments of the heat cycle
detection unit comprise a temperature or atmospheric pressure
responsive element, a detection module, data interface, and data
memory. In one disclosed embodiment, the temperature or pressure
responsive element is configured to respond to a characteristic of
a heat cycle event while the heat cycle detection unit is off. In
another disclosed embodiment, the detection module is configured to
automatically power off the heat cycle detection unit in response
to detecting an autoclave cycle. Methods of using the devices are
also disclosed.
Inventors: |
Reynolds, IV; William E.;
(Irvine, CA) ; Garrahy; Robert J.; (Walnut,
CA) ; Hayward; Andrew W.; (Flitwick, GB) ;
Fish; Robert; (Rancho Cucamonga, CA) ; Nathanson;
Jared H.; (Mission Viejo, CA) ; Broadley; Scott
T.; (Laguna Beach, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BROADLEY-JAMES CORPORATION |
Irvine |
CA |
US |
|
|
Family ID: |
50693968 |
Appl. No.: |
15/249295 |
Filed: |
August 26, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14801625 |
Jul 16, 2015 |
9430880 |
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15249295 |
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14207347 |
Mar 12, 2014 |
9117166 |
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14801625 |
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61794355 |
Mar 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61L 9/00 20130101; G06M
1/10 20130101; G07C 3/00 20130101; G01K 13/00 20130101; A61L 2/07
20130101; G06M 1/02 20130101; A61L 2/00 20130101 |
International
Class: |
A61L 2/07 20060101
A61L002/07; G06M 1/10 20060101 G06M001/10; G06M 1/02 20060101
G06M001/02; G01K 13/00 20060101 G01K013/00; G07C 3/00 20060101
G07C003/00 |
Claims
1. A measurement device adapted to withstand and automatically
count a heat sterilization or cleaning cycle, comprising: a
measurement probe comprising a sensor configured to detect a
characteristic of a medium and generate a measurement signal; a
condition responsive element comprising either a temperature
responsive element or an atmospheric pressure responsive element;
and a heat cycle detection unit comprising a detection module, a
data interface, and a data memory; wherein the detection module is
configured to: detect a heat cycle event using the condition
responsive element, and record detection of the heat cycle event in
the data memory.
2. The measurement device of claim 1, wherein the heat cycle event
is an autoclave cycle, a steam-in-place sterilization cycle, or a
clean-in-place sanitizing cycle.
3. (canceled)
4. The measurement device of claim 1, wherein the device is
configured to automatically power on the heat detection unit at the
beginning of the heat cycle in response to a change of state of the
condition responsive element.
5. The measurement device of claim 4, wherein the device comprises
a battery and a capacitor, wherein the device is configured to
charge the capacitor from the battery upon automatically powering
on the heat cycle detection unit and to automatically power off the
heat cycle detection unit when the capacitor is charged, and
wherein the device is configured to discharge the capacitor when
the condition responsive element indicates the heat cycle event is
substantially complete.
6. (canceled)
7. (canceled)
8. The measurement device of claim 1, wherein the condition
responsive element is a first switch configured to transition from
a first state to a second state when the first switch exceeds a
first temperature or a first pressure, and wherein the detection
module is configured to record detection of a heat cycle event in
the data memory in response to the first switch transitioning from
the first state to the second state.
9. The measurement device of claim 8, further comprising a
capacitor coupled to the first switch and configured to discharge
in response to the first switch transitioning from the first state
to the second state, wherein the detection module is configured to
detect a discharged capacitor and record detection of a heat cycle
event in the data memory.
10. The measurement device of claim 9, wherein the detection module
is configured to detect a discharged capacitor and record detection
of a heat cycle event in the data memory after the heat cycle
detection unit is powered on from a dormant state.
11. (canceled)
12. (canceled)
13. (canceled)
14. (canceled)
15. (canceled)
16. (canceled)
17. (canceled)
18. (canceled)
19. (canceled)
20. (canceled)
21. (canceled)
22. (canceled)
23. (canceled)
24. (canceled)
25. (canceled)
26. (canceled)
27. (canceled)
28. (canceled)
29. (canceled)
30. (canceled)
31. (canceled)
32. (canceled)
33. (canceled)
34. (canceled)
35. A method of automatically counting a heat cycle experienced by
a measurement device, comprising: providing a measurement device
comprising: a measurement probe having a sensor configured to
detect a characteristic of a medium and generate a measurement
signal, a condition responsive element, and an heat cycle detection
unit having a detection module, a data interface, and a data
memory; detecting a heat cycle event, using the condition
responsive element; recording detection of the heat cycle event in
the data memory.
36. The method of claim 35, wherein the heat cycle event is an
autoclave cycle, a steam-in-place sterilization cycle, or a
clean-in-place sanitizing cycle.
37. (canceled)
38. (canceled)
39. (canceled)
40. The method of claim 35, wherein the condition responsive
element is a first switch that transitions from a first state to a
second state when the first switch exceeds a first temperature or a
first pressure, and the detection module records detection of a
heat cycle event in the data memory in response to the first switch
transitioning from the first state to the second state.
41. (canceled)
42. (canceled)
43. The method of claim 35, wherein the heat cycle detection unit
receives power from a portable power source electrically coupled to
the measurement device.
44. The method of claim 43, wherein the detection module records
detection of a heat cycle event in the data memory in response to
the condition responsive element exceeding a first temperature or a
first pressure.
45. The method of claim 44, wherein the heat cycle detection unit
powers on in response to the condition responsive element exceeding
the first temperature or the first pressure.
46. (canceled)
47. (canceled)
48. (canceled)
49. (canceled)
50. The method of claim 35, further comprising engaging with a
vessel body such that a distal portion of the measurement device is
positioned within a vessel cavity and a proximal portion of the
measurement device is positioned external to the vessel cavity.
51. The method of claim 50, wherein the condition responsive
element is positioned in or on the distal portion.
52. The method of claim 50, wherein the condition responsive
element is positioned in or on the proximal portion.
53. The method of claim 52, wherein the detection module detects a
heat cycle event and records detection of the heat cycle event in
the data memory in response to either the condition responsive
element exceeding a first temperature or first pressure or a vessel
temperature responsive element positioned in or on the distal
portion exceeding a vessel sterilization temperature.
54. The method of claim 53, wherein detecting a heat cycle event
and recording detection of the heat cycle event in the data memory
comprises: detecting an autoclave cycle and recording detection of
the autoclave cycle in the data memory in response to the condition
responsive element exceeding a first temperature or a first
pressure, and detecting a steam-in-place cycle and recording
detection of the steam-in-place cycle in the data memory in
response to the vessel temperature responsive element exceeding the
vessel sterilization temperature and the condition responsive
element not exceeding a first temperature or a first pressure.
55. The method of claim 54, wherein the heat cycle detection unit
powers off when an autoclave cycle is detected and optionally
powers off when a steam-in-place cycle is detected.
56. (canceled)
57. (canceled)
58. (canceled)
59. (canceled)
60. (canceled)
Description
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/801,625, filed Jul. 16, 2015, which is a
continuation of U.S. patent application Ser. No. 14/207,347, filed
Mar. 12, 2014, granted as U.S. Pat. No. 9,117,166, which claims
priority benefit of U.S. Provisional Patent Application No.
61/794,355, filed Mar. 15, 2013, the disclosure of each of which is
herein incorporated by reference in its entirety.
BACKGROUND
[0002] Field of the Invention
[0003] The present invention relates to measurement probes. More
particularly, the invention relates to devices and methods used to
detect and count heat cycles experienced by measurement probes.
[0004] Description of the Related Art
[0005] Control of industrial processes is largely dependent on
measurement signals received from measurement devices within
process mediums. Measurement probes, which are equipped with
sensors such as pH sensors, temperature sensors, redox sensors,
carbon dioxide sensors, and dissolved oxygen sensors, are
frequently used to monitor biological and chemical processes in the
fields of biotechnology, pharmaceuticals, and food/beverage
processing. In such industries, accuracy of measurements is
critical.
[0006] In such industries, sterilization or cleaning is also
critical. Frequent sterilization or cleaning is often required in
these industries, because bacteria and other microorganisms may
proliferate on unsterilized surfaces and create health risks.
Additionally, sterilization or cleaning of measurement probes is
needed to prevent contamination deposits from building up on the
surface of the probes where they can introduce errors into the
measurement signals.
[0007] Three sterilization or cleaning methods are frequently
employed to sterilize equipment used in biological or chemical
processes: steam-in-place sterilization, clean-in-place, and
autoclaving. Steam-in-place sterilization procedures allow for
in-line pressurized clean-in-place, and autoclaving. Steam-in-place
sterilization procedures allow for in-line pressurized steam
sterilization of all surfaces located within the interior of a
reaction vessel or other processing container (herein referred to
as a processing vessel), thus providing for sterilization without
disassembly. Clean-in-place procedures allow for in-line cleaning
by flushing the process vessel and associated piping with
sanitizing chemical solutions at elevated temperatures. Autoclaving
involves subjecting the processing vessel and the entire probe, to
pressurized steam heat within a separate autoclave chamber.
Autoclaving is often a preferred method of sterilization at least
in part when the processing vessel is relatively small and
transportable to the autoclave chamber. The major drawback to
autoclaving is that the entire probe body is subjected to the high
sterilization temperature and this can have a detrimental effect on
any internal circuitry that is powered up at the time. If the
probes is externally powered then it must be disconnected from its
signal and/or power cable before it is placed in the autoclave. In
many industries, subjecting the process vessel, probes, and
associated equipment to high pressure steam at 121.degree. C. in an
autoclave for 20-30 minutes is sufficient to achieve sterilization.
However, it is not uncommon to find that the vessel, probes, and
associated equipment are exposed to pressurized steam at
temperatures in excess of 130.degree. C. and for periods of 60
minutes or longer to insure complete sterilization.
[0008] Measurement probes can experience structural changes, aging,
and decreased functionality and accuracy through exposure to
extreme conditions. Particularly, the rapid increase and decrease
of temperature associated with common steam heat sterilization or
hot chemical solution cleaning methods leads to probe degradation;
thus, measurement probes are consumable products which must be
replaced regularly. In industry, a balance is required when
determining how frequently to replace measurement probes. Premature
exchange of probes unnecessarily increases costs, whereas a probe
that has reached the end of its life may fail during use. Loss of
the probe measurement in mid-process often results in loss of
process control and the subsequent ruin of an entire biological or
chemical batch, leading to costly waste and delays. Accordingly, it
is important for the probe operator to monitor the condition and
evaluate the fitness for service of industrial measurement probes
by tracking the number of heat cycles that it has experienced.
SUMMARY
[0009] The present disclosure describes devices and methods used to
detect and count heat cycles experienced by measurement probes,
particularly heat cycles associated with steam heat sterilization
and hot chemical solution cleaning procedures. These procedures are
among the greatest contributors to probe degradation and failure.
Accordingly, by providing means for detecting and maintaining a
count of the heat cycles associated with these procedures, the
devices and methods described herein will help probe operators
determine the risk associated with continued use of the probe and
determine when it is time to replace the measurement probes.
[0010] The embodiments disclosed herein each have several
innovative aspects, no single one of which is solely responsible
for the desirable attributes of the invention. Without limiting the
scope, as expressed by the claims that follow, the more prominent
features will be briefly disclosed here. After considering this
discussion, one will understand how the features of the various
embodiments provide several advantages over current measurement
probes.
[0011] One aspect of the disclosure is a measurement device adapted
to withstand and automatically detect a heat sterilization or
cleaning cycle and increment and maintain a counter of the total
number of cycles for later review by the operator, particularly
when the measurement device is disconnected from all external power
sources. The device includes a measurement probe including a sensor
configured to detect a characteristic of a medium and generate a
measurement signal; a condition responsive element including either
a temperature responsive element or an atmospheric pressure
responsive element; and a heat cycle detection unit including a
detection module, a data interface, and a data memory. The
detection module is configured to detect a heat cycle event using
the condition responsive element, and record detection of the heat
cycle event in the data memory. In some embodiments the heat cycle
event is part of an autoclave procedure, a steam-in-place
sterilization procedure, or a clean-in-place procedure. In some
embodiments the device is configured to automatically power up the
heat cycle detection unit as soon as the heat cycle is detected,
the heat cycle detection unit then increments a counter, and then
the device powers itself off to protect the circuit from prolonged
and excessive heat exposure as in the case of an autoclave
procedure where the entire probe is autoclaved. In some other
embodiments the device will automatically turn itself back on when
the heat cycle is complete and the device has cooled off to a safe
operating temperature. In some embodiments, the device will
automatically turn itself back on when the heat cycle is complete
and the device has cooled off to a safe operating temperature, at
which point the device records the occurrence of the heat cycle,
and then the device automatically powers off until the next heat
cycle is detected. In other embodiments the device will remain off
to conserve battery power and only turn itself back on briefly when
another heat cycle is detected and the cycle needs to be counted by
the heat cycle detection unit. In some embodiments, the measurement
probe and the heat cycle detection unit are separably connected. In
other embodiments, the measurement probe and the heat cycle
detection unit are fixedly integrated.
[0012] In some embodiments, the condition responsive element is a
first switch configured to transition from a first state to a
second state when the first switch exceeds a first temperature or a
first pressure. In such embodiments, the detection module is
configured to record detection of a heat cycle event in the data
memory in response to the first switch transitioning from the first
state to the second state. The measurement device may further
include a capacitor coupled to the first switch, which is
configured to discharge in response to the first switch
transitioning from the first state to the second state. In such
embodiments, the detection module need not be powered up during an
autoclave cycle but is configured to detect the discharged
capacitor and record detection of a heat cycle event in the data
memory after the autoclave detection unit is powered back on
following an autoclave cycle. The first switch changes to its
second state at some pre-defined temperature that marks the
beginning of the heat cycle. This second state discharges a
capacitor. When the detection module powers back up it detects the
discharged capacitor and increments the event counter.
[0013] In some embodiments, the measurement device also includes a
portable power source in addition to, or instead of a capacitor. In
such embodiments, the detection module is configured to record
detection of a heat cycle event in the data memory in response to a
temperature responsive element exceeding a first temperature or an
atmospheric pressure responsive element exceeding a first pressure.
After the counter is incremented the autoclave detection unit is
configured to power off in response to the temperature responsive
element exceeding the first temperature or in response to the
atmospheric pressure responsive element exceeding the first
pressure. In some such embodiments, the measurement device includes
a second switch configured to transition from a power-off state to
a power-on state when the second switch falls below a power-on
temperature or a power-on pressure. In such embodiments, the
autoclave detection unit is configured to automatically power on
when the second switch transitions from the power-off state to the
power-on state. In some embodiments, the second switch and the
condition responsive element are one and the same; a universal
switch can acts as both the second switch and the condition
responsive element.
[0014] The first switch and/or the second switch in various
embodiments are selected from the group consisting of: a bimetallic
strip, an integrated thermal switch, and a pressure switch. The
condition responsive element of other embodiments may be selected
from the group consisting of: a resistance temperature detector, a
bimetallic strip, an integrated thermal switch, a positive
temperature coefficient thermistor, switching PCT thermistor, or
other thermistor, a pressure switch, a piezoelectric pressure
sensor, an electromagnetic pressure sensor, a capacitive pressure
sensor, and a piezoresistive strain gauge. In various embodiments,
the first temperature and/or power-on temperature are within a
range of 50 to 120 degrees Celsius, and the first pressure and/or
power-on pressure are within a range of 15 to 45 psi.
[0015] In some embodiments, the measurement device also includes a
coupling element configured to engage with a Vessel body such that,
when the coupling element is engaged with the vessel body, the
measurement device includes a distal portion that is positioned
within a vessel cavity and a proximal portion that is positioned
external to the vessel cavity. In some such embodiments, the
condition responsive element is positioned in or on the distal
portion. In other embodiments, the condition responsive element is
positioned in or on the proximal portion. When the condition
responsive element is positioned in or on the proximal portion, the
measurement device may additionally include a vessel temperature
responsive element positioned in or on the distal portion. In such
embodiments, the detection module is configured to detect a heat
cycle event and record detection of the heat cycle event in the
data memory in response to either the condition responsive element
exceeding a first temperature or pressure or the vessel temperature
responsive element exceeding a vessel sterilization temperature.
Additionally, in such embodiments, the detection module may be
configured to detect an autoclave cycle and record detection of the
autoclave cycle in the data memory in response to the condition
responsive element exceeding a first temperature or pressure, and
the module may be further configured to detect a steam-in-place
cycle and record detection of the steam-in-place cycle in the data
memory in response to only the vessel temperature responsive
element exceeding the vessel sterilization temperature. The
autoclave detection unit can be configured to power off when an
autoclave cycle is detected and optionally power off when a
steam-in-place cycle is detected.
[0016] In some embodiments both a condition responsive element and
a temperature responsive element are located in the distal end of
the measurement device and another temperature responsive element
is located in the proximal end of the device. When a preset
temperature limit is exceeded in the sterilization or cleaning
procedure in the distal end of the device, the condition responsive
element changes state and powers on the circuit in the detector
module. The module then increments the heat cycle counter and
additionally uses the temperature responsive element in the distal
end to measure additional information such as maximum heat exposure
and length of exposure time in the case of steam-in-place or
clean-in-place procedures. The temperature responsive element in
the proximal end is also powered on and it monitors the device
temperature at the proximal end. If the proximal temperature
exceeds a preset limit then the device logic determines that the
device is being autoclaved and the circuit completely shuts down
after incrementing the heat cycle counter.
[0017] In some embodiments, the measurement device also includes a
pH sensor positioned in the distal portion. In one such embodiment,
a condition responsive element in the distal end can change state
due to a process heat cycle and switch on the device's power and
the detection module can be configured to differentiate and detect
a clean-in-place cycle and record detection of the clean-in-place
cycle when a distally-located temperature responsive element
exceeds a clean-in-place temperature and a measurement from the pH
sensor exceeds a clean-in-place pH level, both within a defined
period of time. The distally-located temperature responsive element
of some embodiments is the vessel temperature responsive element
disclosed above. In at least some embodiments, the clean-in-place
temperature is within a range of 65 to 95 degrees Celsius, and the
clean-in-place pH is within the extreme ranges of either 9 to 14 pH
or 1 to 4 pH.
[0018] In various embodiments, the first temperature and/or the
vessel temperature are within a range of 50 to 120 degrees Celsius,
and the first pressure is within a range of 15 to 45 psi. The
measurement probe is selected from the group consisting of an
amperometric, a potentiometric, an optical, a capacitive, and a
conductive probe. Additionally, in some embodiments, the sensor is
selected from the group consisting of a pH sensor, a temperature
sensor, a dissolved oxygen sensor, and a combination thereof. The
detection module of some embodiments is selected from the group
consisting of a circuit, a microprocessor, a Digital Signal
Processor, an Application Specific Integrated Circuit, and a Field
Programmable Gate Array. The data interface of some embodiments is
selected from the group consisting of a wireless transmitter, an
input/output terminal, a data bus, a contactless inductive coupling
interface (see e.g. DE 19540854A1, DE 4344071A1, and U.S. Pat. Nos.
7,785,151, 6,705,898, 6,476,520; each of which is incorporated
herein by reference in its entirety and for disclosure thereof),
and an industry standard 8 pin connector. In some embodiments, the
measurement device also includes a power-gathering system, such as,
for example, a photodiode or a photovoltaic cell.
[0019] An additional aspect of the disclosure is a method of
automatically counting autoclave and other heat sterilization
cycles and/or cleaning cycles experienced by any embodiment of the
measurement device described above, while protecting the circuitry
contained within the measurement device and managing the device's
power supply. The method includes detecting a heat sterilization
cycle using a first temperature responsive element that is
configured to respond when the temperature exceeds a first
temperature, automatically powering up the detection unit circuitry
if off, recording detection of the heat sterilization cycle in a
data memory and incrementing a counter, and automatically powering
off the detection unit circuitry after detection of the heat
sterilization cycle, if it is desired in a particular process
procedure to protect the device's circuit from excessive heat
during the heat cycle and to conserve the device's power.
[0020] Another aspect of the disclosure is a method of
automatically counting a heat cycle experienced by a measurement
device. The method includes providing a measurement device, the
device including a measurement probe having a sensor configured to
detect a characteristic of a medium and generate a measurement
signal, a condition responsive element, and a heat cycle detection
unit having a detection module, a data interface, and a data
memory. The method further includes detecting a heat cycle event,
using the condition responsive element and recording detection of
the heat cycle event in the data memory. In some embodiments, the
heat cycle event is an autoclave cycle, a steam-in-place
sterilization event, or a clean-in-place event. In some
embodiments, the device is configured to automatically power up the
heat cycle detection unit after detection of the heat cycle event
and then, after incrementing the counter, power it down if the heat
cycle event comprises an autoclave cycle.
[0021] In some embodiments of the method, the condition responsive
element is a first switch that transitions from a first state to a
second state when the first switch exceeds a first temperature or a
first pressure, and the detection module records detection of a
heat cycle event in the data memory in response to the first switch
transitioning from the first state to the second state. In some
such embodiments, the method also includes discharging a capacitor
coupled to the first switch in response to the first switch
transitioning from the first state to the second state. In such
embodiments, detecting a heat cycle event using the condition
responsive element involves detecting a discharged capacitor. In
some such embodiments, detecting a discharged capacitor and
recording detection of a heat cycle event in the data memory occur
after the autoclave detection unit is powered on following an
autoclave cycle.
[0022] In some embodiments of the method, the autoclave detection
unit receives power from a portable power source electrically
coupled to the measurement device. The detection module of some
such embodiments records detection of a heat cycle event in the
data memory in response to the condition responsive element
exceeding a first temperature or a first pressure. The autoclave
detection unit of some such embodiments powers off in response to
the condition responsive element exceeding the first temperature or
the first pressure. In some embodiments, the method additionally
includes automatically powering on the autoclave detection unit
when a second switch in the measurement device transitions from a
power-off state to a power-on state. In such embodiments, the
second switch transitions from the power-off state to the power-on
state when the second switch falls below a power-on temperature or
pressure. In some embodiments, a universal switch within the
measurement device includes both the second switch and the
condition responsive element.
[0023] In various embodiments of the method, the first temperature
and/or the power-on temperature are within a range of 50 to 120
degrees Celsius, and the first pressure and/or the power-on
pressure are within a range of 15 to 45 psi.
[0024] The method of some embodiments also includes engaging with a
vessel body such that a distal portion of the measurement device is
positioned within a vessel cavity and a proximal portion of the
measurement device is positioned external to the vessel cavity. In
some such embodiments, the condition responsive element is
positioned in or on the distal portion. In other embodiments, the
condition responsive element is positioned in or on the proximal
portion.
[0025] In some embodiments having the condition responsive element
positioned in or on the proximal portion, the detection module
detects a heat cycle event and records detection of the heat cycle
event in the data memory in response to either the condition
responsive element exceeding a first temperature or first pressure
or a vessel temperature responsive element positioned in or on the
distal portion exceeding a vessel sterilization temperature. In
some such embodiments, the step of detecting a heat cycle event and
recording detection of the heat cycle event in the data memory
includes one of: detecting an autoclave cycle and recording
detection of the autoclave cycle in the data memory in response to
the condition responsive element exceeding a first temperature or a
first pressure, or detecting a steam-in-place cycle and recording
detection of the steam-in-place cycle in the data memory in
response to the vessel temperature responsive element exceeding the
vessel sterilization temperature and the condition responsive
element not exceeding a first temperature or a first pressure. In
some such embodiments, the autoclave detection unit powers off when
an autoclave cycle is detected and optionally powers off when a
steam-in-place cycle is detected.
[0026] In the method of some embodiments, the detection module
detects a clean-in-place cycle and records detection of the
clean-in-place cycle when: (1) a temperature responsive element
located in or on the distal portion exceeds a clean-in-place
temperature, and (2) a measurement from a pH sensor positioned in
the distal portion exceeds a clean-in-place pH level, both within a
defined period of time. In some such embodiments, the temperature
responsive element located in or on the distal portion is the
vessel temperature responsive element.
[0027] In some embodiments of the method, the clean-in-place
temperature is within a range of 65 to 90 degrees Celsius and/or
the clean-in-place pH is within a range of either 9 to 14 pH or 1
to 4 pH. Additionally or alternatively, in some embodiments, the
first temperature and the vessel temperature are within a range of
50 to 120 degrees Celsius and the first pressure is within a range
of 15 to 45 psi.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The above-mentioned aspects, as well as other features,
aspects, and advantages of the present technology will now be
described in connection with various embodiments, with reference to
the accompanying drawings. The illustrated embodiments, however,
are merely examples and are not intended to be limiting. Throughout
the drawings, similar symbols typically identify similar
components, unless context dictates otherwise. Note that the
relative dimensions of the following figures may not be drawn to
scale.
[0029] FIG. 1 depicts a perspective view of one embodiment of a
measurement device,
[0030] FIG. 2 depicts a block diagram of one embodiment of a
measurement device.
[0031] FIG. 3A depicts a block diagram of another embodiment of a
measurement device.
[0032] FIG. 3B is a flowchart illustrating one method of operations
performed by the measurement device of FIG. 3A.
[0033] FIG. 4A depicts a block diagram of another embodiment of a
measurement device.
[0034] FIG. 4B is a flowchart illustrating one method of operations
performed by the measurement device of FIG. 4A.
[0035] FIG. 5A depicts a block diagram of another embodiment of a
measurement device.
[0036] FIG. 5B is a flowchart illustrating one method of operations
performed by the measurement device of FIG. 4A.
[0037] FIG. 6A depicts a block diagram of another embodiment of a
measurement device.
[0038] FIG. 6B is a flowchart illustrating one method of operations
performed by the measurement device of FIG. 5A,
[0039] FIG. 7A depicts a block diagram of another embodiment of a
measurement device.
[0040] FIG. 7B is a flowchart illustrating one method of operations
performed by the measurement device of FIG. 6A.
[0041] FIG. 8 depicts a block diagram of another embodiment of a
measurement device.
[0042] FIG. 9 depicts a block diagram of another embodiment of a
measurement device.
[0043] FIG. 10 depicts a circuit diagram for an embodiment of a
heat cycle detection unit.
[0044] FIG. 11 depicts a schematic circuit diagram for an
embodiment of a heat cycle detection unit.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
[0045] In the following detailed description, reference is made to
the accompanying drawings, which form a part of the present
disclosure. The illustrative embodiments described in the detailed
description, drawings, and claims are not meant to be limiting.
Other embodiments may be utilized, and other changes may be made,
without departing from the spirit or scope of the subject matter
presented here. It will be readily understood that the aspects of
the present disclosure, as generally described herein, and
illustrated in the Figures, can be arranged, substituted, combined,
and designed in a wide variety of different configurations, all of
which are explicitly contemplated and form part of this
disclosure.
[0046] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the disclosure. It will be understood by those within the art that
if a specific number of a claim element is intended, such intent
will be explicitly recited in the claim, and in the absence of such
recitation, no such intent is present. For example, as used herein,
the singular forms "a", "an" and "the" are intended to include the
plural forms as well, unless the context clearly indicates
otherwise. As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items. It will
be further understood that the terms "comprises," "comprising,"
"includes," and "including," when used in this specification,
specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
Expressions such as "at least one of," when preceding a list of
elements, modify the entire list of elements and do not modify the
individual elements of the list.
[0047] To assist in the description of the devices and methods
described herein, some relational and directional terms are used.
"Connected" and "coupled," and variations thereof, as used herein
include direct connections, such as being contiguously formed with
or attached directly to, on, within, etc. another element, as well
as indirect connections where one or more elements are disposed
between the connected elements. "Connected" and "coupled" may refer
to a permanent or non-permanent (i.e., removable) connection.
[0048] "Secured" and variations thereof as used herein include
methods by which an element is directly fastened to another
element, such as being glued, screwed or otherwise affixed directly
to, on, within, etc. another element, as well as indirect means of
attaching two elements together where one or more elements are
disposed between the secured elements.
[0049] "Proximal" and "distal" are relational terms used herein to
describe position. For clarity purposes only, in this disclosure,
position is viewed from the perspective of an individual operating
a measurement device positioned partially within a processing
vessel. The portion of the measurement device located external to
the vessel is viewed as being closest, and therefore, most proximal
to the operator. The portion of the device positioned within the
container is more distally located.
[0050] There is a need for a measurement probe that monitors and
quantifies its own usage and operational fitness in the bioprocess
industries. A leading cause of probe degradation in bioprocess
applications is the thermo shock associated with the increase and
decrease of temperature associated with some heat sterilization
procedures that utilize pressurized steam and cleaning procedures
that utilize hot sanitizing chemical solutions. A bioprocess
industry standard for keeping track of wear on a measurement probe
is the number of these heat cycles experienced by the probe. In
some applications, probes are exposed to no more than two to ten
heat cycles before being retired. In other applications, the count
may be higher. The particular number of heat sterilization or
cleaning cycles that a probe can withstand varies by probe
manufacturer, sterilization or cleaning method, operator
maintenance, and the environmental conditions within the processing
medium; thus, probe operators familiar with their unique uses and
processes are best equipped to predict the lifespans of their
respective probes. Currently, however, in bioprocess laboratory and
production settings, it is often easy to lose track of the number
of heat sterilization or cleaning cycles experienced by each
probe.
[0051] Accordingly, there is more than one probe design currently
on the market that is configured to detect and record
steam-in-place sterilization cycles. However, the design of such
probes renders them inoperable during autoclave cycles. In the
current models, the probes must be unplugged and fully powered down
before being placed in an autoclave chamber; as a result, they can
neither detect nor count autoclave cycles. Without being able to
automatically detect and count this widely used sterilization
method, in many bioprocess applications the current generation of
sterilization-counting probes provides little benefit over
conventional probe designs. In addition, probes are often
disconnected from external power sources during steam-in-place
cycles to avoid damaging cables which may come in contact with
steam supply pipes or the hot vessel wall. Probes which require an
external power source to detect and record steam-in-place cycles
will not record the steam-in-place event if the operator
disconnects the probe cables.
[0052] Another existing probe design uses recorded temperature and
time-at-temperature data to self-calculate the length of its
remaining lifespan. However, these calculations can provide probe
lifespan estimates that are not particularly accurate for the
application at hand. This can lead the process operator into a
false sense of safety as he reuses a probe that self-predicts that
it has plenty of lifespan left and then the probe fails. Lifespans
vary across industries and companies and are dependent on nearly
innumerable factors. Additionally, the cost of probe failure, and
thus, the willingness to accept risk of probe failure, varies
across companies.
[0053] Various embodiments disclosed herein may overcome some or
all of the deficiencies mentioned above. The embodiments relate to
devices and methods used to monitor and quantify the usage and
operational fitness of measurement probes by automatically (without
user input) counting heat cycle events experienced by said probes,
even when disconnected from external power supplies. The
measurement devices of various embodiments are each configured to
detect exposure to heat sterilization or hot chemical cleaning
cycles, including autoclave cycles, steam-in-place cycles and/or
clean-in-place cycles, and subsequently maintain an accurate count
of the sterilization or cleaning cycles experienced. With such an
accurate count, laboratory technicians and other probe operators
may be able to easily and efficiently determine when it is time to
order new probes and/or throw away existing probes based on their
own unique experience with that particular bioprocess application.
There is currently no commercial probe in the bioprocess industries
that can automatically count and record to memory the number of
autoclave cycles that it has experienced. The preferred embodiments
disclosed herein provide an accurate count of the heat cycles
completely automatically and with no operator input or assistance.
It is completely automated. These preferred devices also improve
the accuracy of the heat cycle count for probes undergoing
steam-in-place and clean-in-place procedures. These devices enable
accurate heat cycles counts for probes even when not connected to
associated instrumentation for any heat cycle procedure.
[0054] As shown in FIG. 1, the measurement device 100 of various
embodiments includes at least a measurement probe 102, a condition
responsive element 106, and an heat cycle detection unit 108. The
measurement probe 102 includes a sensor 104 configured to detect a
characteristic of a medium and generate an electrical measurement
signal, typically an analog signal. The sensor 104 can be any
electrochemical sensor known to those skilled in the art. For
example, in some embodiments, the sensor 104 is a pH sensor, a
temperature sensor, a dissolved oxygen sensor, or a combination
thereof. The measurement probe 102 can be amperometric,
potentiometric, optical, capacitive, conductive, or any other
suitable probe type known to those skilled in the art.
[0055] In various embodiments, the condition responsive element 106
is in the form of a temperature responsive element or an
atmospheric pressure responsive element. In the simplest
embodiments, the condition responsive element 106 is a mechanical
switch or other element that undergoes a physical transformation in
response to an environmental trigger. For example, in some
embodiments, the condition responsive element 106 is a bimetallic,
strip (also referred to as a thermostat or thermal switch) or a
shape memory alloy, such as, for example, nickel-titanium
(Nitinol), which undergoes a physical change in shape when the
temperature rises above a certain threshold. In some embodiments,
the materials are selected and configured such that the physical
change occurs within a temperature range of 50 to 120 degrees
Celsius, and more preferably, within a range of 100 to 115 degrees
Celsius and any sub-range or value therebetween. For example, the
physical transformation may occur at 50.degree. C., 55.degree. C.,
60.degree. C., 65.degree. C., 70.degree. C., 75.degree. C.,
80.degree. C., 85.degree. C., 90.degree. C., 91.degree. C.,
92.degree. C., 93.degree. C., 94.degree. C., 95.degree. C.,
96.degree. C., 97.degree. C., 98.degree. C., 99.degree. C.,
100.degree. C., 101.degree. C., 102.degree. C., 103.degree. C.,
104.degree. C., 105.degree. C., 106.degree. C., 107.degree. C.,
108.degree. C., 109.degree. C., 110.degree. C., 111.degree. C.,
112.degree. C., 113.degree. C., 114.degree. C., 115.degree. C.,
116.degree. C., 117.degree. C., 118.degree. C., 119.degree. C., or
120.degree. C.
[0056] In other embodiments, the condition responsive element 106
is an integrated thermal switch or pressure switch, which opens or
closes an electrical contact when a threshold temperature or
pressure, respectively, has been reached. The threshold temperature
may be within the range disclosed above. The threshold pressure may
be within a range of 10 to 60 psi, and preferably, within a range
of 15 to 45 psi. The threshold pressure may include any sub-range
or value therebetween, including, for example, 15 psi, 16 psi, 17
psi, 18 psi, 19 psi, 20 psi, 21 psi, 22 psi, 23 psi, 24 psi, 25
psi, 26 psi, 27 psi, 28 psi, 29 psi, 30 psi, 31 psi, 32 psi, 33
psi, 34 psi, 35 psi, 36 psi, 37 psi, 38 psi, 39 psi, 40 psi, 41
psi, 42 psi, 43 psi, 44 psi, or 45 psi.
[0057] In still other embodiments, the condition responsive element
106 is an electrical element, such as a resistive element, which
produces a change in the electrical signal at least when a
threshold value is reached. In some such embodiments; the threshold
value may be any of the threshold temperatures and pressures
disclosed above. The condition responsive element 106 of some
embodiments is, for example, a positive temperature coefficient
thermistor, switching PCT thermistor, or other thermistor, a
resistance temperature detector (RTD), a piezoelectric pressure
sensor, an electromagnetic pressure sensor, a capacitive pressure
sensor, a piezoresistive strain gauge, or any other suitable
electrical component known to those skilled in the art.
[0058] The heat cycle detection unit 108 preferably includes at
least a detection module, a data memory, and a data interface 112.
In FIG. 1, the detection module and data memory are not
individually visible; however, they are preferably printed on
stacked circuit cards 110. The detection module of some embodiments
is a general purpose processor. In other embodiments, it is a
Digital Signal Processor (DSP), an Application Specific Integrated
Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other
programmable logic device, discrete gate or transistor logic,
discrete hardware components, or any combination thereof designed
to perform the functions described herein. A general purpose
processor may be a microprocessor, but in the alternative, the
processor may be any processor, controller, microcontroller, or
state machine. A detection module may also be implemented as a
combination of computing devices.
[0059] The data memory may include Random Access Memory (RAM),
flash memory, Read Only Memory (ROM), Electrically Programmable ROM
(EPROM), Electrically Erasable Programmable ROM (EEPROM),
registers, hard disk, a micro-secure digital (SD) card or other
removable disk, or any other suitable form of storage medium known
in the art. The data memory is coupled to the detection module such
that the module can read information from, and write information
to, the data memory. In some but not all embodiments, the data
memory is integral to the detection module. The detection module
and the data memory of some embodiments reside in an ASIC. In
alternative embodiments, the detection module and the data memory
reside as individual discrete components.
[0060] Continuing with FIG. 1, the data interface 112 allows for
the communication of signals and information from the detection
module to a data output. In some embodiments, the detection module
conditions and/or transforms electrical signals before they reach
the data interface 112. Consequently, the data interface 112 of
various embodiments transmits analog and/or digital signals. The
data interface 112 of some embodiments includes one or more radio
frequency transmitters, other wireless transmitters, couplers,
universal serial buses (USB) and/or other data buses. In FIG. 1,
the data interface 112 comprises an eight-pin connector configured
to physically and electrically couple to an external transmitter
and power supply (not shown). In some embodiments, the measurement
device 100 includes an output component, such as, for example, a
display screen or signal lights, to display processed data to a
user. In other embodiments, the measurement device 100 transmits
the data to an external display screen or other output device via
near-field communications, radio frequency signals, Bluetooth
signals, or other wireless signals, or through a physical
electrical connection (e.g., electrical wires, cables, or connector
pins) or a contactless inductive coupling interface (see e.g. DE
19540854A1, DE 4344071A1, and U.S. Pat. Nos. 7,785,151, 6,705,898,
6,476,520; each of which is incorporated herein by reference in its
entirety and for disclosure thereof). The data output of various
embodiments includes, preferably, a count of autoclave cycles
and/or total sterilization or cleaning cycles experienced by the
device as well as probe serial ID number, manufactured date, and
other meta data useful to the operator.
[0061] In some embodiments, the heat cycle detection unit 108
additionally includes a protective housing 114 or other casing that
wholly or partially surrounds at least some of the electronic
components of the measurement device 100. The housing 114 of FIG. 1
is configured to withstand high temperatures, such as, for example,
at least temperatures up to 140 degrees Celsius, and/or from steam
and moisture. The housing 114 may be further configured to protect
the electronic components disposed within the housing from such
temperatures and/or moisture. In the embodiment of FIG. 1, the
housing 114 encases stacked circuit cards 110 on which the
detection module and the data memory are printed. Additionally, in
FIG. 1, the housing 114 includes a plurality of glass or
plastic-covered windows 116. The windows are designed to permit the
entrance of light into the interior of the housing. In such
embodiments, one or more photodiodes or photovoltaic cells (not
visible in FIG. 1) are included in the heat cycle detection unit
108 to convert light energy into current or voltage. As described
in more detail below, the photodiodes and photovoltaic cells are
coupled to batteries and/or capacitors within the system to help
replace leaking current or charge. In some embodiments, the windows
116 are covered by a clear plastic or other suitable transparent
material. Other embodiments include no windows or only one
transparent window.
[0062] In some embodiments, such as the embodiment depicted in FIG.
1, the measurement probe 102 and the heat cycle detection unit 108
are fixedly connected. In other embodiments, the measurement probe
102 and the heat cycle detection unit 108 are separably coupled. In
some such embodiments, the heat cycle detection unit forms, or is
positioned within, a removable cap. In other embodiments, the heat
cycle detection unit is positioned within a separate transmitter or
dongle.
[0063] The measurement device 100 of FIG. 1 further includes a
vessel-coupling element 118. The vessel-coupling element 118 is
configured to interact with, and securely connect to, a receiving
port in a processing vessel (not shown). Such receiving ports may
be positioned on the side or in the lid of a processing vessel or
in a pipe or channel that is fluidly connected to the processing
vessel. In FIG. 1, the measurement device 100 couples to processing
vessels via complementary threading. In other embodiments, a snap
fit or other suitable connection means is used. Once connected, a
distal portion 120 of the measurement device 100, comprising at
least the sensor 104, is positioned within an interior of the
processing vessel. A proximal portion 122 of the measurement device
100, comprising at least the data interface 112, is positioned
outside the processing vessel.
[0064] Many of the steps of a method or algorithm and functions
described in connection with the embodiments disclosed herein may
be embodied directly in hardware, in a software module executed by
a processor, or in a combination of the two. All such embodiments
are contemplated and incorporated into use of the term: detection
module. If implemented in software, the functions may be stored on,
or transmitted over as, one or more instructions or code on a
tangible, non-transitory computer-readable medium.
[0065] The steps the detection module is configured and/or
programmed to perform include: detecting a sterilization or
cleaning event using the condition responsive element, recording
detection of the sterilization or cleaning event in the data
memory, and automatically powering off the heat cycle detection
unit if the heat cycle detection unit is still on and the detected
sterilization or cleaning event includes an autoclave cycle. The
logic and processes needed to perform these functions are described
in more detail below.
[0066] In a basic embodiment, such as the embodiment depicted
schematically in FIG. 2, the measurement device 200 includes a
sensor 204 and a condition responsive element 206 positioned
within, or coupled to, a measurement probe 202. The device also
includes a heat cycle detection unit 208, which is preferably
positioned within a transmitter, dongle, or removable cap. In some
embodiments, the condition responsive element 206 is located in the
heat cycle detection unit 208, rather than the measurement probe
202. In some embodiments, the heat cycle detection unit 208 is
physically separable from the measurement probe 202. The heat cycle
detection unit 208 includes a detection module 209, a data memory
211, and an interface 212. In one method of using the measurement
device 200 of FIG. 2, the measurement probe 202 is disconnected
from the heat cycle detection unit 208 and from any power source
prior to being placed within an autoclave. Autoclaving is then
initiated. The condition responsive element 206 deforms or
otherwise changes shape in response to the temperature or pressure
in the autoclave increasing to near or above a certain threshold.
The set threshold for a given condition responsive element 206 is
determined by the materials and configuration of the condition
responsive element 206. The condition responsive element 206 may
have a range of a few degrees within which it undergoes
deformation. In some such embodiments, the condition responsive
element 206 is a bimetallic strip or a shape memory alloy that
deforms in response to an increase in temperature. In some
embodiments, when the condition responsive element 206 deforms, it
or another movable member in contact with the condition responsive
element 206 mechanically locks into a second position, remaining in
the second position even as the temperature drops. In one
embodiment of the method, after the autoclaving is complete, the
measurement probe 202 is removed from the autoclave and connected
to the heat cycle detection unit 208. During or upon connection to
the measurement probe 202, the heat cycle detection unit 208
detects the presence of an element locked in a second position. The
heat cycle detection unit 208 resets the element, causing the
element to move back to a first position, and the detection module
209 stores a sterilization or cleaning cycle (e.g. autoclave cycle)
count in the data memory 211. Although in some embodiments the heat
cycle detection unit comprises an atmospheric pressure responsive
element, and thus the heat cycle detection unit is responding to
atmospheric rather than temperature events, those of skill in the
art will understand that the change in atmospheric pressure within
the probe is associated with an autoclave cycle and also signals
that a heat cycle has occurred.
[0067] FIG. 3A provides a schematic of another measurement device
embodiment.
[0068] In FIG. 3A, the measurement device 300 includes a
measurement probe 302 having a sensor 304 and a condition
responsive element 306. In some embodiments, the condition
responsive element 306 is located in the heat cycle detection unit
308, rather than the measurement probe 302. The sensor 304 is
electrically coupled to a measurement interface 305 configured to
provide probe operators with information about the environmental
condition being sensed by the measurement probe 302. The condition
responsive element 306 is electrically connected to a heat cycle
detection unit 308, which includes a detection module 309, a data
memory 311, a capacitor 313, and an interface 312. In some
embodiments, the interface 312 and interface 305 are the same
interface.
[0069] A method of operations for the measurement device embodiment
of FIG. 3A, is shown in the flowchart of FIG. 3B. When describing
the functions of specific components, reference numbers from FIG.
3A will be used. At block 331, the measurement device 300 is
disconnected from an external power supply, causing the detection
module 309 to power down. The measurement device 300 can then be
placed in an autoclave chamber and subjected to the high
temperatures and pressures of an autoclave cycle. At block 332, the
condition responsive element 306, which is in the form of a
mechanical thermal switch or pressure switch, moves or deforms at a
set threshold temperature or pressure value, respectively, with the
set threshold value determined by the physical and chemical
properties of the switch 306. The deformation/movement of the
switch 306 closes an electrical contact within a circuit. As shown
at block 333, the closing of the electrical contact within the
circuit causes a capacitor or similar charge storage unit 313 to
drain. In some embodiments, the switch 306 returns to a first,
non-deformed position when the temperature or pressure falls below
the threshold value, which returns the circuit to its first state.
The capacitor remains drained until the measurement device 300 is
reconnected to a power supply and additional current flows to the
capacitor 313, As shown in block 334, after the measurement device
300 is reconnected to a power supply, the detection module 309
powers back on and detects the discharged capacitor 313. In
response, as shown in block 335, the detection module 309 updates a
count of heat cycle events and saves the updated count to the data
memory 311.
[0070] An additional embodiment of a measurement device is depicted
schematically in FIG. 4A. As in the previous embodiment, the
measurement device 400 includes a measurement probe 402 having a
sensor 404 electrically coupled to a measurement interface 405 and
a condition responsive element 406 electrically coupled to a heat
cycle detection unit 408. In some embodiments, the condition
responsive element 406 is located in the heat cycle detection unit
408, rather than the measurement probe 402. The heat cycle
detection unit 408 includes a detection module 409, a data memory
411, and an interface 412. In the present embodiment, the detection
module 409 is preferably a microprocessor programmed to control the
heat cycle detection unit 408 and programmed to transform analog
signals received from the condition responsive element 406 to
digital signals. The interface 412 is preferably a wireless
transmitter configured to output wireless signals, such as, for
example, near-field communication, Bluetooth, Wi-Fi, or
radiofrequency signals. The interface 412 of some embodiments
includes multiple wireless transmitters capable, of outputting
multiple forms of wireless signals. In some embodiments, the
wireless signals are received by, and displayed on, a handheld
device having a display screen. Additionally or alternatively, the
interface 412 of some embodiments includes a data bus for wired
digital outputs. In some embodiments, the interface 412 and
interface 405 are the same interface.
[0071] In FIG. 4A, the capacitor 313 of FIG. 3A has been replaced
with a battery 413. In other embodiments, the measurement device
includes both a battery and a capacitor. In the depicted
embodiment, the battery 413 is part of the heat cycle detection
unit 408, disposed within a housing unit 414. In other embodiments,
the battery 413 is electrically coupled to the detection module 409
but physically separable from the heat cycle detection unit 408, In
some embodiments, the battery 413 is readily accessible to
facilitate battery replacement. In some embodiments, the battery in
FIG. 4A is a rechargeable battery. In other embodiments, a
disposable battery is used. The battery 413 functions as a portable
power source, thereby allowing at least some of the electronics
within the measurement device 400 to remain powered when the device
400 is disconnected from an external power source. Consequently,
the heat cycle detection unit 408 is configured to continue
functioning when the measurement device 400 is placed within an
autoclave chamber, or otherwise disconnected from an external power
source, e.g. during a steam-in-place cycle. The embodiment of FIG.
4A additionally includes a power-gathering system 415. The
power-gathering system 415 can include any portable element capable
of converting energy from light into voltage or current, such as,
for example, a photodiode or a photovoltaic cell. In the embodiment
of FIG. 4A, a photodiode 415 is included to trickle charge the
battery 413 to help maintain charge in the system.
[0072] FIG. 4B provides a flowchart depicting a method of counting
exposures to sterilization or cleaning cycles performed by the
detection module 409 of FIG. 4A. At block 440 the probe is
disconnected from the external power supply and the internal
battery continues to power the device. At block 441, the detection
module 409, which is electrically coupled to the condition
responsive element 406, receives a modified signal from the
condition responsive element 406. In the embodiments of FIGS.
4A-4B, the condition responsive element 406 is an electrical
resistive element, for example, a thermistor or RTD, which
experiences significant changes in resistance with changing
temperature. In other embodiments, the condition responsive element
406 is an atmospheric pressure sensor, which generates a changed
signal, for example, due to a change in resistance or inductance,
as the surrounding pressure changes. The detection module 409 of
various embodiments is configured to detect changes in the received
signal. The detection module 409 is also programmed to determine,
using known equations, when the changed signal indicates that a
select threshold temperature or pressure has been reached.
[0073] In other embodiments (not shown), the condition responsive
element is a condition responsive circuit that includes a thermal
or pressure switch. In some such embodiments, when the temperature
or pressure rises near or above a threshold level, the thermal
switch or pressure switch changes state, causing the condition
responsive circuit to open. The detection module (which receives
power from a battery to which it is connected via an alternate
circuit), detects the cessation of current in the condition
responsive circuit. In other such embodiments, when the temperature
or pressure rises near or above a threshold level, a thermal switch
or pressure switch changes state, causing a condition responsive
circuit to close. The detection module (which receives power from a
battery to which it is connected via an alternate circuit), detects
the flow of current in the condition responsive circuit. Through
such mechanisms, the detection module, in effect, detects that the
threshold temperature or pressure value has been reached.
[0074] As shown at block 442 and 443, when the detection module 409
detects that the threshold temperature or pressure has been
reached, the count of heat cycle events is updated and saved in the
data memory 411. In some embodiments, the detection module 409
increments a counter and stores the new count within the data
memory 411. In other embodiments, the detection module 409 stores
the date, and optionally the time, of heat cycle (e.g. autoclave)
detection in the data memory 411.
[0075] To protect the circuitry from extreme temperatures and
pressures, the detection module 409 then optionally powers down, as
shown at block 444 (if the circuitry of the device can operate
under high temperature/pressure, the device need not power down).
To better protect the circuitry, in some embodiments, a threshold
temperature or pressure is selected that is lower than the ranges
described above. For example, in biotechnology, measurement probes
are often used to monitor processes occurring at a temperature
range around 37 degrees Celsius, such as, for example, 35-40
degrees Celsius. In such industries, measurement devices may be
selected having a threshold temperature of 60-70 degrees Celsius,
for example. It will be appreciated by those having ordinary skill
in the art that any threshold temperature or pressure may be
selected for counting sterilization or cleaning cycles that is
above the maximum temperature or pressure experienced by the
measurement device during normal (non-sterilization or cleaning)
operations.
[0076] An additional embodiment of a measurement device is depicted
schematically in FIG. 5A. As in the previous embodiment 4A, the
measurement device 500 includes a measurement probe 502 having a
sensor 504 electrically coupled to a measurement interface 505 and
a condition responsive element 506 electrically coupled to a heat
cycle detection unit 508. In some embodiments, the condition
responsive element 506 is located in the heat cycle detection unit
508, rather than the measurement probe 502. The heat cycle
detection unit 508 includes a detection module 509, a data memory
511, and an interface 512. In the present embodiment, the detection
module 509 is preferably a microprocessor programmed to control the
heat cycle detection unit 508. The interface 512 is preferably a
wireless transmitter configured to output wireless signals, such
as, for example, near-field communication, Bluetooth, Wi-Fi, or
radiofrequency signals. The interface 512 of some embodiments
includes multiple wireless transmitters capable of outputting
multiple forms of wireless signals. In some embodiments, the
wireless signals are received by, and displayed on, a handheld
device having a display screen (not shown). Additionally or
alternatively, the interface 512 of some embodiments includes a
data bus for wired digital outputs. In some embodiments, the
interface 512 and interface 505 are the same interface.
[0077] In FIG. 5A, the capacitor 313 of FIG. 3A has been replaced
with a battery 513 and a capacitor or similar charge storage
element 514. In the depicted embodiment, the battery 513 is part of
the heat cycle detection unit 508, disposed within a housing unit
515. In other embodiments, the battery 513 is electrically coupled
to the detection module 509 but physically separable from the heat
cycle detection unit 508. In some embodiments, the battery in 513
is readily accessible to facilitate battery replacement. In some
embodiments the battery in FIG. 5A is a rechargeable battery. In
other embodiments, a disposable battery is used. The battery 513
functions as a portable power source, thereby allowing at least
some of the electronics within the measurement device 500 to power
up on its own when the device 500 is disconnected from an external
power source. Consequently, the heat cycle detection unit 508 is
configured to power on when the measurement device 500 is placed
within an autoclave chamber (or otherwise disconnected from and
external power source) and the condition responsive element 506
changes state when it exceeds its threshold limit.
[0078] FIG. 5B provides a flowchart depicting a method of counting
exposures to sterilization or cleaning cycles performed by the
detection module 509 of FIG. 5A. At block 550 the device has been
disconnected from an external power source whereupon the device
automatically powers down. At block 551, the condition responsive
element 506, in this embodiment a thermal switch, changes state in
response to the temperature rising above the threshold value. This
change in state closes the thermal switch which in turn supplies
internal battery power 513 to the detection module 509 and the
memory 511 and begins charging capacitor 514. At block 552 the
detection module 509 increments the heat cycle counter, and saves
the new number in memory 511. In block 553 the capacitor has now
completely charged and this causes power to be shut off to the
detection module and memory which in turn saves battery power and
protects the microprocessor in 509 and other components of the
detection unit 508 from operating in the excessive heat of an
autoclave cycle. In block 554, heat event ends, the probe's
temperature sinks back down past the threshold value of the thermal
switch 506, the switch changes back to its original open state, the
battery is disconnected from the circuit, and the capacitor
discharges. As a result of the automatic actions in block 554 the
device is now in a state represented by block 555 where the device
is now off, conserving the battery 513, and ready to automatically
and autonomously auto-start again when the next heat cycle
begins.
[0079] FIG. 6A provides a schematic of another embodiment of a
measurement device 600 having a battery 613 and a heat cycle
detection unit 608. The heat cycle detection unit 608 includes a
detection module 609, a data memory 611, and an interface 612. As
in previous embodiments, the measurement device 600 also includes a
measurement probe 602 with a sensor 604 electrically coupled to a
measurement interface 605. In other embodiments, the sensor 604 is
electrically coupled to the detection module 609. In such
embodiments, the detection module 609 is configured to amplify the
signal received from the sensor 604 and convert it to a digital
output. The digital output can then be provided to an output device
via the interface 612 in a similar manner as the sterilization or
cleaning count data that is transmitted to an output device via the
interface 612. In addition, in some embodiments a capacitor or
other charge storage unit (not shown) is included and functions as
described in FIG. 5.
[0080] The measurement device 600 of FIG. 6A also has a vessel
coupling device 618, which is configured to secure the measurement
device 600 to a perimeter wall or lid (i.e., the body) of a
processing vessel. In various embodiments, the measurement device
600 is secured to the body of a processing vessel such that a
distal portion 620 of the measurement device 600 is disposed within
an interior cavity of the vessel and a proximal portion 622 of the
measurement device 600 is positioned outside the vessel.
[0081] In some embodiments, the measurement device includes only
one condition responsive element. In such embodiments, if the
condition responsive element is positioned on or within a proximal
portion of the measurement device, it will not be subjected to, nor
respond to, temperature or pressure changes that occur within the
processing vessel. Consequently, if a steam-in-place cycle or
clean-in-place cycle is run within the processing vessel, the
condition responsive element will not respond, and the
sterilization or cleaning cycle will not be counted. In contrast,
autoclaving requires placement of the entire measurement probe
within an autoclave chamber. Consequently, even condition
responsive elements positioned on or within a proximal portion of
the measurement device will experience the elevated temperatures
and pressures of an autoclave cycle. Thus, when a condition
responsive element is only positioned within a proximal portion of
the measurement device, the measurement device is tailored to
count, specifically, autoclave cycles.
[0082] Conversely, if only one condition responsive element is
present and positioned on or within a distal portion of the
measurement device, the condition responsive device will be
subjected to any elevated temperatures and pressures that occur
within the processing vessel as well as elevated temperatures and
pressures that occur while the measurement device is disposed
within an autoclave chamber. In such embodiments, the measurement
device is configured to detect and count multiple forms of
sterilization or cleaning cycles. Each detected cycle is counted
and stored in memory as a generic sterilization or cleaning
cycle.
[0083] In some measurement device embodiments, such as the
embodiment of FIG. 6A, the measurement device 600 includes both a
condition responsive element 606 positioned on or within the distal
portion 620 and a condition responsive element 607 positioned on or
within the proximal portion 622. Such embodiments may be configured
to detect and count multiple forms of heat cycles and distinguish
between the various forms.
[0084] A method of detecting, distinguishing, and counting various
forms of sterilization or cleaning is provided in the flowchart of
FIG. 6B. As shown in block 660, the detection module 609 receives a
modified signal from a condition responsive element 606 or 607 as
the temperature or pressure rises. From the modifications in the
signal, the detection module 609 determines when a threshold
temperature or pressure has been reached, as shown in block 661. In
block 662, the detection module 609 determines whether the modified
signal is being received from the proximal condition responsive
element 607. If it is, then the entire measurement device 600 is
being subjected to an elevated temperature and/or pressure, and one
can conclude that the measurement device 600 is in an autoclave
chamber undergoing an autoclave cycle. In such cases, the detection
module 609 is programmed to update a count of autoclave cycles
(and/or a count of generic sterilization or cleaning cycles) as
indicated in block 666, save the updated count in the data memory
611 as indicated in block 667, and optionally power down the
detection module 609 to protect the electronics in the heat cycle
detection unit 608, as indicated in block 668.
[0085] If the detection module 609 determines that the modified
signal is not being received from the proximal condition responsive
element 607, (and thus, is instead coming from only the distal
condition responsive element 606), the detection module 609 is
programmed to update a count of steam-in-place cycles (and/or a
count of generic sterilization or cleaning cycles) as indicated in
block 663, and save the updated count in the data memory 611 as
indicated in block 664. The detection module 609 may optionally be
programmed to power down in response to detecting the heat cycle,
although such programming is not necessary for steam-in-place
cycles when the heat cycle detection unit electronics are located
outside the processing vessel.
[0086] FIG. 7A schematically depicts an embodiment of a measurement
device 700 configured to detect clean-in-place cycles, along with,
preferably, autoclave cycles. The provided measurement device 700
includes a heat cycle detection unit 708 having an interface 712, a
data memory 711, a detection module 709, and a battery 713. The
measurement device 700 also includes a measurement probe 702 having
a pH sensor 704 disposed on or within the probe 702. The pH sensor
704 of the current embodiment is electrically coupled to the heat
cycle detection unit 708. In some embodiments, the pH sensor 704 is
provided to help detect clean-in-place cycles, and the measurement
probe 702 includes one or more other sensors configured to sense a
condition of the processing medium. In other embodiments, the pH
sensor 704 serves as both the primary sensor of the measurement
probe 702 and the sensor used during detection of clean-in-place
cycles, and thus may be coupled to an interface (not shown) which
is used during normal operation for monitoring pH levels.
[0087] In FIG. 7A, a vessel coupling device 718 is permanently or
separably affixed to an outer portion of the measurement probe 702.
A first temperature responsive element 706 is positioned on or
within a distal portion 720 of the measurement device 700, and a
second condition responsive element 707 is positioned on or within
a proximal portion 722 of the measurement device 700.
[0088] FIG. 7B depicts one embodiment of a method performed by the
measurement device of FIG. 7A when counting clean-in-place and
other heat cycle events. The detection module 709 receives signals
from the condition responsive elements 706 and 707, and the signals
change as the temperature or pressure increases and/or crosses a
threshold. As shown in blocks 770 and 771, detection module 709
receives a modified signal from a condition responsive unit, and
from the signal, determines when a threshold value has been
reached. The detection module 709 also performs the operation in
block 772 to determine if the modified signal was received from the
proximal condition responsive element 707. If it was, then the
detection module 709 follows the autoclave detection protocol
described previously. As shown in blocks 773-775, the detection
module 709 updates a count of autoclave cycles, saves the updated
count to the data memory 711, and optionally powers down (if the
circuitry of the device can operate under high
temperature/pressure, the device need not power down). If the
modified signal was not received from the proximal condition
responsive element 707, (and thus, is instead coming from only the
distal condition responsive element 706), the detection module 709
processes signal inputs from the pH sensor 704. In block 776, the
device determines if any measurement reading from the pH sensor 704
exceeds a clean-in-place pH threshold within a defined time period,
a clean-in-place detection protocol is performed (blocks 777-778).
If no pH reading exceeds the clean-in-place threshold during the
defined time period, the steam-in-place detection protocol is
performed (block 779-780). The clean-in-place protocol, shown in
blocks 777 and 778, involves updating a count of clean-in-place
cycles and saving the updated count to the data memory 711.
Similarly, the steam-in-place protocol, shown in blocks 779 and
780, includes updating a count of steam-in-place cycles and saving
the updated count to the data memory 711. The detection module 709
can further be optionally programmed to shut down in response to
detection of a steam-in-place cycle and/or a clean-in-place
cycle.
[0089] In some embodiments, the clean-in-place threshold is at
least 60 degrees Celsius and less than 100 degrees Celsius.
Typically, the clean-in-place threshold is between 65 and 90
degrees Celsius, and it can include any sub-range or individual
value within that disclosed range, including 65, 70, 75, 80, 85 and
90 degrees Celsius. In some embodiments, the pH threshold is within
the ranges of either 9 to 14 pH or 1 to 4 pH and may be any
sub-range or individual value therebetween. For example, the
clean-in-place pH threshold of some embodiments is 9, 10, 11, 12,
13, or 14. In some embodiments, the defined period of time is
between about 30 seconds and about 5 minutes, and includes any
sub-range or individual value therebetween, including 0.5-4, 0.5-3,
0.5-2, 1-5, 1-4, 1-3, 1-2, 2-5, 2-4, and 2-3 minutes. The defined
period of time includes both the about 30 seconds to about 5
minutes preceding the temperature-threshold-reaching event and the
about 30 seconds to about 5 minutes following the
temperature-threshold-reaching event.
[0090] In some embodiments of a measurement device, the measurement
device can both automatically power up (i.e., auto-start) and
automatically power itself off at certain points in a heat
sterilization or cleaning, or autoclave cycle. This auto-start
feature may advantageously provide for more accurate counting of
heat cycles as well as provide better power management of the
battery and thus longer shelf life of the probe. For example,
without an auto-start feature, if multiple successive heat cycles
are performed on a measurement device without turning it on between
cycles, only one cycle will be counted. In some embodiments, that
cycle is counted during the cycle, just prior to the measurement
device shutting down. In other embodiments, a cycle is counted when
the measurement device powers back on, for example, by detecting a
drained capacitor. By either method it is desirable to have the
probe automatically self-start whenever a heat cycle begins again.
By automatically powering back on as a cycle starts, the
measurement device of the current embodiment is ready to detect and
count each new cycle that occurs. By use of a thermal switch as a
condition responsive element the device can be configured to
auto-start each time there is a new heat cycle. Furthermore, since
the device can auto-start at the beginning of the heat cycle, there
is no need to keep it on after the counter is incremented and the
device can shut itself off for the remainder of the cycle to
conserve the battery and protect the microprocessor from excessive
heat.
[0091] Measurement device embodiments that perform the method of
FIG. 8 include an integral power supply, such as a battery. In some
embodiments, both a battery and a capacitor are included. In some
embodiments the power supply is augmented by a portable power
supply such as an attachable battery. In block 880 the device is in
a state of complete power down. The device is disconnected from the
external power supply and the internal battery power is turned off.
In block 881 the condition responsive element changes state at a
pre-determined temperature threshold, discharges a capacitor, and
switches power on to the device. In block 882 the detection module
detects that the capacitor has been discharged and this signals
that a heat cycle has begun. In block 883 the count is incremented
by 1 in memory and saved. In block 884 the device powers off the
microprocessor for it to better endure the extreme temperatures of
an autoclave cycle and to conserve the internal battery. In block
885 the probe's temperature cools to below the temperature
threshold of the condition responsive device, the element's state
changes back and the device's capacitor is recharged from the
battery. In block 886 the device is once again completely powered
down and ready to automatically count the next heat cycle.
[0092] Another method performed by some embodiments of a
measurement device is provided in the flowchart of FIG. 9. In the
depicted method, the measurement device can both automatically shut
itself off and automatically turn itself back on (i.e., auto-start)
at certain points in a heat sterilization or cleaning, e.g.,
autoclave cycle.
[0093] Measurement device embodiments that perform the method of
FIG. 9 include a portable power supply, such as a battery. In some
embodiments, both a battery and a capacitor are included. In block
990 at least the heat cycle detection portion of the device is
powered on. As shown in blocks 991-994, the detection module of
such measurement devices detects that a threshold temperature or
pressure has been reached, updates a count of heat cycle event
(e.g. autoclave), saves the updated count in the data memory, and
optionally powers down (if the circuitry of the device can operate
under high temperature/pressure, the device need not power down).
In one embodiment, a thermal or pressure switch is used. When a
threshold temperature or pressure is reached, the switch physically
deforms and opens a circuit connecting the switch, capacitor,
battery, and detection module. When this occurs, the battery no
longer provides voltage and current to the detection module, and
the capacitor or other charge storage unit begins to drain. The
detection module receives current from the draining capacitor long
enough to detect the opened switch and record the occurrence of a
heat cycle event (sterilization or cleaning) in the data memory.
The detection module powers down as the current wanes. As shown in
block 995, when the temperature or pressure falls below a second
threshold value (also referred to as a power-on temperature or
pressure), the switch returns to its first, non-deformed position,
which completes the circuit. Charge and voltage from the battery
are again delivered to the detection module, and the detection
module turns back on. In embodiments having one universal switch
that functions to both power off and power on the detection module,
the first threshold value and second threshold value are generally
equal. Shape memory materials and bimetallic strips are generally
configured to deform and reform to their original shapes at
substantially similar or equal temperatures.
[0094] In an alternative embodiment, the detection module may
perform blocks 991-994 in response to receiving a changing signal
from an electrical condition responsive element. From the change in
signal, the detection module is configured to calculate/detect that
a first threshold value has been reached. In such an embodiment, a
second condition responsive element in the form of a mechanical
switch is included in a second circuit in the measurement device.
The detection module is configured to automatically power up, as
recited in block 995, when the mechanical switch changes state and
closes an electrical contact in the second circuit. This occurs
when a second threshold value is reached. In such embodiments, the
first threshold value may be the same or different than the second
threshold value. In some embodiments, the counter increments after
the heat cycle ends, rather than at the start of the heat
cycle.
[0095] FIG. 10 depicts a circuit diagram of one embodiment of a
heat cycle detection unit. This particular embodiment automatically
detects and records heat cycles according to the embodiment
described with reference to FIG. 5B. FIG. 11 is a schematic of a
circuit diagram of one embodiment of a heat cycle detection
unit
[0096] The various operations and methods described above may be
performed by any suitable means capable of performing the
operations, such as various hardware and/or software component(s),
circuits, and/or module(s). Generally, any operations illustrated
in the Figures may be performed by corresponding functional means
capable of performing the operations.
[0097] Information and signals may be represented using any of a
variety of different technologies and techniques. For example,
data, instructions, commands, information, signals, bits, symbols,
and chips that may be referenced throughout the above description
may be represented by voltages, currents, electromagnetic waves,
magnetic fields or particles, optical fields or particles, or any
combination thereof.
[0098] The various illustrative logical blocks, modules, circuits,
and algorithm steps described in connection with the embodiments
disclosed herein may be implemented as electronic hardware,
computer software, or combinations of both. To clearly illustrate
this interchangeability of hardware and software, various
illustrative components, blocks, modules, circuits, and steps have
been described above generally in terms of their functionality.
Whether such functionality is implemented as hardware or software
depends upon the particular application and design constraints
imposed on the overall system. The described functionality may be
implemented in varying ways for each particular application, but
such implementation decisions should not be interpreted as causing
a departure from the scope of the embodiments of the invention.
[0099] For purposes of summarizing the disclosure, certain aspects,
advantages and features have been described herein. It is to be
understood that not necessarily all such advantages may be achieved
in accordance with any particular embodiment. Thus, the invention
may be embodied or carried out in a manner that achieves or
optimizes one advantage or group of advantages as taught herein
without necessarily achieving other advantages as may be taught or
suggested herein.
[0100] While this invention has been described in connection with
what is are presently considered to be practical embodiments, it
will be appreciated by those skilled in the art that various
modifications and changes may be made without departing from the
scope of the present disclosure. It will also be appreciated by
those of skill in the art that parts mixed with one embodiment are
interchangeable with other embodiments; one or more parts from a
depicted embodiment can be included with other depicted embodiments
in any combination. For example, any of the various components
described herein and/or depicted in the Figures may be combined,
interchanged or excluded from other embodiments. With respect to
the use of substantially any plural and/or singular terms herein,
those having skill in the art can translate from the plural to the
singular and/or from the singular to the plural as is appropriate
to the context and/or application. The various singular/plural
permutations may be expressly set forth herein for sake of clarity.
Thus, while the present disclosure has described certain exemplary
embodiments, it is to be understood that the invention is not
limited to the disclosed embodiments, but, on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the scope of the appended claims, and equivalents
thereof.
* * * * *