U.S. patent application number 17/669010 was filed with the patent office on 2022-07-28 for medical methods and systems for skin treatment.
The applicant listed for this patent is R2 Technologies, Inc.. Invention is credited to Michael O'Neil, Jesse Rosen, Kevin Springer, Erik Stauber, Benjamin Sun, Kristine Tatsutani.
Application Number | 20220233345 17/669010 |
Document ID | / |
Family ID | 1000006261685 |
Filed Date | 2022-07-28 |
United States Patent
Application |
20220233345 |
Kind Code |
A1 |
Rosen; Jesse ; et
al. |
July 28, 2022 |
MEDICAL METHODS AND SYSTEMS FOR SKIN TREATMENT
Abstract
The present invention generally relates to improved medical
devices, systems, and methods, with exemplary embodiments providing
improved cooling treatment probes and cooling treatment methods and
systems. In some embodiments, freezing of the skin may be desirable
to effect the hypopigmentation of the skin of the patient.
Generally, embodiments may limit supercooling of the skin of the
patient during a cooling treatment. Additionally, embodiments may
limit adverse side effects such as hyperpigmentation. It has been
found that the freezing behavior (frequency and time to freeze) can
be modified by adjusting the thermal parameters of the cooling
applicator. Accordingly, in some aspects of the invention, a method
of treating the skin may be provided where the thermal parameters
of the cooling applicator are adjusted during treatment.
Inventors: |
Rosen; Jesse; (Albany,
CA) ; Springer; Kevin; (Livermore, CA) ;
Tatsutani; Kristine; (Redwood City, CA) ; O'Neil;
Michael; (Dublin, CA) ; Sun; Benjamin;
(Mountain View, CA) ; Stauber; Erik; (Albany,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
R2 Technologies, Inc. |
San Roman |
CA |
US |
|
|
Family ID: |
1000006261685 |
Appl. No.: |
17/669010 |
Filed: |
February 10, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15612740 |
Jun 2, 2017 |
11266524 |
|
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17669010 |
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62430782 |
Dec 6, 2016 |
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62345303 |
Jun 3, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2007/0086 20130101;
A61H 2201/0257 20130101; A61H 2201/0214 20130101; A61H 2201/0153
20130101; A61H 2230/505 20130101; A61F 2007/0093 20130101; A61F
2007/0087 20130101; A61F 7/007 20130101; A61H 2201/5028 20130101;
A61H 23/008 20130101; A61F 2007/0096 20130101; A61H 2201/5061
20130101; A61H 2201/0285 20130101; A61F 2007/0063 20130101; A61F
7/0085 20130101; A61H 23/0236 20130101; A61F 2007/0075 20130101;
A61H 23/0245 20130101; A61H 23/0263 20130101; A61F 2007/0052
20130101 |
International
Class: |
A61F 7/00 20060101
A61F007/00; A61H 23/00 20060101 A61H023/00 |
Claims
1. (canceled)
2. A skin hypopigmentation treatment system comprising: a cooling
applicator for contacting a skin of a patient; a cooling
arrangement thermally coupled with the cooling applicator; a
controller operably coupled with the cooling arrangement, the
controller configured to control the cooling arrangement to provide
a cooling treatment cycle, the cooling treatment cycle including:
pre-cooling of the cooling applicator to a pre-treatment
temperature prior to contact with the skin of the patient and
cooling of the cooling applicator toward the pre-treatment
temperature for a first duration of time after the cooling
applicator is placed against the skin of the patient to condition
at least an epidermal skin tissue to freeze while minimizing
supercooling; and after the first duration of time and while the
cooling applicator is held against the skin, controllably adjusting
the temperature of the cooling applicator toward a treatment
temperature for a predetermined second duration of time, the
treatment temperature configured to freeze at least the epidermal
skin tissue for hypopigmentation, wherein the treatment temperature
is higher than the pre-treatment temperature and below freezing,
wherein the second duration of time is longer than the first
duration of time, and wherein the second duration of time begins
after termination of the first duration of time.
3. The skin treatment system of claim 2, wherein the pre-treatment
temperature is -10.degree. C. to -20.degree. C.
4. The skin treatment system of claim 3, wherein the treatment
temperature is -2.degree. C. to -10.degree. C.
5. The skin treatment system of claim 2, wherein the second
duration of time is three to ten times longer in duration than the
first duration of time.
6. The skin treatment system of claim 5, wherein the second
duration of time is less than 5 seconds.
7. The skin treatment system of claim 2, wherein the cooling
treatment cycle further includes, after the second duration of time
and while the cooling applicator is placed against the skin,
adjustment of the cooling applicator toward a post-treatment
temperature that is higher than the treatment temperature.
8. The skin treatment system of claim 7, wherein the cooling
applicator comprises a thermoelectric cooler and wherein the
controller adjusts the cooling applicator toward the post-treatment
temperature by reversing a current through the thermoelectric
cooler.
9. The skin treatment system of claim 7, wherein the post-treatment
temperature is above 0.degree. C.
10. The skin treatment system of claim 9, wherein the
post-treatment temperature is less than 10.degree. C.
11. The skin treatment system of claim 2, further comprising a
contact sensor coupled with the controller, the contact sensor
configured to measure a force between the cooling applicator and
the skin of the patient; and wherein the first duration of time or
the second duration of time is automatically adjusted based on the
force measured by the contact sensor.
12. The skin treatment system of claim 2, further comprising a
contact sensor coupled with the controller, the contact sensor
configured to measure a force between the cooling applicator and
the skin of the patient; and wherein the pre-treatment temperature
or the treatment temperature is automatically adjusted based on the
force measured by the contact sensor.
13. The skin treatment system of claim 2, further comprising a
contact sensor coupled with the controller, the contact sensor
configured to determine contact between the cooling applicator and
the skin of the patient, and wherein the controller automatically
initiates the cooling treatment cycle based on skin contact as
determined by the contact sensor.
14. The skin treatment system of claim 13, wherein the contact
sensor comprises a force sensor, optical sensor, IR sensor, or
temperature sensor.
15. The skin treatment system of claim 14, wherein the contact
sensor comprises the force sensor and wherein the skin treatment
system further comprises an orientation sensor configured to sense
an orientation of the skin treatment system and wherein the
controller is configured to adjust a pressure measurement from the
force sensor based on the orientation of the skin treatment system
sensed by the orientation sensor.
16. The skin treatment system of claim 2, further comprising a
contact sensor coupled with the controller, the contact sensor
configured to determine contact between the cooling applicator and
the skin of the patient, and wherein the controller automatically
returns the cooling arrangement to the pre-treatment temperature
when skin contact is not sensed by the contact sensor.
17. The skin treatment system of claim 16, wherein the contact
sensor comprises a force sensor, optical sensor, IR sensor, or
temperature sensor.
18. The skin treatment system of claim 17, wherein the contact
sensor comprises the force sensor and wherein the skin treatment
system further comprises an orientation sensor configured to sense
an orientation of the skin treatment system and wherein the
controller is configured to adjust a pressure measurement from the
force sensor based on the orientation of the skin treatment system
sensed by the orientation sensor.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S.
Non-Provisional patent application Ser. No. 15/612,740, filed Jun.
2, 2017, which claims the benefit of U.S. Provisional Patent Appln.
No. 62/345,303 filed Jun. 3, 2016, and U.S. Provisional Patent
Appln. No. 62/430,782 filed Dec. 6, 2016; the full disclosures of
which are incorporated herein by reference in their entirety for
all purposes.
BACKGROUND
[0002] Embodiments of the present invention generally relate to
methods, devices, and systems for reducing a pigmentation of a skin
of a patient. More specifically, embodiments generally relate to
methods, devices, and systems to increase the consistency of skin
treatment by reliably freezing (water phase transition) the skin
during treatment and limiting adverse side effects from the skin
freezing.
[0003] Controlled freezing of biological tissue, such as skin
tissue, can produce various effects. Certain tissue freezing
procedures and devices, such as conventional cryoprobes, can cause
severe freezing of tissue and generate cellular damage. It has been
observed that moderate degrees of freezing can produce particular
effects, such as affecting the expression of skin pigmentation
(e.g., hypopigmentation).
[0004] There is a demand for cosmetic products that can lighten the
appearance of skin or otherwise controllably affect skin
pigmentation. For example, it may be desirable to lighten the
overall complexion or color of a region of skin to alter the
general appearance for cosmetic reasons. Also, lightening of
particular hyperpigmented regions of skin, such as large freckles,
`cafe au lait` spots, melasma, or dark circles under the eyes that
may result from excessive local amounts of pigment in the skin, may
also be desirable for cosmetic reasons. Hyperpigmentation can
result from a variety of factors such as UV exposure, aging,
stress, trauma, inflammation, etc. Such factors can lead to an
excess production of melanin, or melanogenesis, in the skin by
melanocytes, which can lead to formation of hyperpigmented areas.
Such hyperpigmented areas are typically associated with excess
melanin within the epidermis; however, they can also result from
excess melanin deposited within the dermis.
[0005] Hypopigmentation of skin tissue has been observed as a side
effect in response to temporary cooling or freezing of the tissue,
such as may occur during cryosurgery procedures. Loss of
pigmentation following skin cooling or freezing may result from
decreased melanin production, decreased melanosome production,
destruction of melanocytes, or inhibited transfer of melanosome
into the keratinocytes in the lower region of the epidermal layer.
The resultant hypopigmentation may be long-lasting or permanent.
However, it has also been observed that some of these freezing
procedures can generate regions of hyperpigmentation (or skin
darkening) of skin tissue. The level of increase or decrease in
pigmentation may be dependent upon certain aspects of the cooling
or freezing conditions, including the temperature of the cooling
treatment, and the length of time the tissue is maintained in a
frozen state.
[0006] While some hypopigmentation treatments, devices, and systems
have been previously developed, further improvements may be
desired. Toward this end, it may be desirable to improve the
consistency of skin freezing. Such improvements may be desirable to
improve overall hypopigmentation consistency. For example, with
some cooling treatments, the skin may sometimes freeze toward the
beginning of the cooling treatment, or may sometimes cool to a
temperature below the freezing point (e.g., 0 to -5.degree. C.) for
a period and then freeze some variable time thereafter. With some
cooling treatments, the skin may become supercooled (cooled to a
temperature below the freezing point) and may not freeze at all
during the cooling treatment. Such variability in the skin freezing
(i.e., the formation of water ice in the skin) may result in less
than optimal treatment. Additionally, prolonging treatment and/or
applying colder temperatures is not necessarily a solution as it
may result in adverse side effects such as hyperpigmentation.
[0007] In light of the above, it may be desirable to improve the
consistency or repeatability of hypopigmentation treatments, in
particular hypopigmentation treatments provided via skin freezing.
At least some embodiments of the present invention may provide
additional control over the occurrence of freezing and may limit
supercooling of the skin during a cooling treatment. Additionally,
at least some embodiments may provide skin treatment while limiting
adverse side effects, such as hyperpigmentation.
SUMMARY
[0008] The present invention generally relates to improved medical
devices, systems, and methods, with exemplary embodiments providing
improved cooling treatment probes and cooling treatment methods and
systems. In some embodiments, freezing of the skin may be desirable
to effect the hypopigmentation of the skin of the patient.
Generally, embodiments may limit supercooling of the skin of the
patient during a cooling treatment. Additionally, embodiments may
limit adverse side effects such as hyperpigmentation.
[0009] In some aspects of the present invention, a method of
altering pigmentation in a skin of a patient may be provided. The
method may include pre-cooling a cooling applicator of a treatment
device to a pre-treatment temperature prior to contact of the
cooling applicator with a skin surface of the patient. The
pre-treatment temperature may be colder than a treatment
temperature. After the cooling applicator is positioned onto the
skin surface and while the applicator is maintained against the
skin, the cooling applicator may be driven toward the pre-treatment
temperature for a first duration of time to pre-condition the skin
to freeze. After the first duration of time and while the cooling
applicator is positioned and maintained against the skin surface,
the cooling applicator may be adjusted toward the treatment
temperature for a second duration of time. The treatment
temperature may be configured to freeze at least a portion of the
skin tissue in contact with the cooling applicator.
[0010] In some embodiments, the second duration of time may be
longer than the first duration of time. The treatment temperature
may be below 0.degree. C. The pre-treatment temperature may be in a
range from -10.degree. C. to -20.degree. C. The treatment
temperature may be in a range from -2.degree. C. to -10.degree.
C.
[0011] Optionally, the second duration of time may be three to ten
times longer in duration than the first duration of time. In
certain embodiments, the second duration of time may be less than 5
seconds.
[0012] The method may further include adjusting the cooling
applicator toward a post-treatment temperature that is higher than
the treatment temperature after the second duration of time and
while the cooling applicator is positioned and maintained against
the skin. The post-treatment temperature may be applied so as to
thaw the frozen skin tissue. In some embodiments, a thermoelectric
cooler is thermally coupled with the cooling applicator. Adjusting
the cooling applicator to the post-treatment temperature may
include the step of reversing a current through the thermoelectric
cooler. Optionally, the current may be reversed until the cooling
applicator reaches the post-treatment temperature. In some
embodiments, the post-treatment temperature is above 0.degree. C.
The post treatment temperature may be less than 10.degree. C., or
less than less than 40.degree. C. The cooling applicator may be
maintained in contact with the skin at the post-treatment
temperature until the frozen portion of skin thaws.
[0013] In still further aspects, a method of treating a skin of a
patient may be provided that includes cooling a cooling applicator
of a treatment device to a pre-treatment temperature prior to
contacting the skin with the cooling applicator of the treatment
device. The pre-treatment temperature may be colder than a
treatment temperature. The pre-treatment temperature may be
configured to pre-condition at least a portion of the skin to
freeze. The cooling applicator may then be placed onto the skin and
the treatment device may cool the cooling applicator toward the
pre-treatment temperature during the first duration of time. After
the first duration of time, the cooling applicator may be
maintained against the skin for a second duration of time while the
treatment device adjusts the cooling applicator toward the
treatment temperature. The cooling applicator may be removed from
the skin of the patient after treating the skin to the treatment
temperature using the cooling applicator of the treatment device.
In some embodiments, the second duration of time may be longer than
the first duration of time.
[0014] In still further aspects, a skin treatment system may
include a cooling applicator for contacting a skin of a patient, a
cooling arrangement thermally coupled with the cooling applicator;
and a controller operably coupled with the cooling arrangement. The
controller may be configured to control the cooling arrangement to
provide a cooling treatment cycle. The cooling treatment cycle may
include pre-cooling of the cooling applicator to a pre-treatment
temperature prior to contact with the skin of the patient and
cooling of the cooling applicator toward the pre-treatment
temperature for a first duration of time after the cooling
applicator is placed against the skin of the patient. The cooling
treatment cycle may further include, after the first duration of
time, adjustment of the temperature of the cooling applicator
toward a treatment temperature that is higher than the
pre-treatment temperature while the cooling applicator is held
against the skin and cooling of the cooling applicator toward the
treatment temperature for a second duration of time while the
cooling applicator is held against the skin.
[0015] In some embodiments, the second duration of time may be
longer than the first duration of time. The treatment temperature
may be below zero. The pre-treatment temperature may be -10.degree.
C. to -20.degree. C. Optionally, the treatment temperature may be
-2.degree. C. to -10.degree. C.
[0016] The second duration of time may be three to ten times longer
in duration than the first duration of time. In some embodiments,
the second duration of time may be less than 5 seconds.
[0017] The cooling treatment cycle may further include, after the
second duration of time and while the cooling applicator is placed
against the skin, adjustment of the temperature of the cooling
applicator toward a post-treatment temperature that is higher than
the treatment temperature.
[0018] In some embodiments, the cooling applicator may be a
thermoelectric cooler. The controller may adjust the cooling
applicator toward the post-treatment temperature by reversing a
current through the thermoelectric cooler.
[0019] The post-treatment temperature may be above 0.degree. C. The
post-treatment temperature may be less than 10.degree. C., or less
than 40.degree. C. in certain embodiments.
[0020] In some embodiments, the device may further comprise a force
sensor coupled with the controller. The force sensor may be
configured to measure a force between the cooling applicator and
the skin of a patient. The first duration of time or the second
duration of time may be variable based on the force measured by the
force sensor.
[0021] In some embodiments, the device may further include a force
sensor coupled with the controller. The force sensor may be
configured to measure a force between the cooling applicator and
the skin of a patient. The pre-treatment temperature or the
treatment temperature may be variable based on the force measured
by the force sensor.
[0022] Optionally, the device may include a contact sensor coupled
with the controller. The contact sensor may be configured to
determine contact between the cooling applicator and the skin of
the patient. The controller may initiate the cooling treatment
cycle based on skin contact as determined by the contact
sensor.
[0023] In some embodiments, a contact sensor may be coupled with
the controller. The contact sensor may be configured to determine
contact between the cooling applicator and the skin of the patient.
The controller may return the cooling arrangement to the
pre-treatment temperature when skin contact is not sensed by the
contact sensor.
[0024] In still further aspects, a method of reducing melanin in a
skin of a patient using a cooling applicator of a treatment device
may be provided. The method may include pre-cooling the cooling
applicator to a pre-treatment temperature of -10.degree. C. to
-20.degree. C. prior to positioning cooling applicator in contact
with the skin; cooling the cooling applicator toward the
pre-treatment temperature for a first duration of time after the
cooling applicator has been positioned onto the skin; after the
first duration of time and while the cooling applicator is placed
against the skin, adjusting the cooling applicator toward a
treatment temperature of -2.degree. C. to -12.degree. C. for a
second duration of time that is longer than the first duration of
time; and after the second duration of time and while the cooling
applicator is placed against the skin, adjusting the cooling
applicator toward a post-treatment temperature between 0.degree. C.
to 40.degree. C. In some embodiments, the cooling applicator can be
adjusted toward a treatment temperature of -2.degree. C. to
-10.degree. C. In some embodiments, the cooling applicator can be
adjusted toward a post-treatment temperature between 0.degree. C.
to 10.degree. C. or between 0.degree. C. to 40.degree. C.
[0025] In other aspects, a skin pigmentation treatment system is
provided that may include a cooling applicator for contacting a
skin of a patient; a thermoelectric cooler thermally coupled with
the cooling applicator; and a controller operably coupled with the
thermoelectric cooler. The controller may be configured to control
a current to the thermoelectric cooler to provide a cooling
treatment cycle. The cooling treatment cycle may include
application of a current to the thermoelectric cooler to cool the
cooling applicator toward a treatment temperature while the cooling
applicator is held against the skin for a duration of time; and,
after the duration of time, reversing the current to the
thermoelectric cooler to adjust a temperature of the cooling
applicator toward a post-treatment temperature while the cooling
applicator is held against the skin. The post-treatment temperature
may be less than 10.degree. C. or less than 40.degree. C.
[0026] In still further embodiments, a method of altering
pigmentation in a skin of a patient may be provided that includes
supercooling the skin of the patient by placing a cooling
applicator of a treatment device against a skin surface. After
supercooling the skin, the method may include applying vibrations
to the skin of the patient to facilitate ice crystal formation in
the supercooled skin.
[0027] In some embodiments, the skin of the patient may be
supercooled for a predetermined amount of time before the
application of vibrations.
[0028] Optionally, after applying vibrations to the skin of the
patient, the method may include maintaining the cooling applicator
against the skin surface for a first duration of time. After the
first duration of time, and while the cooling applicator is
positioned and maintained against the skin, the method may include
adjusting the temperature toward a post-treatment temperature to
thaw the frozen skin tissue. The post-treatment temperature may be
between 0.degree. C. to 10.degree. C. or between 0.degree. C. to
40.degree. C. The first duration of time may be between 10-30
seconds. Optionally, the cooling applicator may be driven toward a
treatment temperature during the first duration of time. The
treatment temperature may be between -2.degree. C. to -10.degree.
C. or between -2.degree. C. to -12.degree. C.
[0029] In some embodiments, the treatment temperature or the first
duration of time may be variable based on a force between the
cooling applicator and the skin of the patient.
[0030] In some embodiments, the method may include returning the
cooling applicator of the treatment device toward an idle state
based on a signal from a contact sensor indicating removal of the
cooling applicator from the skin of the patient.
[0031] In still further embodiments, a skin treatment system may be
provided that includes a cooling applicator for contacting a skin
of a patient, a cooling arrangement thermally coupled with the
cooling applicator, and a controller operably coupled with the
cooling arrangement and a vibrator. The controller may be
configured to control the cooling arrangement and the vibrator to
provide a cooling treatment. The cooling treatment may include
cooling of the cooling applicator to supercool the skin of the
patient and application of the vibrator to deliver vibrations into
the supercooled skin to facilitate ice formation in the skin.
[0032] The controller may be configured to supercool the skin of
the patient for a predetermined amount of time before applying
vibrations from the vibrator.
[0033] The controller may be configured to adjust the cooling
applicator to a treatment temperature for a first duration of time
after applying vibrations to the skin of the patient.
[0034] The controller may be configured to adjust the temperature
of the cooling applicator toward a post-treatment temperature to
thaw the frozen skin tissue after the first duration of time, and
while the cooling applicator is positioned and maintained against
the skin.
[0035] In some embodiments, the post-treatment temperature may be
between 0.degree. C. to 10.degree. C., or between 0.degree. C. to
40.degree. C.
[0036] In some embodiments, the first duration of time may be
between 10-30 seconds.
[0037] Optionally, the treatment temperature may be between
-2.degree. C. to -10.degree. C.
[0038] The device may further include a force sensor coupled with
the controller. The force sensor may be configured to measure a
force between the cooling applicator and the skin of the patient.
The treatment temperature or the first duration of time may be
variable based on a force between the cooling applicator and the
skin of the patient.
[0039] In some embodiments, the system may further include a
contact sensor coupled with the controller. The controller may be
configured to return the cooling applicator of the treatment device
toward an idle state based on a signal from a contact sensor
indicating removal of the cooling applicator from the skin of the
patient.
[0040] Embodiments of the invention covered by this patent are
defined by the claims below, not this summary. This summary is a
high-level overview of various aspects of the invention and
introduces some of the concepts that are further described in the
Detailed Description section below. This summary is not intended to
identify key or essential features of the claimed subject matter,
nor is it intended to be used in isolation to determine the scope
of the claimed subject matter. The subject matter should be
understood by reference to appropriate portions of the entire
specification of this patent, any or all drawings, and each
claim.
[0041] The invention will be better understood upon reading the
following description and examining the figures which accompany it.
These figures are provided by way of illustration only and are in
no way limiting on the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Further details, aspects, and embodiments of the invention
will be described by way of example only and with reference to the
drawings. In the drawings, like reference numbers are used to
identify like or functionally similar elements. Elements in the
figures are illustrated for simplicity and clarity and have not
necessarily been drawn to scale.
[0043] FIG. 1 illustrates an exemplary treatment method according
to some embodiments of the present invention.
[0044] FIGS. 2-2E illustrate cross-sectional side views of
exemplary apparatuses that can be used to produce hypopigmentation
in a skin tissue according to some embodiments of the present
invention.
[0045] FIG. 3 illustrates an exemplary method for delivering
treatment cycles according to some embodiments.
[0046] FIG. 4 illustrates a cross-sectional view of an exemplary
treatment device with one or more force sensors according to some
embodiments.
[0047] FIG. 5 illustrates another exemplary treatment method
according to some embodiments of the present invention.
[0048] FIG. 6 illustrates another exemplary cooling apparatus that
can be used to produce hypopigmentation in skin tissue according to
some embodiments of the present invention.
DETAILED DESCRIPTION
[0049] As set forth above, some embodiments of the present
invention may be directed to techniques to affect melanocytes
and/or keratinocytes of a patient. For example, some embodiments
may be directed to methods and systems for reducing skin
pigmentation by cooling the skin of a patient. In some embodiments
it may be beneficial to freeze the skin. Additionally, it may be
advantageous to freeze the skin in a more controllable and
consistent manner. The freezing event, although it may not be
required, has been shown to have an effect on both the desired
outcome of reduced pigmentation, but also the short term side
effects of epidermal necrosis and in some cases prolonged erythema
and hyperpigmentation. In previous studies, the timing of skin
freezing has been found to be inconsistent. Different results (time
to freezing, or lack of freezing) have been seen when replicates of
the same treatment parameters are performed. Accordingly, some
embodiments of the present invention provide increased control over
the occurrence of freezing in the skin of a patient and may limit
supercooling in the skin. Methods and systems described herein may
thus increase the chance, predictability, and/or consistency of
freezing in the skin of a patient (e.g., repeatable freezing at
certain temperatures and/or cooling rates) and may thereby provide
additional control over a duration of skin freezing during
treatment. Some embodiments may be directed to limiting
supercooling of the skin of a patient during a cooling treatment.
Supercooling of the skin may be cooling of the skin below the water
freezing point without solidification or crystallization of water
in the skin.
[0050] A number of cooling systems have been developed for
lightening the pigmentation of skin (see e.g., U.S. Patent
Publication 2011/0313411 filed Aug. 7, 2009; U.S. Patent
Publication 2014/0303696 filed Nov. 16, 2012; U.S. Patent
Publication 2014/0303697 filed Nov. 16, 2012; U.S. Patent
Publication 2015/0223975 filed Feb. 12, 2015 and U.S. patent
application Ser. No. 15/257,827 filed Sep. 6, 2016, the contents of
which are incorporated herein by reference in their entirety). In
general, the systems provide a cooling contact surface configured
to contact and freeze skin tissue (typically the superficial layer
of skin down to the dermal/epidermal junction). The freezing of the
skin tissue may decrease melanin production, decrease melanosome
production, destroy melanoncytes, and/or inhibit transfer of
melanosomes into keratinocytes in the lower region of the epidermal
layer, thereby leading to skin lightening (i.e., hypopigmentation)
for a period of time or permanently.
[0051] Some treatments may use relatively modest skin cooling to
temperatures in the range of 0.degree. C. to -20.degree. C. over
fairly short times frames, e.g., as short as 15 seconds or less and
up to 2 minutes or more. In some embodiments, skin cooling may be
performed by controlling the temperature of an aluminum plate (e.g.
cooler or cooling applicator) and applying the cooler directly to
the skin 13 thereby cooling the skin through thermal conduction
from the skin to the cooler.
[0052] It has been found that controlling certain aspects of the
interface between the cooling applicator and the skin may modify
freezing behavior of the skin. For example, freezing may be
triggered more reliably by specifying and maintaining a fluid at
the interface between the applied applicator and the skin. Water is
a coupling fluid that can be used to reduce the thermal contact
resistance between the applicator and the skin and thereby improve
cooling. Water can either be pure or contain a thickening agent to
increase viscosity. Water has a freezing point generally of
0.degree. C. which is very near that of the tissue. However water,
particularly in small quantities, has been known to supercool below
its typical freezing point, particularly at slower rates of
cooling. Substances can therefore be mixed with the water to
minimize the chance of supercooling but not significantly decrease
the freezing point, which would be undesirable. Some such
substances are inorganic materials such as soot, dust, fine
particulates, or silver iodide crystals. Other materials that can
be added are organic substances such as proteins, lipoproteins,
bacteria or fungi. Long chain aliphatic alcohols and amino acids,
such as l-aspartic acid can also be added to the water, or another
fluid with a freezing point near 0.degree. C., to reduce the chance
of supercooling in the tissue.
[0053] Freezing can additionally be encouraged by applying a
carrier at the interface, such as a saturated piece of gauze or
another woven or non-woven material. The carrier should occupy some
volume, but allow the free transfer of water across it. This
carrier will ensure a sufficiently large and uniform quantity of
water or other fluid is present at the interface which facilitates
freezing of the skin.
[0054] Supercooling can be minimized by presenting a seed crystal
which serves as a nucleation source for water at or just below its
freezing point. One of the best seed crystals is frozen water, or
ice. To ensure the applicator has ice crystals, which are available
from the air even when the humidity is relatively low, the surface
roughness of the applicator surface can be increased. By providing
nooks and crannies on the applicator surface, the surface area of
the applicator is increased and recessed areas will retain ice
crystals even after being cleaned with alcohol or other cleaners.
In addition these recessed areas prevent the ice from melting when
first applied to warm skin. It may be helpful to allow the
applicator surface to dwell at a temperature below freezing for a
period of time prior to the treatment to ensure water from the air
freezes on its surface. Alternately it can be sprayed with a mist
of water or other liquid, which will freeze on its surface prior to
the treatment.
[0055] Other mechanisms to trigger ice nucleation in a supercooled
medium include vibration or other mechanical perturbations, and
ultrasound or acoustic irradiation. The design of the cooler may
include a vibrating element to induce freezing at some point in the
cooling cycle. Ultrasound or acoustic transducers may also be
incorporated in the system design to control the nucleation
event.
[0056] Once ice starts to form at the interface it then needs to
propagate into the skin. The epidermis is generally impervious to
water, although there are specialized areas such as sweat glands
that are specifically designed to control the flow of moisture
across this barrier. It may be however that ice propagation is
limited across the epidermis as the skin is cooled which could
result in supercooling in the tissue. To prevent this, small holes
can be made in the epidermis to allow ice to freely propagate
across this barrier. Holes can be initiated by abrasions with a
rough cloth or brush, with a microderm abrasion roller or system,
with a laser, or with a number of additional techniques. Further
details of methods and devices for controlling aspects of the
interface between the cooling applicator and the skin are described
in U.S. patent application Ser. No. 15/257,827, the entire contents
of which were previously incorporated by reference, and which may
be used with aspects of the disclosure described herein.
[0057] In addition to controlling aspects of the interface between
the cooling applicator and the skin, it has been found that the
freezing behavior (frequency and time to freeze) can be modified by
adjusting the thermal parameters of the cooling applicator.
Accordingly, in some aspects of the invention, a method of treating
the skin may be provided where the thermal parameters of the
cooling applicator are adjusted during treatment. For example, FIG.
1 illustrates an exemplary treatment method 100 according to some
embodiments. The method 100 may include modifying the skin of the
patient in a manner described in U.S. patent application Ser. No.
15/257,827, previously incorporated by reference. For instance, in
some embodiments, the method 100 may start by placing small holes
in the skin. For example, a 0.3 mm, a 0.25 mm, or a 0.5 mm
dermaroller may be used to place small holes in the epidermis. This
may allow the subsequently generated ice to freely propagate across
the stratum corneum. In prior studies, the stratum corneum appeared
to create a barrier to ice propagation and although freezing
occurred at the interface, the skin would freeze at a variable and
unpredictable times even with consistent treatment conditions.
[0058] The method 100 may further include pre-cooling a cooling
applicator to a pretreatment temperature prior to contact of the
cooling applicator with a skin surface of the patient 102. After
pre-cooling the cooling applicator to the pretreatment temperature,
the applicator may be placed onto the skin of the patient 103.
After the cooling applicator is positioned onto the skin surface,
the cooling applicator may be driven toward the pre-treatment
temperature for a first duration of time to pre-condition the skin
to freeze 104. After the first duration of time and while the
cooling applicator is positioned and maintained against the skin
surface, the temperature of the cooling applicator may be adjusted
toward the treatment temperature for a second duration of time 106.
After the second duration of time and while the cooling applicator
is positioned and maintained against the skin, the temperature of
the cooling applicator may be adjusted toward a post-treatment
temperature so as to thaw the frozen skin tissue 108. Thereafter,
the cooling applicator may be removed from the skin of the patient
after the interface between the cooling applicator and the skin
thaws 110.
[0059] It has been found that by initially applying a colder
temperature, therefore setting up a larger temperature gradient
between the cooler and the skin, the skin can be made to freeze
more consistently. With other conditions being equal, applying a
colder temperature of -5.degree. C. to the skin will cause freezing
more consistently over a shorter period of time than applying a
temperature of -2.degree. C. A temperature of -10.degree. C. will
freeze more consistently and more quickly than a temperature of
-5.degree. C. and a temperature of -20.degree. C. will freeze more
consistently and more quickly than a temperature of -10.degree. C.
While colder temperatures will freeze skin more consistently and
more quickly, it may not be desirable to apply such a low
temperature to the skin for the duration of the treatment as lower
temperatures and/or longer durations may lead to increased adverse
side effects, such as hyperpigmentation. Therefore, the cooler may
be applied at a first colder temperature (or a pre-treatment or
pre-conditioning temperature) to trigger freezing and then may be
adjusted to a higher/warmer temperature that is still below the
freezing point of the skin tissue for the duration of the
treatment.
[0060] Additionally by precooling the cooling applicator prior to
skin contact, ice crystal formation on the cooling applicator
through moisture in the air or through water application directly
to the cooling applicator (e.g., misting or the like) may be
provided. Further, with colder precooling temperatures, it will be
less likely that ice crystals that have formed on the surface of
the applicator melt when the applicator is placed in contact with
the patient skin. Accordingly, ice formation on the cooling
applicator may remain after initial contact with the patient skin
to seed ice formation at the interface and into the skin.
[0061] If the precooling temperature is too warm, the ice formed on
the cooling applicator may melt upon the initial contact between
the applicator and the skin and may be unavailable to seed ice
formation at the interface and into the skin. Instead the water may
return to and stay in the liquid state and may supercool for some
variable amount of time, thereby reducing the consistency of
freezing.
[0062] In some embodiments, the cooling applicator is pre-cooled
102 to a temperature between -10.degree. C. and -20.degree. C.
Optionally, the cooling applicator is pre-cooled 102 to between
-12.degree. C. and -18.degree. C., for example -15.degree. C. In
some embodiments, the cooling applicator is pre-cooled 102 to a
temperature of -15.degree. C. or colder.
[0063] As mentioned above, after contact with a skin of the
patient, the temperature of the cooling applicator may increase due
to heat transfer from the skin of the patient. Accordingly, in some
embodiments, the cooling applicator is driven toward the
pre-treatment temperature for a duration of time after the initial
contact 104. The duration of time where the cooling applicator is
driven toward the pre-treatment temperature may be less than five
seconds in some embodiments (e.g., 0-3 seconds or the like). In
some embodiments, the duration of time may be a preset parameter of
a preprogrammed treatment cycle. The colder pre-treatment
temperature may provide the larger temperature gradient between the
cooling applicator and the skin and may thereby condition the skin
to freeze in a more consistent manner and/or maintain previously
seeded ice crystals at the interface between the cooling applicator
and the skin.
[0064] The thermal effusivity of the interface material and the
applicator material may come into play here. If the applicator has
a high thermal effusivity relative to the interface, its
temperature may remain relatively stable (e.g. it doesn't warm
much) and therefore it is able to initiate freezing because any
small ice crystals that have formed on its surface may stay frozen.
The thickness of the applicator material also comes into play. A
thick material of a high thermal effusivity maintains a relatively
constant temperature, whereas a thin material backed by another
material of a lower thermal effusivity would warm significantly. In
some embodiments, the applicator may comprise an aluminum surface
having an approximately 0.5 inch thickness.
[0065] Alternately, the applicator may have a cooling surface with
a thickness of 0.25 inches or less combined with a more powerful
TEC that is able to respond to high transient heat loads. The cold
plate may also be made out of copper or another material with a
suitably high thermal effusivity.
[0066] After the applicator is applied, it is driven toward the
pretreatment temperature for a short period of time to ensure
sufficient energy is extracted from the interface to initiate
freezing then the applicator may be adjusted or warmed to a second
temperature (or treatment temperature) 106, warmer than the first
temperature. The treatment temperature, while warmer than the
pre-treatment temperature, is preferably below a skin freezing
temperature, at least in certain embodiments. In some embodiments,
the treatment temperature is between -2.degree. C. to -12.degree.
C., or between -2.degree. C. and -10.degree. C., for example
-8.degree. C. to -10.degree. C. The second warmer treatment
temperature allows the treatment effect to be modulated (the warmer
the temperature the less the effect) and reduce side effects (more
prevalent at colder temperatures). The applicator may then be
driven toward the second temperature for a period of time
sufficient to achieve the desired treatment effect but avoid
undesired side effects. In some embodiments, the temperature of the
cooling applicator may be adjusted toward the treatment temperature
for a duration between 10-30 seconds while the applicator is
positioned against the skin. In some embodiments, the duration of
applying the second treatment temperature may be a preset parameter
of a preprogrammed treatment cycle.
[0067] As set forth above, the duration of time where the cooling
applicator is driven toward the treatment temperature may be a
predetermined parameter that is programmed into a preset treatment
cycle. In some embodiments, the duration of time where the cooling
applicator is driven toward the treatment temperature may be
variable and may, in certain embodiments, depend on the initiation
of a skin freeze. For example, in some embodiments, a sensor may be
incorporated to detect a freezing of a tissue proximal to the
applicator. After the freeze is detected, the more moderate
(warmer) second freezing temperature may be applied for a preset
duration of time following the detection of the freeze. Such an
embodiment may modulate the treatment effect by maintaining the
tissue in the frozen state for a pre-specified duration of
time.
[0068] In certain embodiments, the freeze detection sensor may be a
temperature sensor that is configured to detect the occurrence of
local tissue freezing. The temperature detected by a temperature
sensor may correspond to the temperature of the cooling applicator
that it is in contact with. When the applicator is placed on the
skin surface, the detected temperature will rise as the bottom
surface of the applicator is warmed slightly by the skin. As
conductive cooling of the skin by the applicator proceeds, the
measured temperature will then decrease. The rate and extent of
such decrease can depend on several factors, e.g., the initial
temperature, material, and geometry of the applicator, the
efficiency of the cooling arrangement used to cool the applicator,
etc. When tissue freezing occurs proximal to the bottom surface of
the applicator, a slight temporary increase in local temperature
may be detected that arises from latent heat released during the
freezing phase transformation. The detected temperature may then
continue to decrease as further cooling of the frozen tissue
proceeds. Accordingly, a "bump" detected in the temporal cooling
curve by a temperature sensor can also indicate the occurrence of
local tissue freezing. U.S. Patent Publication 2014/0303696 and
U.S. Patent Publication 2014/0303697, previously incorporated,
describe other freeze detection sensors that may be incorporated
with embodiments of the present disclosure for the purpose of
determining the initiation of a skin freeze.
[0069] Similarly, the duration of time where the cooling applicator
is driven toward the pre-treatment temperature after initial
contact may be variable and may, in certain embodiments, depend on
the initiation of a skin freeze. For example, the freeze detection
sensor may be incorporated to detect the freezing of the tissue
proximal to the applicator. After the freeze is detected, the
cooling applicator may cease to be driven toward the pre-treatment
temperature and the more moderate (warmer) second freezing
temperature may be applied thereafter.
[0070] After the duration of cooling treatment, the temperature of
the cooling applicator may be adjusted toward a post-treatment
temperature 108. In some embodiments, the post treatment
temperature stops treatment and may be above 0.degree. C. to thaw
the interface or otherwise unstick the cooling applicator from the
skin. In some embodiments, the post-treatment temperature is
between 0.degree. C. and 10.degree. C. (e.g., 5.degree. C. or the
like), or between 0.degree. C. to 40.degree. C. In some
embodiments, the applicator may be maintained against the skin of
the patient for upwards of 30 seconds after the treatment. After
the interface thaws, the applicator may be removed from the skin
110. It should be understood that the times and temperatures are
not critical. In some embodiments, the goal is to unfreeze the
tissue in a relatively short period of time and to release the
applicator from the tissue.
[0071] FIG. 2 illustrates an exemplary cross-sectional side view of
an exemplary apparatus 10 that can be used to produce
hypopigmentation in a skin tissue according to some embodiments of
the present invention. The exemplary apparatus 10 can include a
cooling applicator 11 provided in a thermal communication with a
thermoelectric cooler 12. A heat exchanger 16 may be thermally
coupled with the thermoelectric cooler 12 on a side opposite from
the cooling applicator 11. In certain exemplary embodiments, the
cooling applicator 11 and the cooling arrangement 12 can be formed
at least in part from a single material. A controller 15 can be
provided and used to control certain aspects of the thermoelectric
cooler 12, e.g., temperature, timed shutoff, etc., to perform
aspects of method 100. The thermoelectric cooler 12, controller 15,
and/or cooling applicator 11 can optionally be provided within or
affixed to a housing or handpiece 13, as shown in FIG. 2, e.g., to
facilitate handling and positioning of the apparatus 10. The
exemplary apparatus 10 shown in FIG. 2 is not necessarily drawn to
scale. For example, the relative dimensions of the thermoelectric
cooler 12 and cooling applicator 11 are not limited to the
proportions illustrated in the FIG. 2. In further exemplary
embodiments of the present disclosure, the cooling applicator 11
can be larger or smaller in width or cross-sectional area as
compared to the dimensions of the thermoelectric cooler 12.
[0072] The cooling applicator 11 can include a distal (contact)
surface 14 that is configured to contact a skin surface. The distal
surface 14 can be substantially flat. In further exemplary
embodiments of the present disclosure, the distal surface 14 can be
convex or concave to better match the local shape of skin tissue
being treated and/or to provide good thermal contact with the skin
surface when the apparatus 10 is placed on the area of the skin to
be treated. In still further exemplary embodiments of the present
disclosure, the cooling applicator 11 can be detachable from the
thermoelectric cooler 12, e.g., so that a plurality of cooling
applicator 11 having different sizes, shapes, and/or surface
features as described herein can be used with a single
thermoelectric cooler 12.
[0073] The distal contact surface 14 can have a large width or
diameter configured to contact the surface of a region of skin,
e.g., a diameter or width that is greater than about 3-10 cm, or
greater than about 5 cm, to facilitate treatment of large areas of
skin. In further embodiments, the width of the distal surface 14
can be small, e.g., on the order of 1-2 cm or less which may
facilitate improved temperature control and/or treatment of
particular features on the skin.
[0074] The cooling applicator 11 can be formed from a metal or a
metal alloy, or another material having a high thermal effusivity,
e.g., such that values of these thermophysical properties are
greater than the corresponding values for skin tissue. The thermal
effusivity c is equal to the square root of the product of a
material's thermal conductivity and its volumetric heat capacity.
The thermal effusivity is a measure of the ability of a material to
exchange heat with its surroundings and to maintain a consistent
temperature as it does so. For example, the interface temperature
Ti where two semi-infinite materials at temperature T1 and T2,
respectively, are brought into contact will depend on their
relative effusivities, .epsilon.1 and .epsilon.2, as
Ti=T1+(T2-T1).times. [.epsilon.2/(.epsilon.2+.epsilon.1)].
Accordingly, e.g., with .epsilon.2>>.epsilon.1, the interface
temperature where the two materials are in contacts will remain
close to T2 as heat flows from one to the other. In this manner,
the surface of a first material will be cooled down close to the
temperature of a second material having a much higher thermal
effusivity when the second material is brought into contact with
the first material.
[0075] For example, the cooling applicator 11, at least in part or
wholly, can be made of brass, copper, silver, aluminum, an aluminum
alloy, steel, graphite, diamond, diamond-like carbon, other
materials which are used in conventional contact cryoprobes, or
combinations thereof. For example, the cooling applicator 11 can be
formed, wholly or at least in part, from materials having a much
higher thermal conductivity than the skin tissue, and can be used
to facilitate an extraction of heat from the portion of the tissue
contacted by the distal surface 14 of the cooling applicator 11.
Further, materials having a much higher thermal effusivity than the
skin tissue, e.g. at least about 10 times the thermal effusivity of
skin can be more readily maintained at a cold temperature. Such
high-effusivity materials thereby may extract heat more effectively
from the portion of tissue contacted by the cooling applicator 11
than materials having lower thermal effusivities, and facilitate a
better control of the tissue temperature at a contact
interface.
[0076] In certain exemplary embodiments of the present disclosure,
the distal contact surface 14 of the cooling applicator 11 can be
smaller in area than the proximal end of the cooling applicator 11
that contacts the thermoelectric cooler 12. Such geometry can
provide certain advantages. For example, the narrower or tapered
distal end of the cooling applicator 11 can facilitate a more
precise placement of the distal surface 14 on a particular location
of the skin surface to be cooled, e.g., while reducing visual
obstruction by the housing 13. Further, the relatively larger
proximal end of the cooling applicator 11 can provide a larger area
that can be directly cooled by the thermoelectric cooler 12 to
facilitate increased extraction of heat from the smaller distal
contact surface 14. In certain embodiments, the area of the
proximal end of the cooling applicator 11 can be at least twice as
large as the area of the distal contact surface 14, e.g., 3-5 times
as large.
[0077] In some embodiments, the distal surface 14 of the cooling
applicator 11 can be provided with a plurality of protrusions,
similar to those described in U.S. Patent Publication 2011/0313411
or U.S. Patent Pub. 2014/0303697, previously incorporated by
reference. FIGS. 2A and 2B illustrate exemplary treatment devices
with protrusions 17 for discontinuous treatment of a region of skin
which may provide cooling treatments according to the present
disclosure. Alternatively, as mentioned above, the distal surface
may be flat or rounded to provide a continuous contact surface
similar to the applicators described in U.S. Patent Publication
2014/0303696. FIG. 2C illustrates an exemplary treatment device
with a flat surface for continuous contact and treatment of a
region of skin which may provide cooling treatments according to
the present disclosure. In still further embodiments, the distal
surface 14 may include dimples similar to the applicators described
in U.S. Patent Publication 2015/0223975. FIG. 2D illustrates an
exemplary treatment device with a dimpled surface 21 for treatment
of a region of skin which may provide cooling treatments according
to the present disclosure. Optionally, the distal surface 14 may be
roughened or knurled similar to the applicators described in U.S.
Provisional Patent Application 62/214,446. FIG. 2E illustrates an
exemplary treatment device with a roughened surface for treatment
of a region of skin which may provide cooling treatments according
to the present disclosure.
[0078] As set forth above, a controller 15 may be provided to
control the thermoelectric cooler 12. FIG. 3 illustrates an
exemplary method 300 for delivering treatment cycles according to
some embodiments. In some embodiments, the controller 15 may be
configured to control the thermoelectric cooler 12 or other cooling
arrangement to provide a cooling treatment cycle that performs
certain aspects of method 100. For example, the controller 15 may
deliver a first electrical current to the thermoelectric cooler 12
to pre-cool the cooling applicator 11 to a pre-treatment
temperature prior to contact with the skin of the patient 302. The
first electrical current may be delivered to the thermoelectric
cooler 12 to cool the cooling applicator toward the pre-treatment
temperature for a first duration of time after the cooling
applicator is placed against the skin of the patient 302. After the
first duration of time and while the cooling applicator is held
against the skin of the patient, a second electrical current may be
delivered to the thermoelectric cooler 12 to adjust the temperature
of the cooling applicator 11 toward a treatment temperature that is
higher (warmer but generally below a temperature for skin freezing)
than the pre-treatment temperature for a second duration of time
304. After the second duration of time and while the cooling
applicator is held against the skin of the patient, a third
electrical current may be delivered to the thermoelectric cooler 12
to adjust the temperature of the cooling applicator 11 toward a
post-treatment temperature that is higher than the treatment
temperature for a third duration of time 306.
[0079] In some embodiments, a temperature sensor may be provided to
provide a signal to the controller 15 that is associated with a
temperature of the cooling applicator 11. The signal from the
temperature sensor may indicate when the cooling applicator 11 has
reached the pre-treatment temperature and is ready for application
to the skin of the patient. In some embodiments, the controller 15
may provide a user perceptible signal to indicate that the device
10 is ready for application to the skin of the patient. The user
perceptible signal may be audio, visual, or haptic or the like.
[0080] The controller 15 may also, in response to the temperature
signal, automatically adjust the current and/or power delivered to
the thermoelectric cooler 12 to drive the cooling applicator toward
the desired temperature. Depending on the responsiveness of the
control system, in some embodiments, the current delivered to the
thermoelectric cooler may be temporarily reversed during transition
from the delivery of the first electrical current to the delivery
of the second electrical current. Similarly, in some embodiments,
the current delivered to the thermoelectrical cooler may be
temporarily reversed during transition from the delivery of the
second electrical current to the delivery of the third electrical
current.
[0081] Optionally, in some embodiments, the power delivered to the
thermoelectric cooler may be reduced or turned off during
transition from the delivery of the first electrical current to the
delivery of the second electrical current. Similarly, in some
embodiments, the power delivered to the thermoelectric cooler may
be reduced or turned off during transition from the delivery of the
second electrical current to the delivery of the third electrical
current.
[0082] In some embodiments, the adjustments to the thermoelectric
cooler 12 after the first duration of time and the second duration
of time may be automatic as well. For example, a user may actuate a
switch when the cooling applicator is applied against the skin of a
patient. Actuation of the switch may signal the start of a
treatment cycle to the controller 15. Thereafter the controller 15
may adjust the current and/or power delivered to the thermoelectric
cooler 12 in a preprogrammed manner to adjust the temperatures at
the preset times.
[0083] In further examples, a contact sensor may be provided that
provides a signal to the controller 15 that indicates that the
cooling applicator 11 is placed against the skin of the patient.
Thereafter, the controller 15 may automatically initiate a cooling
treatment cycle (e.g., where the controller 15 automatically
adjusts temperatures in which the cooling arrangement 12 is driven
toward after the first and second durations of time). The contact
sensor may be a force sensor, optical sensor, IR sensor,
temperature sensor, or a sensor that measures a change in the
electrical properties of the plate and interface such as a change
in resistance, capacitance, or the like.
[0084] For example, in some embodiments, a temperature sensor may
be provided. The treatment cycle may be initiated when the
temperature sensor detects an increase in temperature from the
pre-treatment temperature. The increase in temperature may be due
to contact with the skin of the patient and heat transfer from the
skin into the cooling plate. Thereafter, the treatment cycle may be
triggered (e.g., automatically) by the increase in temperature. In
some embodiments, the temperature signal from the sensor may be
averaged over a duration of time (e.g., 1-2 seconds) or moving time
window, and then compared to the threshold. This may help reduce
unintended triggers due to transient drops or spikes in
temperatures sensed.
[0085] In some embodiments, a force sensor may be provided that
detects when the cooling applicator is contacted with the skin
based on a force experienced at the cooling applicator. An increase
in force sensed may indicate that the applicator is being pressed
against the skin of the patient. Thereafter, the treatment cycle
may be triggered (e.g., automatically) by the increase in force
sensed. Similarly, a negative force sensed may indicate that the
applicator is still frozen/attached to the patient skin during an
inadvertent device removal. A warning to the end user could then be
triggered to prevent potential damage to the patient skin. In some
embodiments, the force signal from the sensor may be averaged over
a duration of time (e.g., 1-2 seconds) or moving time window, and
then compared to the threshold. This may help reduce unintended
triggers due to transient drops or spikes in forces sensed.
[0086] The initial contact of the cooling apparatus with the skin
may also be detected based on a change in the amount of power
delivered to a thermoelectric cooler. For example, when the
apparatus makes initial contact with the skin of the patient, a
temperature of the thermoelectric cooler may increase due to heat
transfer from the skin of the patient. Accordingly, the controller
15, using temperature feedback, may deliver additional power to the
thermoelectric cooler to maintain the thermoelectric cooler at a
desired temperature. The increase in power delivered to the
thermoelectric cooler may trigger the initiation of the treatment
cycle. Alternately, the contact may be detected by observing a
change in the measured temperature of the cold plate.
[0087] Alternately, the treatment may be triggered by a mechanical
switch that is user actuated when the applicator is placed in
contact with the skin. Accordingly, one or more signals from
contact sensors, power consumption measurements, heat flux
measurements, or other measured signals may also modify treatment
parameters/algorithm during treatment.
[0088] In some embodiments, the treatment device may be provided
with one or more force sensors, as shown in the exemplary
cross-sectional configuration of FIG. 4. The exemplary apparatus
400 can include a handle 402, a cooling arrangement 420, and an
optional cooling plate 422 provided on a lower surface of a cooling
arrangement 420. The force sensor(s) 410 can be used to detect
force which may be translated into a pressure based on the
application surface size of the cold plate thereby communicating,
e.g., a contact pressure between the contact surface 440 of the
apparatus 400 and the skin or tissue surface during operation of
the apparatus 400. Such pressure detection can be useful, e.g., to
ensure a sufficient or appropriate pressure is applied to
facilitate good thermal contact between the contact element 422 and
the tissue being treated. A contact pressure of a few PSI or more
(e.g., greater than the systolic pressure in a blood vessel, for
example about 2.5 PSI or more) can also produce some local
blanching or restriction of blood flow near the tissue surface.
Local blanching can reduce the heat transfer to the local tissue by
flowing blood, and thereby improve the cooling or heat extraction
by the apparatus 400 near the tissue or skin surface.
[0089] The force sensor(s) 410 can include any conventional
components that can be used to detect force such as, e.g., a
piezoelectric material, a piezoresistive strain gauge, a capacitive
or inductive sensor, pressure sensitive inks, etc. One or more
force sensors 410 can be provided in the apparatus 400. Their
number, type and/or locations of the force sensors 410 can be
selected based on several factors including, e.g., reliability of
the detected contact force. For example, the force sensor 410 can
be small, have a low thermal mass and/or have a high thermal
conductivity to minimize or avoid any reduction in the heat
transfer characteristics of the apparatus 400.
[0090] The location of the one or more force sensors 410 can be
selected to provide an accurate indication of the contact pressure
between the contact surface 440 and the skin surface during use of
the apparatus 400. For example, one or more force sensors 410 can
be provided between an upper portion of the cooling arrangement 420
and the handle 402, as shown in FIG. 4, if the cooling arrangement
420 and handle 402 are in good mechanical contact. This exemplary
configuration can provide force sensing capabilities while avoiding
any reduction of the heat flow or transfer between the cooling
arrangement 420 and the skin surface. In further exemplary
embodiments of the present disclosure, one or more force sensors
410 can be provided between the cooling arrangement 420 and the
contact element 422, on the contact surface 440 of the contact
element 422, within the contact element 422, or any combination of
such locations.
[0091] A force indicator 460 can be provided on or near the
apparatus 400. Such force indicator can include a digital or analog
readout of the detected contact force, an indicator light that can
turn on/off or change color to indicate when the contact force is
within or outside a particular force range or above/below a
particular limit, an audible signal, etc.
[0092] The force indicator can be used to provide or otherwise
transmit a signal to the operator to ensure the presence of an
appropriate contact force during use of the apparatus 400. This
force-sensing feature can be used with any of the exemplary
embodiments of the apparatus and method described herein.
[0093] Optionally, in some embodiments, the force sensor 410 may be
coupled with the controller 450 and the duration of time where the
cooling applicator is driven toward the pre-treatment and/or
treatment temperature may be automatically modulated based on the
force sensed by force sensor 410. For example, if the force sensor
410 senses a force below a certain threshold, a duration of time
where the cooling applicator is driven toward the pre-treatment
and/or treatment temperature may be adjusted (prolonged or
adjusted). Similarly, if the force sensor 410 senses a force above
a certain threshold, a duration of time where the cooling
applicator is driven toward the pre-treatment and/or treatment
temperature may be adjusted (e.g., prolonged or shortened). In some
cases, the force will be normalized by the surface area of the
contact surface resulting in a pressure. In some embodiments, a
timer for the pre-treatment time or the treatment time may be
paused when the pressure sensed is below the threshold and
restarted when the pressure sensed rises above the threshold.
Optionally, the timer for the pre-treatment time or the treatment
time may be reset if the pressure sensed falls below the threshold.
In further examples, the treatment time may be extended if the
pressure drops below a threshold, for example 1 psi. Additionally,
the treatment time may be extended if the pressure exceeds a
threshold. These treatment times may be similarly modified based on
thresholds of TEC power and/or measured heat flux.
[0094] In some embodiments, if a force sensor 410 senses a force
outside of a desired range, a temperature of the cooling applicator
may be adjusted. For example, in some embodiments, if the force
sensor 410 senses a force below a threshold, controller 450 may
adjust the cooling arrangement to deliver a colder temperature
(during pre-treatment and/or treatment). Additionally, in some
embodiments, if the force sensor 410 senses a force above a
threshold, controller 450 may adjust the cooling arrangement to
deliver a warmer temperature (during pre-treatment and/or
treatment). In some embodiments, the signal from the sensor may be
averaged over a duration of time (e.g., 1-2 seconds) or moving time
window, and then compared to the threshold. This may help reduce
triggers due to transient drops or spikes in forces sensed.
[0095] Furthermore, in some embodiments, feedback from force sensor
410 may signal the end of a treatment cycle. For example, a
pressure drop may be detected by force sensor 410, e.g., sensing a
transition from 2-5 lbs. to about 0 lbs., which signals that the
user (clinician or the like) has removed the apparatus from the
skin of the patient. Thereafter, the controller 450 may reset the
apparatus to a desired state or idle state. For example, in some
embodiments, the controller 450 may control the cooling arrangement
420 to drive the contact surface 422 toward the pre-treatment
temperature to prepare for the next cooling treatment application.
Alternatively, in some embodiments, the controller 450 may cease
power delivery to the cooling arrangement 420 when the force sensor
410 indicates that the contact surface 422 has been disengaged from
the skin of the patient. While several aspects above have been
generally described with use of a force sensor 410, it will be
appreciated that other contact sensors or measured signals (e.g.,
heat flux measurement) may be used as discussed above. For example,
spring-based contact sensor, infrared contact sensors, or the like
may be used to sense the disengagement of the contact surface 422
from the skin of the patient so as to automatically trigger the
return of the apparatus to a desired or idle state.
[0096] For embodiments utilizing a force sensor (e.g., sensor 410)
for sensing when the apparatus is removed from the skin of the
patient, it may be beneficial to utilize a signal from an
orientation sensor 470 (e.g., an accelerometer or the like) to
calibrate the pressure reading (e.g., to adjust for gravitational
effects detected by the sensor). For example, when the apparatus
400 is oriented with the contact element 422 facing upward (i.e.,
opposite of what is illustrated in FIG. 4), force sensors 410 may
sense the weight of cooling arrangement 420 and contact element
422. In the alternative, when the apparatus 400 is oriented with
the contact element 422 facing downward (as illustrated in FIG. 4),
force sensors 410 may not sense the weight of cooling arrangement
420 and contact element 422. Accordingly, in some embodiments, an
accelerometer or other orientation sensor 470 may be provided to
sense an orientation of the apparatus 400 to adjust for the
gravitational or orientational effects to ensure that the
controller 450 accurately determines when the apparatus is removed
from the skin of the patient.
[0097] Additionally, in embodiments utilizing an orientation
sensor, the controller coupled with multiple force sensors may be
configured to determine when the apparatus is applied to the skin
at an improper tilt or angle during a treatment cycle. When the
tilt of the apparatus relative to the skin falls outside of a
desired range, the precooling duration/temperature and/or treatment
duration/temperature may be adjusted to account for the improper
tilt of the apparatus relative to the skin. In some embodiments,
the signal from the orientation sensor may be averaged over a
duration of time (e.g., 1-2 seconds) and then compared to the tilt
threshold.
[0098] While many of the embodiments described above are generally
discussed as limiting unintentional supercooling of the skin
tissue, other embodiments of the present invention may
intentionally supercool the tissue before initiating a freeze. For
example, FIG. 5 illustrates another exemplary treatment method 500
according to some embodiments of the present invention. The method
500 may start with placing a cooling applicator onto the skin of
the patient 502. The skin of the patient may then be intentionally
supercooled with the cooling applicator 504. After supercooling the
skin and while the cooling applicator is positioned and maintained
against the skin surface, a freeze of the skin may be initiated
with a vibrator 506. Thereafter, the cooling applicator may be
maintained against the skin surface for a first duration of time
after freeze initiation 508. After the first duration of time and
while the cooling applicator is positioned and maintained against
the skin, the temperature of the cooling applicator may be adjusted
toward a post-treatment temperature so as to thaw the frozen skin
tissue 510. After the interface between the cooling applicator and
the skin thaws, the cooling applicator may be removed from the skin
of the patient 512. For example, the skin might be supercooled for
20 seconds prior to inducing crystallization in the tissue. The
tissue might then be held in the frozen state for an additional 15
seconds before rewarming to thaw the tissue. Without being bound by
theory, the structure of the ice crystals change depending on the
level of supercooling. In addition, the crystallization happens
more rapidly in supercooled tissue. Both the structure and the
speed of formation of ice crystals in the skin may lead to a
beneficial clinical outcome when induced in supercooled tissue.
Finally, by initiating ice crystallization with an external
stimulus, the treatment becomes more controllable and
consistent.
[0099] FIG. 6 illustrates an exemplary cooling apparatus 600 that
can be used to produce hypopigmentation in skin tissue according to
method 500. The exemplary apparatus 600 can include a cooling
applicator 611 provided in a thermal communication with a
thermoelectric cooler 612. A heat exchanger 616 may be thermally
coupled with the thermoelectric cooler 612 on a side opposite from
the cooling applicator 611. In certain exemplary embodiments, the
cooling applicator 611 and the cooling arrangement 612 can be
formed at least in part from a single material. A vibrator 618
(e.g., acoustic transducer, ultrasound transducer, or the like) may
be provided. In some embodiments, the vibrator 618 may be coupled
with a distal side of the heat exchanger 616 so that the vibrator
618 is on the opposite side of the heat exchanger 616 relative to
the thermal electric cooler. A controller 615 can be provided and
used to control certain aspects of the thermoelectric cooler 612,
e.g., temperature, etc. Additionally, the controller 615 may be
coupled with the vibrator 618 to control the delivery (e.g.,
timing, power, frequency, etc.) of the ultrasound from the vibrator
618. The thermoelectric cooler 612, controller 615, vibrator 618,
and/or cooling applicator 611 can optionally be provided within or
affixed to a housing or handpiece 613, as shown in FIG. 6, e.g., to
facilitate handling and positioning of the apparatus 600. The
exemplary apparatus 600 shown in FIG. 6 is not necessarily drawn to
scale.
[0100] For example, the relative dimensions of the thermoelectric
cooler 612 and cooling applicator 611 are not limited to the
proportions illustrated in the FIG. 6. In further exemplary
embodiments of the present disclosure, the cooling applicator 611
can be larger or smaller in width or cross-sectional area as
compared to the dimensions of the thermoelectric cooler 612.
[0101] The cooling applicator 611 can include a distal (contact)
surface 614 that is configured to contact a skin surface. The
distal surface 614 can be substantially flat. In further exemplary
embodiments of the present disclosure, the distal surface 614 can
be convex or concave to better match the local shape of skin tissue
being treated and/or to provide good thermal contact with the skin
surface when the apparatus 600 is placed on the area of the skin to
be treated. In still further exemplary embodiments of the present
disclosure, the cooling applicator 611 can be detachable from the
thermoelectric cooler 612, e.g., so that a plurality of cooling
applicator 611 having different sizes, shapes, and/or surface
features as described herein can be used with a single
thermoelectric cooler 612.
[0102] The distal contact surface 614 can have a large width or
diameter configured to contact the surface of a region of skin,
e.g., a diameter or width that is greater than about 3-10 cm, or
greater than about 5 cm, to facilitate treatment of large areas of
skin. In further embodiments, the width of the distal surface 614
can be small, e.g., on the order of 1-2 cm or less which may
facilitate improved temperature control and/or treatment of
particular features on the skin.
[0103] The cooling apparatus 600 may be configured to intentionally
supercool the skin of the patient 504 for a period after initial
contact with the skin of the patient. The cooling apparatus 600 may
supercool the skin by gradually cooling the target surface to a
first temperature, which could be between 0-5.degree. C. or between
5-10.degree. C. Possibly, after the freezing is initiated, the
tissue could be warmed to a warmer temperature, still below the
freezing point of tissue.
[0104] After supercooling the skin and while the cooling applicator
600 is positioned and maintained against the skin surface, a freeze
of the skin may be initiated with a vibrator 506. The vibrations or
other kinds of mechanical perturbations may help trigger or
otherwise facilitate or promote ice nucleation in the fluid medium
and/or the skin of the patient. Accordingly in some embodiments,
the vibrator 618 may include one or more acoustic or ultrasound
transducers (piezo elements or the like). The ultrasound transducer
may deliver acoustic energy in the 20-100 kHz range. Optionally the
vibrator 618 may be an electrical motor with an unbalanced mass on
its drive shaft. While method 500 may be performed with device 600
which has an integrated vibrator 618, it should be understood that
method 500 may be performed with a cooling apparatus and a separate
vibration device in other embodiments of the present invention.
[0105] Thereafter, the cooling applicator 600 may be maintained
against the skin surface for a first duration of time after freeze
initiation 508. In some embodiments, the cooling applicator 600 may
be driven towards a treatment temperature during the first duration
of time. The treatment temperature may be below a skin freezing
temperature, at least in certain embodiments. In some embodiments,
the treatment temperature is between -2.degree. C. to -12.degree.
C., or between -2.degree. C. and -10.degree. C., for example
-8.degree. C. to -10.degree. C. In some embodiments, the cooling
applicator 600 may be driven toward the treatment temperature for
duration between 10-30 seconds while the applicator 600 is
positioned against the skin. In some embodiments, the duration of
applying the treatment temperature may be a preset parameter of a
preprogrammed treatment cycle. In some embodiments, the duration of
time may be variable and may be reset or paused based on signals
from sensors (e.g., contact sensor, orientation sensor) or other
measured signals similar to the embodiments described above.
[0106] After the first duration of time and while the cooling
applicator is positioned and maintained against the skin, the
temperature of the cooling applicator may be adjusted toward a
post-treatment temperature so as to thaw the frozen skin tissue
510. In some embodiments, the post treatment temperature stops
treatment and may be above 0.degree. C. to thaw the interface or
otherwise unstick the cooling applicator from the skin. In some
embodiments, the post-treatment temperature is between 0.degree. C.
and 10.degree. C. (e.g., 5.degree. C. or the like), or between
0.degree. C. to 40.degree. C. In some embodiments, the applicator
may be maintained against the skin of the patient for upwards of 30
seconds after the treatment. After the interface between the
cooling applicator and the skin thaws, the cooling applicator may
be removed from the skin of the patient 512. It should be
understood that the times and temperatures are not critical. In
some embodiments, the goal is to unfreeze the tissue in a
relatively short period of time and to release the applicator from
the tissue.
[0107] One or more computing devices may be adapted to provide
desired functionality by accessing software instructions rendered
in a computer-readable form. When software is used, any suitable
programming, scripting, or other type of language or combinations
of languages may be used to implement the teachings contained
herein. However, software need not be used exclusively, or at all.
For example, some embodiments of the methods and systems set forth
herein may also be implemented by hard-wired logic or other
circuitry, including but not limited to application-specific
circuits. Combinations of computer-executed software and hard-wired
logic or other circuitry may be suitable as well.
[0108] Embodiments of the methods disclosed herein may be executed
by one or more suitable computing devices. Such system(s) may
comprise one or more computing devices adapted to perform one or
more embodiments of the methods disclosed herein. As noted above,
such devices may access one or more computer-readable media that
embody computer-readable instructions which, when executed by at
least one computer, cause the at least one computer to implement
one or more embodiments of the methods of the present subject
matter. Additionally or alternatively, the computing device(s) may
comprise circuitry that renders the device(s) operative to
implement one or more of the methods of the present subject
matter.
[0109] Any suitable computer-readable medium or media may be used
to implement or practice the presently-disclosed subject matter,
including but not limited to, diskettes, drives, and other
magnetic-based storage media, optical storage media, including
disks (e.g., CD-ROMS, DVD-ROMS, variants thereof, etc.), flash,
RAM, ROM, and other memory devices, and the like.
[0110] The subject matter of the present invention is described
here with specificity, but the claimed subject matter may be
embodied in other ways, may include different elements or steps,
and may be used in conjunction with other existing or future
technologies.
[0111] This description should not be interpreted as implying any
particular order or arrangement among or between various steps or
elements except when the order of individual steps or arrangement
of elements is explicitly described. Different arrangements of the
components depicted in the drawings or described above, as well as
components and steps not shown or described are possible.
Similarly, some features and sub-combinations are useful and may be
employed without reference to other features and sub-combinations.
Embodiments of the invention have been described for illustrative
and not restrictive purposes, and alternative embodiments will
become apparent to readers of this patent. Accordingly, the present
invention is not limited to the embodiments described above or
depicted in the drawings, and various embodiments and modifications
may be made without departing from the scope of the claims
below.
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