Method and system for determining skin freeze during cooling

Abstract

The present disclosure relates to applicators, cooling systems comprising such applicators, and methods for cooling treatment of skin wrinkles of a subject. The method for determining a freeze event comprises measuring an electrical impedance between a contact plate of the applicator and a return electrode. The method further comprises determining a possible movement, which can also be based on the measurement of the electrical impedance.

Description

Technical Field

[0001] This application claims priority to European Patent Application No. 21382374.3, filed on April 28, 2021.

[0002] This disclosure relates to methods and systems for determining skin freezing events during cooling. Specifically, this disclosure relates to applications of such systems and to methods for determining freezing events based on measured electrical impedance.

[0003] This disclosure also relates to methods and systems for treating subjects and specifically for cosmetic treatment to locally reduce adipose tissue, and more specifically, to methods and systems for safely and locally reducing adipose tissue.

[0004] US2016 / 0045755 discloses systems and methods for reducing fat. In some embodiments, these include an applicator having electrodes that form a capacitor to heat tissue.

[0005] US2012 / 0022518 discloses systems and methods that enable the delivery of radiofrequency and cryotherapy applications to adipose tissue to reduce body fat and sculpt body contours.

[0006] WO 2007 / 093998 discloses a method and apparatus for processing adipose tissue. The method includes applying ultrasonic energy to a region of adipose tissue. In an embodiment, an RF electric field is generated within the adipose tissue region along with the ultrasonic energy.

[0007] US2002 / 0049483 discloses a fluid delivery device for introducing a fluid cooling medium to a skin surface, the fluid delivery device including a template having a skin interface surface. An energy delivery device is coupled to the template. Background Technology

[0008] Liposuction has been used for many years to reduce excess body fat. A much less invasive treatment designed to locally reduce adipose tissue by applying cold to the folds of the subject's skin has also been commercially available for many years. It has been found that subcutaneous adipose tissue is more sensitive to cold than other tissues. By applying cold to the skin, the underlying lipid-rich cells are damaged and destroyed, while other tissues are left undamaged or minimally damaged. Over time, the lipid-rich cells die and disappear through a natural apoptosis process. This allows for cosmetic treatments for localized fat reduction.

[0009] For this type of cold therapy, treatment devices having one or more applicators including a cavity are known. Suction can be applied into the cavity to draw in skin folds of the subject. One or more thermally conductive (metallic) contact plates can be disposed on the inside of the cavity. Thermoelectric cooling elements (Peltier elements) can be used to cool the plates to a low temperature. Although thermoelectric cooling elements are the most widely used, alternative cooling methods based on cold fluids, such as cooling conduction plates, can also be used.

[0010] The contact plate can be substantially flat. One or more contact plates can be positioned within the cavity of the applicator. A single curved contact plate or multiple curved contact plates can also be used to conform to an area of ​​the subject's body.

[0011] Typically, some form of temperature control is provided to control the temperature of the contact plate and thus the temperature of the skin. In some known devices, the temperature of the skin can be measured during treatment. Conversely, in other known devices, the temperature of the conductive plate is measured during treatment.

[0012] Improved contact between the skin and the cooling element (e.g., a metal contact plate) is achieved by drawing the skin into the skin folds. Additionally, by compressing the skin folds between the metal plates, local blood flow is reduced. This reduces the amount of heat supplied to the area, making cooling more effective. Applicators that do not rely on drawing the skin into the folds are also known.

[0013] The risk of pain and serious injury to patients is associated with skin freezing or crystal formation in the skin during this treatment. Skin freezing is known to occur at or below 0°C, depending on the duration of exposure.

[0014] Cryoprotectants are known to be used to prevent skin from freezing. Cryoprotectants are substances that can be used to protect biological tissues from freezing damage (e.g., due to the formation of large ice crystals).

[0015] One of the challenges associated with using cryoprotectants in such cold treatments involves effectively protecting the skin with cryoprotectants. In order to perform cold treatments effectively, the treatment can apply temperatures below -5°C or lower (e.g., -10°C or lower) to the metal plate for extended periods of time (e.g., more than 30 minutes and more specifically more than 45 minutes and even more than an hour).

[0016] US 7,367,341 relates to methods for selectively destroying lipid-rich cells through controlled cooling. Feedback mechanisms to be employed in these methods to monitor and control skin temperature are described. Such feedback mechanisms may include, for example, invasive thermocouples for local temperature measurement. Additionally, ultrasound imaging, acoustic, optical, and mechanical measurements are mentioned for monitoring crystal formation. Electrical feedback devices may be used to monitor changes in epidermal impedance caused by ice formation in the epidermis. These monitoring systems are not explained in detail except for invasive temperature measurements.

[0017] WO 2009 / 026471 discloses a monitoring system, or describes the detection of events during thermal removal from subcutaneous, lipid-rich tissue. In some examples, the system detects an increase in temperature at a treatment device in contact with the subject's skin, determines that the temperature increase is associated with a treatment event, and performs an action based on that determination. In some examples, the system shuts off the treatment device, issues an alarm to the operator, or reduces cooling in response to a determined treatment event.

[0018] One drawback associated with some of these existing technology systems is their complexity and therefore high cost when integrated into systems for localized adipose tissue reduction. Another drawback associated with many of these existing technology systems is that localized freezing events in the subject's skin may go undetected. That is, if freezing occurs in a part of the skin that is not exactly near the probe or sensor, the freezing may not be detected until it spreads. By the time freezing is detected, damage may have already occurred.

[0019] There is still a need for devices that can provide safe and effective treatment for the skin and avoid or reduce one or more of the aforementioned problems. Summary of the Invention

[0020] In a first aspect, an applicator is provided for a system for cooling a portion of a subject's skin. The applicator includes a cooling element having a cooling surface for contacting the subject's skin portion to cool it. The cooling element is conductive, and the cooling surface has a lower conductivity than the remainder of the cooling element. The cooling system is configured to determine the impedance between the cooling element and a first return electrode, which is configured to be placed on the subject's body.

[0021] By using the applicator according to this aspect, a freezing event can be determined using impedance. Instead of point-by-point measurements as known from the prior art, the impedance between a significant portion of the cooled surface and the first return electrode is measured using the applicator according to this aspect. Therefore, the determination of a freezing event can be more reliable than in the prior art.

[0022] Low conductivity means that the conductivity of the surface is at least 30% lower than that of the cooling element, specifically at least 50% lower. In certain examples, the surface of the cooling element may be substantially non-conductive. As used throughout this disclosure, substantially non-conductive can be understood to mean a conductivity of 1,000 Ω·cm or more specifically 10,000 Ω·cm or more.

[0023] In some examples, the cooling element may be a metal contact plate, optionally an aluminum plate, with an anodized aluminum layer as the cooling surface. Aluminum has high thermal conductivity and is therefore an effective and efficient cooling element. Anodized aluminum can be provided relatively readily. Its electrical properties vary depending on its composition, but can have, for example, 10... 9 Ω.cm or more, even 10 11 High resistivity of Ω.cm or more.

[0024] In some examples, cables are used to supply current to cooling elements, with the cables attached to the cooling elements by screws.

[0025] In some examples, the current used to determine the impedance is less than 35 mA, specifically less than 1 mA, more specifically 0.5 mA or less. Very small currents can be used to measure the impedance, and therefore the user experience during cooling therapy is not negatively affected.

[0026] In some examples, the applicator may include an accelerometer for measuring the subject's movement. In other examples, the impedance between other electrodes may be used to determine the possible movement of the subject or the possible movement of the applicator relative to the subject's skin folds.

[0027] In another aspect, a cooling system is provided for cooling a portion of a subject's skin, the cooling system comprising a base station and one or more applicators according to any of the examples disclosed herein. The applicator is optionally coupled to the base station via a flexible tube. In the examples, such a flexible tube may be configured to provide an electrical and / or electronic and / or pneumatic connection between the control base station and the applicator.

[0028] Control circuitry, power supply, and pneumatic systems can be located in the base station. The applicator can be controlled from the base station. Measurements (e.g., temperature, impedance) can be taken from the applicator and provided to the base station. In this example, some control circuitry can be located in a separate applicator.

[0029] In some examples, the first return electrode is configured to be placed on the subject's limbs. To improve impedance measurements, a certain distance is beneficial between the cooling element and the return electrode. The subject's arms and legs can be suitable for this purpose, particularly when performing cooling therapy on the abdomen, submental tissue, or buttocks.

[0030] In some examples, the cooling system can also be configured to determine skin freezing based on impedance, specifically on changes in impedance. If a freezing event is determined based on impedance, the applicator does not require a specific additional auxiliary system to measure movement.

[0031] In some examples, the cooling system can also be configured to determine skin freezing based on the time derivative of the impedance. It has been found that the change in impedance (and specifically the time derivative) is a better indicator of freezing events than the absolute value of the measured impedance.

[0032] In addition to freezing events, impedance can also be used to determine movement. By using the same electrical parameters to measure both movement and freezing events, systems or components can be combined and integrated to reduce complexity and minimize independent system failures. The system can be configured to determine the movement of a subject or the movement of a skin portion relative to a cooling element by determining the impedance between the movement sensor electrode and the movement sensor return electrode. Optionally, the movement sensor return electrode can be a first return electrode, i.e., the same electrode used in the measurement of freezing events.

[0033] Motion sensor electrodes can be positioned near or around a cavity in the applicator configured to receive a skin fold, allowing movement of the applicator relative to the skin fold to be measured by both systems. Conversely, if only the system involving the cooling element measures a significant event while the other system used to detect the movement fails to do so, the likelihood of a real event increases. This reduces both false negatives and false positives.

[0034] In another aspect, a method is provided for determining a freezing event during a cooling treatment. A cooling element cools a portion of a subject's skin during the cooling treatment. The method includes determining a first impedance between the cooling element and a first return electrode placed on the subject, and determining the time derivative of the determined first impedance. The method also includes determining movement using a mechanism for detecting movement, said movement including movement of the subject and / or movement of a portion of the subject's skin relative to the cooling element. The method includes determining a freezing event if, during a first time slot, the time derivative of the first impedance satisfies one or more freezing conditions, and if distortion of the first impedance caused by movement is discarded within the same time slot.

[0035] More than one freeze condition can be established to reduce positive false recognitions. More than one criterion can be established to determine possible moves to reduce negative false recognitions.

[0036] The time derivative can be understood as the derivative of a function of time (in this case, the measured first impedance). The time derivative of the determined first impedance can be, in particular, the first or second time derivative.

[0037] If no indication of possible movement is obtained from the mechanism used to detect movement, or if the possible movement obtained from the mechanism used to detect movement is insufficient to satisfy the freeze condition, the distortion caused by movement in the first time slot can be discarded.

[0038] Throughout this disclosure, the term "first time derivative" can be understood as the first-order time derivative, that is, it represents the rate of change of a variable with respect to time. Throughout this disclosure, the terms "first time derivative," "first derivative," and "first-order time derivative" can be used interchangeably.

[0039] In another aspect, a method for reducing adipose tissue is provided, particularly a cosmetic method for reducing adipose tissue. The method includes: providing a cooling system according to any of the examples disclosed herein; providing contact between a portion of a subject's skin and a cooling element of the cooling system; and cooling the portion of the subject's skin, for example, for a period of up to 70 minutes, 90 minutes, 120 minutes, or more. The method also includes performing methods as disclosed herein for determining cooling events during the cooling period.

[0040] In the example, if a freezing event is detected, cooling of the skin area can be interrupted, and / or an alarm can be generated, and / or temporary heating (instead of cooling) can be performed to avoid damage to the subject's skin.

[0041] In this example, the method may also include checking the proper operation of the cooling system by determining the impedance between the cooling element and the first return electrode and / or by determining the impedance between the moving electrode and the moving return electrode. If proper contact with the skin is provided, the impedance will be within the expected range. This measurement can be used during, at the start of, or even before the start of cooling treatment to determine the contact between the skin folds and the contact plate. If a cryoprotectant (pad) is used, the proper placement of the cryoprotectant pad can also be checked by measuring the impedance.

[0042] Throughout this disclosure, the term "skin" may refer to the dermis, epidermis, or both when used in conjunction with freezing time. Attached Figure Description

[0043] Non-limiting examples of this disclosure will be described below with reference to the accompanying drawings, in which:

[0044] Figure 1 An example of a cooling system is shown schematically;

[0045] Figure 2A and Figure 2B An example of an applicator and a cooling system including such an applicator is shown schematically;

[0046] Figure 3 The illustration schematically depicts a method for reducing adipose tissue, based on an example.

[0047] Figure 4 The method for determining a freezing event during cooling therapy is illustrated schematically according to an example;

[0048] Figure 5 and Figure 6 Further examples of methods for determining freezing events during cooling therapy are illustrated schematically; and

[0049] Figure 7 and Figure 7A The diagram schematically illustrates the signal of an impedance sensor according to an example and the method for evaluating such a signal. Detailed Implementation

[0050] Figure 1 An example of a cooling system that can be used in methods for reducing adipose tissue, particularly in cosmetic methods for reducing adipose tissue, is illustrated schematically.

[0051] The method may include providing, for example Figure 1 The cooling system shown. Figure 1 The cooling system includes a base station 100 and one or more applicators 110, 120. The base station may include a user interface 150, which includes a screen that can display information about the cooling treatment.

[0052] The user interface 150 may include a touchscreen. The touchscreen and / or one or more control buttons or handles may be used to select appropriate cooling treatments and / or adjust the parameters of the cooling treatments.

[0053] Applicators 110 and 120 can each be connected to the base station via flexible tubes or hoses 105 and 115. Such flexible tubes 105 and 115 can be configured to provide electrical and / or electronic and / or pneumatic connections between the base station and the applicator.

[0054] Base stations can have a power supply, for example, a cable with a plug.

[0055] The applicator can have different sizes and shapes to suit different parts of the subject's body. In methods for reducing adipose tissue, the subject's skin folds can be introduced into the cavity of the applicator, and a portion of the subject's skin can be brought into contact with the cooling element of the applicator.

[0056] Cooling therapy may involve cooling a portion of the subject's skin for a period of up to 90 minutes. Depending on the portion of skin to be cooled, and depending on the purpose of the treatment, the duration and other settings (e.g., temperature) may vary.

[0057] In the example, cooling the skin area involves controlling the temperature of the cooling element between 0 and -15°C, specifically between -5°C and -13°C. The subject's skin area can be one or more of the following: thigh, buttocks, abdomen, submental tissue, knee, back, face, and arm. The cooling system may include multiple applicators and can treat multiple skin folds simultaneously.

[0058] When temperatures remain below 0°C for extended periods, skin may freeze. To prevent this, pads or absorbents with a cryoprotectant can be used. The cryoprotectant is placed between the skin and the cooling element to protect the skin.

[0059] In the examples disclosed herein, methods for determining a freezing event can be continuously executed throughout the cooling element. If a freezing event is detected, the cooling treatment can be interrupted or otherwise altered to avoid damaging or injuring the subject's skin. Cooling of the skin portion can be interrupted if a freezing event is detected. In the examples, one method may include temporarily heating the cooling element if a freezing event is detected. In the examples, an audible or visual alarm can be generated so that if a freezing event is detected, an operator can intervene by manually altering the treatment, interrupting the treatment, disconnecting the base station, etc.

[0060] Figure 2A and Figure 2B An example of an applicator 10 and a cooling system for treating skin folds of a subject 90 is schematically shown. (As in...) Figure 1 In the example, Figure 2B The cooling system may include a base station 100 with a user interface 150 and multiple applicators 110, 120, and 160. The applicators may be similar to... Figure 2A The applicator 10 is shown.

[0061] The applicator 10 may include a cavity 2 for receiving skin folds. An orifice for connecting to a suction system may be located in the bottom of the cavity 2. A pump for drawing the skin folds into the applicator and a power source may be integrated into a base station. A flexible tube or hose 5 may connect the applicator 10 to a corresponding base station. The applicator 10 may include suitable couplings for attaching to the tube 5. Providing suction or vacuum can help ensure contact between the skin fold to be treated and one or more contact plates 3 arranged within the cavity.

[0062] Depending on the skin fold to be treated, the applicator may include one or more flat, direct contact plates, for example, two contact plates at two opposite locations within a cavity. In other examples, it may include a single contact plate that can be curved and / or shaped like a cup.

[0063] The applicator 10 of the system for cooling a portion of a subject's skin includes a cooling element 3 having a cooling surface for contacting the subject's skin to cool that portion. The cooling element is conductive, and the cooling surface has a lower conductivity than the remainder of the cooling element. The cooling system can be configured to determine the impedance between the cooling element 3 and a first return electrode 190, which is configured to be placed on the subject's body.

[0064] Cooling element 3 can be a metal contact plate, optionally an aluminum plate. The aluminum plate can have relatively good thermal conductivity. The applicator may also include a thermoelectric cooler configured to cool the metal contact plates. Each of the contact plates can be cooled using a Peltier element. By controlling the power supplied to the Peltier element, the temperature of the contact plate can be controlled, and thus the cooling of the skin folds can be controlled. A temperature sensor can be arranged to contact the skin, or alternatively, can measure the temperature of the contact plate or the Peltier element.

[0065] The cooling surface can be substantially non-conductive. The high resistivity of the cooling surface means the entire contact plate can act as an electrode for impedance measurement. The cooling surface includes a non-conductive coating. The cooling surface can be an anodized aluminum layer.

[0066] The applicator 10 may include a cable for supplying current to the cooling element, wherein the cable is attached to the cooling element by screws. The current used to determine the impedance may be less than 35mA, specifically less than 1mA, more specifically 0.5mA or less.

[0067] The applicator 10 may also include a mechanism for determining movement. Movement may include movement of the applicator, movement of skin folds relative to the applicator, or movement of the subject. Such movement can affect the measurement of electrical impedance and therefore the reliability of the determination of a freezing event.

[0068] In some examples, the applicator 10 may include an accelerometer for measuring the subject's movement. In other examples, another impedance measurement may be used to detect the movement.

[0069] In some examples, the first return electrode 190 can be configured to be placed on the subject's limbs. The impedance between the contact plate 3 and the first return electrode 190 can be measured to determine the possible freezing of the skin.

[0070] The cooling system can be configured to determine the freezing of the subject's skin based on impedance, specifically based on changes in impedance by receiving signals and analyzing signals about impedance from the applicator.

[0071] In the example, the cooling system can be configured to determine skin freezing based on the time derivative of the impedance. It has been found, in particular, that changes in impedance can be a reliable indicator of a freezing event.

[0072] In the example, the cooling system is also configured to determine the movement of sensor electrode 14 (in Figure 2A The impedance between the sensor's return electrode and the moving sensor's electrode determines the subject's movement or the movement of a skin portion relative to the cooling element. Figure 2B In this application, the movable sensor electrode 14 is integrated into the applicator. The movable sensor electrode can be attached to the applicator, for example, by fasteners (such as screws) or by adhesive or any other suitable means. In the example, a kit can be provided where the applicator can be upgraded or modified using a suitable system to determine possible freezing conditions by measuring impedance.

[0073] In an alternative example, the moving sensor electrode 180 can be separated from the applicator.

[0074] In the example, the motion sensor return electrode can be the first return electrode 190, that is, the same return electrode used in conjunction with the contact plate.

[0075] Figure 3 The methods for reducing adipose tissue according to examples are illustrated schematically. In any of the examples disclosed herein, the skin folds to be treated may be one of the following areas of the subject: thigh, buttocks, abdomen, submental tissue, knee, back, face, and arm. In any of the examples disclosed herein, several skin folds may be treated simultaneously. For example, a single treatment device may include more than one applicator, and the applicator may be applied to different skin folds simultaneously.

[0076] At box 210, the configuration for cooling can be determined. This configuration can be particularly dependent on which body part is being treated. Specifically, the cooling temperature and cooling time can be configured. The cooling temperature can be related to the temperature of the subject's body in the treated area (e.g., the temperature measured at the epidermis) or the temperature of the cooling element.

[0077] In the example, the contact plate of the treatment device can be maintained at a temperature below 0°C, more specifically below -5°C, for a period of 15 to 90 minutes. In particular, the contact plate can be kept in contact with the skin for a period of 20 to 75 minutes. The treatment time can be adapted to the area of ​​skin being treated. The treatment time for some areas of the skin can be, for example, 30 to 50 minutes, and for other areas of the skin, the treatment time can be, for example, 60 to 75 minutes.

[0078] In some examples, the base station of the cooling system may have multiple predefined and stored cooling programs. The operator can simply select the optimal treatment or body part to be treated. Alternatively, the base station may be able to determine which applicator to activate or connect to. If the applicator can only be used in a single area, the base station can therefore automatically identify the area or body part being treated and automatically select the appropriate configuration. Alternatively, the base station may identify the applicator, and the operator may instruct (e.g., select on the base station) which specific area, zone, or body part among the different areas or zones that can be treated with a particular applicator to be treated.

[0079] Skin folds can be introduced into the applicator. A cryoprotectant can be placed between the skin fold and the contact plate in the applicator. At frame 220, the skin folds can be specifically cooled, with the aim of cooling adipose tissue to locally reduce fat.

[0080] During the cooling treatment, continuous monitoring can be performed at box 230 to detect freezing events. If such a freezing event is detected at box 230, the freezing can be mitigated at box 240 by any of the various methods commented herein, including disconnecting the cooling system, heating the contact plate (temporarily), or shutting down the cooling system.

[0081] Figure 4 The method for determining a freezing event during cryotherapy is illustrated schematically according to an example. Impedance can be measured substantially continuously during cryotherapy. The measured impedance at box 310 means the resistance between the metal contact plate and the first return electrode. The impedance measurement can be performed at frequencies, for example, between 1 kHz and 1000 kHz, specifically between 10 kHz and 200 kHz.

[0082] At box 320, based on the measured impedance, a possible freezing event of the user's skin can be determined. If the impedance develops in a manner that does not raise suspicion of a freezing event, the flowchart proceeds to box 340, and the conclusion is that no freezing event occurred. It should be understood that this method is sequential, i.e., impedance measurements can be performed continuously, and therefore conclusions regarding freezing can be drawn continuously.

[0083] If a possible freeze event is detected at box 320, then at box 350, a determination can be made regarding the existence of possible movement. In the example, movement can be continuously measured at box 330. If the impedance measured at box 310 develops in a manner that detects a freeze, and no movement is detected simultaneously, then a conclusion can be drawn at box 360 that a freeze event exists. The reason for checking for possible movement is to reduce false positives and false negatives, as movement can cause impedance changes similar to those of a freeze event.

[0084] According to this example, possible movements can be measured continuously, but an assessment of possible movements is only performed if a freezing event is suspected.

[0085] exist Figure 5 Alternative examples are shown in [the document / reference]. For example, in [the document / reference]... Figure 4 In this configuration, movement and the impedance between the cooling element and a first return electrode placed on the subject can be continuously measured (boxes 310, 330). Movement can be measured by determining the impedance between the movement sensor electrode and the movement sensor return electrode. The movement sensor return electrode can be the first return electrode.

[0086] It can detect possible frozen elements independently and continuously, and it can detect possible movements (boxes 320, 340).

[0087] If no freeze event is suspected, conclude at box 340 that no freeze event occurred, and therefore there is no reason to interrupt or modify the cooling treatment. If a freeze event is suspected, verify whether movement might affect the determination of a freeze event. If, at the same time, a freeze element is suspected and movement does not result in such a determination, conclude at box 360 that a freeze event has occurred or is occurring.

[0088] exist Figure 5 In the example, another box 370 is introduced. If a freeze event is suspected along with movement, further investigation is conducted to determine if an actual freeze event exists. At box 370, further evaluation can be performed by comparing the development or change of the impedance measured for movement detection with the impedance measured to determine a freeze event. If a freeze event occurs, the impedance in both measurements may increase, but it may be more pronounced between the cooling element and the return electrode.

[0089] exist Figure 4 and Figure 5 In any of the examples, if the impedance satisfies one or more freezing conditions, a freezing event can be suspected.

[0090] In any of the examples, the method for determining a freezing event during a cooling treatment includes determining (box 310) a first impedance between a cooling element and a first return electrode placed on the subject, and determining the time derivative of the determined first impedance, wherein the cooling element cools a portion of the subject's skin.

[0091] In particular, the first-order time derivative can be used. The first-order time derivative indicates the rate of change of the first impedance and has been found to reliably indicate possible freezing events, even when the first-order time derivative is above a threshold.

[0092] In other examples, the second time derivative can be used. The second time derivative indicates the acceleration of the first impedance. Outliers in the second time derivative over time can also indicate possible freeze events. In one example, the absolute value of the second time derivative can be compared to a threshold.

[0093] The method may also include using a mechanism for detecting movement to determine movement (box 320), which includes movement of the subject and / or movement of a portion of the subject's skin relative to the cooling element.

[0094] A freeze event can be determined if the first time derivative of the first impedance satisfies one or more freeze conditions during the first time slot, and if distortion of the first impedance caused by movement is discarded in the same time slot. The first freeze condition is that the first time derivative of the first impedance is higher than a first freeze threshold during the first time slot.

[0095] In some examples, the first freeze threshold is determined at least in part based on a measurement of the first time derivative. In these examples, the first freeze threshold may vary over time.

[0096] exist Figure 6 Another example is shown below. At block 405, a signal regarding the impedance between the cooling element and the first return electrode can be received. At block 410, a filter can be applied to the received signal. In particular, an averaging filter can be applied, for example, by summing and averaging multiple individual measurement points and relating them to a single measurement time (at the midpoint of the averaged measurement points).

[0097] In the example, impedance measurements can be performed at frequencies ranging from 1 kHz to 1,000 kHz, and more specifically between 50 and 200 kHz, and even more specifically around 100 kHz.

[0098] The sampling time of the averaging filter can be from 0.1 seconds to several seconds, and specifically between 0.5 seconds and 2.5 seconds.

[0099] Similarly, at block 505, a signal regarding the impedance between the motion sensor electrode and the motion return electrode is received. At block 510, a similar averaging filter can be applied. The measurement frequency and averaging can be the same or on the same order of magnitude as the impedance measurement used for motion and the impedance measurement used to detect potential freezing events.

[0100] After filtering, the time derivatives of the two measurements, particularly the first-order time derivative, can be determined at boxes 415 and 515. At boxes 430 and 440, multiple freeze conditions can be defined for the first-order time derivative of the impedance.

[0101] The first freeze condition (box 430) can be that the first time derivative of the first impedance is above a first freeze threshold or between a predefined first freeze threshold during the first time slot. Therefore, the freeze threshold corresponds to the value of the rate of change of the impedance. In some examples, the first freeze threshold can vary over time. Optionally, instead of comparing a single value of the first time derivative to the threshold, an average of two or more time points can be used.

[0102] In one example:

[0103] Impedance change = (Current impedance change - Final impedance change) / 2 (Equation 1)

[0104] Peak value = Impedance change / First threshold value (Equation 2)

[0105] First threshold = (fixed threshold * gain threshold) + (abs[impedance change] * gain impedance) (Equation 3)

[0106] Equation 1 expresses the average of the first-time derivative of the impedance over two time slots. Equation 2 defines the peak value as the ratio between the first-time derivative of the impedance and a threshold. If the peak value is at a predefined level, a freeze event can be detected. If the peak value is low, a freeze event is impossible because the impedance change is too small. If the peak value is too high, a freeze event is impossible because there must be another reason for the impedance to change very rapidly (e.g., loss of contact between the skin and the cooling element). Equation 3 considers measurements from a specific component in a particular cooling treatment to indicate how the first threshold can change over time.

[0107] At box 440, a second freeze condition can be defined. In this example, the second freeze condition is that the integer value of the (natural) logarithm of the first time derivative during the second time slot is higher than a second freeze threshold, where the second time slot is longer than the first time slot.

[0108] Ln_value = ∑(ln(peak value) / second time slot) (Equation 4)

[0109] The second time slot can be longer than the first time slot. The first time slot (for the first time derivative) can be between 1 second and 5 seconds, specifically between 1 second and 4 seconds. The second time slot can be even longer. In the example, the second time slot could be 5 seconds.

[0110] If both the first and second freezing conditions are met, the algorithm proceeds to box 450 or box 540, as explained below. If neither freezing condition is met, the conclusion that no freezing occurred is reached at box 490.

[0111] Meanwhile, at box 515, the first time derivative of the impedance between the moving sensor electrode and the return electrode can be determined, and at box 530, the first motion criterion can be defined.

[0112] If, during the first time slot, the first time derivative of the impedance between the motion sensor electrode and the motion sensor return electrode is higher than a motion threshold or falls within a predefined motion threshold (box 530), a possible motion can be derived. At box 530, similar equations 1 through 3 can be applied, but to the signal associated with the motion sensor.

[0113] The shift threshold can be determined, at least in part, based on a measurement of the first time derivative. The first shift threshold can vary over time.

[0114] If no movement is confirmed or suspected at box 530, and a freeze is suspected at boxes 430 and 440, then a third freeze condition can be checked at box 450.

[0115] In the example, the first time derivative (specifically, the first time derivative of the impedance between the cooling element and the return electrode) can be determined over a time window with a first span and a second span, the second span being longer than the first span. In practice, different averaging filters can be applied. For example, a first averaging filter based on 32 measurement points can be applied, and simultaneously, a second averaging filter based on 64 measurements can be applied. It should be understood that 32 and 64 are mentioned only as examples. In this example, a "Haar" filter is used.

[0116] The third freeze condition at box 450 can be defined as the first time derivative determined over the first span during the first time slot (in this example, the average filter with 32 points) being substantially different from the first time derivative measured over the second span (the average filter with 64 points). If a freeze occurs, the first time derivative of the average filter over the shorter time span will be different from the first time derivative of the average filter over the longer time span. If, conversely, the averages are not significantly different, the third freeze condition is not met, and the conclusion of no freeze event is drawn at box 490.

[0117] If the first and second freezing conditions are met at boxes 430 and 440, and the movement criterion is met at box 530, then a further determination can be made as to whether the movement has distorted the impedance measurement.

[0118] In the example, if no indication of possible movement is derived from the mechanism used to detect movement, or if the possible movement derived from the mechanism used to detect movement is insufficient to satisfy the freeze condition, the distortion caused by movement in the first time slot can be discarded.

[0119] Therefore, the method may include checking additional criteria based on the time derivative of the first impedance and the impedance between the moving sensor electrode and the moving sensor return electrode.

[0120] An additional criterion is that the ratio of the time derivative of the first impedance to the time derivative of the impedance between the moving sensor electrode and the moving sensor return electrode is higher than a threshold.

[0121] Ratio = Impedance Change_Freeze / Impedance Change_Shift (Equation 5)

[0122] If the ratio in Equation 5 is higher than a certain threshold, this indicates that the first-time derivative of the impedance used for freezing is significantly higher than the first-time derivative of the impedance used for moving.

[0123] In some examples, additional criteria can be determined within the first time slot (i.e., the same time slot as the first and second freeze conditions) (box 540). In other examples, additional criteria can be determined after the first time slot.

[0124] Figure 7 and Figure 7A The diagram schematically illustrates the signal from an example impedance sensor and the method used to evaluate such signals. Figure 7 In the top section, a filtered signal for impedance measurement used for freezing (between the cooling element and the return electrode, reference numeral 600) and a filtered signal for impedance measurement used for movement (between the moving electrode and the corresponding electrode, reference numeral 610) are shown.

[0125] After applying the averaging filter and deriving the first-order time derivative, the results are shown at the bottom of the figures using reference numerals 602 and 612, respectively. Figure 7 In the diagram, two distinct time windows, A and B, have been identified as potentially indicating a freezing event. Specifically, within window B, specific “jumps” or increases in impedance can be identified.

[0126] Methods for determining freeze events Figure 4 , Figure 5 and Figure 6The aforementioned example can be applied to these three time windows, as follows.

[0127] Figure 7A Time window A is shown in more detail. Reference numeral 620 indicates the threshold of the first-order time derivative as it changes over time. Referring to equations 1 to 3, the threshold can correspond to the minimum peak value. Figure 7A As can be seen, the signal obtained after applying the averaging filter allows for the easier identification of specific enhancements compared to the unfiltered signal. (See example...) Figure 6 In the example, within time window A, the first freezing condition may be met, but the second freezing condition may not be met. The result is that no freezing event is detected, and the cooling treatment can continue normally.

[0128] Within time window B, both the first and second freezing conditions are observed to be met. Simultaneously, the motion sensor also indicates a peak value exceeding the corresponding threshold. That is, in Figure 6 At frame 530, possible movement was detected because a significant increase in impedance was measured between the moving sensor electrode and the return electrode. Application Figure 6 In the example, the algorithm will proceed to box 540, where the first-order time derivatives of the two impedances can be compared. In the case of time window B, a ratio satisfying as defined in Equation 5 can be found, and a conclusion can be drawn that a freeze event has occurred or is occurring.

[0129] The measurements from the impedance sensor can also be used to determine the correct positioning of the applicator and skin folds. If the sensor measurements indicate an abnormal pattern, especially at the start of treatment, this could indicate that the applicator is not properly positioned, the cryoprotectant pad is not properly positioned, or another problem, and therefore, the user's skin is not adequately protected and / or the cooling treatment will not be effective.

[0130] Examples of the methods disclosed in this paper can be implemented using hardware, software, firmware, and combinations thereof.

[0131] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the disclosure herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps have been described above in general terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and design constraints for the implementation of the entire system. Those skilled in the art can implement the described functionality in different ways for each specific application.

[0132] The various illustrative logic blocks, modules, and circuits described herein can be implemented or executed using one or more general-purpose processors, digital signal processors (DSPs), cloud computing architectures, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices (PLCs), discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. The general-purpose processor can be a microprocessor, but alternatively, the processor can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0133] Various aspects of this disclosure are set forth in the following numbered clauses:

[0134] 1. An applicator for a system used to cool a portion of a subject's skin, the applicator comprising:

[0135] A cooling element having a cooling surface for contacting the skin portion of the subject to cool the skin portion of the subject.

[0136] The cooling element is conductive, and the cooling surface has a lower conductivity than the remainder of the cooling element.

[0137] The cooling system is configured to determine the impedance between the cooling element and a first return electrode, which is configured to be placed on the subject's body.

[0138] 2. The applicator according to Clause 1, wherein the cooling element is a metal contact plate, optionally an aluminum plate.

[0139] 3. The applicator according to Clause 2, the applicator further comprising a thermoelectric cooler configured to cool the metal contact plate.

[0140] 4. The applicator according to clause 2 or 3, wherein the cooling surface is an anodized aluminum layer.

[0141] 5. The applicator according to any one of clauses 1 to 4, wherein the cooling surface is substantially non-conductive.

[0142] 6. The applicator according to Clause 5, wherein the cooling surface comprises a non-conductive coating.

[0143] 7. An applicator according to any one of clauses 1 to 6, the applicator comprising a cable for supplying current to the cooling element, wherein the cable is attached to the cooling element by a screw.

[0144] 8. The applicator according to any one of clauses 1 to 7, the applicator comprising a cavity configured to receive a skin fold, wherein a cooling element is disposed within the cavity and configured to cool the skin fold.

[0145] 9. The applicator according to any one of clauses 1 to 8, wherein the current used to determine the impedance is less than 35 mA, specifically less than 1 mA, more specifically 0.5 mA or less.

[0146] 10. The applicator according to any one of clauses 1 to 9, the applicator comprising an accelerometer for measuring the movement of the subject.

[0147] 11. A cooling system for cooling a portion of a subject's skin, the cooling system comprising a base station and one or more applicators according to any one of clauses 1 to 10, the applicators being configured to be coupled to the base station.

[0148] 12. The cooling system according to Clause 11, wherein the applicator is connected to the base station via a flexible tube.

[0149] 13. The cooling system according to Clause 12, wherein the flexible tube is configured to provide an electrical and / or electronic and / or pneumatic connection between the control base station and the applicator.

[0150] 14. The cooling system according to any one of clauses 11 to 13, wherein the first return electrode is configured to be placed on the limbs of the subject.

[0151] 15. The cooling system according to any one of clauses 11 to 14, wherein the cooling system is further configured to determine the freezing of the subject's skin based on the impedance, specifically based on changes in the impedance.

[0152] 16. The cooling system according to Clause 15, wherein the cooling system is configured to determine the freezing of the skin based on the time derivative of the impedance.

[0153] 17. The cooling system according to any one of clauses 11 to 16, wherein the cooling system is further configured to determine the movement of the subject or the movement of the skin portion relative to the cooling element.

[0154] 18. The cooling system of claim 17, wherein the system is configured to determine the movement of the subject or the movement of the skin portion relative to the cooling element by determining the impedance between the motion sensor electrode and the motion sensor return electrode.

[0155] 19. The cooling system according to Clause 18, wherein the motion sensor return electrode is the first return electrode.

[0156] 20. The cooling system according to Clause 18 or 19, wherein the movable sensor electrode is disposed on the applicator.

[0157] 21. The cooling system according to Clause 20, wherein the movable sensor electrode is disposed near or around a cavity of the applicator configured to receive skin folds.

[0158] 22. The system of claim 20 or 21, wherein the movable sensor electrode is specifically attached to the applicator with an adhesive or fastener.

[0159] 23. A method for determining a freezing event during a cooling treatment, wherein a cooling element cools a portion of a subject's skin, the method comprising:

[0160] Determine the first impedance between the cooling element and the first return electrode placed on the subject.

[0161] Determine the time derivative of the determined first impedance.

[0162] Movement is determined using a mechanism for detecting movement, including movement of the subject and / or movement of a portion of the subject's skin relative to the cooling element.

[0163] The freeze event is determined if the time derivative of the first impedance satisfies one or more freezing conditions during the first time slot, and if distortion of the first impedance caused by movement is discarded in the same time slot.

[0164] 24. The method according to Clause 23, wherein the time derivative of the determined first impedance is the second time derivative of the first impedance.

[0165] 25. The method according to Clause 23, wherein the time derivative of the determined first impedance is the first time derivative of the first impedance.

[0166] 26. The method according to Clause 25, wherein the first freezing condition is: during the first time slot, the first time derivative of the first impedance is higher than the first freezing threshold.

[0167] 27. The method according to Clause 26, wherein the first freeze threshold is determined at least in part based on a measurement of the first time derivative.

[0168] 28. The method according to Clause 27, wherein the first freezing threshold changes over time.

[0169] 29. The method according to any one of claims 26 to 28, wherein the second freezing condition is that the integer value of the logarithm of the first time derivative is higher than the second freezing threshold during the second time slot, wherein the second time slot is longer than the first time slot.

[0170] 30. The method according to any one of claims 26 to 29, wherein the first-order time derivative is determined over a time window having a first span and a time window having a second span, the second span being longer than the first span.

[0171] 31. The method according to Clause 30, wherein the third freezing condition is: the first time derivative determined over the first span during the first time slot is substantially different from the first time derivative measured over the second span.

[0172] 32. The method according to any one of clauses 23 to 31, wherein if no indication of possible movement is derived from the mechanism for detecting movement, or if the possible movement derived from the mechanism for detecting movement is insufficient to satisfy the freezing condition, then distortion caused by movement in the first time slot is discarded.

[0173] 33. The method according to any one of clauses 23 to 32, wherein detecting possible movement comprises determining the impedance between the movement sensor electrode and the movement sensor return electrode.

[0174] 34. The method according to clause 33, wherein the motion sensor return electrode is the first return electrode.

[0175] 35. The method according to clause 33 or 34, wherein a possible movement is derived if the first time derivative of the impedance between the motion sensor electrode and the motion sensor return electrode is higher than a movement threshold during the first time slot.

[0176] 36. The method according to Clause 35, wherein the movement threshold is determined at least in part based on a measurement of the first time derivative.

[0177] 37. The method according to Clause 36, wherein the movement threshold varies over time.

[0178] 38. The method according to any one of clauses 35 to 37, the method further comprising checking an additional criterion based on the time derivative of the first impedance and the impedance between the motion sensor electrode and the motion sensor return electrode.

[0179] 39. The method according to Clause 38, wherein the additional criterion is that the ratio of the time derivative of the first impedance to the time derivative of the impedance between the moving sensor electrode and the moving sensor return electrode is higher than a threshold.

[0180] 40. The method according to Clause 39, wherein the additional standard is determined within the first time slot.

[0181] 41. The method according to Clause 39, wherein the additional criterion is determined after the first time slot.

[0182] 42. A method for reducing adipose tissue, particularly a cosmetic method for reducing adipose tissue, said method comprising:

[0183] Provide a cooling system in accordance with any one of Clauses 11 to 22;

[0184] Provides contact between the subject's skin and the cooling element of the cooling system;

[0185] The subject's skin was cooled for a period of up to 90 minutes; and

[0186] The method according to any one of clauses 23 to 41 is performed during the cooling period.

[0187] 43. The method according to Clause 42, wherein cooling the skin portion comprises: controlling the temperature of the cooling element between 0 and -15°C, specifically between -5°C and -13°C.

[0188] 44. The method according to clause 42 or 43, wherein if a freezing event is detected, the cooling of the skin portion is interrupted.

[0189] 45. The method according to any one of clauses 42 to 44, the method comprising: temporarily heating the cooling element if a freezing event is detected.

[0190] 46. ​​The method according to any one of clauses 42 to 45, wherein an alarm is generated if a freeze event is detected.

[0191] 47. The method according to any one of clauses 42 to 46, wherein the skin portion of the subject is one or more of the thigh, buttocks, abdomen, submental tissue, knee, back, face, and arm.

[0192] 48. The method according to any one of clauses 42 to 47, the method further comprising checking the proper operation of the cooling system by determining the impedance between the cooling element and the first return electrode and / or by determining the impedance between the moving electrode and the moving return electrode.

[0193] Although only a few examples are disclosed herein, other alternatives, modifications, uses, and / or equivalents are possible. Furthermore, all possible combinations of the described examples are covered. Therefore, the scope of this disclosure should not be limited to the specific examples, but should only be determined through a reasonable reading of the appended claims.

Claims

1. A cooling system for reducing adipose tissue by cooling a portion of a subject's skin, the cooling system comprising a base station and one or more applicators, the applicator comprising: A cooling element having a cooling surface for contacting the subject's skin portion to cool the subject's skin portion. The cooling element is conductive and the cooling surface is substantially non-conductive. The cooling system is configured to determine the freezing of the subject's skin based on the time derivative of the impedance between the cooling element and the first return electrode, the first return electrode being configured to be placed on the subject's body, and wherein... The cooling system is also configured to determine the movement of the subject or the movement of the skin portion relative to the cooling element by determining the impedance between the motion sensor electrode and the motion sensor return electrode.

2. The cooling system of claim 1, wherein the cooling element of the applicator is a metal contact plate.

3. The cooling system according to claim 2, wherein the cooling element of the applicator is an aluminum plate.

4. The cooling system of claim 3, wherein the cooling surface of the applicator is an anodized aluminum layer.

5. The cooling system according to any one of claims 1 to 4, wherein the current used to determine the impedance is less than 35 mA.

6. The cooling system of claim 5, wherein the current used to determine the resistivity is less than 1 mA.

7. The cooling system of claim 6, wherein the current used to determine the resistivity is less than or equal to 0.5 mA.

8. The cooling system according to any one of claims 1 to 4, wherein the applicator is coupled to the base station by a flexible tube, and wherein the flexible tube is configured to provide an electrical and / or electronic and / or pneumatic connection between the base station and the applicator.

9. The cooling system according to any one of claims 1 to 4, wherein the first return electrode is configured to be placed on the limbs of the subject.

10. The cooling system according to any one of claims 1 to 4, wherein the cooling system is configured to determine a freezing event during cooling therapy by: Determine the first impedance between the cooling element and the first return electrode placed on the subject. Determine the time derivative of the determined first impedance. Movement is determined using a mechanism for detecting movement, including movement of the subject and / or movement of a portion of the subject's skin relative to the cooling element. The freeze event is determined if the time derivative of the first impedance satisfies one or more freezing conditions during the first time slot, and if distortion of the first impedance caused by movement is discarded in the same time slot.

11. The cooling system of claim 10, wherein the time derivative of the first impedance is a first-order time derivative, and wherein the first freezing condition is: during the first time slot, the first-order time derivative of the first impedance is higher than a first freezing threshold.

12. The cooling system of claim 11, wherein the first freezing threshold is determined at least in part based on a measurement of the first time derivative.

13. The cooling system of claim 10, wherein if no indication of possible movement is derived from the mechanism for detecting movement, or if the possible movement derived from the mechanism for detecting movement is insufficient to satisfy the freezing condition, then distortion caused by movement in the first time slot is discarded.

14. The cooling system of claim 13, wherein the cooling system is configured to detect possible movement if the first time derivative of the impedance between the movement sensor electrode and the movement sensor return electrode is higher than a movement threshold during the first time slot.

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