Patent Application
20070193278
The present invention relates to a device that provides cooling to a body in response to a measured, sensed or anticipated change in the temperature of the body.
Hot flashes are sudden increases in core and surface body temperature and are perceived as intense increases in body temperature that are characteristically manifested by nearly instant flushing, sweating, dizziness, nausea, palpitations, and diaphoresis. Hot flashes can disrupt sleep, interfere with mental concentration and adversely affect the quality of life. Hot flashes are characterized by a sudden onset of warmth in the face, neck and chest. Hot flashes may occur many times per day and several times per hour. Hot flashes typically pass within minutes, but can be debilitating until their passage and during a complete recovery period that can last up to 30 minutes.
Hot flashes in menopausal women, and in men following androgen-deprivation therapy for the control of metastatic prostate cancer, are common. Brief, episodic skin surface temperature rises due to thermoregulatory problems are also common in persons having diabetes, multiple sclerosis and cancer patients undergoing chemotherapy.
Hot flashes can be treated with hormone replacement therapy (HRT). However, increasingly, women are reluctant to undertake this therapy because of a number of clinical trials that have indicated a significant correlation between HRT and an increased incidence of heart disease, stroke and breast cancer. For this reason, many women have shunned HRT, leaving them with few effective alternatives for treating or controlling their hot flashes. There are herbal remedies which are purported to relieve the discomfort or reduce the frequency or severity of hot flashes. Some women have been prescribed anti-depressant medication for their hot flashes. While somewhat helpful in some women, neither herbal remedies nor anti-depressants have been proven generally effective and safe. There is clearly a need for a practical device and method for treating hot flashes which is both effective and avoids undesired and dangerous side effects of all known treatment methods.
The invention concerns a cooling device for providing cooling to a body. The cooling device comprises a thermoelectric cooler having a heat absorbing surface engageable with the body and a heat rejecting surface. A heat absorbing reservoir is engaged with the heat rejecting surface. The heat absorbing reservoir comprises a phase change material. A temperature sensor is positionable proximate to, and preferably in contact with, the body for sensing a temperature change thereon. A controller is operatively connected with the temperature sensor and the thermoelectric cooler. An electrical power source is operatively connected with the thermoelectric cooler and the controller and provides power to these components. The controller provides power from the power source to the thermoelectric cooler in response to an increase in body surface temperature at a predetermined rate as sensed by the temperature sensor. Alternately, the cooling may be user-activated. The heat absorbing reservoir maintains the heat rejecting surface at a substantially constant temperature during operation.
In one embodiment according to the invention, the thermoelectric cooler is a Peltier device, the controller comprises a microprocessor, the electrical power source comprises a battery and the temperature sensor may be a thermistor, a thermocouple, an infrared sensor or a resistance temperature detector sensor.
The phase change material comprises a solid which melts at a temperature between about 25° C. and about 42° C. The phase change material may comprise metals or metal alloys having a melting point between about 25° C. and about 42° C. or may be salt hydrate phase change materials, organic phase change materials, linear crystalline alkyl hydrocarbons, fatty acids, fatty esters, polyethylene glycols, long alkyl side chain polymers, the solid state series of pentaerythritol, pentaglycerine, and neopentyl glycol, quaternary ammonium clathrates and semi-clathrates, salt hydrides and combinations thereof.
The heat absorbing reservoir may be removably mounted on the heat rejecting surface of the thermoelectric cooler to allow for rapid replacement.
The invention also encompasses a method of treating hot flashes. The method comprises:
(a) providing a cooling device proximate to a skin surface of a body;
(b) monitoring skin surface temperature;
(c) activating the cooling device in response to a measured rise in the skin surface temperature over a first time period; and
(d) operating the cooling device for a second predetermined time period to provide cooling to the body.
In an alternate embodiment, the method may include manual activation of the cooling device in response to a sensed or anticipated hot flash episode.
Monitoring the skin surface temperature may comprise sampling the skin surface temperature at predetermined time intervals. Additionally, the method may include providing a heat absorbing reservoir mounted on the cooling device and absorbing heat from the cooling device with the heat absorbing reservoir while maintaining a substantially constant temperature of the heat absorbing reservoir.
In the drawings, like numerals indicate like elements throughout. The terminology includes the words specifically mentioned, derivatives thereof and words of similar import. The embodiments illustrated below are not intended to be exhaustive or to limit the invention to the precise form disclosed. These embodiments are chosen and described to best explain the principle of the invention and its application and practical use and to enable others skilled in the art to best utilize the invention.
An exemplary embodiment of a cooling device 100 according to the present invention is shown schematically in
Preferably, the cooling device 100 takes the form of a unitary, compact unit attachable to a body by means of a strap, sling, insert band or adhesive patch. The device could also be attached to an article of clothing such as an under garment, a shirt or blouse as well as a hat, cap or helmet. The device components will preferably be removable from the garment, headgear, strap or other mounting media so that the media can be washed. Alternately, the cooling device 100 may comprise a plurality of components connected to each other by wires or with a wireless communication system.
The temperature sensor 110 can be, for example, a thermistor, a thermocouple, an infrared temperature sensor or a resistance temperature detector sensor. The temperature sensor 110 is electronically connected to the controller 150 so that the controller receives a signal in the form of a change in voltage (if a thermocouple is used) or a change in resistance (if a thermistor is used) across the temperature sensor 110, which the controller correlates to a temperature at the temperature sensing device 110.
The thermoelectric cooler 120 has a heat absorbing surface 121 and a heat rejecting surface 123. These surfaces may be, for example, formed of a metal or a heat conducting ceramic. An exemplary thermoelectric cooler 120 is a Peltier Effect device, although other devices that perform the same function may also be used. The thermoelectric cooler 120 is electrically connected to the power source 140 which provides power to the thermoelectric cooler when cooling is required.
When the temperature sensor 110 detects a temperature rise at a predetermined rate, for example, one that is known to be indicative of the onset of hot flashes, the controller 150 allows electrical energy to flow from power source 140 to power the thermoelectric cooler 120.
The heat absorbing reservoir 130 is used to absorb the heat generated during operation of the thermoelectric cooler. Preferably the heat absorbing reservoir 130 contains a material that has the capacity to absorb heat without significantly changing its temperature, such as a phase change material. To absorb energy at constant temperature, the phase change material changes from solid to liquid (melts), liquid to gas (evaporates), or solid to gas (sublimates). In a preferred embodiment of the invention, the phase change material is in a solid state when the thermoelectric cooler 120 is inactive, i.e., when no power is being provided.
Examples of phase change materials contained in the heat absorbing reservoir 130 include salt hydrate phase change materials, organic phase change materials, linear crystalline alkyl hydrocarbons, fatty acids and esters, polyethylene glycols, long alkyl side chain polymers, the solid state series of pentaerythritol, pentaglycerine, and neopentyl glycol, quaternary ammonium clathrates and semi-clathrates, and salt hydrides. Metals and metal alloys having a low melting point are also feasible. By mixing some of the above compounds, or by mixing the low melting point metals (including Gad, Son and/or In, BP, Bi, etc.), a material having a desired single phase change temperature may be produced. By adjusting the percentage of the constituents that comprise the phase change material, it is possible to achieve an optimum phase change temperature that will allow the cooling device 100 to operate effectively in view of an expected ambient temperature range, as well as the location of the cooling device 100 on the user. In an exemplary embodiment, the phase change material melts at a temperature between approximately 25° C. and 42° C.
The heat absorbing reservoir 130 may be comprised of several components, including a container that will prevent leakage or evaporation of the phase change material and an internal structure, such as cooling fins to augment heat transfer to the phase change material. The heat absorbing reservoir is preferably easily connectable and removable from the heat rejecting surface 123 of the thermoelectric cooler 120 in order to quickly switch to a fresh heat absorbing reservoir if additional hot flashes are expected and there is insufficient time for the melted material to resolidify. While connected to the thermoelectric cooler 120, the heat absorbing reservoir 130 maintains good thermal contact with the heat rejecting side of thermoelectric cooler.
In a practical application of the device according to the invention, the melting point temperature Tmelt of the phase change material is higher than the maximum temperature Tpower off of the heat rejecting side of thermoelectric cooler 120 with power off, when the cooling device 100 is positioned in contact with the human body, typically under the clothing. Therefore, the phase change material will undergo a phase change only during “power on” operation, for example, when the device is operated in response to a hot flash, in which the peak heat sensation typically lasts about 1 to 2 minutes. During “power off” periods between activations (typically an hour between hot flashes), the phase change material will resolidify, because the device temperature Tpower off is lower than the melting point Tmelt. The magnitude of Tpower off is approximately equal to the skin temperature under clothing, about 30° C., but may vary depending upon the ambient temperature, and clothing being worn.
As an example, Tpower off=30° C. and Tmelt=35° C. As the heat absorbing reservoir 130 absorbs heat from the thermoelectric cooler 120 during operation of the device 100 in response to a hot flash, the temperature of the heat absorbing component 130 will increase from 30° C. to 35° C. At 35° C., the phase change material will start undergoing a phase change (i.e. melting, evaporating, or sublimating). During the change of phase, the temperature of the heat absorbing reservoir 130 will not change (it will stay at 35° C. in this example). Consequently, even though heat energy is being absorbed by the heat absorbing reservoir 130, it does not heat up, thereby allowing the thermoelectric cooler to operate efficiently and prevent discomfort.
The power source 140 can be a DC power source, preferably approximately 1.5 to 12 volts, provided by an electric battery that is preferably integrated into the cooling device 100. Alkaline batteries may be used, but rechargeable batteries, such as lithium ion or nickel cadmium are preferred to enable the user to easily keep the power source 140 at or near full charge capacity. The power source 140 may be removable and replaceable within the device 100 or, alternatively, a power cable, for example, a USB cable (not shown) may be connectable to the power source 140 to recharge it from a computer or other source of electrical energy. The power source 140 is electrically connected to the thermoelectric cooler 120 and to the controller 150 to provide electrical power to both components.
The temperature sensor 110 is electrically connected to the controller 150 such that electrical signals in the form of voltage or resistance differences indicative of changes in temperature generated by the sensor are processed by the controller. The controller thereby monitors the rate of temperature change of the body over time. The controller 150 is preferably a microprocessor, and may provide ON-OFF, proportional, derivative, integral, or programmed process control, or any combination thereof, as well as any other type of process control.
The controller 150 is also electronically connected to the power source 140. When a predetermined rise in temperature over a predetermined time period is sensed by the temperature sensor 110 and communicated to the controller 150, the controller recognizes this data, for example, as indicative of a hot flash, and transmits a signal which closes a switch, allowing the power source 140 to supply electrical power to the thermoelectric cooler 120 and thereby activate the device 100. The controller 150 is programmed to allow electrical power to flow to the thermoelectric cooler 120 for a predetermined time period, for example, approximately two minutes to effectively treat hot flashes. While the time period of device operation may be longer than two minutes for other applications, it is generally impractical for the time period to significantly exceed the time required for the heat absorbing reservoir 130 to completely change phase.
Although the time period over which electrical power is supplied to the thermoelectric cooler 120 may be preset by the controller programming, the time period may also be varied by the user, such as by using a switch or dial electronically connected to the processor 150, which will allow the user to selectively determine the operational time of the device 100 from a range of potential durations. Additionally, the device may be capable of different modes of operation, for example, one mode which may provide intense cooling and another for less intense cooling. The device 100 may also include an “ON/OFF” switch 160 that may be employed to prevent operation of the device 100, overriding the actions of the controller.
Referring now to
In the embodiment shown in
As the heat absorbing reservoir 130 absorbs heat during a hot flash, the phase change material changes phase, for example, from solid to liquid. Preferably, the controller 150 is programmed to operate for a time period long enough to mitigate the hot flashes but short enough such that the phase change material of the heat absorbing reservoir 130 does not completely change phase. Studies thus far have shown that about two minutes of operation is sufficient for a device having a heat transfer capacity of about 1 to about 10 watts, worn on the chest of the subject, is sufficient for relieving symptom of a hot flash. After the predetermined time period of operation has passed, the controller 150 shuts off the power source 140 so that electrical power ceases to be supplied to the thermoelectric cooler 120. The heat absorbing reservoir 130 ceases to absorb heat from the thermoelectric cooler 120 and returns to its no power equilibrium phase, which is preferably a solid state. The device 100 is again ready for operation, the controller continuing to monitor the body temperature, ready to activate the device at the onset of the next hot flash.
In another embodiment, the phase change material is contained in a cartridge that is removably attached to the heat rejecting surface of the thermoelectric cooler so that it may be easily replaced in the event that a second hot flash is expected before the phase change material can solidify from a preceding hot flash. This embodiment can be used in a hot environment which does not allow the phase change material to solidify between the flashes or in an anticipated stressful situation. The user may place the cartridge on a cool surface, in a cold location such as air conditioned room, or in a refrigerator if very rapid cooling is desired to solidify the phase change material.
In an exemplary embodiment, if the device 100 is integrated into an article of clothing, the article of clothing includes at least one opening or surface to allow direct contact by at least a portion of the temperature sensor 110 with the body 170. The temperature sensor may be in proximate, but preferably in actual, contact with the wearer's body, allowing for accurate sensing of the body temperature proximate to the device. Preferably, the heat absorbing surface 121 is in direct contact with the body as well for rapid cooling of the body when the thermoelectric cooler 120 is in operation.
A manually operated embodiment of the present invention is shown schematically in the device 200, shown in
Although an exemplary use of the present invention is described for the alleviation of hot flashes, those skilled in the art will recognize that the device 200 may have other uses, such as for the alleviation of migraine headaches wherein cerebral vasodilation is a known symptom and where applied cold is a known effective treatment. The device 200 may be applied to the user's head or neck region 270 to provide cooling relief to that area of the user. When the user desires the cooling effect of the device 200, such as a recognizable prodrome preceding a migraine headache, or based on a perceived rise in skin surface temperature over a first time period, the user turns the “ON/OFF” switch 260 to the “ON” position. The switch 260 completes an electrical circuit, and the power source 240 provides electrical power to the thermoelectric cooler 220. The heat absorbing reservoir 230 absorbs the heat from the heat rejecting surface of the thermoelectric cooler by changing phase, for example, from solid to a liquid, without a change in temperature. After a second period of time, the user opens the “ON/OFF” switch 260, stopping operation of the device 200 or after a predetermined limit, the device automatically turns off
Although the size of the devices 100, 200 is preferably relatively small, such as a footprint of approximately 1 to 5 square inches, those skilled in the art will recognize that a larger version of the device 200 can be used to stem blood flow in an open wound by cooling the wound opening and the skin area surrounding the wound.
Further, the inventors believe that the devices 100, 200 can be used in other applications such as in patients suffering from diabetes, multiple sclerosis and cancer who are being treated with chemotherapy, where cooling is required to be applied to a surface for a period of time to relieve the discomfort of episodes of heating due to abnormal thermoregulation associated with these disorders or their treatment.
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.
This application is based on and claims priority to U.S. Provisional Application No. 60/773,945, filed Feb. 16, 2006, the contents of which are fully incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60773945 | Feb 2006 | US |
