Patent Application
20180235341
The invention relates to a hair care device and method for enhancing uptake of a topical in hair.
Applications of topicals in hair include moisturization and protection. For example, excessive heat treatments of hair can cause a reduction in moisture content and potentially lead to hair damage or even breakage. Often it is advised to use a heat protection topical to safeguard the hair from excessive heat or to moisturize the hair when it is damaged. This resonates with consumers because they want to make their hair healthier and more resistant to damage from styling. The applied topicals can be in the form of oil (e.g. Argan oil), or watery solutions that contain a mixture of ingredients. These solutions are often applied by hand into the hair pre-styling but the downside is that the user has neither control over how well the topical is distributed on the hairs, nor how well the topical penetrates into the hair structure. Solutions can also be applied through appliances or onto appliances during styling to enhance protection to heat based styling or to moisturize the hair.
U.S. Pat. No. 5,267,985 provides a method and apparatus for enhancing the diffusion of a substance to a local area of material or tissue by providing ultrasonic energy to the substance and material in two or more distinct frequencies simultaneously. Each of the distinct frequencies of ultrasonic energy is chosen to enhance permeation of the substance through one or more diffusion rate-limiting sections of the material. The preferred frequency range for each signal is from 100 Hz to 100 MHz. Preferred combinations for two-frequency methods include 1 MHz & 3 MHz; 3 MHz & 9 MHz, and 5 MHz & 15 MHz. A first frequency may be selected to enhance diffusion of the substance through a first portion of the material. In that case, the material may be living tissue and the first portion of the material may be a stratum corneum layer of skin. In that case, the first frequency may lie in the range of 10 kHz to 100 MHz. This prior art document is primarily concerned with providing ultrasonic energy to living tissue in two or more distinct frequencies simultaneously in which a first portion of the material is a diffusion rate limiting membrane, so that a suitable first frequency is needed to enhance permeation of the substance through that first portion; hair (which is not a living tissue) is not discussed in this prior art document.
US 20060272665 discloses an ultrasonic hair treatment device to apply ultrasonic vibrations to a user's hair for enhancing the penetration of a hair treatment composition into the hair. A piezoelectric transducer is supplied with an electric power and is controlled by a controller to produce vibrations of 500 kHz to 10 MHz frequency at a power of 0.1 to 5 W/cm.
WO 99/51295 discloses a system for enhancing and improving the transcutaneous or transdermal delivery of topical chemicals or drugs. A disposable container contains a substantially sterile unit dose of an active agent adapted for a single use in a medical treatment. The unit dose is formulated to enhance transport of the active agent through mammalian skin when the active agent is applied to the skin and the skin is exposed to light and/or ultrasound defined by at least one specific parameter. Preferred ultrasound parameters may be determined in accordance with both efficacy and safety requirements. For example, one preferred range for lower frequency ultrasound may be between about 25 kHz and about 3 MHz at about 0.5-2.0 W/cm2 (either continuous or pulsed, using about a 20-25% duty cycle if pulsed). A preferred setting within this range may be at about 1.0 MHz at about 2.0 W/cm2, with a continuous wave beam and a treatment time of between about five and ten minutes. A preferred setting within this range for non-continuous beam (i.e. pulsed delivery) may be at about 1.0 MHz at about 0.2-0.5 W/cm2 with a 20-25% duty cycle with around a 2.0-20.0 ms “on” cycle and a treatment time of about five and ten minutes. One preferred range for higher frequency ultrasound may be between about 3 MHz and about 16 MHz at about 0.2-1.0 W/cm2 (either continuous or pulsed, using about a 20% duty cycle if pulses), with a treatment time of between about one and twenty minutes. A preferred setting within this range may be at about 10 MHz at about 0.2 W/cm2, with a continuous treatment time of between about five and twenty minutes. A preferred embodiment may be useful to specifically stimulate (or inhibit) the growth of hair or other skin appendages (such as nails, etc.). A preferred embodiment, may also be useful to stimulate the growth, or re-growth, of fine vellus or dormant or inactive hairs (e.g. to treat hair loss, for example). For example, the effectiveness of Rogaine or similar drugs used in the treatment of male pattern baldness may be enhanced. It is noted that the above ultrasound parameters are disclosed in a paragraph between two paragraphs relating to skin treatment; no ultrasound parameters are disclosed specifically in relation to hair treatment.
It is, inter alia, an object of the invention to provide an improved hair care device and method for enhancing uptake of a topical in hair. The invention is defined by the independent claims. Advantageous embodiments are defined in the dependent claims. Advantageous features of the hair care device are also advantageous features of the hair care method.
Embodiments of the present invention feature ways to enhance the safe and effective uptake of topicals in the hair structure by using ultrasound (15-50 MHz) induced cavitation. This provides a simple and low-cost solution to enhance topical uptake by the hair structure before or during styling and thereby reducing the risk on hair damage. The lower frequency limit of 15 MHz has been chosen to trigger the largest inclusions to be activated on the hair surface. The upper frequency limit of 50 MHz has to do with the fact that, when frequency increases, the power needed to trigger smaller inclusions will increase as well. 50 MHz is preferred as the upper frequency limit since at this frequency we can still find a reasonable combination of duty cycle and treatment time to limit thermal issues.
Embodiments of the present invention provide enhanced topical uptake for small and large tresses of hair. This is based on the insight that the indentation depth of cuticles is 0.3-2 μm, resulting in poor hair permeability for frequencies in the kHz range up to 10 MHz. In phonophoresis, the increase in tissue permeability is mostly due to cavitating bubbles: therefore, low frequencies (20-100 kHz) are usually employed. In this context, acoustic cavitation refers broadly to violent oscillations of pre-existing gas inclusions. However, the typical size of the indentation depth between cuticle scales on a healthy and undamaged/untreated hair surface is about 0.3-0.5 μm, i.e. approximately 1 cuticle cell. When stressed (particularly if bent) or damaged, the indent can be much larger, in the order of 1-2 μm. When hair is wet, we may expect gas bubbles to be trapped in these indentation depths, meaning that available gas bubbles for cavitation activity will probably be in the range of 0.3-2 μm. Therefore, using a frequency range of 15-50 MHz should ensure gentle cavitation of trapped gas bubbles in damaged and undamaged cuticle scales. The power required for inertial cavitation increases significantly at higher frequencies (from about 2 W/cm2 at 1 MHz to about 100 W/cm2 at 50 MHz). Higher power usage leads to higher temperature increases per second. If cavitation is used to increase the permeability of cuticle scales and to increase moisture uptake, cuticle scales should be closed after treatment (for instance using a conditioner or simply by surface moisturization) to avoid fast moisture loss after treatment. Alternatively, cavitation may be set at a very gentle reversible level, limiting the damage to cuticle: also to this purpose, the choice of higher frequencies (MHz range) will be beneficial.
If hair is exposed to ultrasound at a specific frequency and intensity (or pressure), inertial cavitation will be induced in a range of bubbles with different radii. Assuming an input ultrasound of twice the pressure threshold to induce cavitation, a conservative assumption considering appropriate safety ranges, it is possible to derive a range of initial bubble radius that undergoes inertial cavitation at different frequencies. The inventors have recognized that this range decreases with increasing frequency, and that at low frequencies, cavitation may occur in gas bubbles larger than the range of bubbles in hair cuticle. This should be avoided since this may cause violent cavitation, forming uncontrolled shock waves that may damage hair structures. At frequencies between 20 MHz and 50 MHz, the generated inertial cavitation is confined to the bubbles with radii within the range of the dimension of the hair cuticle indentation depth. The inventors have thus recognized that it is preferred to use ultrasound frequencies within the range of 20 MHz to 50 MHz to induce selective cavitation in hair cuticles for improved topical uptake.
Embodiments of the present invention provide a safer treatment, as cavitation at low frequencies requires less energy than at higher frequencies and the range of bubbles excited tends to be larger. Ultrasound at megahertz frequencies will create less inertial cavitation (mechanical index cavitation). The higher the frequency the less violent cavitation is created, thereby reducing the likelihood of mechanically damaging the hair structure.
Embodiments of the present invention provide ease of use, simple execution, low-power requirements, a small footprint, e.g. a small handheld device.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
Embodiments of the present invention provide a handheld, preferably cordless system which generates ultrasound to treat hairs coated by a topical for enhanced uptake of said topical. The ultrasound treatment is applied through direct contact with the topical covered hairs, preferably by clamping a tress of hair.
Piezoelectric crystals (PMUT) are used to produce ultrasound (>20 kHz). Non-piezoelectric techniques like Capacitive Micro-machined Ultrasonic Transducers (CMUT) can be used for higher frequencies (typically up to 100 MHz) and can be used with this invention.
In a preferred embodiment the ultrasound transducer is embedded in the hair interface. It features a clamp to provide optimal contact with the hairs. The treatment clamps will be positioned close together in operating mode, where the distance between the clamps ideally should be smaller than one wavelength to promote uniformity, increasing the amplitude of the signal and time to result. Especially at higher frequencies this becomes an option since the energy is absorbed very quickly and might not even reach the opposed clamp. This will enable lower power usage and increase uniformity while enhancing cavitation to achieve better penetration into the hair structure. To minimize unwanted thermal effects the ultrasound could be configured in pulsed mode with 1% duty cycle and a maximum treatment time of 4 s to stay below a maximum increased temperature threshold of 100° C.
One alternative embodiment features two or multiple ultrasound transducers instead of one. Having two ultrasound sources or an array of ultrasound transducers opposed to each other in both clamps of the device will decrease the time to result and probably create constructive interference. If the distance between the clamps is not predetermined the chance of destructive interference is large. This will not happen if the distance between the closed clamps is exactly multiple times the wavelength of the frequency used or (2N+1)*lambda/4 for multiple ultrasound sources.
Preferably, the ultrasound intensity is in a range between 2 W/cm2 and 100 W/cm2.
Preferably, the predetermined duty cycle is in a range between 1% and 50%. The inventors have found that at an ultrasound frequency of 20 MHz, a preferred upper limit of the duty cycle is 12.5%, while at an ultrasound frequency of 50 MHz, the preferred upper limit of the duty cycle is 5%.
Preferably, the hair care device comprises an array of ultrasound transducers.
Preferably, the controller comprises a look-up-table for determining the level of ultrasound intensity and the predetermined duty cycle for a specific hair type or topical.
Preferably, the hair care device comprises a sensor connected to the controller, the sensor being configured for sensing a parameter associated with the properties, e.g. temperature, moisture, of the topical and the hair. Preferably, the sensor is selected from a list comprising a temperature sensor for sensing a temperature increase caused by the application of ultrasound, an optical sensor for sensing a change of the optical properties e.g. scattering, reflectance, caused by the application of ultrasound, an acoustical sensor for sensing a change of the acoustic properties, e.g. acoustic impedance, speed of sound, caused by the application of ultrasound, and an electrical sensor for sensing a change in electrical properties, e.g. radio frequency impedance, capacitance, caused by the application of ultrasound.
Preferably, the controller is configured to stop the applying of ultrasound to the topical before a predetermined temperature limit is reached, the predetermined temperature limit being preferably 100° C. and more preferably 50° C. Alternatively, in dependence on the temperature, the intensity and/or the duty cycle of the ultrasound could be adjusted so as to prevent the temperature from becoming too high.
Preferably, in use the transducer is in physical contact with the topical and/or the hair and positioned at a distance of preferably more than 0.3 cm, more preferably more than 1 cm, away from the skin surface. This distance ensures that the ultrasound application will have its intended positive effects without unintended negative effects to hair health. To this end, the hair care device preferably is provided with a suitable distance holder to ensure this minimum distance between the transducer and the skin surface.
One alternative embodiment features systems and methods that initiate a feedback loop to measure attenuation of ultrasound in the hair structure to determine moisture content and adjust settings accordingly.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15194604.3 | Nov 2015 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/076469 | 11/3/2016 | WO | 00 |
