WO1997022325A1

WO1997022325A1 - Sonic method and apparatus for cosmetic applications

Info

Publication number: WO1997022325A1
Application number: PCT/US1996/020334
Authority: WO
Inventors: Robert T. Bock
Original assignee: Sonex International Corporation
Priority date: 1995-12-20
Filing date: 1996-12-20
Publication date: 1997-06-26
Also published as: ZA9610826B; AU1339397A

Abstract

Sonic pressure is applied to the skin of sufficiently high intensity to cause sonic vibrations (2) within the skin. A therapeutic agent (20) is applied to skin either before or promptly after the sonic pressure waves are applied to the skin. The device (1) includes a rigid handle (16) and a flexible applicator (3). A motor (13) within the handle (16) has a weight eccentrically (11) mounted on the output shaft (17) thereof to cause rotary vibrations of the handle (16) about its central axis (4) which are translated into linear vibrations of the applicator (3). Sonic pressure waves are applied in repetitive burst type modality, and ultrasonic pressure waves may be applied between the bursts of sonic waves (2) to control the depth of penetration of therapeutic agents.

Description

SONIC METHOD AND APPARATUS FOR COSMETIC APPLICATIONS

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to sonic devices for medical and cosmetic

applications More particularly the invention is concerned with methods

and apparatus facilitating the use of sonic energy coupled to anatomical tissue to precondition the skin to allow the penetration of medical and

cosmetic compounds, and to drive these compounds into and through the

epidermis into the dermis These compounds may be generally referred

to as therapeutic agents

Description of Prior Art

Numerous attempts have been made in the past to deliver

medications and cosmetic compounds into the skin by chemical, electrical

and ultrasonic means The application of chemicals to modify the skin

structure to allow the penetration of drugs was found to be dangerous because while it provided access for drugs to penetrate, it left the body

unprotected against harmful environments The application of electrical

fields to create transient transport pathways by a method called electroporation, and the method to electrically charge drug molecules to increase their penetration through the skin called iontophoresis, have

both been proven ineffective to deliver therapeutically adequate dosage of medications through the skin Past applications of high frequency (0 5 to 3 megahertz) and high intensity (0 5 to 5 W/cm²) therapeutic

ultrasound, called sonophoresis, were found to be uncertain, inefficient,

and the method found limited applications

The efforts of the prior art of ultrasonically induced drug delivery (sonophoresis) which were focused on driving drug molecules through the skin by the applications of high (megahertz) frequency high energy

ultrasonic pressure waves particularly suffered from the disadvantage of

tissue heating and the associated modification and sometimes destruction of healthy cells Once adequate ultrasonic power is applied either in a

continuous wave ultrasonic modality, or maximum burst length that were practicable without adverse tissue heating effects to force cosmetic

compounds through the highly resistive outermost sealing layer of the

skin, the stratum corneum (SC), the cosmetic compounds will proceed

uncontrollably through the less resistive dermis into the blood system,

creating systemic absorption of the cosmetic compounds which is

undesirable in most cosmetic applications

What has occurred to date is that notwithstanding the teachings of

the prior art, the ability to deliver large molecular weight cosmetic

compounds, such as proteins, vitamins, moisturizers, etc , into the deeper layers of the skin remained unresolved SUMMARY OF THE INVENTION

Responding to the above described unresolved needs, the object

of this invention is to provide a method and apparatus for the pre¬

treatment of the skin to open up passage ways through the epidermis to

allow the penetration of therapeutic agents

Another object of the invention is to provide a method and apparatus to enhance the penetration of therapeutic agents into the deeper layers of the skin, past the stratum corneum

In the method of the invention, sonic pressure waves are applied

to the skin of sufficiently high intensity to cause sonic vibrations within the skin A therapeutic agent is applied to the skin either before or promptly

after the sonic pressure waves are applied to the skin

The apparatus of the invention includes a rigid handle portion and

a flexible applicator portion The handle portion supports means for

producing vibrations which cause the applicator portion to vibrate in a

linear manner so as to transmit sonic energy to the skin and cause sonic

vibrations within the skin

The depth of penetration of the therapeutic agent is controlled by

applying sonic pressure waves in repetitive burst type modality, and

ultrasonic pressure waves may be applied between the bursts of sonic

waves BRIEF DESCRIPTION OF THE DRAWINGS

Fig 1 shows a cross sectional view of the skin and the invention

designed for developing passage ways in the stratum corneum and to

enhance the penetration of therapeutic agents into the skin under the force of sonic pressure waves,

Fig 2 shows a perspective view of the invention,

Fig 3 shows the conversion of the rotational vibrations of the handle into linear vibrations of the flexible applicator tip, and the

separation of the resulting linear vibrations into vibration vectors

perpendicular and parallel to the skin, and

Fig 4 shows a modified form of the invention

DESCRIPTION OF THE PREFERRED METHODS AND EMBODIMENTS

Referring in detail to the drawings, the reference numerals herein

refer to the like numbered parts in the drawings In the following discussion, unless otherwise qualified, the term "sound" or "sonic waves"

refer to either continuous sound waves or a repetitive burst type or pulsed

sonic wave modality, and refer to audible frequency sound waves, typically at frequencies between 15 hertz to 25 kilohertz A sonic skin conditioning device 1, in accordance with the simplest

form of the present invention, is shown in FIG 1 The skin conditioning

device 1 comprises of a rigid handle 16 and a flexible applicator end 3 These components may be formed of plastic or metal and the like. The

handle contains an electric motor 13 with a weight 11 mounted

eccentrically on the rotatable output shaft 17 of the motor. The handle 16

has a removable end portion 22 which contains a replaceable battery 14.

The battery 14 is connected to the motor 13 via switch 15 and electrical

conductors including lines 23 and 24.

When the user energizes motor 13 by closing switch 15, the motor

13 will rotate the eccentrically mounted weight 1 f about the shaft 17,

generating rotary vibrations of the entire handle 16 about its central axis

X as shown by arrow 4. The flexible applicator end 3 is designed to

resonate between about 15 hertz and 25 kilohertz, coinciding with the

vibration frequency generated by the motor 13. The vibrating flexible

applicator end 3 acts as a transducer converting the rotary vibrations of

the body 16 indicated by curving arrow 4 into linear vibrations of the

applicator end 3 indicated by arrows 7 and 8.

The outermost skin layer, the stratum corneum 10, consists of flat

dead cells filled with keratin fibers that are surrounded by ordered lipid

bilayers. This ordered structure of the lipid bilayers normally provides an impermeable protection of the anatomy and prevents the entrance of

medical and cosmetic compounds into the deeper layers of the skin. The

linear vibration vector in the direction of arrow 7, in frequencies between

about 15 hertz and 25 kilohertz, creates corresponding frequency sonic wave vibrations indicated by lines 2 in the stratum corneum 10. The sonic

wave vibrations 2 create physical vibrations which separate and

disorganize the lipid bilayers. The disorganization of the lipid bilayers

temporarily eliminates the barrier properties of the skin, and provides

penetrable channels for medical and cosmetic compounds along paths

indicated by arrows 26 through the epidermis into the deeper layers of the

living skin and the underlying tissues. A body 20 of a therapeutic agent

is shown in Fig. 1 as being disposed between the outer surface of the skin

and the applicator portion of the skin conditioning device. Body 20 is

applied to the skin manually, and then is engaged by the applicator portion so that the sonic pressure waves are applied through the therapeutic agent into the skin. In another method of the invention, sonic

pressure waves are first applied to the skin to cause sonic frequency

vibrations within the skin. The pressure waves are then terminated and a therapeutic agent is promptly applied to the skin before the natural

function of the person's body decreases permeability of the skin.

Fig. 2 shows a perspective view of the invention to explain the

conversion of the rotary vibration pattern of the handle 16 along the

curved arrow 4 into the linear vibration pattems of the flexible applicator

end 3 along the arrows 5 and 6. The flexible applicator end 3 is designed

to have a wide relatively inflexible dimension in the direction of arrow 5

and a thin, flexible dimension in the direction of arrow 6. The thin section of the flexible applicator end 3 is designed such a way that its natural

resonant frequency coincides with the vibration frequency generated by

the motor 13 and the eccentrically mounted weight 11 shown in FIG 1

The vibration amplitude of the applicator end 3 is minimized in the

direction of the thick dimension indicated by arrow 5, and maximized in

the direction of the thin dimension indicated by arrow 6 It should be

understood that the flexibility of applicator end 3 must be such that is

capable of vibrating in the desired frequency range much in the same

manner as a tuning fork Fig 3 shows separation of the linear vibration of the flexible

applicator end 3 in direction 6 into vibration vectors in the direction of

arrow 7 perpendicular to the skin and the direction of arrow 8 parallel to

the skin The vibration vector perpendicular to the skin in direction 7

transfers the mechanical vibration into sound wave vibrations 2 in the

tissues to disorder the lipid bilayers within the stratum corneum 10 The

sound wave vibrations 2, sometimes called sonic pressure waves, also

act to drive the therapeutic medical or cosmetic compounds into the

deeper layers of the skin past the stratum corneum The vibration vector

parallel to the skin in direction 8 is utilized to spread the medical

therapeutic or cosmetic compounds on the outer surface of the stratum

corneum 10 Referring to Fig 4, a modified form of the skin conditioning device

includes an applicator portion 32 having an inner end portion 34 which

has a friction fit within a complementary recess within the handle This arrangement enables the applicator portion of the device to be readily removed for cleaning or replacement when desired

A method to control the penetration depth of therapeutic agents

under the influence of sonic pressure waves was discovered by applying sonic pressure waves in a burst type modality When the sonic pressure

waves are applied in such a modality, for example, for one-tenth of a

second, followed by a pause of nine-tenths of a second, the burst width is one-tenth of a second and the repetition time is one second Therefore, the duty cycle is ten percent The depth of penetration of therapeutic

agents for a particular application frequency is proportional to the burst

width of this frequency When a burst is terminated and the sonic

pressure waves are stopped, the molecules passing through the passageways will also stop When the next burst is applied, it tends to

introduce new molecules into the passage, finding channels which are still open rather than the partially blocked channels caused by the previously introduced molecules Therefore, to limit the penetration depth of the

therapeutic agents, very short, microseconds length bursts are applied

To deepen penetration, the burst width is increased, keeping molecules

introduced into the passageways moving The dosage delivered is proportional to the sum of the sonic energy applied Therefore, to deliver

a particular dosage into the top layer of the skin, a large number of very

short bursts are applied To deliver the same dosage deep into the skin

and into the underlying tissues, a smaller number but longer duration

bursts are applied

It was also discovered that high frequency ultrasonic waves in the

megahertz frequency range tend to help the body reestablish the order of the lipid bilayers This knowledge can be utilized to limit the penetration

depth of the therapeutic materials under the influence of sonic pressure

waves to the stratum corneum In this enhanced method, short burst

width pulsed modality sonic waves in the frequency range of 15 hertz to 25 kilohertz are applied to the skin to enhance the penetration of

therapeutic agents, followed by the application of megahertz frequency

low intensity noncavitating ultrasonic waves, instead of the pause

described in the previous method above The megahertz frequency range ultrasound produces gentle angstrom wavelength vibrations in the stratum corneum which tends to reorder the lipid bilayers, and contain the penetration of the therapeutic agents within the stratum corneum A

typical sequencing, for example, is one-tenth of a second low frequency

(15 hertz to 25 kilohertz) sound wave burst followed by a nine-tenths of a second high frequency (megahertz frequency range) ultrasonic wave

burst While the preceding description contains many specificities, these

should not be construed as limitations on the scope of the invention, but

rather as an exemplification of a preferred and additional embodiments

thereof Many other variations are possible The important element of the

method invented is the generation and application of linear vibrations perpendicular to the skin to generate sonic pressure waves toward the deeper layers of the skin past the stratum corneum These linear

vibrations can be generated by numerous ways other than conversion of

a rotary vibration into linear vibration For example, a piezoelectric transducer placed on the surface of the skin driven by a sonic frequency power supply could achieve the same result Skilled artisans will readily

be able to change dimensions, shapes and construction materials of the

various components described in the preferred embodiment and adapt the

invention to various types of applications Accordingly, the scope of the

invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents

Claims

WHAT IS CLAIMED

1 The method of facilitating the penetration of a therapeutic agent

through a person's skin comprising, applying sonic pressure waves to the skin of sufficiently high intensity to cause sonic frequency vibrations within

the skin thereby opening up passageways through the stratum corneum

by disordering the lipid bilayers and increasing the permeability of the

skin to allow the penetration of a therapeutic agent for a limited time period, terminating the application of sonic pressure waves to the skin,

then promptly applying a therapeutic agent to the skin before the natural

function of the person's body decreases the permeability of the skin and

restores the normal environmental protection of the body

2 The method as defined in claim 1 wherein the sonic pressure

waves are applied in a repetitive burst type modality to reduce the tissue

heating effects of the said sonic vibrations

3 The method as defined in claim 2 wherein said bursts are

repeated about every second with a burst width of about one-tenth of a second to provide a duty cycle of about ten percent 4 The method of facilitating the penetration of a therapeutic agent through a person's skin comprising, applying a therapeutic agent to the

skin, then applying sonic pressure waves through the therapeutic agent

to the skin of sufficiently high intensity to force said therapeutic agent into

the skin and concurrently cause vibrations in the skin thereby opening up passageways through the stratum corneum by disordering the lipid

bilayers and increasing the permeability of the skin to allow the

penetration of the therapeutic agent

5 The method as defined in claim 4 wherein the sonic pressure

waves are applied in a repetitive burst type modality to control the depth

of penetration of the therapeutic agent

6 The method as defined in claim 5 wherein said bursts are

repeated about every second with a burst width of about one-tenth of a second to provide a duty cycle of about ten percent

7 The method as defined in claim 5 wherein bursts of ultrasonic

megahertz frequency low intensity noncavitating ultrasonic waves are applied to the skin between said bursts of sonic pressure waves 8 An apparatus for facilitating the penetration of a therapeutic

agent through a person's skin comprising, a rigid handle portion and a

flexible applicator portion extending from the said rigid handle portion,

said handle portion having a central axis, means located within said handle portion for creating a rotational vibration of said handle portion

about its central axis, means to convert said rotational vibration of said

handle into multidirectional linear vibrations of said flexible applicator portion which generate vibrations of sonic energy, said flexible applicator

portion being operative to transmit said sonic energy through the dead

outer surface of a person's skin into the underlying living tissue causing sonic frequency vibrations in the stratum corneum and underlying living

tissue to open up passage ways for said therapeutic agents

9 An apparatus as defined in claim 8 wherein the means located within said handle portion for creating a rotational vibration of said handle portion about its central axis comprises an electric motor having an output

shaft, and means eccentrically mounted on said output shaft to generate rotary vibrations of the handle portion

10 An apparatus as defined in claim 8 wherein the said flexible

applicator portion is removable from the said rigid handle portion 11. An apparatus as defined in claim 8 wherein said flexible

applicator portion has a wide relatively inflexible dimension in one

direction and a thin flexible dimension in another direction.