Acoustic device for skin treatment and methods of using the same

Abstract

Methods of treating the skin and in particular removing pigment from a tattoo are provided. In preferred embodiments, a piezoelectric transducer is placed at a plurality of locations above the skin and focused acoustic waves at 7 MHz or more are transmitted into the skin. The focal point of the focused acoustic waves is between 0.1 mm and 5 mm below the surface of the skin. The design of the piezoelectric transducer along with the frequency of operation are carefully chosen to create points of treatment with a desired size and shape. The correct amount of energy is supplied to the points of treatment to produce a lesion of a desired size and shape. The lesions are spaced and located to effect the treatment of the skin.

What is claimed is: 
     
         1 . An acoustic device comprising:
 a housing with a first end and a central axis that extends from the first end along a longitudinal length of the housing;   an optical monitoring system coupled to the housing and having an optical axis aligned with the central axis;   an acoustic generating device with a hole in the center coupled to the housing between the first end and the optical monitoring system wherein the acoustic generating device has an acoustic axis aligned with the central axis   wherein the acoustic generating device is designed to focus acoustic waves to a point of maximum pressure outside the housing past the first end; and   wherein an optically transparent pathway extends along the central axis from the optical monitoring system, through the hole in the acoustic generating device, past the first end to the skin surface such that a line of sight exists from the optical monitoring system all the way to the skin surface.   
     
     
         2 . The acoustic generating device of  claim 1 , wherein the optical monitoring system is configured to allow real-time observation simultaneously with production of focused acoustic waves by the acoustic generating device. 
     
     
         3 . The acoustic generating device of  claim 1 , further comprising a light source configured to illuminate the skin surface. 
     
     
         4 . The acoustic device of  claim 1 , further comprising a power unit that is in electrical communication with the acoustic generating device and is configured to operate the acoustic generating device at a third, or higher, harmonic resonance frequency. 
     
     
         5 . The acoustic device of  claim 1 , wherein the point of maximum pressure is between 0.1 mm and 10 mm past the first end. 
     
     
         6 . The acoustic device of  claim 1 , wherein the optical monitoring system comprises at least one lens. 
     
     
         7 . The acoustic device of  claim 1 , wherein the optical monitoring system comprises at least one image sensor. 
     
     
         8 . The acoustic device of  claim 1 , wherein the acoustic generating device has a F-number equal or higher than 0.5. 
     
     
         9 . The acoustic device of  claim 1 , wherein the acoustic generating device is a piezoelectric element composed of a ceramic material containing Lead. 
     
     
         10 . The acoustic device of  claim 1 , wherein the acoustic generating device is a piezoelectric element composed of a ceramic material containing Bismuth. 
     
     
         11 . The acoustic device of  claim 1 , wherein the acoustic generating device is a capacitive micromachined ultrasonic transducer. 
     
     
         12 . The acoustic device of  claim 1 , wherein the acoustic generating device is a piezoelectric micromachined ultrasonic transducer comprising a combination of Silicon and a piezoelectric material. 
     
     
         13 . The acoustic device of  claim 1  wherein the acoustic wave generation dose emitted from the acoustic generating to the point of treatment can be adjusted in a control unit by a user to form separate uniform transmissions with duration of 10 ms-1000 ms and acoustic output power levels of 0.1 W to 15 W with a resolution in resulting transmitted energy of less than 1 J/dose. 
     
     
         14 . The acoustic device of  claim 1 , wherein the light source is emitting light in the spectrum from 400 nm to 700 nm. 
     
     
         15 . The acoustic device of  claim 1 , wherein the light source is emitting light in the spectrum from 290 nm to 1100 nm. 
     
     
         16 . The acoustic device of  claim 1 , further comprising a cavity in the housing between the the acoustic generating device and the first end wherein the cavity contains a coupling medium. 
     
     
         17 . The acoustic device of  claim 16 , wherein the coupling medium is water. 
     
     
         18 . The acoustic device of  claim 1 , wherein the housing has a hole in the first end that is covered by an acoustic window. 
     
     
         19 . The acoustic device of  claim 18 , wherein the acoustic window is optically and acoustically transparent. 
     
     
         20 . An acoustic device comprising:
 a housing with a first end and a central axis that extends from the first end along a longitudinal length of the housing;   a lens coupled to the housing and having an optical axis aligned with the central axis;   an acoustic generating device with a hole in the center coupled to the housing between the first end and the lens wherein the acoustic generating device has an acoustic axis aligned with the central axis   wherein the acoustic generating device is designed to focus acoustic waves to a point of maximum pressure outside the housing past the first end; and   wherein a line of sight extends along the central axis from the lens, through the hole in the acoustic generating device, past the first end to the skin surface.   
     
     
         21 . An acoustic device comprising:
 a housing with a first end and a central axis that extends from the first end along a longitudinal length of the housing;   a lens coupled to the housing and having an optical axis aligned with the central axis;   an acoustic generating device with a hole in the center coupled to the housing between the first end and the lens wherein the acoustic generating device has an acoustic axis aligned with the central axis   wherein the acoustic generating device is designed to focus acoustic waves to a point of maximum pressure outside the housing past the first end; and   wherein an optically transparent pathway extends along the central axis from the lens, through the hole in the acoustic generating device, past the first end to the skin surface.