Abstract:
The invention relates to a skin or tissue treatment device or energy delivery device and the associated tip device for contacting skin or tissue. The devices can be advantageously used to treat facial wrinkles, blemishes, or fine lines without damaging the surface of the skin. A number of systems or control systems can be incorporated into the devices to afford manual or automatic control of the energy delivered. In preferred embodiments, microwave range energy is used in the treatments.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional application No. 60/842,943, filed Sep. 8, 2006, which is hereby incorporated by reference as though fully set forth herein. 
     
     FIELD OF INVENTION 
       [0002]    The invention relates to electronic devices and methods for using them to non-invasively treat or affect tissues. In particular, the devices can be used to deliver an effective amount of energy, typically microwave energy, from the surface of skin, such as the face, to the underlying layers of tissue in order to reduce wrinkles, fine lines, fissures, and/or skin discoloration or marks. In other aspects, the invention relates to devices and methods for effectively concentrating the effects of microwave energy to treat a selected volume of tissue. 
       BACKGROUND OF INVENTION 
       [0003]    While the use of microwave energy to treat skin has been proposed in the past, methods to effectively reduce facial wrinkles and other age-related blemishes have not been in use. Generally, microwave devices have been implemented in catheter-based and invasive methods, which are distinctly disadvantageous compared to non-invasive methods. Accordingly, improved microwave devices and methods for noninvasive treatment of tissue are desired in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    The invention provides an energy delivery device for treating tissues, particularly skin tissues and wrinkled, contoured, or fissured skin. The device comprises a hand held energy delivery device (EDD) with a removable tip that directs energy, originating from a sinusoidal wave generator (in the microwave frequency range), amplifier and wave-guide, controlled by a computer, into the wrinkle, fissure, etc. The energy is given in pulses, the duration of which can be varied, for example, in the range of 1 ms to 1 sec, according to the type of treatment, type of skin to be treated, etc. The pulse interval can also be controlled in a similar range. The power of the pulsed waves, supplied by the generator through the amplifier, is in the range of 0.1-100 Watts. The applied wave parameters can also be controlled by feedback loop activated by sensors monitoring the skin condition. These sensors can be for temperature (thermocouples, thermistors, radiometers), reflected wave measuring system, optic, etc. Optionally, a cover around the EDD tip can be used to flatten the skin surface when in contact with it, or within which a negative (vacuum) pressure can be created to flatten skin tissue for the tip to more directly apply energy to the skin and the layers of tissue below the skin surface. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
           [0006]    For a more complete understanding of the invention and some advantages thereof, reference is now made to the following descriptions taken in connection with the accompanying drawings in which: 
           [0007]      FIG. 1  schematically represents the EDD. 
           [0008]      FIG. 2  represents an exploded view of the EDD in order to show its components. 
           [0009]      FIG. 3  represents a cross-sectional view of the EDD and describes the possible connections between the energy conduit or waveguide through the replaceable unit or tip, or applicator tip or antenna body, and the coaxial cable. 
           [0010]      FIG. 4  represents means for interlocking the core ( 14 ) of the coaxial cable and the core ( 5 ) of the replaceable unit. 
           [0011]      FIG. 5  illustrates relative dimensions of the core ( 5 ) of the replaceable unit and the dielectric ( 6 ). 
           [0012]      FIG. 6  represents a screw-on or bolt assembly or mechanism between the handheld portion and the tip portion of an EDD. 
           [0013]      FIG. 7  represents a bayonet connection between the handheld portion and the tip portion of an EDD. 
           [0014]      FIG. 8  represents a clamping mechanism between the handheld portion and the tip portion of an EDD. 
           [0015]      FIG. 9  represents an assembly whereby a click mechanism connects the handheld portion and the tip portion of the EDD. 
           [0016]      FIGS. 10 through 12  illustrate steps that may be carried out in removing the tip portion from the handheld portion. 
           [0017]      FIG. 13  depicts an exemplary block diagram of the system of the invention and its operation. 
           [0018]      FIG. 14  shows an example of a software simulated energy density field of the energy delivery device in tissue. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    In one aspect, the invention comprises a microwave emitting or delivery device, referred to herein as an energy delivery device (EDD), that provides a controlled delivery of energy to the skin and/or its underlying layers. The use of the device of the invention induces regeneration of the skin and particularly areas having collagen fibers. Typically, the degree of fibrous bundling or cross-linking in these areas increases with age, resulting in fine lines, wrinkles, and eventually pronounced fissures or furrows. In general, the devices and methods of the invention and the energy delivery device are used in direct contact with the surface of the skin and the emitted energy affects tissue below the surface of the skin, especially the underlying collagen fiber layer, such as the dermis or epidermis. Treatment of the collagen fibers affects the cross-links in the fibrous material causing it to heal or regenerate. The healing or regenerating tissue will impart an improved appearance to the surface of the skin, removing wrinkles and fine lines. Thus, the appearance of desired areas or portions of the skin&#39;s surface are improved. 
         [0020]    In a preferred embodiment, the method of the invention encompasses a treatment mode wherein the tissue is skin and the emitted microwaves are directed to an area of the body where aged or wrinkled skin is present, such as around the eyes, lips, chin, neck, and forehead. 
         [0021]    The devices and methods of the invention can be adapted and used with a variety of tissues and other targets at a variety of energy penetrating depths. While skin tissue is discussed in general here, other tissue can also be treated. For example, the devices and methods disclosed herein may be utilized to good advantage on uterine tissue and/or in the treatment of endometriosis. Thus, while the use on skin tissue is discussed in particular, the invention is not limited to use with any particular tissue or target. 
         [0022]    In preferred aspects, the invention comprises an EDD tip or probe. Once a target area has been identified for treatment, the energy delivered depends on the patient, the type of skin, the size of the wrinkles or other skin blemish or area, and the desired or appropriate temperature for the treatment. The duration of the pulses of the microwave energy of the preferred wavelength is chosen for the type of treatment desired. Depending on the treatment desired, a microwave pulse can be about 1 msec in length, or between about 1 msec and 100 msec, or between about 1 msec and 10 msec. 
         [0023]    In a generic version of the microwave emitting device, the power supplied from the microwave generator or source can be applied in a range of about 0.1-100 Watts per probe or tip and, preferably, in a range of about 1-15 Watts per tip. While preferably only one tip is used, more than one can also be used. A coaxial cable of 50 Ohm can be used to supply power to the EDD tip or tips. The power may be applied in short high power pulses, preferably in the Microwave frequency range of about 300 MHz-30 GHz, and most preferably at a wave frequency of about 2.45 GHz. Treatment is continued for a desired length of time in accordance with the desired results. 
         [0024]    The amount of energy delivered to disrupt or break the fibrous bonds depends on the condition of the skin. An electromagnetic field, particularly in the microwave region between 300 MHz and 10 GHz, is effective at treating these fibrous layers. In various embodiments, the microwave delivery device and treatment regimen provides a controlled delivery of electromagnetic energy to the skin. The control system employed can comprise or include a pulse controller for selecting the desired average power and duration of the energy pulse delivered to the EDD tip. The control system employed is used for selection of the frequency, pulse width and amplitude, pulse interval, etc. The microwaves are generated by different oscillators delivering a sinusoidal signals at a frequency in the range of about 433 MHz to about 5800 MHz to the EDD. The pulse duration can be controlled, but preferably about a 10 msec pulse, the intensity of which is in the range of about 0.1-20 W, is used. A standing wave ratio indicator can be used to both adjust the position of the EDD or the pressure the EDD exerts on the skin, and to control the power transmitted to the skin so as to adjust the required transmitted power to the skin. 
         [0025]    In optimal procedures, the skin, at the treatment area, is gently straightened or flattened, for example by hand or by one or more appropriate devices that do not interfere with the microwave delivery. The energy is thus delivered into, or as close as possible to, the wrinkled area and/or inside the flattened area of a wrinkle or fissure. In other optional embodiments, a vacuum can be used around the EDD tip so that the skin is flattened by the vacuum action 
         [0026]    In one example of the devices and methods of treating skin or layers of skin, the EDD tip receives microwave energy from a source fed through a flexible, coaxial line. A single tip is generally used, where the tip is either pointed or blunt-ended at the distal end designated to be in contact with the skin during use. In a preferred embodiment, the tip is a shielded, directional emitter of microwave energy having a central microwave conductor, such as a rigid wire, that terminates in a blunt shape at the distal end, and where the distal end extends beyond a metallic shield that surrounds a portion of the conductor or rigid wire. One or more dielectric compounds or media with appropriate dielectric properties, such as Teflon, is positioned in the space between the shield and the rigid wire. The shield design and shape can vary and the distance between the distal end of the central conductor and the shield can vary, but a preferred distance is between about 0.1 mm and 5 mm. 
         [0027]    The proximal end of the conducting tip is functionally connected to the waveguide originating in the generator (e.g., via a coaxial cable). The features of the handheld unit can include an ON/OFF switch and an intensity control knob or actuator for controlling the pulse, for example the pulse length and/or pulse energy. The length of the tip is generally designed for use at one or more frequencies, and as noted a preferred frequency is about 2.45 GHz. Various frequencies and tip lengths can be selected and a system incorporated in the handheld unit can be structured to accommodate different, interchangeable tips that connect to the same waveguide and controllable generator. 
         [0028]    In a preferred embodiment, the tip is disposable and can be removed and replaced for use with different patients. A connection point within the handheld unit, for example, connects the coaxial cable or other flexible waveguide to the rigid waveguide ending in the tip. Also, the tip can have differing diameters in the range of about 0.5 mm to 5 mm. More generally and as noted, the distal end of the tip can comprise a short tapered shape, a conical shape, or any other size and/or shape that can be inserted into a wrinkled region or fissure in the skin to be treated. The tip can also include a dielectric compound to provide impedance matching with the treatment area. Optionally, a tube carrying gas or liquid can extend from the handheld unit, along the waveguide and within the unit housing, to provide cooling gas or liquid to the treatment site. A similar tube can be used for suction to provide a negative pressure at the treatment site. The gas, fluid, and/or vacuum lines can be controlled, according to the amount of energy delivered, or controlled independently. 
         [0029]    An exemplary system for the handheld microwave energy delivery device comprises a handheld unit coupled to one or more flexible lines that are functionally connected to a generator or source of pulsed microwave energy, gas, or liquid supply, vacuum, and a computer-controlled circuit to control the timing, frequency, power and pulse duration of the microwave energy. The computer-controlled circuit can also be used to processes or monitor and optimize operation using feedback data such as the reflected standing wave ratio, as known in the art. The treatment of different skin conditions and areas can involve differences in reflected waves, and adjusting one or more of several parameters can control the energy delivery from the tip of the device. The handheld unit can consist of a housing and switches for initiating and terminating the pulse, adjusting the frequency, power or pulse duration, for initiating and terminating vacuum, and optionally for cooling air or liquid supply. Indicator lights on the handheld housing can also be connected to the reflected energy monitor, or other measuring sensor in the system. 
         [0030]    Preferably, the EDD device employs bipolar microwave energy delivery to affect a small treatment area and/or ensure consistent delivery of energy to the skin. However, unipolar and combination of unipolar/bipolar devices can also be used according to the invention. A temperature sensor (e.g., a thermocouple of thermistor) can optionally be incorporated at the distal part of the EDD device, and the sensor can be linked to a control device so as to control or limit the heating at the skin surface. 
         [0031]    Other embodiments and advantages of the invention are set forth in part in the description that follows, and in part, will be understood from this description, or may be learned from the practice of the invention. 
         [0032]    For a more complete understanding of the invention and some advantages thereof, reference is now made to the following descriptions taken in connection with the accompanying drawings. 
         [0033]      FIG. 1  schematically represents the EDD  10  as a handheld unit including a handheld housing  20  and a tip portion  22 .  FIG. 2  represents an exploded view of the EDD  10  in order to show the components. 
         [0034]    Handheld housing  20  includes the main body ( 1 ), which can be of plastic or other materials, and which is designed to have an ergonomic form to hold by hand. The sleeve ( 2 ) is generally textured and formed to fit comfortably in the hand without sliding. The coaxial cable ( 3 ) connects the EDD  10  (in particular, the metallic core  5 ) to the base station (not shown). 
         [0035]    The replaceable EDD tip portion  22  unit is generally composed of a metallic antenna body ( 4 ) (preferably silver coated copper), a metallic core ( 5 ) (preferably silver coated copper), and a dielectric ( 6 ) (preferably Teflon) disposed between the metallic core  5  and the antenna body  4  (seen in  FIGS. 3 and 4 ). A protective cap ( 7 ) can be used to protect the tip portion  22  of the EDD  10 . 
         [0036]      FIGS. 3 and 4  are cross-sectional views of the EDD  10  illustrating possible connections between the replaceable tip unit  22  of the EDD  10  and the coaxial cable ( 3 ). The coaxial cable ( 3 ) is held in the main body ( 1 ). The shielding ( 11 ) of the coaxial cable ( 3 ) is in contact with the antenna body ( 4 ).  FIG. 3  represents a gripping or snap-on mechanism ( 12 ) between the core ( 14 ) of the coaxial cable ( 3 ) and the core ( 5 ) of the replaceable unit.  FIG. 4  represents a connection by interlocking the core ( 14 ) of the coaxial cable and the core ( 5 ) of the replaceable unit. Of course, other methods of connecting the coaxial cable  3  and the core  5  are within the spirit and scope of the present invention. 
         [0037]    The core ( 5 ) of the replaceable EDD tip  22  can be of different diameters (e.g., about 0.5 mm to 5 mm) depending on the tissue to be treated. The protective cap ( 7 ) can be fixed to the tip or antenna body by a click-on design or mechanism ( 13 ), a threaded connection, a friction fit, or any other suitable method. The protective cap ( 7 ) protects the tip of the core ( 5 ) from mechanical damage or contamination. The protective cap ( 7 ) can be made out of an insulating material. 
         [0038]      FIG. 5  illustrates the relative dimensions of the core  5  and the dielectric  6 . In use, the metallic core  5  of the EDD tip  22  is in contact at its distal end with a complex impedance Z b , which is the impedance of the contact plan between the EDD tip  22  and the skin being treated. Z b  is highly frequency dependent. At its proximal end, the core  5  is in contact with the coaxial cable  3 , for which the impedance may be represented as Z 0 . Z 0  is typically about 50 Ohms. 
         [0039]    One function of metallic core  5  is impedance matching—that is, to enable efficient transmission of the wave from Z 0  to Z b . For this matching, the core  5  may be constructed out of two stages, as shown in  FIG. 5 . Stage  1  is of length L 1  and has a characteristic impeadance Z 1 . Stage  2  is of length L 2  and has a characteristic impedance Z 2 . 
         [0040]    As known in the art, the impedance of a coaxial wave guide depends on the permittivity and the inner and outer diameters of the dielectric. This impedance is frequency independent, and can be calculated using the equations 
         [0000]    
       
         
           
             
               
                 Z 
                 1 
               
               = 
               
                 
                   
                     60 
                     
                       
                         ɛ 
                         r 
                       
                     
                   
                    
                   
                     ln 
                      
                     
                       ( 
                       
                         
                           D 
                           4 
                         
                         
                           D 
                           3 
                         
                       
                       ) 
                     
                   
                    
                   
                       
                   
                    
                   and 
                    
                   
                       
                   
                    
                   
                     Z 
                     2 
                   
                 
                 = 
                 
                   
                     60 
                     
                       
                         ɛ 
                         r 
                       
                     
                   
                    
                   
                     ln 
                      
                     
                       ( 
                       
                         
                           D 
                           2 
                         
                         
                           D 
                           1 
                         
                       
                       ) 
                     
                   
                 
               
             
             , 
           
         
       
     
         [0000]    where D 3  and D 4  are, respectively, the inner and outer diameter of the Stage  1  of the dielectric and D 1  and D 2  are, respectively, the inner and outer diameter of Stage  2  of the dielectric. 
         [0041]    The first step in calculating the dimensions of the two stages of core  5  is to determine the impedance Z b . For this, a coaxial cable with a chosen length of L, chosen diameters D 1  and D 2 , and of characteristic impedance Z 2  (typically about 50 Ohms) may be attached to a network analyzer. As shown in  FIGS. 3 and 4 , the core  5  is longer than the antenna body  4  by a distance D, which is preferably about 1 mm. This “tip” (e.g., the exposed length of core  5 ) may be placed on the skin, and, using the network analyzer to measure impedance, Z b  may be calculated according to the equation 
         [0000]    
       
         
           
             
               
                 Z 
                 b 
               
               = 
               
                 
                   Z 
                   measured 
                 
                  
                 
                    
                   
                     2 
                      
                     γ 
                      
                     
                         
                     
                      
                     L 
                   
                 
               
             
             , 
           
         
       
     
         [0000]    where 
         [0000]    
       
         
           
             
               γ 
               = 
               
                 j 
                 * 
                 
                   
                     2 
                      
                     π 
                   
                   λ 
                 
               
             
             , 
           
         
       
     
         [0000]    where λ is the wavelength in the dielectric having permittivity ε r . 
         [0042]    The second step is to calculate the length L 2  of Stage  2 . L 2  is preferably calculated in order to define a characteristic impedance Z c  of the interface between Stage  1  and Stage  2  that is real only (e.g., lacking an imaginary component). L 2  can be found using the equation Z c =Z b e −2γL     2   . 
         [0043]    The third and final step is to match Z c  with Z 0  (e.g., about 50 Ohms). Since Z c  is designed to be real-only, an impedance transformer can be used. The length L 1  of Stage  1  is preferably a quarter wavelength (e.g., λ/4), and Z 1  is given by the equation Z 1 =√{square root over (Z c *Z 0 )}. 
         [0044]    In order to perform the above calculations, an electromagnetic field distribution simulation software may be used. In particular, it is desirable for the electromagnetic field distribution simulation software to account for each discontinuity between stages. The length of core  5  can be reduced by using a dielectric with intermediate or high permittivity. 
         [0045]    For example, in order to calculate L 2 , one needs to know Z b . In order to have a real-only Z c , two solutions of L 2  are possible. Preferably, the solution which gives the minimum value of Z c  is chosen. The following equation may be employed: Z 1 =√{square root over (Z c     min   *Z 0 )}, where 
         [0000]    
       
         
           
             
               
                 Z 
                 
                   c 
                   min 
                 
               
               = 
               
                 
                   Z 
                   0 
                 
                 * 
                 
                   
                     1 
                     - 
                     
                        
                       Γ 
                        
                     
                   
                   
                     1 
                     + 
                     
                        
                       Γ 
                        
                     
                   
                 
               
             
             , 
           
         
       
     
         [0000]    and where Γ is the reflection coefficient of the core  5  as measured by the network analyzer. The following table provides some representative values for the core  5 . 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 Frequency 
                 ε r   
                 L 1  (mm) 
                 L 2  (mm) 
                 Z 1  (Ohms) 
                 D 4 /D 3   
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 433 
                 MHz 
                 9 
                 57 
                 114 (max)  
                 13 
                 1.9 
               
               
                 868 
                 MHz 
                 9 
                 29 
                 58 (max) 
                 17 
                 2.3 
               
               
                 2.45 
                 GHz 
                 9 
                 10 
                 20 (max) 
                 21 
                 2.8 
               
               
                 5.8 
                 GHz 
                 9 
                 4 
                  8 (max) 
                 30 
                 4.5 
               
               
                   
               
             
          
         
       
     
         [0046]      FIGS. 6-9  represent possible assemblies between the handheld portion  20  and the tip portion  22 .  FIG. 6  represents an assembly comprising a snap or click mechanism between the tip portion  22  and the handheld portion  20 .  FIG. 7  represents a bolt assembly or mechanism between the tip portion  22  and the handheld portion  20   FIG. 8  represents a bayonet-type connection between the tip portion  22  and the handheld portion  20 .  FIG. 9  represents a clamping-type connection between the tip portion  22  and the handheld portion  20 . 
         [0047]      FIGS. 10-12  illustrate steps that may be carried out in detaching the tip portion  22  from the handheld portion  20 .  FIG. 10  represents an assembly whereby a snap or click mechanism connects the protective cap ( 7 ) to the EDD  10 .  FIGS. 11 and 12  represent the removal/extraction of the tip portion  22 . By following the illustrated steps, a user can extract the tip portion  22 , including core  5 , antenna  4 , and dielectric  6 , without touching it.  FIG. 13  is a block diagram of an exemplary complete system of the invention and its operation. The distal end RF part relates to the EDD tip, here depicted by the symbol for an antenna. 
         [0048]      FIG. 14  illustrates an exemplary energy density field of the energy delivered by EDD  10  in tissue. The power of the microwaves delivered to the skin can be controlled manually or automatically. The automatic control may be based on an optional feedback loop that is activated, for example, by one or more of the following sensory devices: skin temperature measurement or monitoring by thermocouples, thermistors, or IR optic sensors, reflected wave monitoring system, and the like. The temperature of the tissues underlying the skin surface can be monitored by radiometers or IR optic sensors, for example, or other mechanisms or methods known or available in the art. The feedback system preferably adjusts the microwave power in order to obtain optimal treatment of the specific tissues without overheating that may cause damage. A timer can also be set to prevent excess treatment. It is known in the art that the depth of penetration of microwaves into tissue is frequency dependent. The table below gives the depth of penetration as a function of frequency for tissues with high water content (e.g., muscle, internal organs such as the liver and the heart, and connective tissue with little fat). 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Frequency 
                 Conductivity 
                 Penetration depth 
               
               
                 MHz 
                 S/cm 
                 Mm 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 10 
                 0.625 
                 200 
               
               
                 100 
                 0.889 
                 53 
               
               
                 300 
                 1.37 
                 25 
               
               
                 915 
                 1.6 
                 13 
               
               
                 2450 
                 2.21 
                 6.8 
               
               
                 10000 
                 10.3 
                 1.6 
               
               
                   
               
             
          
         
       
     
         [0049]    In view of the above, the frequency of the microwaves can be varied so as to more effectively treat the tissues at the desired depth. This goal can be achieved by waves that carry a number of frequency components or by alternatively mixing pulses of different frequency. 
         [0050]    As described, the EDD tip portion  22  can be replaced. This property provides distinct functions or advantages, for example enabling the user to select and use the tip portion optimal to the specific need and/or to replace the tip portion for each new patient. The size and/or shape of the terminal (e.g., distal) part of the EDD tip portion may vary according to need: it can be flat, curved, conical, or have the form of a cylinder running parallel to the skin surface. Such a cylinder tip can, for example, be placed along a wrinkle to obtain optimal treatment of an elongated or long target area with one “shot” or application. Preferably, the tip portion is designed in order to generate a microwave field that is generally restricted to a volume of about 10 mm 3 , taking into consideration both the size and shape of the tip portion as well as the tissue penetration of the selected microwave frequency. 
         [0051]    To avoid the contamination of the skin of one patient by the use of the same tip on more than one patient, the tip can be covered by a specially constructed protection cover that does not interfere with the spread of the microwave field from the tip to the tissues. The protection cover can be made of a dielectric having dielectric properties that ensure impedance matching between the tip and the tissues. Alternatively the protective cover can have electric conductivity similar to that of the skin but be impermeable to bacteria and viruses as well as other contaminants. This could be, for example, a hard gel, wet cellophane, or the like. A material that improves the tip—tissue impedance matching, such as a gel with the proper dielectric properties, can optionally be added to the gap between the tip and the underlying skin. Of course, as described above, it is also contemplated that the tip may be replaced between patients. 
         [0052]    The following Examples and forgoing description are intended to show merely optional configurations for the devices of the invention. Variations, modifications, and additional attachments can be made by one of skill in the art. Thus, the scope of the invention is not limited to any specific Example or any specific embodiment described herein. Furthermore, the claims are not limited to any particular embodiment shown or described here. 
       EXAMPLES 
     Dermatology Treatment 
       [0053]    In a first example, a shielded, directional tip is used on a device of the invention and applied directly against the surface of the skin without water, hydrating solutions, or other liquids. The tip has a blunt end to maximize the contact surface of the conductor with the skin. The aperture or distance between the shield and the tip (e.g., dimension D in  FIG. 3 ) can be varied by changing tips, thereby changing the energy or field shape or size. A preferred aperture is about 1 mm. The tip is preferably a silver coated copper wire, but can be coated, for example with gold to prevent skin reactions in sensitive skin. 
         [0054]    In another example of a device in accordance with the invention, the distal end optionally includes a vacuum (negative pressure) line to apply negative pressure to a selected area to be treated. The tip cover is optionally transparent to allow the user to visually monitor the placement of the tip in a wrinkle or fissure. Water or an aqueous solution can be applied to the skin to be treated. The layer of material between the surface where microwaves are emitted and the tissue can affect the ability or efficiency of the microwaves to penetrate the heated tissue, as known in the art. 
         [0055]    For treatment around the mouth or at the upper lip, the duration of the treatment varies by condition of the skin, but can be between about 1 minute and 20 minutes, typically with pauses to avoid excessive tissue heating. Typically, visual changes in the exterior appearance of the skin dictate the amount of treatment for a particular subject or condition. 
         [0056]    An exemplary treatment regimen includes settings to deliver approximately 0.5-20 J/sec, using approximately 10 msec pulses with 10 msec intervals in between pulses. The treatment duration can vary from about 20 sec to about 90 sec per treatment site. This regimen is particularly suited for facial rhytides, perioral rhytides, and lentigo, especially on arms, hands, and legs. The treatment area can be cleaned and a hydrating gel and/or analgesic gel can be applied prior to treatment. During treatment the probe is gently applied against the surface of the skin to ensure electrical coupling and delivery of energy below the surface. Heating of the tissue by resistive (or ohmic) heating is generally desired in a small area of tissue, which is typically the tissue below the surface in direct contact with the distal end of the treatment tip. Methods that avoid burning or implication of physical marks at the surface of the skin are desired, and treatment regimens and varying energy pulses, pulse lengths, frequency, or all of these can accomplish this. 
         [0057]    In another example of a device of the invention, two or more tips or delivery tips are positioned to be adjacent and to engage adjacent areas of skin. Energy setting and control is substantially the same for each tip. For a double tip aspect, two parallel and adjacent waveguides from the proximal to the distal end are fed by a single switch within the housing. This may be a single pole double throw RF switch having a single input from a coaxial waveguide with parallel outputs feeding to individual coaxial waveguides coupled to each tip. 
         [0058]    One skilled in the art can devise and create numerous other examples according to this invention. Examples may also incorporate additional imaging, thermometry, and other elements known in the art. As but one example, the device and method disclosed herein may be employed in combination with other tissue treatment devices and methods, collectively referred to herein as “secondary tissue treatment devices,” such as the use of laser, IPL, or radiofrequency devices. One skilled in the art is familiar with techniques and devices for incorporating the invention into a variety of devices and of designing improved devices though the use of the concepts presented here.