Abstract:
RF energy for skin conditioning with a non-ablative electrode is applied with a handpiece incorporating means to prevent electrical shock to the patient when the energized electrode surface makes or breaks contact with the skin. In a preferred embodiment, switch means are incorporated in the handpiece and configured such that the active electrode surface is not energized until it is in actual contact with the patient&#39;s skin, and remains energized only while the active electrode surface remains in contact with the patient&#39;s skin, so that no voltage is present on the electrode, when an air gap whose dielectric breakdown can cause an electrical shock to the patient arises, immediately before or immediately after skin contact during a skin conditioning procedure. In another preferred embodiment, the electrode to skin impedance change as the electrode touches the skin is used to activate a switch that transfers RF to the electrode.

Description:
This invention relates to apparatus and a procedure for treating skin tissue using non-ablative radio-frequency energy. It also relates to novel handpieces using monopolar or bipolar electrodes for use in such procedures. 
     BACKGROUND OF THE INVENTION 
     A commonly-assigned copending application Ser. No. 11/709,672, filed Feb. 23, 2007, the contents of which are herein incorporated by reference, describes an electrode configuration and procedure for use for topical application to the tissue surface or skin of a patient for the non-ablative treatment of periorbital rhytides and midface laxity or in general removal of wrinkles or other cosmetic skin tightening procedures to improve the appearance of skin tissue. 
     In this radio-frequency (RF) non-ablative tissue surface treatment, it is desirable to raise the tissue temperature to about 41-65° C. to affect underlying skin collagen to tighten the surface tissue, being careful to avoid overheating the skin tissue possibly causing burns and residual scarring. To achieve this result, this prior application describes the use of specially configured electrodes to provide a reasonably uniform electric field distribution at the skin surface, pre-applying to the skin a thermal gel, a known thermally and electrically-conductive material, to help cool the surface, using low RF power, relying on the natural cooling provided by a highly conductive electrode material, and continuously manually moving the activated electrode while in contact with the skin. 
     A later-filed commonly-assigned copending application Ser. No. 12/012,447, filed Feb. 4, 2008, the contents of which are herein incorporated by reference, describes further RF handpieces for RF skin tightening incorporating skin temperature sensors and/or movable electrodes and/or dual electrode arrangements which can be used to spread the skin heating and to sense skin temperature to avoid overheating the skin tissue. 
     In the execution of such skin tightening procedures, typically the physician or other practitioner employs a foot switch to energize the handpiece which simultaneously energizes the active electrode surface of the supported electrode. An electrical shock may be felt by the patient as the energized electrode surface makes or breaks contact with the skin, as the voltage potential applied to the electrode by the RF generator is usually great enough to cause dielectric breakdown of the small air gap created when the active electrode surface is close to but not in actual physical contact with the patient&#39;s skin. This shock can cause significant discomfort to the patient. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to employ RF energy for skin conditioning with non-ablative electrodes in a handpiece incorporating means to prevent electrical shock to the patient when the energized electrode surface makes or breaks contact with the skin. 
     A further object of the invention is an indicator to indicate to the physician when skin contact is made or broken. 
     In a first group of preferred embodiments in accordance with the invention, switch means are incorporated in the handpiece and configured such that the active electrode surface is not energized until it is in actual contact with the patient&#39;s skin, and remains energized only while the active electrode surface remains in contact with the patient&#39;s skin, so that no voltage is present on the electrode, when an air gap whose dielectric breakdown can cause an electrical shock to the patient arises, immediately before or immediately after skin contact during the skin tightening procedure. “Switch means” as used in this specification and claims is defined to mean a device capable of selective electrical engagement and disengagement of electrical contacts or members. 
     In this first group of preferred embodiments, the electrode or its shank is movable within the handpiece but is initially physically, and thus electrically, separated from the cable or an electrical extension of the cable supplying the RF energy when the opposite end of the cable plugged into an output connector of the RF generator is energized. The structure is configured such that when the electrode is brought into contact with the skin, the pressure exerted by the physician on the handpiece moves the electrode, axially or radially, so that it or its shank electrically engages the cable or its extension so that the active electrode surface then becomes energized. Similarly, as the physician withdraws the handpiece from the patient, the first action before the electrode actually separates from the skin will be for the switch connection to be broken deenergizing the electrode immediately before the electrode-skin contact is broken. 
     In a second group of preferred embodiments in accordance with the invention, skin-sensing means associated with the electrode is connected to a relay in the handpiece or to the RF generator such that power is not supplied to the electrode until the sensing means indicates that the electrode has come into actual contact with the skin. 
     In this second group of embodiments, the sensing can be implemented with a capacitance sensor connected to the electrode, as the capacitance of the electrode to the patient&#39;s body reduces as the skin is approached and reaches a minimum on contact. Alternatively, the impedance of the RF circuit, or the output impedance at the electrode-skin interface, can be measured at the RF generator and the generator output to which the handpiece is connected energized only when the output impedance drops below a certain impedance level typically of approximately 100-200 ohms. In monopolar operation, the electrode forms one pole of the output and a neutral plate connected to the patient forms the other pole, the impedance, e.g., capacitance, measurement taking place between the poles. In bipolar operation, the two poles are formed by dual electrodes in the handpiece. 
     The various schemes described in the incorporated application disclosures can also be used with the handpiece of the present invention, specifically, the specially configured electrodes providing a reasonably uniform electric field distribution at the skin surface, pre-applying to the skin a gel, using RF power, relying on the natural cooling provided by a highly conductive electrode material, continuously manually moving the activated electrode while in contact with the skin, incorporating skin temperature sensors to shut down the power when the skin temperature rises too high, and means for maintaining the skin-touching active part of the electrode in continuous motion. 
     RF non-ablative skin tightening is preferred as it is believed that the RF technology produces an electric current that generates heat through resistance in the dermis and subcutaneous skin tissue. The thermal effect depends on the conductivity features of the treated tissue. Collagen fibrils, when heated, will denature and contract, which is believed to lead to the observed tissue tightening. Non-ablative RF treatment has a lower risk of complications, shorter recovery time and less disruption of regular activities than other skin tightening procedures. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention, like reference numerals designating the same or similar elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic view of one form of a shock-free handpiece with a dome electrode according to the invention, shown schematically connected to an RF generator of a known type; 
         FIG. 2  is cross-sectional view along lines  2 - 2  of the handpiece of  FIG. 1  showing the electrode in its RF-disconnected position; 
         FIG. 3  is a cross-sectional view similar to  FIG. 2  showing the electrode in its RF-connected position; 
         FIG. 4  is a cross-sectional view similar to  FIG. 2  of a modified embodiment in accordance with the invention in the RF-disconnected position providing RF connection when the electrode is subjected either to axial or to lateral loading; 
         FIG. 5  is a cross-sectional view similar to  FIG. 2  of a modified embodiment in accordance with the invention in the RF-disconnected position providing both RF connection and closing of a second circuit upon axial loading of the electrode; 
         FIG. 6  is a cross-sectional view similar to  FIG. 5  showing the handpiece in its RF-connected position; 
         FIG. 7  is a circuit schematic schematically illustrating how loading of the electrode can connect the RF to the electrode as well as close the contacts of a second circuit; 
         FIG. 8  is a circuit schematic similar to  FIG. 7  showing how the second circuit can be used to activate an indicator light; 
         FIG. 9  is a circuit schematic similar to  FIG. 7  based on the  FIG. 5  embodiment showing how loading of the electrode can connect the RF to the electrode as well as close the contacts of both a second and a third circuit; 
         FIG. 10  is one form of a circuit schematic capable of responding to impedance changes at the electrode to sense skin contact and activate the RF generator; 
         FIG. 11  is one form of a circuit schematic of a suitable power supply for the circuitry of  FIG. 10 ; 
         FIG. 12  is a block diagram of one form of RF generator incorporating means for sensing the output impedance of the RF generator; 
         FIG. 13A  is a schematic of one form of power sense circuit that can be employed in the generator of  FIG. 12 ; 
         FIG. 13B  is a schematic of one form of current sense circuit that can be employed in the generator of  FIG. 12 ; 
         FIG. 14  is a side view of one form of a shock-free handpiece with a bipolar electrode according to the invention; 
         FIG. 15  is cross-sectional view along lines  15 - 15  of the handpiece of  FIG. 14  showing the bipolar electrode in its RF-disconnected position; 
         FIGS. 16 and 17  are views similar, respectively, to  FIGS. 14 and 15  showing the bipolar electrode in its RF-connected position; 
         FIG. 18  is a circuit schematic schematically illustrating the operation of the bipolar embodiment of  FIGS. 14-17 ; 
         FIG. 19  is a circuit schematic schematically illustrating the operation of a first modified version of the bipolar embodiment of  FIGS. 14-17 ; 
         FIG. 20  is a circuit schematic schematically illustrating the operation of a second modified version of the bipolar embodiment of  FIGS. 14-17 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the present application,  FIG. 1  is a schematic view of one form of RF applying device  10  in accordance with the invention. It comprises a handle or handpiece  12  with operating buttons  14  and with a front end adapted to receive and hold for axial movement the electrically-conductive shank end  16  of an electrically-conductive electrode  18  whose active electrode surface  20  is dome-shaped as shown. The handpiece  12  is electrically-insulating. The electrode  18  is screwed  19  onto the elongated electrically-conductive shank  16 , and both move together as a unit axially within the center bore of the handle  12 . Axially in  FIGS. 1 and 2  is the longitudinal horizontal axis of the assembly. The electrode is biased outwardly in a first position as shown in the figure by an internal compression spring  24 . The proximal end  26  of the shank, that contains a small hollow, is spaced by a contact gap  28  from a fixed electrically-conductive contact  30  mounted in a rear part of the handle, and forming at the rear a connector which internally via a circuit board connected to the operating buttons  14  (not shown) is connected at the right end for receiving an RF cable  32 .  FIG. 1  shows the handpiece  12  connected by the cable  32  to an output connector  33  on the chassis of a conventional RF electrosurgical generator  34 , for example, of a type manufactured by Ellman International, Inc. of Oceanside, N.Y. The axial movement of the electrode  18  indicated at  36  is equal to the contact gap  28 . When the active electrode surface  20  of the handpiece  12  held by the physician is pressed against the patient&#39;s skin, the electrode  18  is displaced from its first to a second position, compressing the spring  24 , and with sufficient pressure the contact gap  28  is closed and the electrode shank  16  becomes electrically-connected to the fixed contact  30 , and thus voltage available at the output connector  33  of the RF generator  34  becomes active on the active electrode surface  20  thus applying RF energy to the skin tissue. The first position of the electrode illustrated in  FIG. 2  will be referred to as the RF-disconnected position, whereas the second position illustrated in  FIG. 3  will be referred to as the RF-connected position. Note that placing the electrode  18  in contact with the skin does not energize the electrode with RF; the electrode must be displaced a certain distance, the contact gap  28 , before the electrode becomes energized. Similarly, withdrawing the handpiece from the patient will first break the electrical contact internally as the spring expands and deenergizes the electrode before it breaks contact with the skin. While the internal contact end of the shank is shown as a cup, other shapes may be used if desired. 
     The embodiment illustrated in  FIGS. 2 and 3  utilizes axial loading of the electrode to implement the RF-connecting position.  FIG. 4  illustrates a modification wherein axial or lateral loading of the electrode applied by the physician is needed before energizing and deenergizing the electrode. In this embodiment, a handpiece  40  in accordance with the invention comprises an electrode  42  integral with a reduced diameter shank  44  supported by two elastic O-rings  46  for axial and lateral movement within the handle. A nut  48  fixed to the shank keeps the electrode from moving to the left under the biasing force of a spring  50  beyond the position shown in  FIG. 4 . The spaces  52  allow some lateral movement of the electrode, and the electrode can also move axially to the right until the shank end  54  contacts the surface of a cup-shaped end  56  of the fixed contact  30 . The extension of the shank end  54  within the cup-shaped end  56  of the fixed contact allows both axial and lateral movement of the electrode  42  to effect the RF-connected position from the RF-disconnected position shown in the figure. 
     This result is possible because of the coaxial position of the shank end  54  within the cup-shaped end  56  of the fixed contact. A similar result can be obtained by mounting two concentric tubes spaced by rubber O-rings or similar elastomeric material such that the tubes do not touch when no load is applied to the electrode in front but will deflect and touch as in  FIG. 4  when transverse or axial load is applied. In this case, one tube can be connected to the active cable from the generator and the second tube connected to the electrode. 
       FIGS. 5 and 6  show another embodiment in accordance with the invention with  FIG. 5  showing the RF-disconnected position and  FIG. 6  the RF-connected position similarly to the embodiment of  FIGS. 2 and 3 . In this case, when the electrode  60  is axially displaced as shown in  FIG. 6 , not only does the contact end  64  of the electrode shank  62  make RF connection with the fixed contact  66 , but in addition, an electrically-conductive annular member  68 , positioned on the internal shank end but electrically-insulated from the shank itself, contacts and shorts together two electrically-conductive cylinders  70 ,  72  mounted at the rear of the handpiece but electrically-insulated from the fixed contact  66 . In other words, the movement of the electrode from its RF-disconnected position to its RF-connected position also closes a second circuit schematically illustrated at  74  that can be used for various purposes, as will be illustrated in  FIGS. 7-9 . This is essentially a double pole, single throw switch. 
     This double pole, single throw switch offers two sets of contacts (poles) that make or break through the same “push” action. The first  76  indicated in  FIG. 7  at terminal RF is a direct connection from the electrode tip  60  to the RF energy source (central contact), while the second pole  78  allows current to flow between the cylinders  70 ,  72  to activate a control switch (not shown) on the generator which is connected to both lines (+/−) to control RF supply switching at the source. This second pole switch functions effectively like (and is wired in a similar manner identical to) the finger switch handpiece buttons and foot switch buttons—both legs of the switch are passed through the handpiece and onto the generator. This second switching circuit provided at terminals S 1 + and S 1 − can also be used to activate a light  80  ( FIG. 8 ), sound or tactile (vibration, click, etc.) signal to let the user know that the electrode  60  is active. This is typically accomplished through the existing generator circuitry, but could be incorporated within the handpiece itself as well Alternatively, multiple switches can be incorporated to be activated; for example, as shown in  FIG. 9 , a third switch provided at terminal S 2 + and S 2 − can be incorporated for separate, isolated signaling, source activation and RF thru-circuits. 
     This entire spring-loaded electrode end scheme works to prevent shock to the patient essentially by moving the initial “spark” contact gap away from the patient&#39;s skin and puts the spark gap within the handpiece itself, and forces the user to make skin contact prior to RF energy being supplied. During release, the contact is opened first within the handle itself and not at the patient&#39;s skin. 
     The preceding embodiments relied on physical movement of the electrode immediately before energizing and immediately after deenergizing of the electrode by directly electrically connecting to or disconnecting from the energized cable. Indirect connection can also be effected, for example, magnetically or optically, by sensing movement or position of the electrode and using the generated signal to operate a relay effecting the required connection to the power source. Other common motion and position sensor types are well known by those skilled in the art and can be readily substituted to function in a similar manner. Using a signal this way is also described in the following embodiments. 
     In the following embodiment, the electrode is fixed to the handpiece and its contact with the patient&#39;s skin is sensed electrically before RF energy is supplied. In these embodiments, conventional handpieces can be used, for example, handpieces of the type illustrated in the two referenced incorporated pending applications. The electrical characteristic measured can be the capacitance impedance between the active electrode surface and the patient&#39;s skin. This can be measured internally of the RF generator or externally by a circuit of the type shown in  FIG. 10 . This circuit is somewhat similar to those used in charge transfer touch sensors used commercially in control panels, lighting controls, etc., in place of mechanical switches, except that this circuit maintains a relay closed while the sensor detects skin touch, and opens the relay when touch is removed. 
     The circuit of  FIG. 10  is connected as shown to a typical conventional handpiece  84  having a dome electrode  86 . RF power from the RF generator is supplied at terminal  88  of a relay  90  having  2  sets of contacts, the top set of which is unused for present purposes. A signal from the dome electrode  86  representing the capacitance of the electrode to the skin (recalling that the neutral electrode to the body is at ground potential) is derived at  92  and inputted at the left via a series-connected resistor and capacitor to a terminal  96  of a commercially available charge transfer touch sensor IC  94  which can be configured as is known by the choice of bias and other components to establish at an output terminal  98  a high value that turns on a signal transistor  100  which in turn drives a power transistor  102  that will via relay coil  104  operate the relay to switch the lower set of contacts  106  from the shown OFF position to the ON position, thus feeding RF power from the generator to the electrode  86 . The active treatment electrode  86  may be coupled to the RF source through a known series capacitor (not shown), or some other mechanism to couple the RF portion of the RF signal to the treatment electrode  86  while isolating the DC portion of the RF signal from the treatment electrode to improve the touch-sensor circuit&#39;s sensing sensitivity, at the same time preventing the RF power from feeding back to the charge transfer circuit. So long as the sensed capacitance remains low during touch of the electrode to the skin, the relay  90  remains activated and the electrode is energized by the RF. As the electrode  86  starts to withdraw from the skin tissue, the capacitance rises quickly and the resultant signal switches the IC output  98  to a low value deactivating the relay and deenergizing the electrode. Other circuits can be readily devised by those skilled in this art to function similarly. 
     The circuit of  FIG. 10  can if desired be separately powered by a battery in a preferred embodiment as illustrated in  FIG. 11 , with the battery designated  110 ′, and an on-off switch  112 ′. The battery may be connected to a conventional voltage regulator  114 ′ to output constant operating voltages used by the sensing circuit. Any power source could be used for the sensing circuit but the circuit of  FIG. 11  is a preferred embodiment that would allow it to be self contained and portable. 
     In a similar manner, the electrical characteristic measured could be the electrical impedance at the output connector at the generator, which is the impedance between the electrode surface and the usual neutral electrode in contact with the patient&#39;s body. In the absence of contact between the active electrode surface and the patient&#39;s skin, the impedance measured at the output connector will be of the order of Kohms. As contact is made between the active electrode surface and the patient&#39;s skin, the measured impedance will drop to a value of the order of hundreds of ohms. That impedance change can be used to operate a relay as shown in  FIG. 10  to pass the RF power to the electrode. Thus, the active electrode surface will become active when the output connector impedance drops, and when the electrode is withdrawn from the skin the output impedance rises deactivating the relay and deenergizing the output connector and thus the electrode. 
       FIGS. 12, 13A and 13B  illustrate one form of output impedance measuring circuit.  FIG. 12  represents a basic block diagram of an RF generator, with a conventional frequency generator  110  whose output RF signal is fed into an amplifier  112  whose output in turn is fed through a filter  114 . The resulting RF line  115  then passes through a power sensing circuit  116  and a current sensing circuit  118  before exiting the generator unit via a cable leading to the handpiece  12 .  FIG. 13A  illustrates one possible embodiment of the power sensing circuit  116  utilizing a directional coupler, wherein the RF transmission line  115  is capacitively coupled to a conductive line  120  whose length  122  is equal to one quarter of the signal wavelength. The conductive line  120  is connected to a terminating resistor  122  and a diode detector circuit  124  which will measure the forward power on the RF transmission line  115 . 
       FIG. 13B  illustrates one possible embodiment of the current sensing circuit  118 , where a line  128  having a primary winding in block  118  is carrying the current to be measured. The line is routed through a transformer  126  with the primary winding of the line  128  having fewer windings than the secondary winding  130  to step up the signal voltage across a resistor  132 . The signal is then rectified by a diode  134  and smoothed by a capacitor  136  to create a DC voltage across terminals  138  and  140  that is proportional to the current on line  128 . 
     Once the power and current have been determined as indicated in the forgoing circuits, then the impedance is readily determined by a calculation by known software or hardware dividing the power by the square of the current, which can then be used to activate a relay as described above. 
       FIGS. 1-13B  illustrate a monopolar handpiece in accordance with the invention. Similar principles can be employed to implement the invention in a bipolar handpiece. In the monopolar handpiece, one pole of the RF power is not applied to the electrode until it contacts the tissue. In the application to a bipolar handpiece, both poles of the RF power are not applied to, respectively, both electrodes housed in the handpiece until contact with the tissue is made. 
       FIGS. 14 and 15  illustrate a bipolar handpiece having an insulating housing  149  with fixed inner  150  and outer  152  concentric electrodes with a spring-loaded, slidable, tubular insulator  154  surrounding the inner electrode  150 , separating the two electrodes, and extending outward in front of the two electrodes. The spring is shown at  156  biasing the insulating tube into its RF-disconnected position. The RF power supplied from a cable (not shown) on the right is connected to electrical members  158  and  159 . The tubular insulator  154  carries conductive spring loaded sliding connectors (or carriers), one of which  160  contacts the outer electrode  152  at  162 , and the other of which  164  contacts the inner electrode  150  at  166 . The extending insulator  154  acts as the arm of a double pole single throw switch, which is activated when the insulator tube is depressed as the physician brings the active end of the handpiece into contact with the patient&#39;s skin, simultaneously exposing the inner electrode ( FIG. 17 ) and connecting both electrodes to their corresponding plus and minus RF sources (or poles)  158 ,  159 . Note in  FIG. 17  the carrier  160  at  168  in contact with conductive member corresponding to pole  159 . The carrier  164  makes contact at  170  to the other pole  158 . This embodiment uses these small contact springs  160 ,  164  attached to the insulator tube  154  which slide into contact with each pole  158 ,  159  of the effective switch to make and break contact as needed. The pre-contact inactive state is illustrated in  FIG. 15 , and the post-contact active state is illustrated in  FIG. 17 . 
     The circuit schematic illustrating the operation is shown in simplified form in  FIG. 18 . Two separate normally off “momentary” switches  172 ,  174  .make contact when the center post  154  is pushed in.  FIG. 19  illustrates a modification that behaves effectively like two parallel versions of the monopolar embodiment, where the switches  176 ,  178  are activated by the depression of both spring-loaded bipolar electrodes  180 ,  182 , activating a relay or relays which power the RF energy to each electrode. In this latter instance, it is preferred that the energy is supplied only when both switches  176 ,  178  have made contact, ensuring that both electrodes are in contact with the skin—this is readily implemented by a simple logic circuit that could be provided within the handpiece or within the switching circuitry of the energy source. 
       FIG. 20  shows a third bipolar embodiment, a modified version of the  FIG. 18  version with a movable central post  154  for accomplishing the switching to the fixed bipolar electrodes  150 ,  152 . In this case, the central post  154  preferably switches a relay (not shown) on and off as needed to supply the RF power. 
     The  FIG. 19  embodiment, effectively two parallel versions of the direct RF-switching monopolar embodiment working together, can also be implemented (not shown) like the  FIG. 20  embodiment with the electrically “floating” electrodes  150 ,  152  switching directly with the RF supply rather than activating via relays. 
     The RF generator used preferably output RF currents in the range of about 0.2-10 MHz. Continuous wave power can be used. 
     While the invention has been described in connection with preferred embodiments, it will be understood that modifications thereof within the principles outlined above will be evident to those skilled in the art and thus the invention is not limited to the preferred embodiments but is intended to encompass such modifications.