Abstract:
A device for successively injecting material at predetermined distances between successive injections to body tissue along a desired path of skin surface includes an injector sub-assembly having a needle configured for injecting the material into body tissue, and a displacement sub-assembly configured to facilitate precise displacement of the needle or of the device along the path between successive injections.

Description:
RELATED APPLICATION 
     This application claims benefit of provisional application Ser. No. 61/315,964 filed Mar. 21, 2010 whose contents are included herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a device or system and method for the delivery of fluids or gels by injection into or underneath the human skin for wrinkle treatment or for other purposes. 
     BACKGROUND OF THE INVENTION 
     A wide range of subcutaneous drug delivery devices is known. 
     Several years ago the needs of society in the medical field were different from today&#39;s needs and the technology abilities then were also different from modern technology. In the 1950&#39;s there was a very big need to treat diabetes mellitus with self-administered insulin injections. These needs were met by several devices, whose purpose was to allow a person to administer self injections of the drug at home. Such devices are disclosed, for example, by U.S. Pat. No. 2,660,169 titled “Devices for supporting and operating hypodermic syringes and injecting a fluid into the body”. The device is very simple, with no electronics in it, operated by manual pressure only. Its only function is to inject the whole contents of the syringe at once into the patient. 
     Later, in the 1970&#39;s another need arose—to vaccinate a large population in a short period of time. This need was addressed by “gun-like” injection devices, such as disclosed in U.S. Pat. No. 3,727,614, which discloses a multiple dosage inoculator for administrating vaccines, where the vacuum is used to draw the skin of the patient onto the needle using only one hand. 
     Another “gun-like” injection device adapted for the self-injection of insulin is disclosed in U.S. Pat. No. 4,067,334. This device is manually operated. The syringe is connected to a spring, that allows its movement, and a drug is injected by releasing the air pressure contained in the bulb, operated by the user. 
     Another field of the medicine/cosmetic treatments that was developed around the 1980&#39;s is mesotherapy. U.S. Pat. No. 4,108,177 discloses a gun-like device, operated by an electro-magnet and a motor. This is the first invention that uses an electric mechanism to create motion. The device is able to perform many injections in a short period of time, and create very fast syringe motion and very fast fluid injection. 
     U.S. Pat. No. 4,512,767 discloses a gun-like mesotherapy mechanical injection device, which includes means for positioning the penetration needle and to predetermine the degree of penetration of the needle. 
     U.S. Pat. No. 4,790,823 discloses another such device having an optical sight for a precise needle direction and a micro-controller for controlling the quantity of the injected fluid and the speed of injection. 
     U.S. Pat. No. 4,600,403 discloses a suction injector where an electric motor is used to create suction. The injection is triggered by the skin, as soon as it has been raised high enough and the amount of injected fluid is electronically controlled. 
     In U.S. Pat. No. 4,833,384 a motor is coupled to a lead screw that moves a syringe plunger whose position is accurately controlled by a digital encoder. 
     A very important factor in automatic injection devices is the need to control needle penetration depth. One solution is taught by U.S. Pat. No. 5,015,235 where the user selects an adjuster from a set of adjusters of different sizes and fits it over a part of a hub. 
     U.S. Pat. No. 5,690,618 discloses an electronic syringe for administrating anesthetic injections, particularly suited in dental applications where a precise level of hand control is required. A drive means is provided in electrical communication with an electronic controller, which controls the amount of the injected fluid and the injection flow rate. 
     U.S. Pat. No. Re. 35,986 discloses an automatic injector having two chambers containing different ingredients of medicament separated by a membrane and mixed during injection. Needle penetration depth is limited by placing a disc on the needle. 
     U.S. Pat. No. 5,906,592 discloses a device for accurately infusing fluids into a patient at specific rates over an extended period of time. 
     U.S. Pat. No. 5,921,962 discloses an injection device having a flow indicator that provides an indication at any given time about the amount of fluid remaining in the device. 
     U.S. Pat. No. 6,994,691 discloses an injection device for making injection at a predetermined depth in skin. A skin positioning member is positioned on a patch of skin within an area of skin such that at least a part of the patch of skin may be held elevated above or depressed below the area of skin. A guidance mechanism guides an injection needle to slide beneath the skin positioning member to an injection position. 
     As it can be seen in the prior art study, known injection devices are able to penetrate the skin perpendicularly, but they cannot perform a series of injections while controlling the distance between those injections; neither can they control the needle penetration speed. For all the reasons listed above, filler injection procedures are being performed manually. 
     The problem of the filler&#39;s manual injections methods used in today&#39;s practice is that the needle penetration is done in parallel to the skin surface. In that way consequently, it is very difficult to control the injection depth accurately and to control the amount of the injected drug/filler. Moreover, it is difficult or impossible to maintain the layer of the injected drug/filler under the skin surface uniform without lumps. Additionally, the procedure is painful owing to internal skin tissue tearing and patient bleeding due to the blood vessels injury. Also, it is difficult to avoid swelling, pain and redness following treatment. 
     Additionally, it emerges from the prior art review that there is a need for an advanced injection device able to control the speed of needle penetration into the skin. There is a need for the device to be able to control the depth of needle penetration, injection flow rate, and the volume of the injected fluid or gel. 
     There is a need for the device to be painless, able to perform a series of injections, to control the distance between those injections, and to be capable of computer control or/and manual control. 
     The present invention overcomes the disadvantages of the injection devices associated with prior art drug delivery devices, the disadvantages of the devices existing on today&#39;s market and the disadvantages of manual injecting of drugs or fillers. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention there is provided a device for successively injecting material at predetermined distances between successive injections to body tissue along a desired path of skin surface, said device comprising: 
     an injector sub-assembly having a needle configured for injecting said material into body tissue, and 
     a displacement sub-assembly configured to facilitate precise displacement of the needle or of the device along said path between successive injections. 
     The invention thus principally resides in a device that is adapted to inject a needle into a surface of the skin to a required depth of penetration for injecting a required amount of material and which is adapted to move the needle by a required displacement between successive injections. 
     According to this invention there is provided a device or system and method of delivery of fluids or gels by injection into or underneath the epidermis layer, or into or underneath the dermis layer of human beings. 
     The device allows injecting the fluid or gel to a predetermined, settable or controllable depth under the skin surface either for wrinkle treatment or for other purposes thus avoiding blood vessels injury. 
     The device allows the treated skin area to be subjected to a series of injections along a desired path at a predetermined, settable or controllable distance between the injections. The device also allows a predetermined, settable or controllable amount of fluid or gel to be injected in each injection, thereby achieving a uniform layer of fluid or gel. The device further allows injecting the fluid or gel at a predetermined, settable or controllable flow rate. 
     The injection needle is very thin (32 G and above) in order to minimize the injury to the patient&#39;s skin. 
     In some embodiments, the device allows the speed of needle penetration into the skin to be predetermined, settable or controllable speed thus allowing use of very thin needles (32 G and above). 
     In some embodiments, the device may be used to inject one of the currently available fillers for wrinkle treatment. The device includes a thin needle attached to either a syringe or to a container, containing the fluid or gel to be injected. 
     In some embodiments, the injections can be carried out by a needle, or alternatively by a group of two or more needles linked to the fluid/gel syringe or container. 
     In some embodiments, the device includes a mechanism, which controls the injecting mechanism movement and the speed of needle penetration into the skin. The device includes another mechanism whose purpose is to limit or set the needle&#39;s penetration depth beneath the skin surface. 
     In one embodiment, the device includes a mechanical stopper, which stops the needle penetration once it touches the skin surface. 
     Alternatively, a mechanical end-stop may be mounted on the needle in fixed spatial relationship with an end thereof. For example, a disc may be mounted on the needle to limit the depth of needle penetration into the skin. 
     In some embodiments this mechanism is based on a sensor or micro-switch, that detects contact with the skin surface once the needle has penetrated a desired depth beneath the skin surface, and stops the needle insertion. 
     In some embodiments, a muzzle surrounds the needle and a vacuum source draws the patient&#39;s skin into the muzzle in order to perform the injection. 
     The device includes a mechanism for pushing the liquid or gel contained in the syringe or the container, so when this mechanism is activated, the liquid or gel is injected through the needle into the treated area. This mechanism is able to inject a predetermined, settable or controllable amount of fluid or gel at a predetermined, settable or controllable flow rate in each injection. 
     In some embodiments, the device indicates the user about the amount of fluid or gel containing in the syringe or container. 
     The device includes a mechanism, which causes the device to advance a predetermined, settable or controllable distance between injections. 
     In some embodiments, the user directs the device along the desired treatment path (along a wrinkle for instance) manually, using a mechanical or optical pointer attached to the device. 
     Alternatively, the device is capable to move forward automatically along the treatment path without external manual interaction by the user. 
     In some embodiments, the device includes an optical sensor such as a camera, connected to an external TV set, screen or computer, so the image captured by the optical sensor can be seen on the screen. This allows the operator to direct the device more precisely. 
     In some embodiments, the desired treatment path is dictated by using an optical sensor. The device controller controls the advancement direction of device by analyzing the data received from the optical sensor in such a way that the device follows and treats the desired treatment path, such as a skin wrinkle. 
     In such an embodiment the device is capable to move forward along the desired treatment path automatically. 
     In some embodiments, the device comprises a light source, such as, but not limited to, one or more LED&#39;s located close to the needle or the injection place in order to improve visibility of the treated area by the person carrying out the treatment. 
     In some embodiments, the device includes a massaging mechanism for massaging the already treated skin area. The massaging mechanism is located behind the syringe and the needle, so that each time it is activated, it massages a different treated skin area along the treatment path. 
     In some embodiments, the user can manually select the device operation mode according to the needed treatment. For instance, for wrinkle filling the user may select shallow, medium or deep wrinkle setting. The device controller sets the injection filler quantity to be injected each time, the needle&#39;s penetration depth, the distance between consecutive injections and the massaging session duration according to the selected setting. 
     In some embodiments, the user can manually select the flow rate of the gel or fluid according to the needed treatment. 
     In some embodiments the device controller analyzes the data received from an optical, electronic or mechanical sensor, estimates the wrinkle depth and sets accordingly the injection filler quantity to be injected each time, the injecting flow rate, the needle&#39;s penetration depth, the distance between consecutive injections and the massaging session duration. 
     In some embodiments, the device includes a mechanism which allows also a widthwise motion of the described above mechanism, so a skin area can be treated by applying a matrix-like pattern of injections rather than a linear path of injections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic view showing the principal sub-assemblies in a device according to the invention; 
         FIG. 2  is a perspective view of a base sub-assembly and injector sub assembly with a syringe mounted in its place; 
         FIG. 3  is a perspective view of the injector sub-assembly; 
         FIG. 4  is a perspective partial view of the device showing in greater detail the displacement control sub-assembly; 
         FIGS. 5   a  and  5   b  show details of a linkage that induces relative movement between the injector sub assembly and the displacement control sub-assembly; 
         FIG. 6  is a detailed view of the displacement control sub-assembly and the electronic printed circuit board; 
         FIG. 7   a  is a partial detailed view of the device in use; 
         FIG. 7   b  shows detailed views of the needle and the injection depth limiter when separated; 
         FIGS. 8   a  and  8   b  is a schematic diagram of an electronic circuit used to control the device; and 
         FIG. 9  is a flow diagram showing the principal operations carried out during operation of the device. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Mechanical System Description 
       FIG. 1  shows schematically a device  100  according to the invention comprising four sub-assemblies, namely an enclosure  1 , a base  200  shown in  FIG. 2 , an injector sub-assembly  300  shown in  FIG. 3  and a displacement control sub-assembly  400  shown in  FIG. 4 . The base sub-assembly  200  serves to move an injection needle  30  into close proximity to the skin being treated and to advance the needle to a controlled depth of penetration. The injector sub-assembly  300  serves to inject a controlled amount of material into or beneath the skin. The displacement control sub-assembly  400  is adapted to operate only when the injector sub-assembly  300  is retracted (so that the needle is withdrawn) and serves to advance the device a controlled distance along the skin prior to the next injection of additional material. 
     The enclosure  1  is in the shape of a box from one side of which there protrudes a transparent polycarbonate pipe  5 . In order to start the treatment, the transparent pipe  5  is perpendicularly placed in contact with the treated person&#39;s skin  51  (shown in  FIG. 7   a ) directly over an area to be treated (typically a wrinkle). By doing this, the base  200  is located at the correct distance from the treated person&#39;s skin  51 . The pipe  5  thus constitutes a safety stop that at least partially surrounds the end of the needle and prevents inadvertent penetration thereof. The enclosure  1  further comprises an on-off switch  2 , a power connector  3  for allowing connection of the unit to an external power supply, a data connector  4  for allowing connection of the unit to a computer and ventilation openings  6 . 
     The function of the base  200  is to support and drive the injector  300  and the displacement control unit  400 , as well as to support an electronic circuit by means of which the device is controlled. 
     The base  200 , which is fixed to the enclosure  1 , includes a base plate  7  that is folded at two adjacent edges to form first and second mutually perpendicular support surfaces that are each perpendicular to the base plate  7 , the first at an end thereof for supporting a stepper motor  8  (constituting a first drive unit) and the second at a side thereof for supporting a linear bearing  37 . A shaft of the stepper motor  8  is coupled to a screw rod  10 , which threadably engages a pair of nuts  49   a  and  49   b  (shown in  FIGS. 5   a  and  5   b ), fixed to a carriage  14  that supports the injector sub-assembly  300  so that rotation of the motor shaft induces linear motion of the injector. The carriage  14  is slidably supported within a linear bearing  11  fixed to the base plate  7  and comprises nut holders  12  and  13 , an electrical contact  15  and it supports an injector base plate  19 . The base plate  7  also supports, a linear bearing  37  slidably supporting the displacement control unit  400 , a rotary bearing  41  (shown in  FIG. 4 ) supporting a lever  18 , an electronic PCB  54  (shown in  FIG. 6 ) and two electrical limit switch contacts  16  and  17 . 
     The attachment of the stepper motor  8  to the base plate  7  allows for a limited amount of flexibility, achieved through rubber discs  9 . This compensates for slight inaccuracies and misalignments without creating distortion of mechanical parts or causing stress or friction between the screw rod  10  and the nuts  49   a  and  49   b  during rotation of the stepper motor  8 . 
     When the stepper motor  8  rotates, it moves the nuts  49   a  and  49   b , which are supported by the nut holders  12  and  13 , consequently shifting the carriage  14  supporting the injector sub-assembly  300  along the screw rod  10 . The extent of this movement is limited: at the retracted “home” position, a contact  15  fixed to the carriage and constituting a moving contact  14  makes electrical contact with the switch contact  17 , which is mounted on a rubber isolator glued to the base plate  7  thus closing an electrical switch comprising contacts  15  and  17 . At the extended “end of travel” position, the carriage  14  makes electrical contact with the switch contact  16 , which is mounted on a rubber isolator glued to a bracket  56  fixed to the base plate  7  thus closing an electrical switch comprising contacts  15  and  16 . In this way, the stepper motor  8  can be controlled to move within its movement range without exceeding it. Rotating the stepper motor  8  in a clockwise direction will move the injector sub-assembly towards its extended “end of travel” position, while rotating it in a counter-clockwise direction will move the injector sub-assembly towards its retracted “home” position. 
     Injector aligners  47  and  48  (shown in  FIG. 4 ) allow the injector sub-assembly  300  mounted on the carriage  14  to move linearly along its path, thereby avoiding any undesired moment in the linear bearing  11  due to lateral forces such as the injector weight. 
     During normal operation the injector sub-assembly  300  is periodically moved from its “home” position towards its “end of travel” position, without reaching it, and back to the “home” position. 
     During the movement towards the “end of travel” position, a needle  30  supported by the injector sub-assembly  300  is inserted a predetermined depth into the skin  51 . The length of the transparent pipe  5  in the enclosure is such that when the needle  30  is in its inserted position, the “end of travel” position is not yet reached. The “end of travel” contact  16  provides a security means for avoiding mechanical overdrive of the carriage  14  within the linear bearing  11  beyond its permitted range of movement. 
     As can be seen in  FIGS. 2 ,  3 ,  4  and  5 , a pin  31  protrudes outward from a side surface of the injector sub-assembly  300  and engages an upper slot within a lever arm  18  that is pivotally mounted by a rotary bearing  41 , which is fixed to the second surface at the side of the base  7 . In similar manner, a lower slot in the lever arm  18  engages a pin  50  that protrudes outwardly from the displacement control sub-assembly  400 . Pin  50  is attached to a support plate  36  that is slidably supported within the linear bearing  37 , which is fixed to the second surface at the side of the base  7 . As the injector sub-assembly  300  moves in a first direction within the linear bearing  11 , the pin  31  induces rotation of the lever arm  18  thereby causing the displacement control sub-assembly  400  to move in the opposite direction as shown in  FIGS. 5   a  and  5   b . In this way, when the injector sub-assembly  300  is extracted towards the skin  51  in order to inject, the displacement control sub-assembly  400  is retracted backwards away from the skin  51 , and when the injector sub-assembly is retracted backwards towards its “home” position, the displacement control sub-assembly  400  is extracted towards the skin  51 . 
     The injector sub-assembly  300  serves to support a syringe  27  (constituting a container for storing a reservoir of material) and to shift a piston  28  therein, which is pushed in such way that a precise amount of the syringe&#39;s contents is injected into the treated skin  51  at a precise flow rate during each injection while allowing the needle  30  to penetrate the skin  51  to a precise, predetermined depth. 
     As seen best in  FIG. 3 , the injector sub-assembly  300  comprises a base  19  supporting mutually perpendicular opposing side support surfaces and an end support surface. Mounted on the end support surface is a stepper motor  20  (constituting a second drive unit) whose shaft is coupled to a screw rod  21 . The syringe  27  is supported within opposing syringe holders  25  and  26  protruding from an end of the base  19  opposite the stepper motor  20 . A piston shifter  23  is slidably supported within a linear bearing  22  mounted on the base  19  and supports a nuts holder  24 . Nuts  49   c  and  49   d  (shown in  FIGS. 5   a  and  5   b ) fixed to the nuts holder  24  are threadably supported on the screw rod  21  so that rotation of the stepper motor  20  induces linear movement of the piston shifter  23 . The piston shifter constitutes a release unit operable by the second drive unit for releasing a desired quantity of material from the container. 
     The extent of this movement is limited. At the retracted “home” position, the piston shifter  23  makes electrical contact with the switch contact  34 , which is mounted on a rubber isolator glued to the injector&#39;s base plate  19  proximate the stepper motor  20 , thus closing an electrical switch comprising the contact  34  that is fixed to the base plate  19  and a contact  32  that is fixed to the piston shifter  23 . The piston shifter  23  is formed of electrically conductive material and is electrically coupled to the switch contact  32 . At its extended “end of travel” position, the piston shifter  23  makes electrical contact with a switch contact  33 , which is mounted on a rubber isolator glued to the end of travel contact holder  57 , thus closing an electrical switch comprising contacts  32  and  33 . In this way, the stepper motor  20  can be controlled to move the piston shifter  23  within its movement range without exceeding it. Rotating the stepper motor  20  in a counter-clockwise direction will move the piston shifter  23  towards its retracted “home” position, conveniently allowing the user to install the syringe  27  in its place and to secure it by tightening the screws that hold the syringe holder  26 . Rotating the stepper motor  20  in a clockwise direction will move the piston shifter towards its extended “end of travel” position, advancing towards the syringe&#39;s piston  28 . Once the piston shifter  23  reaches the piston  28 , it makes electrical contact with the switch contact  35 , which is mounted on the piston thus closing an electrical switch comprising the contact  35  and a contact  32  that is fixed to the piston shifter  23 . This allows the stepper motor  20  to be controlled to quickly advance the piston shifter  23  until it reaches the piston  28 , and afterwards to move forward slowly injecting a precise amount of the syringe&#39;s contents into the treated skin  51  at a precise, controlled flow rate. 
     The “end of travel” contact  33  is located in such position that the piston shifter  23  will reach and make contact with it a short distance before the syringe&#39;s piston  28  reaches the end of the syringe  27 , thus avoiding mechanical overdrive of the piston shifter  23 . This contact may also serve as an “Empty Syringe” alarm activation signal. 
     An injection depth limiter as depicted in  FIGS. 7   a  and  7   b  is provided. The injection depth limiter&#39;s role is to enable the control of the injector&#39;s movement while the needle  30  is inserted into the skin  51 , so it penetrates the skin  51  down to a precise, controlled depth. 
       FIG. 4  shows in greater detail the displacement control sub-assembly  400 , which comprises a generally L-shaped advancement lever holder  39  pivotally mounted on bearing  45  and urged into a rest position where it engages a limiter  40  by a spring  44 . As explained above with reference to  FIGS. 5   a  and  5   b , the displacement control sub-assembly  400  is articulated to the injector sub-assembly  300  by the lever arm  18  so that when the injector sub-assembly  300  is retracted away from the skin, the displacement control sub-assembly  400  is moved toward the skin. When this happens, an advancement feeler lever  38  attached to a horizontal portion of the advancement feeler lever holder  39  is brought into contact with the skin  51 . In addition to that an electrical circuit provides an audible “beep” for alerting the user that the injection needle is withdrawn and prompting him or her to manually move the device along the treatment path to the next location for a subsequent injection. 
     Downward movement of the device along the treatment path while the advancement feeler lever  38  is in contact with the skin  51  induces clockwise rotation of the displacement control sub-assembly  400  about the bearing  45 , causing the advancement lever holder  39  to rotate clockwise and to be raised above the limiter  40  against the biasing force of the spring  44 . Rotation of the displacement control sub-assembly  400  also causes a lever  43  fixed to the vertical portion of the advancement lever holder  39  to rotate so that a lower end of the lever  43  is brought into the path of an optical sensor  46 . When this happens, circuitry coupled to the optical sensor  46  is adapted to provide another audible “beep” for alerting the user that the device is now located at the correct position for the next injection and prompting him or her to stop downward movement of the device. In actual use, the device is oriented so that the spring  44  is substantially parallel to the treatment path. 
     As the device is advanced along the path to be treated and advancement lever holder  39  moves, the spring  44  is further extended. When the device has reached the position for the next injection, the injector sub-assembly is extracted thus retracting the displacement control sub-assembly  400  owing to their interconnection via the lever arm  18 . When the advancement feeler lever  38  loses its contact with the skin  51 , the spring  44  returns the advancement lever holder  39  to its rest position. This rest position is determined by the limiter  40  position, which is adjustable. Once the advancement lever holder  39  and the advancement feeler lever  38  are back in their rest position, the device is ready for the next cycle. 
     The position of the lever  43  is adjustable such that the distance it has to travel before intercepting the optical sensor  46  can be varied. In this way the distance between consecutive injections can be set. In another embodiment, this adjustment may include a small motor, or any other means to enable control of the distance between consecutive injections once the device is activated, or while the device is operating. 
     The displacement control sub-assembly  400  serves to allow for a predetermined distance between consecutive injections along the treated path. 
     In the embodiment shown in the figures, the device is advanced along the treatment path manually, while the person holding the device is alerted when the device has to be shifted, and when movement of the device has to be stopped as it has reached the position for the next injection. In this way a predetermined distance between consecutive injections is achieved. In other embodiments, the device may include a motor or any other mechanical provision for moving the device a predetermined distance between consecutive injections. 
       FIGS. 7   a  and  7   b  show details of an injection depth limiter having two mutually insulated contacts  53   a  and  53   b  which are supported by a plastic electrically insulating tube  52 , of complementary shape to a base  29  of the needle  30 , so that when mounted on the needle&#39;s base  29  the contacts  53   a  and  53   b  are always at the same distance from the end of the needle. In this way when the needle  30  penetrates the skin  51  to the correct depth, both contacts  53   a  and  53   b  touch the skin  51 . The contacts  53   a  and  53   b  detect skin conductivity between them and serve as a skin sensor by means of which the electronic circuit shown in  FIGS. 8   a  and  8   b  sends a signal to the controller within motor  8  and controller stops the needle&#39;s insertion into the skin, thus achieving a precise depth of injection. Furthermore, the plastic tube  52  not only supports the contacts  53   a  and  53   b , but also has the mechanical role of physically limiting the injection depth, ensuring improved safety for the treated person. 
       FIG. 7   b  shows in enlarged scale a detail of the depth limiter and the needle prior to engagement. A “V” shaped bore in the end of the plastic tube  52  intermediate the two contacts  53   a  and  53   b , serves to avoid the unwanted creation of a continuous wet pattern between the two contacts which might result in a residual conductance that would jeopardize the correct operation of the depth limiter. 
     In the embodiment shown in the figures, the insertion depth is fixed depending on the geometry of the injection depth limiter, but it is possible to implement other embodiments, which use a different kind of injection depth limiter so the injection depth will be controllable during the operation of the device. Other embodiments may use an injection depth limiter based only on mechanical components. 
     Operation of the device during actual use will now be described with reference to the schematic circuit diagram shown  FIGS. 8   a ,  8   b  and the flow chart shown in  FIGS. 9   a ,  9   b.    
     Operation of Motor  8  for Control of Carriage  14  of Injector Sub-Assembly  300 :
         1. A user programs the motion profile of the motor  8 : nominal current, holding current, microstep size, acceleration and velocity.   2. The motor  8  turns counter-clockwise and retracts the injector sub-assembly  300  to its fully retracted “home” position. When the injector sub-assembly  300  reaches this position, it touches the limit switch contact  17 , thereby shorting pins  1  and  2  of connector J 8 , and as a result input  3  fed to connector J 3  pin  7  changes from “1” to “0”. Additionally, the same signal enters pin  1  of U 5  (74HC160) and, as a result, the user hears one short buzzer beep.   3. The motor  8  turns clockwise and extracts the injector sub-assembly  300  until the contacts  53   a  and  53   b  of the skin sensor detect contact with the skin. The skin contact sensor is connected to a connector J 2  a first of whose pins is at positive potential and to a second of whose inputs a transistor Q 1  is connected, such that Q 1  starts conducting only when the sensor is contacting a skin surface. When Q 1  conducts, transistor Q 2  is likewise biased into conduction and a signal I/O 2  fed to pin  4  of connector J 3  changes from “0” to “1”.   4. The motor  8  keeps checking the signal I/O 1  at pin  2  of connector J 3  and waits until it changes from “1” to “0” when the motor  20  has finished injecting.   5. The motor  8  turns counter clockwise and retracts the injector sub-assembly  300  to its retracted “Home” position. When the injecting mechanism reaches its retracted position, it contacts the switch contact  34 , thereby shorting pins  1  and  2  of connector J 8 . As a result an input  3  fed to pin  7  of connector J 3  changes from “1” to “0”. In addition, the same signal is fed to pin  1  of U 5  (74HC160) and, as a result, the user hears one short buzzer beep. This short beep is a sign for a user to advance the device along the treated path.   6. The motor  8  checks the signal IN 2  fed to pin  5  of connector J 3 . A user moves the device forward along the wrinkle. When the device has advanced sufficiently, the signal at pin  4  of connector J 6  changes from “1” to “0”. This signal is fed to pin  9  of U 5  (74HC160). As a result two things occur: the user hears a long buzzer beep and stops the device advancing; and the signal at pin  5  of connector J 3  changes from “0” to “1”. When this input changes to “1”, the motor&#39;s processor knows that the device had finished its movement forward along the wrinkle   7. After step 6 the program jumps again to step 3.       

     Operation of Motor  20  for Control of Piston Shifter
         1. Programming the motion profile of the motor  20 : nominal current, holding current, microstep size, acceleration and velocity.   2. The motor  20  turns counter-clockwise and retracts the piston shifter  23  to its fully retracted “Home” position, where it contacts the switch contact  34 . As a result pins  1  and  2  of connector J 9  are shorted, and input  3  fed to pin  7  of connector J 4  changes from “1” to “0”.   3. The motor  20  turns clockwise and advances the piston shifter  23  until it contacts the piston. The switch contact  35  mounted on the piston  28  is then connected to pin  1  of connector J 10 . When the piston shifter  23  contacts the switch contact  35 , pins  1  and  2  of connector J 10  are shorted, and as a result, contacts of a relay K 2  are closed, and remain closed until the device power is down. When the relay K 2  is closed, the signal I/O 2  fed to pin  4  of connector J 4  changes from “0” to “1”.   4. The velocity is reprogrammed to lower velocity, for slow injection flow rate.   5. The output I/O 1  of the motor  20  is programmed to “1” and is fed to the motor  8 .   6. The motor  20  waits until the skin contact sensor  53  detects contact with the skin. As explained above, the skin contact sensor  53  is connected to J 2  and the transistor Q 1  connected to pin  2  of connector J 2  starts conducting only when the sensor  53  makes contact with the surface of the skin. As a result signal IN 2  at pin  5  of connector J 4  changes from “0” to “1”.   7. The motor  20  turns clockwise a predetermined number of microsteps, depending on the volume of material to be injected.   8. The motor  20  waits 20 seconds.   9. The output I/O 1  of the motor  20  is programmed to “0” and is fed to the motor  8 .   10. Go to step 5.       

     Explanation of Additional Hardware:
         1. There is external power supply that is able to supply 24V  5 A. Since we are using 15 Vdc and 5 Vdc in our electronic circuit, we used a voltage regulator L7815 (U 1 ) to create a 15V voltage and used a voltage regulator L7805 (U 3 ) to create a 5V voltage.   2. In order to prevent injury to the person being treated, two sensors are provided as follows. The limit switch contact  16  connected to the connector J 7  is placed at the fully extracted “end of travel” position of the injector sub-assembly  300 . Likewise, the switch contact  33  connected to the connector J 5  is placed at the extended “end of travel” position of the piston. The 24V power is supplied to the electronic circuit and to the motors  8  and  20  through the normally closed relay K 1 . The relay&#39;s coil is permanently connected to the 12V, but is not connected to the ground. Only in case that one or both of the above-mentioned contacts  16  or  33  is shorted, whereby pin  1  of J 5  is shorted to pin  2 ; and/or pin  1  of J 7  is shorted to pin  2 , then the relay&#39;s coil is connected to GND and the 24V supply to the electronic circuit and to the motors  8  and  20  is stopped instantly, without any delay. This prevents any possible disruption of the injection process, and any possible patient injury.       

     In an embodiment of the invention reduced to practice, the motors that were used are SilverPak 17C/CE made by LIN Engineering of Morgan Hill, Calif. 95037, USA. This motor is combination of a step motor, controller and driver. It can communicate with a personal computer (PC) via a RS485 interface, thus allowing the motor controller to be programmed via a USB to RS485 converter card. 
     It will be appreciated that while a specific embodiment has been described, the description is non-limiting and many changes may be made without departing from the scope of the invention, which is limited only by the attached claims. For example, although semi-automatic operation has been described whereby the injector sub-assembly and the displacement sub-assembly are advanced by stepper motors under control of a programmable controller, completely manual operation may be used without the need for either the stepper motors or the programmable controller. 
     Likewise, while screw rods in association with nuts are used to convert rotary motion of the stepper motors to linear movement of the injector sub-assembly, it will be apparent that the same effect can be realized using a worm gear and linear toothed guide. The displacement sub-assembly as described is manually operated but can be automated. 
     It will also be appreciated that while in the embodiment as described, a syringe is used to inject the material, the device may include other forms of receptacle for containing the material and the material may be released using other means. By way of example, a fixed flexible container may be provided and material may be released by applying pressure to the container as is done is tubes of toothpaste and the like or by applying gas pressure. The needle may be fixed directly to a container within the casing as in the case of a syringe or it can be fixed to the casing and material can be fed to the needle from a remote source that does not necessarily have to part of the device but is coupled thereto, for example by means of a flexible tubing. 
     In order to inject material the needle must penetrate the skin to a predetermined depth of penetration, which may be preset by the manufacturer or by the user, for example by fixing to the needle a mechanical stop that may be adjustable. Alternatively, if may be controlled as disclosed in the above description using a motor. In either case, an indication of the location of the tip of the needle relative to the user&#39;s skin may be obtained via feedback from a skin sensor mounted in known spatial disposition with the needle. This may be used to alert the user that the tip of the needle is ready for injecting material promoting him or her to press a manual lever to move the needle a preset distance so as to penetrate the skin. Alternatively, it may be used to alert the user that the needle has penetrated by a preset distance so as to prompt the user to remove the needle and move it along the treatment path for the next injection. In the case of automatic devices the feedback may be used by a controller to effect penetration to the required depth. 
     Likewise, while in the embodiment as described, electrically operated stepper motors are used to move the injection sub-assembly it will readily be appreciated that other forms of power may be employed, such as manual, pneumatic and hydraulic devices. Manually operated mechanisms may be spring biased so as to adjust the tension in a spring according to a required degree of advancement or penetration of the needle, such that releasing the spring under control of a manual lever or dial or the like, moves the needle by a pre-calibrated distance.