Patent Publication Number: US-8992481-B2

Title: Modular injection device

Description:
RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 13/111,731, filed May 19, 2011, which claims priority to U.S. Provisional Patent Application No. 61/346,354 filed on May 19, 2010, the entire disclosures of which are incorporated herein by this reference. 
    
    
     BACKGROUND 
     A number of medical and cosmetic applications involve the controlled injection of substances into the body. 
     A medical syringe is a simple piston pump consisting of a plunger that fits tightly in a cylindrical barrel. The plunger can be pulled and pushed along inside the barrel, allowing the syringe to take in and expel a fluid through an orifice at the distal open end of the barrel. The distal end of the syringe is typically fitted with a hypodermic needle to transdermally introduce the fluid in the barrel into the body of a patient. Syringes are often used to administer injections. Surprisingly, other than the materials used to make them, the typical, conventional disposable syringes used for administering the advanced injectable substances or medicaments of today, are much the same as the very earliest syringe designs. 
     Unfortunately, the classic syringe/needle system is far from optimal for the administration of today&#39;s injectable aesthetic compositions. Hydrogel-based dermal fillers can be quite difficult to inject using the conventional syringe/needle system or conventional injection techniques. Many dermal fillers are by their nature highly viscous, thus requiring relatively high extrusion forces, especially when injected through preferred fine gauge needles. Moreover, these materials are typically injected into the face to correct wrinkles, including fine wrinkles as well as other minor defects in skin, and are therefore must be sometimes injected in trace amounts, and always with very high precision. Interestingly, these dermal fillers are commonly introduced into skin using quite standard needle and syringe combinations. 
     Using a traditional syringe, physicians are required to supply possibly significant force, which may reduce the practitioner&#39;s ability to control the syringe. Further, traditional syringes typically require the user&#39;s hand to be placed a significant distance from the site of the injection in order to operate the plunger, which may also lead to inaccuracy. Automated injection machines, which supply the force required to perform the injection using a motor, may reduce some of these problems. However, some motorized injection devices have the disadvantage that they may be heavy and bulky, requiring, for example, a battery which may add significantly to the weight of the device. This added bulk and weight may lead to a lack of control because of user fatigue, etc. 
     Systems have been developed and described for facilitating injection of dermal fillers. One such system is described in Mudd, U.S. patent application Ser. No. 12/994,568, filed Jan. 24, 2011, commonly owned herewith, the entire disclosure of which being incorporated herein by this reference. Mudd describes a handheld, motorized dermal filler injector that is capable of dispensing viscous injectable material at a low flow rate, for example, in some instances, a flow rate of only 0.001 ml/sec, at the high pressures necessary to extrude the fluid though a fine gauge needle. 
     The present invention provides an improved system for injecting dermal fillers, or other materials into skin, for example. 
     SUMMARY 
     The present invention provides easy to use, highly accurate, programmable, user-friendly injection systems that have numerous benefits over conventional injection systems. 
     In one aspect of the invention, a modular injection system is provided which generally comprises a handheld injector unit including a grippable housing including a distal end having a coupling portion, and a drive unit contained within the housing, and a separate control unit, remote from the injector unit, the control unit including a controller/processor configured to control the drive unit. The system may further comprise a syringe or cartridge, couplable to the coupling portion of the grippable housing, and containing an injectable fluid, such as a hyaluronic acid-based dermal filler. The injector unit includes a movable plunger driven by the drive unit and is extendable in a distal direction to cause extrusion of the injectable fluid from the cartridge when the cartridge is coupled to the coupling portion. 
     Advantageously, the handheld injector unit component of the present invention is lightweight and easy to manipulate and grip. Many of the heavier components of the system are housed in the separate control unit. In some embodiments, the control unit includes a display, for example, a visual display screen for displaying useful information to the user, for example, amounts of fluid in the cartridge, amounts of fluid already dispensed from the cartridge, rate of injection of fluid, or other information. In some especially advantageous embodiments, the control unit is mountable to a user&#39;s arm or wrist to allow the user to view the display while operating the injector unit within the same field of vision. 
     In some example embodiments, the control unit may be powered by an electrical power source; and the handheld injector unit may draw electrical power from the power source using the cable. In other example embodiments, the control unit may further include a control unit body; a display in communication with the control unit; and an input device in communication with the control unit. 
     In some example embodiments, the input device may be configured to receive the user input indicating the injection rate; and the display may be configured to display the injection rate indicated by the user input. In still other example embodiments, the display may include a video display screen configured to display information indicating a volume of fluid injected. 
     In yet further example embodiments, the injector unit may further include a sensor configured to measure a physical parameter that is correlated with the volume of fluid injected; and the display may be configured to display the volume of fluid injected responsive to information received from the sensor. 
     In some example embodiments, the control unit may further include a wrist strap configured to attach the control unit to a user&#39;s wrist during use. In other example embodiments, a side of the control unit body may be shaped to conform to a user&#39;s wrist. 
     In another example embodiment, the control unit may further include a connector, disposed on the control unit body, configured to connect the control unit to the cable. In yet another example embodiment, the cable may be permanently attached to the control unit. 
     In still another example embodiment, the injector unit may further include an injector unit body; a syringe housing disposed at a proximal end of the injector unit body; a needle mount disposed at a proximal end of the syringe housing; and an input device configured to trigger an injection. 
     In some example embodiments, the drive unit may be configured to extrude fluid from a syringe disposed in the syringe housing, through the needle mount. In other example embodiments, the drive unit may be configured to cause a fluid to be extruded responsive to a user interaction with the input device. In further example embodiments, the input device is an inject button and the drive unit may be configured to stop causing the fluid to be extruded responsive to an indication that the inject button has been released. 
     In some example embodiments, the injector unit may further include a syringe loading door, hinged to the injector unit body, configured to allow loading of a syringe when the door is open. 
     In yet other example embodiments, the syringe housing may be transparent, configured to allow a user to view a syringe disposed within the housing. 
     In some example embodiments, the cable may be permanently attached to the injector unit. 
     In still other example embodiments, the injector unit may further include a connector, disposed on the injector unit body, configured to connect the injector unit to the cable. 
     Some example embodiments may provide a modular injection device, which may include a handheld injector unit including an injector unit body; a motor housed in the injector unit body and configured to apply an extrusion force to a fluid; a syringe housing disposed at a proximal end of the injector unit body and configured to hold a syringe; a needle mount disposed at a proximal end of the syringe housing; and a plunger configured to be driven into the syringe housing by the motor. The injection device may also include a control unit remote from the injector unit, configured to receive a user input indicating an injection rate and configured to control the motor responsive to the user input indicating the injection rate, the control unit which may include a control unit body; an electrical power source configured to supply electrical power to the control unit and the injector unit; a display in communication with the control unit; and an input device in communication with the control unit and configured to receive the user input. In addition, the injection device may include a cable configured to connect the control unit to the injector unit. 
     Further example embodiments provide a modular injection device, which include a handheld injector unit which may include an injector unit body; a drive unit housed in the injector unit body and configured to apply an extrusion force to a fluid; a syringe housing disposed at a proximal end of the injector unit body and configured to hold a syringe; a needle mount disposed at a proximal end of the syringe housing; a first wireless device; and a first electrical power source configured to supply power to the injector unit. The injection device may also include a control unit remote from the injector unit configured to receive a user input indicating an injection rate and configured to control the drive unit responsive to the user input indicating the injection rate, the control unit which may include a control unit body; a second wireless device configured to wirelessly communicate with the first wireless device; a second electrical power source configured to supply electrical power to the control unit; a display in communication with the control unit; and an input device in communication with the control unit and configured to receive the user input. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be more readily understood from a detailed description of example embodiments taken in conjunction with the following figures: 
         FIG. 1  illustrates an example injector device in accordance with an example embodiment. 
         FIG. 2  illustrates another example injector device in accordance with an example embodiment. 
         FIG. 3  illustrates a schematic view of an example injector device in accordance with an example embodiment. 
         FIG. 4  illustrates an example injector device in accordance with an example embodiment. 
         FIG. 5  illustrates an example injector device in accordance with an example embodiment. 
         FIG. 6  illustrates an exemplary injection system in accordance with an example embodiment. 
         FIG. 7  illustrates how to use the system illustrated in  FIG. 6 . 
         FIG. 8  also illustrates how to use the system illustrated in  FIG. 6 . 
         FIG. 9  again illustrates how to use the system illustrated in  FIG. 6 . 
         FIG. 10  illustrates a back view of a base station for housing an unused system illustrated in  FIG. 6  according to an example embodiment. 
         FIG. 11  illustrates a top perspective view of a base station housing an unused system illustrated in  FIG. 6 . 
         FIG. 12  illustrates a top perspective view of an empty base station as illustrated in  FIG. 6 . 
         FIG. 13  illustrates the internal components of an example injector device. 
         FIG. 14  further illustrates the internal components of an example injector device. 
         FIG. 15  further illustrates the internal components of an example injector device. 
         FIG. 16  illustrates an example retention mechanism. 
         FIG. 17  illustrates an example control unit. 
         FIG. 18  shows a back view of the control unit illustrated in  FIG. 17 . 
         FIG. 19  illustrates exemplary internal components of the control unit illustrated in  FIG. 17 . 
         FIG. 20  illustrates further exemplary internal components of the control unit illustrated in  FIG. 17 . 
         FIG. 21  is a perspective view of an injector unit component of a system in accordance with an exemplary embodiment of the invention. 
         FIG. 22  is a perspective view of a control unit component of a system in accordance with an exemplary embodiment of the invention. 
         FIG. 23  is a perspective view of a cartridge and needle component of a system in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION 
     As explained above, a number of medical and cosmetic procedures involve the controlled injection of liquids, gels, and other fluids. For instance, procedures involving the injection of botulinum toxin or the injection of dermal fillers, may require highly controlled injections. In such instances, it may be advantageous to perform the injection with an automated injection device. Using such devices, users need not supply the force which extrudes the injectable fluid though the needle themselves. Rather the device may supply that force, and may extrude the fluid at a user controller rate, leaving the user free to concentrate on the injection itself, e.g. positioning of the needle. Such devices, however, are typically significantly more bulky then traditional syringes, including control hardware, motors, power sources, etc. The additional size and weight may reduce user control, e.g. fatiguing the user, and increasing the distance between the user&#39;s hand and the point of the injection. Example embodiments may address such problems by providing modular injector devices designed to reduce the size and weight of the portion of the device which is held in the user&#39;s hand. 
     Accordingly, dermal filler injector systems are provided, exemplary embodiments thereof being illustrated in  FIG. 1 . The system  10  may include a handheld injector unit  101  and a separate control unit  102 . The two units  101  and  102  are in communication with each other. For instance, the units may be connected together wirelessly, or with a communication cable, a power cable, or both  103 . 
     The injector unit  101  may include a body  120  having a grippable housing  124 , which may be made of any suitable material, e.g. metals, thermoplastics, thermoplastic elastomers (TPEs), silicones, glass, etc., or any combination of materials. The body  120  may be shaped to comfortably accommodate a user&#39;s hand. For instance, as shown in the figure, the body  120  may form a grip, which may allow a user to securely grasp the injector unit  101 . As shown in  FIG. 1 , the body  120  itself may have one or more protrusions near a distal end of the injector unit body  120 , which may, for example, prevent a user&#39;s hand from sliding forward when in use. Similarly, the injector unit body  120  may have one or more protrusions near a proximal end, which may prevent a user&#39;s hand from sliding backwards. In addition, a portion of the injector unit body  120  designed to be gripped may be textured to provide a secure grip, or may be covered in a layer of material designed to provide a secure grip. Another system  10 ′ having an alternative injector unit  101 ′ is shown in  FIG. 2 . In this particular design, the injector unit body  120 ′ is more of a pen-style shape and will be discussed hereinafter with reference to  FIG. 4 . Injector unit  101 ′ may be substantially identical to injector unit  101 , except for the body shape and as discussed elsewhere herein. 
     Turning back to  FIG. 1 , the injector unit  101  may be designed to attach to and operate a standard needle and syringe combination. Alternatively, the injector unit  101  is designed to be couplable to a removable cartridge  121  having a needle though which the injectable material may be extruded. For instance, the injector unit  101  may provide any suitable attachment to cartridge  121 , for example, a luer slip or luer lock attachment. The needle itself may have any suitable gauge, for example, a gauge between about 10 and about 33. 
     The injector unit  101  may provide a syringe housing  122  on which the cartridge  121  or syringe may be secured, although, in other embodiments, a needle is attached directly to the injector unit body  120  which houses a chamber containing a fluid to be injected. The syringe housing  122  may be, for example, substantially in the form of a tube, which may, at a distal end, connect to the injector unit body  120  and, at a distal end, connect to the needle mount  121 . The syringe housing  122  may be designed to hold a syringe  123 , for example a disposable, pre-filled syringe  123 . The syringe housing  122  may be all or partially transparent, allowing a user to view the syringe  123  during operation. For example, the syringe housing  122  may provide a user with a view of both a syringe  123  in the housing and also a syringe plunger which may extrude fluid from the syringe  123  when the device is in operation. 
     The injector unit  101  may also contain an injection drive mechanism, as shown in  FIG. 3 . For instance, in injection drive mechanism may include a motor  301  which may be configured to push a syringe plunger through the syringe  123 . As the syringe plunger moves through the syringe  123 , the pressure exerted by the plunger may cause the material in the syringe  123  to be extruded through the needle  121 . In other example embodiments, other drive systems may be used. For instance, some embodiments may use a pump to extrude the fluid, or may use pressurized syringes, controlling the injection with a valve, etc. The injection drive unit may be capable of delivering a force sufficient to extrude viscous and non-viscous liquids and gels through a needle  121  of standard size. For example, the injection drive mechanism may be capable of applying a force of up to about 100 N, and extruding material at a rate within a range of about 0.001 mL/sec to about 1 mL/sec. The syringe housing  122  may provide users with a view of the plunger in operation, over the entire length which the syringe plunger may travel during use. 
     In example embodiments, the motor  301  may be housed within the injector unit body  120 . The motor  301  may be any suitable electric motor capable of supplying the necessary force. In addition, the motor  301  may be attached to a plunger via a drive mechanism, which may function to transfer the rotational motion of the motor  301  into the linear motion of the plunger. The plunger itself may also be housed within the injector unit body  120 . When in operation, however, the plunger may extend into the syringe housing  122  and the syringe itself  123 , causing the fluid in the syringe  123  to be extruded. 
     The injector unit  101  may also include a syringe retention and ejection mechanism. The mechanism may facilitate loading of, e.g., pre-filled, disposable syringes  123 . The mechanism may also provide for the rotation of syringes  123 . In example embodiments syringes may be loaded though a loading door. 
     For example, as illustrated in  FIG. 4 , the pen-style injector unit  101 ′, discussed briefly hereinabove, may have a loading door  401  formed in the injector unit body  120 . The door  401  may be hingedly attached to the body  120 , e.g., near the distal end of the injector unit  101 , and may rotate from a latched position, shown in  FIG. 2 , to an open position as shown in  FIG. 4 , to allow for the loading and ejection of fluid filled cartridges or standard syringes  123 . The injector unit  101 ′ may be fully sealed to prevent fluid from entering housing, for facilitating maintenance of the system  10 ′. 
     The injector unit  101  may contain a control system, seen in  FIG. 3 , which may be a portion of a control system for the entire device. For instance, the injector unit  101  may include a controller/processor  302  which may control the functioning of the injector unit  101  and may also facilitate communication with the control unit  102 . The processor  302  may be any suitable processor unit of a kind normally used in such devices. Such a processor  302  may have an integrated memory and/or storage system or distinct memory or storage systems may be provided in the injector unit  101 . In addition, the processor  302  may be in communication with other components which may be included in the injector unit  101 . 
     For instance, the injector unit  101  may include a number of sensors. As illustrated, the injector unit  101  may include a syringe inserted sensor  303 . Such a sensor  303  may detect whether a syringe  123  is inserted in the syringe housing  122 . The syringe inserted sensor  303  may prevent the injector unit  101  from attempting to perform an injection without a syringe  123  properly loaded. The injector unit  101  may include other sensors as well. For example, as illustrated, the injector unit  101  may include a home sensor  304 , which may detect whether the injector unit  101  is in a home state. 
     Further, the injector unit  101  may also include a rotation encoder  305 . The rotation encoder  305  may be connected to the motor  301 , and may be capable of sensing the rotation of the motor  301 . For example, the motor  301  may rotate a portion of the encoder  305 . The rotation encoder  305  may be an encoder of any suitable kind. The encoder  305  may be in communication with the processor  302  and may transmit state information to the processor  302 , allowing the processor  302  to control the motor  301 . Based on signals from the encoder  305 , the processor  302  may be able to determine the position of the syringe plunger. 
     The injector unit  101  may also include a motor driver  306 . The motor driver  306  may be in communication with both the processor  302  and the motor  301 . The motor driver  306  may provide the systems necessary to control the operation of the motor  301 . Based on input from the control unit  102 , the sensors  303 ,  304 , the encoder  305 , etc., the processor  302  may direct the motor  301  through the motor driver  306 , which in turn may control the extension of the plunger and thus the injection. 
     The injector unit  101  may also include a user feedback display  307 , which may, in some embodiments, provide the user with information during the injection process. For instance, the display  307  may provide the total volume of fluid that has been injected up to that point in the process, the rate at which it is being injected, etc., or may display error indicators in the case of a malfunction. 
     The injector unit  101  may also include user input devices. For example, the injector unit may include an inject button  308 . The inject button  308  may be located on the injector unit  101  in a position which is conveniently accessible by a user&#39;s fingers or thumb during injection. The inject button  308  may start and stop the injection process. For example, once the syringe  123  is loaded, and the control unit  102  is properly configured, the user may perform an injection with the injector unit  101 . To do so, the user may press and hold the inject button  308  to begin the injection, and may release the button  308  to stop the injection. In other embodiments, the inject button  308  may work in other ways. For instance, the user may press the button  308  once to begin the injection and a second time to stop the injection. The inject button  308  may be in communication with the processor  302 , which may control the injector unit  101  in response to a signal from the inject button  308 . 
     The inject button  308  itself may be constructed of any suitable material and may take any usable form. In addition, like the door  401 , the inject button  308  may be sealed. For instance, the injector unit  101  may include a seal disposed on the button  308  itself, or on the body  120  of the injector unit  101 , etc., which may create a seal between the button  308  and the injector unit body  120 . 
     The injector unit  101  may also be attached to a cable  103 . For instance, a cable  103  may pass through an aperture formed in the injector unit body  120 . The cable  103  may include multiple wires, including wires used for communication and power. The wires may connect to components housed in the injector unit  101 . For instance, the power wires may attach to a power supply system, which may supply power to the motor  301 , processor  302 , and other components of the injector unit  101 . The communication wires may connect to the processor  302 . Connections may be made using any suitable technology. For instance, the wires may be soldered directly to components of the injector unit  101 , or may be attached through connectors, etc. The cable  103  itself may be held in place by the injector unit body  120 , and may form a seal with the injector unit body  120 . In such a configuration, the cable  103  may be permanently attached to the injector unit  101 . In other embodiments, however, the cable  103  need not be permanently attached. For instance, some example embodiments may provide a connector on or in the injector unit body  120 , to which the cable  103  may be attached when in use. 
     The device may also include a control unit  102 . The control unit  102  may, for example, also be portable. For instance, the control unit  102  may be designed to be strapped to the user&#39;s wrist via a VELCRO® strap or other typical strap or connector, or it can be attached to a chair, table or any surface. The strapping mechanism can be any mechanism known in the art, for example, a clasp, a buckle, a snap, a button, or the like. In other embodiments, the control unit  102  may not be portable, e.g. the control unit  102  may be a fixed unit into which the injector unit  101  may plug. 
     The control unit  102  may serve a number of functions, including providing power and electronic control signals through the cable  103  to the injector unit  101 , which may, e.g. control and power the motor  301  of the injection drive mechanism. 
     As shown in  FIG. 1 , the control unit  102  has a control unit body  130 , which may provide a housing for the control unit components  102 . The control unit body  130  may be shaped to be comfortably strapped to a user&#39;s wrist, or arm. For example, a bottom side of the control unit  102  may be curved in order to conform to the shape of a user&#39;s wrist. As noted, the body  130  may also include a strap which may be used to attach the control unit  102  to a user, for instance a VELCRO® strap, or another kind of strap. In other embodiments, the control unit  102  may be shaped to attach to other places, for example, a table, etc. Further, in some embodiments, the shape described herein may be formed by one or more removable mounting pieces, which may be attached to the body  130  of the control unit  102 , and which may be shaped to mount the control unit  102  to different objects, e.g. a user&#39;s wrist, a table, etc. 
     The control unit  102  may include an LCD screen  131 , or other display, which may be located on a front of the control unit body  130 , and which may allow a user to interact with the system. The display  131  may present a user with control information and may provide an interface, using which the user may control the operation of the device. For instance, as shown in  FIG. 1 , the display  131  may be configured to display a number of pieces of information, such as the volume of material that has been injected, the volume of fluid remaining in the syringe  123 , the speed of the injection, battery charge, etc. In addition, other information may be displayed to facilitate different functions. For instance, the display  131  may also be configured to display configuration screens, or summary information, etc. In some example embodiments, the display can be in communication with, for example, the control unit and receive signals therefrom. 
     In addition, the control unit  102  may also include a keypad, or other input device, e.g. a dial, switch, etc. The keypad may include multiple buttons  132  which allow users to access and control the functions of the device. For example, the keypad buttons  132  may allow a user to control the speed and volume of the injection, or may allow the user to set other parameters related to the injection process. In addition, the control unit  102  may allow for other functions as well, for example, allowing a user to review historical use data, maintenance information, etc. The buttons  132  that make up the keypad may take any reasonable shape and configuration. For instance, as illustrated in  FIG. 1 , a number of buttons  132  may be provided on the control unit body  130 , located generally around the display  131 . In some embodiments the location of each button  132  may be coordinated with portions of the display screen  131 . For example, if, as illustrated, injection speed is displayed at the bottom of the display screen  131 , buttons  132  controlling the display speed may be located under the display  131 . Of course, the buttons  132  provided may perform different functions based on context. In addition, in other embodiments the control unit  102  may be equipped with a touch screen. 
     As illustrated in  FIG. 3 , the control unit may have a processor  310 , which may facilitate the functions of the control unit. The processor  310  may be connected to the input and output devices, for example, the display  131  and the keypad buttons  132 . The processor  310  may be configured to provide a user interface using the display  131  and keyboard buttons  132 . Further the processor  310  may be capable of sending signals to the injector unit  101 , and receiving signals from the injector unit  101 . Thus, the control unit  102  may send signals to the injector unit  102 , which may, e.g., be used to control the motor&#39;s  301  rotation, based on the injection speed set using the control unit  102 . In addition, the control unit  102  may receive signals from the injector unit  101 , based on, e.g., information gathered by the encoder  305 , which may allow the control unit  102  to calculate and display the volume of fluid injected, etc. 
     In addition, the control unit  102  may include a power system. For example, the control unit  102  may house a battery  311 , or other power source, e.g. a rechargeable battery, fuel cell, etc., which may be located inside the control unit body  130 . In one embodiment, the power is electrical power. The battery  311  may provide power to the control unit  102  and to the injector unit  101 , via the cable  103 . The battery  311  may be connected to the control unit  102  in any reasonable manner. For example, the battery  311  may be permanently connected, e.g. soldered, or may be connected through a connector. In the later case, a door may be provided in the control unit body  130 , which may allow access to the battery  311  for removal and replacement. As the battery  311  is typically a significant part of the overall weight of such a system, providing the battery  311  in the control unit  102 , reduces the weight of the injector unit  101 , and thus may improve user control. 
     In addition, the control unit  102  may include a battery charger  312 . The battery charger  312  may be capable of charging the battery  311  when connected to an external source of electricity. For example, the control unit  102  may include a connector, which may allow the control unit  102  to connect to a source of electrical power, such a standard 120 or 240 V AC power source. Of course, the control unit  102  need not connect to such a power source directly. Rather the control unit  102  may connect to a power adaptor or supply system, which may in turn connect to the primary power source. In addition, any suitable connector may be provided, e.g. in the body of the control unit  102 , for connection to the external power source. In some embodiments, the same connector may be used to connect the control unit  102  to the cable  103  when in use. 
     As noted, the control unit  102  may be in communication with the injector unit  101  via the cable  103 . Thus, the control unit  102  may provide a connector  133  using which the cable  103  may connect to the control unit&#39;s  102  systems. For instance, as illustrated in  FIG. 1 , a connector  133  may be provided at the top of the control unit  102 , though the connector  133  may be placed in any suitable location. The connector  133  may be designed to connect securely with a complementary connector  501  attached to the end of the cable  103 , as shown in  FIG. 5 . In order to ensure that the cable  103  does not separate during use, a locking mechanism may be provided, which secures the connection when engaged. In other embodiments, however, the cable  103  may be permanently attached to the control unit  102 . 
     It is noted that, in other example embodiments, a cable need not be used. For example, in some example embodiments the injector unit  101  may be in wireless communication with the control unit  102  during use. For instance, each unit  101 ,  102  may include a wireless device, e.g. transmitter and receiver, which may be of any suitable type. During use, a communication channel may be established between the injector unit  101  and the control unit  102 , using the wireless devices. Once established, the wireless communication channel may be used to exchange information and control signals between the units  101 ,  102  as it would be exchanged using an embodiment with a cable. Because wireless communications have a greater chance of being disrupted than communications over a cable, the injector unit  101  may be configured to react if wireless communication should be lost. For instance, the injector unit  101  may poll the control unit  102  periodically to sense whether it is in wireless communication with the control unit  102 . Should a poll fail, the injector unit  101  may be configured to stop operation, to continue operation using locally stored configuration parameters, to activate an alarm, etc. 
     In a system using a wireless communication channel, the injector unit  101  may also include a power source, for example a battery, fuel cell, etc. In addition, the injector unit  101  may include the systems necessary to maintain the power source. For example the injector unit  101  may include a battery charger, and may be equipped to connect to an external power source. 
     In addition, some example embodiments may support both wireless and cabled communication. For instance, the injector unit  101  and control unit  102  may each include wireless devices and cable connectors. In such embodiments, the wireless devices may not be used when the units  101 , 102  are connected via cable. In addition, the injector unit  101  may be configured to house an optional power source. For example, the injector unit  101  may be configured to draw power over a cable, when attached the control unit  101  via cable. In this case, the optional power source need not be installed in the injector unit  101 , reducing the weight of the unit. However, should the wireless devices be used for communication instead of the cable, the optional power source may be installed in the injector unit  101 , which may be configured to draw power directly from the power source when in that configuration. 
     As with the injector unit  101 , the control unit  102  may be sealed in order to allow for wipe down cleaning. For instance, seals may be provided for the cable connector  133 , the buttons  132 , and any other location where the control unit body  130  may open. 
     An exemplary system  600  according to the present description is illustrated in  FIG. 6 . System  600  generally includes, for example, injector unit  601 , including an internal drive unit (not shown in this FIG) and separate control unit  602  remote from the injector unit  601 . The control unit  602  includes a controller/processor such as described elsewhere herein, configured to control the drive unit. The injector unit  601  and control unit  602  are in communication with one another, for example, are electrically connected by line or wire  603 . Control unit  602  includes strap  604  which allows connection to a user&#39;s wrist. Control unit  602  further includes a bank of control buttons  606  for controlling functions of the system through, for example, a menu driven system displayed on LCD screen  605 . 
     The injector unit  601  includes a grippable housing  610  having an enlarged distal end  612  a having a coupling portion  614 . 
     The system  600  may further includes a cartridge  618  sealingly couplable to the coupling portion  614  of the grippable housing  610 , and containing an injectable fluid. The cartridge  618  may be fitted with a needle or cannula  620  of a suitable gauge. In this embodiment, the injector unit  610  includes a movable plunger (not visible in  FIG. 6 ) driven by the drive unit and extendable in a distal direction, into the cartridge  618 , to cause extrusion of the injectable fluid from the cartridge  618 , for example, out of the distal tip of the needle  620 , when the cartridge  618  is coupled to the coupling portion  614 . In the embodiment shown, the enlarged distal end  612  is defined by substantially opposing, laterally extending flanges  626 . The injector unit  601  includes substantially opposing ejection buttons, or triggers  628 , configured to enable ejection of the cartridge from the coupling portion  614 , for example, by simultaneous pressing of the triggers  628  by the user. As shown, each flange  626  includes one of the substantially opposing triggers  628 . 
     System  600  can be used as illustrated in  FIGS. 7-9 . For example, system  600  is used as a right-handed system, meaning injector unit  601  is handled in the right hand  702  and controller unit  602  is strapped to the right wrist  703 . In other embodiments, the system can be a left handed system. Injector device  601  is held in right hand  702  such that first digit  704  rests on or near injection button  705 . Second digit  706  and third digit  707  rest comfortably on top portion  708  of injector device  701 . Left hand  709  is used, for example, to drive bank of control buttons  606  or to detach control unit  602  from base  710  attached to strap  604 . It can be appreciated from  FIG. 9 , that the control unit  602 , mountable to a user&#39;s arm or wrist, allows the user to view the control unit  602  while operating the injector unit  601  within the same field of vision. 
     In another embodiment, system  600  can be used with base station  1000 , illustrated in  FIGS. 10-12 . Base station includes injector unit  601  storage slot  1001 , control unit  602  charging dock  1002 , and strap  604  post  1003 . Storage slot  1001  includes removable cleaning plug  1004  which can be removed from base station  1000  and attached directly to injector unit when the injector unit needs cleaning. Charging dock  1002  includes plate  1005 , or alternately individual magnets, and charging contacts  1006  used to charge control unit  602 . Base station  1000  further includes port  1007  which can accommodate, for example, a power cable to charge injector unit  601  and/or control unit  602  and/or transfer data to or from either device. Base station  1000  can be wall mounted using wall mount slots  1008  or can be placed on a tabletop assisted by cushions  1009 . 
     Exemplary internal components of injector device  601  are illustrated in  FIGS. 13-16 . Injector unit  601  includes inject button  1301  and cartridge eject buttons  628 .  FIG. 13  further illustrates first retention mechanism  1303  and second retention mechanism  1304  which hold a cartridge in place until it is ejected. Drive screw  1305  is driven by motor  1306  and controlled by circuit board  1307 . Drive screw  1305  further drives movable plunger  1308  and inject button  1301  actuates pressure sensitive button  1309  as illustrated in  FIG. 14 . The movable plunger  1308  may be extendable beyond the distal end of the injector unit housing  610  to move fluid in the cartridge distally. 
     Optionally, injector device  601  can include LED indicators (not shown) for indication of injection speed. Injection speed can be indicated on injector device  601  or control unit  602  by, for example, with one or more LED indicators or other illuminating indicators. 
     Non-limiting internal components of control device  602  are illustrated in  FIGS. 17-20 . Control device  602  includes magnets  1701  which hold the unit to strap  604  or charging dock  1002 . Charging contacts  1702  allow unit charging by contact with, for example, charging contacts  1006  on base station  1000 . Information about the device, for example, model number, serial number and the like can be placed at label position  1703 . 
       FIG. 19  further illustrates strain relief  1704  which prevents flexural strain on cable  103  (a strain relief can also be included on injector device  601 ). Battery  1705  is housed just below magnets  1701  within the unit. Control of the unit itself is accomplished using printed circuit board  1706  which is housed opposite battery  1705 . Further included in control unit  602  are power button contact  1707 , LCD screen  605 , and capacitance sensing board  1708 . 
     EXAMPLE 
     Modular Injector System in Accordance with an Embodiment of the Invention Injector Unit 
     The injector unit  1810  is a hand held a syringe-like device, as shown in  FIG. 21 , and it is compatible with specially designed 2 mL cartridges  1812  (shown in  FIG. 23 ) containing a hyaluronic acid based dermal filler. The injector unit  1810  includes a cartridge slot  1816  that houses proximal end of the cartridge  1812 . A plunger rod  1818  inside the cartridge slot  1816  is electromechanically moved forward inside the injector unit  1810  to extrude the cartridge contents when inject button  1819  is pressed. Eject buttons  1820  are provided for ejecting a spent cartridge. LED lights  1824  on the injector unit light up according to the extrusion rate during use. One, two, three or four lights illuminate which correspond to very low, low, medium, and fast extrusion rates. 
     Wrist Unit 
     The control unit  1840 , shown in  FIG. 22 , contains a battery and houses the software which controls the extrusion speed of the dermal filler from the cartridge  1812  ( FIG. 23 ). It is permanently connected to the injector unit  1810  by a cable  1844 . The wrist unit  1840  includes a display screen  1850 , “OK/Yes” button  1852 , “Scroll” button  1854 , “No/Cancel/Exit” button  1856  and power button  1860 . The control unit  1840  attaches magnetically to a wrist strap  1862 . 
     Cartridge 
     The 2 mL cartridge  1812  for containing an injectable fluid such as a dermal filler, for example, Juvéderm Ultra Plus XC gel formulation, available from Allergan, Irvine, Calif., is shown in  FIG. 23 . The cartridge  1812  is made of cyclic olefin copolymer (COC). The cartridge  1812  includes a cartridge ring  1850 , which seals the cartridge  1812  into the cartridge slot  1816  of the injector unit  1810 . In this exemplary embodiment, the cartridge  1812  does not include a plunger or finger grips and cannot be used apart from the injection unit  1810 . The cartridge  1812  is provided with a 30 G×¾″ needle  1854 . 
     The system, including injector unit  1810 , control unit  1840  and cartridge  1812 , is capable of extruding Juvéderm gel at 4 preset speeds: very low, low, medium and high. A fifth, dynamic speed, setting is available which allows injection of the entire range of speeds, from very low to high, depending on the amount of pressure exerted on the “Inject” button of the Injector Unit. Lighter pressure on the “Inject” button of the Injector Unit will correspond to a lower injection speed and higher pressure will correspond to a higher injection speed. The approximate corresponding flow rates are shown in the Table 2. 
     These flow rates were determined based on evaluating physician&#39;s typical extrusion rates. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Injection Rates 
               
            
           
           
               
               
               
            
               
                   
                 Speed Setting 
                 Injection Rate (mL/minute)* 
               
               
                   
                   
               
               
                   
                 Very Low 
                 0.30 
               
               
                   
                 Low 
                 0.60 
               
               
                   
                 Medium 
                 0.90 
               
               
                   
                 High 
                 1.20 
               
               
                   
                 Dynamic 
                 0.30-1.20 
               
               
                   
                   
               
               
                   
                 *APPROXIMATE INJECTION RATE 
               
            
           
         
       
     
     Although the present disclosure has described the inventive injector system generally as being especially advantageous for administration of dermal fillers, it is to be appreciated that the system is also useful for injection of other substances. For instance, systems of the present invention may be used to administer agents such as botulinum toxin, an injectable substance, which is used for cosmetic and medical purposes. For example, a controlled quantity of botulinum toxin must be injected into a patient&#39;s body in a controlled, precise manner, often in very small amounts. The required precision and accuracy may be achieved using an example injector device according to the invention. 
     For example, a patient may seek treatment for a medical condition, e.g. blepharospasm (“excessive blinking”), from a qualified physician. In some cases, the condition may be treated with a controlled injection of a substance, in the example case, a controlled injection of botulinum toxin into the muscle tissue to be treated. In order to perform such an injection, the physician may use an example injector device described herein. For example, the physician may strap a control unit to his or her wrist. The physician may then attach the cable of an injector unit to the control unit, and may use the control unit to configure the system. For instance, the physician may select an injection speed using the control unit and may select other parameters. 
     The user may then load a syringe into the injector unit. For instance, the physician may select a pre-filled syringe filled with botulinum toxin, which may be inserted into the injector unit using a loading door. Once loaded, the physician may also attach a needle to the injector unit. For instance, the physician may select an appropriate needle for the given procedure and may attach that needle to the injector unit, e.g. using a luer lock connection. 
     The injector unit may then be ready for use. The physician may proceed to identify an area of the patient&#39;s body for injection. For instance, the physician may locate a muscle which may be causing the patient discomfort. The physician may then insert the needle into the desired location and may depress the inject button. When the inject button is depressed, the motor in the injector unit may turn, driving a plunger into the syringe and extruding the material in the syringe through the needle, at a rate controlled by the parameters selected using the control unit. 
     While the injector unit is extruding material, the control unit may display information relating to the injection process. The injector unit may also display information relating to the injection process, for example, but not limited to, LEDs that illuminate sequentially as the injection rate increases. For example, the user may be able to read the quantity of material injected off the display. Once the desired amount has been injected, the physician may release the inject button, stopping the injection process, and remove the needle from the patient. If another location is to be injected, and sufficient material remains, the process may be repeated, until material has been injected into all of the areas to be treated, or the syringe has been emptied. 
     The used syringe may then be removed from the device and discarded, along with the needle. The control unit may be disconnected from the injector unit, and both units may be cleaned. In other embodiments, the control unit and injector unit may be permanently attached to each other. In addition, the control unit may be plugged into a power source to recharge the battery if necessary. 
     In the preceding specification, the present invention has been described with reference to specific example embodiments thereof. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the present invention. The description and drawings are accordingly to be regarded in an illustrative rather than restrictive sense. 
     Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. 
     The terms “a,” “an,” “the” and similar referents used in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention. 
     Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims. 
     Certain embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 
     In closing, it is to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the present invention. Other modifications that may be employed are within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations of the present invention may be utilized in accordance with the teachings herein. Accordingly, the present invention is not limited to that precisely as shown and described.