Patent Publication Number: US-8979799-B1

Title: Electronic injector

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation-in-part of and claims the benefit of U.S. patent application Ser. No. 14/052,929, filed on Oct. 14, 2013, entitled THERAPEUTIC AGENT INJECTION DEVICE, which is incorporated by reference in its entirety herein. 
    
    
     TECHNICAL FIELD 
     The technical field of this disclosure is personal medical systems, particularly, electronic injectors. 
     BACKGROUND OF THE INVENTION 
     Certain medical conditions or diseases require that patients intermittently inject a drug or therapeutic agent subcutaneously to maintain the medical condition or disease under control. Multiple daily injections (MDIs) may be required. One such medical condition is diabetes, for which insulin is injected to regulate blood glucose. An estimated twenty-six million people in the United States, or about 8% of the population, have diabetes. This percentage is expected to increase in the near-term as the population ages. 
     Certain patients are unlikely or unable to follow the drug regimen required to maintain their medical condition under control. Some patients are squeamish about injecting the drug themselves and others suffer adverse effects from repeated injections, such as bruising at the injection site. 
     Problems with existing mechanical insulin pens also discourage the patient from using them regularly. Mechanical insulin pens are bulky, requiring an extendable dial and a large working chamber, making the mechanical insulin pen itself large. Use of the mechanical insulin pen is also indiscreet: the patient must manually calculate the dosage, manually crank a large noisy visible dial to set the dosage, and then perform the injection with the large device. The mechanical components are also ill-suited to conversion to electronic operation. 
     To accommodate such patients, injection ports have been developed which only require that the patient puncture their skin every few days to install an injection port, rather than injecting with a needle into their skin numerous times a day. Injection ports employ a cannula inserted subcutaneously, and the patient injects the drug into the injection port adhering to their skin rather than directly into their cutaneous tissue. 
     Unfortunately, injection ports still require that the patient administer the therapeutic agent repeatedly throughout the day. Injection ports with dedicated reservoirs allowing bolus injection have been developed, but maintain a continuous flow path and run the risk of inadvertent bolus injection. Although these problems can be remedied with a dedicated electronic insulin pump, many patients are unwilling or unable to use a dedicated insulin pump due to the expense and complication. 
     It would be desirable to have an electronic injector that would overcome the above disadvantages. 
     SUMMARY OF THE INVENTION 
     One aspect of the invention provides an electronic on-body injector for use with a patient to deliver a fluid through an injection device having an injection port in fluid communication with a delivery tube, the injection port lying on an injection axis. The electronic on-body injector includes a fluid reservoir operable to hold the fluid; a MEMS pump in fluid communication with the fluid reservoir; a bolus injection needle in fluid communication with the MEMS pump, the bolus injection needle having a bolus injection needle tip aligned with the injection port, the bolus injection needle being slideably biased away from the injection port to define a gap between the bolus injection needle tip and the injection port; and a bolus needle button operably connected to the bolus injection needle to slide the bolus injection needle along the injection axis. The bolus needle button is operable to advance the bolus injection needle tip to close the gap and advance the bolus injection needle tip into the injection port to form a bolus injection flow path from the fluid reservoir, through the MEMS pump, through the bolus injection needle, through the delivery tube, and into the patient. The bolus needle button is further operable to activate the MEMS pump to deliver a predetermined bolus volume to the patient through the bolus injection flow path in response to a bolus pump drive signal. 
     Another aspect of the invention provides an electronic on-body injector for use with a patient to deliver a fluid through an injection device having a delivery tube. The electronic on-body injector includes a fluid reservoir operable to hold the fluid; and a MEMS pump in fluid communication with the fluid reservoir and the delivery tube to form a basal injection flow path from the fluid reservoir, through the MEMS pump, through the delivery tube, and into the patient. The MEMS pump is operable to deliver a basal injection to the patient through the basal injection flow path in response to a basal pump drive signal. 
     Another aspect of the invention provides an electronic injector for use with a patient to deliver a fluid, the electronic injector including a fluid reservoir operable to hold the fluid; a MEMS pump in fluid communication with the fluid reservoir; an injection needle in fluid communication with the MEMS pump; a battery having a DC power output; a regulator operably connected to the battery to convert the DC power output to AC power output; a microcontroller operably connected to the regulator to convert the AC power output to a pump drive signal; and a housing to enclose the battery, the regulator, the microcontroller, the fluid reservoir, and the MEMS pump. The MEMS pump is responsive to the pump drive signal to control flow of the fluid from the fluid reservoir, through the MEMS pump, through the injection needle, and into the patient. 
     The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention, rather than limiting the scope of the invention being defined by the appended claims and equivalents thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-4  are perspective, section, perspective, and exploded perspective views, respectively, of one embodiment of an injection device made in accordance with the invention. 
         FIGS. 5A-5C  are perspective views of one embodiment of an injection device made in accordance with the invention. 
         FIG. 6  is a section perspective view of one embodiment of an injection device made in accordance with the invention. 
         FIGS. 7-11  are perspective, perspective, section, section, and perspective section views, respectively, of one embodiment of an injection device made in accordance with the invention. 
         FIGS. 12A-12D  are side and section views of needleless pen injectors for use with an injection device made in accordance with the invention. 
         FIGS. 13A-13F  are section views of pop-up indicator ports for use with an injection device made in accordance with the invention. 
         FIGS. 14A &amp; 14B  are perspective views of one embodiment of an injection device made in accordance with the invention. 
         FIGS. 15-20  are front perspective, top side, left side, bottom side, bottom perspective, and detail views, respectively, of one embodiment of a body for an injection device made in accordance with the invention. 
         FIG. 21  is a perspective view of one embodiment of an introducer septum for use in an injection device made in accordance with the invention. 
         FIG. 22  is a section view of an injection device made in accordance with the invention including the introducer septum of  FIG. 21 . 
         FIG. 23  is a perspective view of one embodiment of a septum for use in an injection device made in accordance with the invention. 
         FIGS. 24A &amp; 24B  are top side and section views, respectively, of one embodiment of a septum for use in an injection device made in accordance with the invention. 
         FIG. 25  is a perspective view of one embodiment of an on-body injector for use with an injection device made in accordance with the invention. 
         FIG. 26  is a partial perspective view of portions of one embodiment of an on-body injector for use with an injection device made in accordance with the invention. 
         FIG. 27  is a partial perspective view of portions of one embodiment of an on-body injector for use with an injection device made in accordance with the invention. 
         FIG. 28  is a section view of one embodiment of an injection device and on-body injector for use with an injection device made in accordance with the invention. 
         FIG. 29  is a block diagram of one embodiment of an injection device and on-body injector made in accordance with the invention. 
         FIG. 30  is a flow chart of a method of use for an on-body injector in accordance with the invention. 
         FIG. 31  is a block diagram of one embodiment of an injection device and electronic on-body injector made in accordance with the invention. 
         FIGS. 32A-32C  are wave form diagrams of bolus, basal, and basal pump drive signals for an electronic injector made in accordance with the invention. 
         FIGS. 33A-33C  are schematic diagrams of a piezoelectric MEMS pump for use in an electronic injector made in accordance with the invention. 
         FIGS. 34A-34C  are an exploded perspective view, a partial perspective view, and a partial perspective view of an injection device and electronic on-body injector made in accordance with the invention. 
         FIG. 35  is a block diagram of one embodiment of an electronic injector made in accordance with the invention. 
         FIGS. 36A-36D  are a perspective view, a top view, a side view, and a partial perspective view of an electronic injector made in accordance with the invention. 
         FIGS. 37A-37E  are a perspective view, a top view, a side view, an exploded perspective view, and a partial top view of an electronic injector made in accordance with the invention. 
         FIG. 38  is a schematic cross section view of an electronic injector made in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-5C , in which like elements share like reference numbers, are various views of one embodiment of an injection device made in accordance with the invention. The injection device includes an introducer port along an introducer axis and an injection port along an injection axis, with the injection axis being non-collinear with the introducer axis. In this embodiment, the injection axis is at an angle to and intersects with the introducer axis. 
       FIG. 1  is a perspective view of the injection device  100  including a body  110  and a patch  120  attached to the body  110 . The patch  120  is operable to adhesively attach the injection device  100  to a patient (not shown). The body  110  has a port face  112 , with an introducer port  130  and an injection port  140  on the port face  112 . The introducer port  130  is used to place a delivery tube subcutaneously in the patient. The injection port  140  is used by the patient to inject a therapeutic agent, which as defined herein can be any liquid such as a liquid including a therapeutic agent, drug, diagnostic agent, or the like. The body  110  also includes cutouts  160 . Those skilled in the art will appreciate that the introducer port  130  can be too small to be effectively used by a patient for injection, but could be used to inject a therapeutic agent, such as a bolus injection using a mechanically attached device, as desired for a particular application. 
       FIG. 2  is a section view of the injection device  100 , the section bisecting the introducer port  130  and the injection port  140 , and includes the introducer axis  134  and injection axis  144 . An axis as defined herein generally follows the centerline of an associated channel through an associated port. The body  110  has a port face  112  and a patient face  114 . A delivery tube  150  for subcutaneous delivery of the therapeutic agent projects from and is generally perpendicular to the patient face  114 . The delivery tube  150  is operably connected to the introducer port  130  and defines an introducer axis  134  along the introducer channel  132 , the delivery tube  150  being in fluid communication with the injection port  140 . The introducer port  130  includes an introducer channel  132 , with an introducer port cover  135  and an introducer septum  136  disposed in the introducer channel  132 . The injection port  140  includes an injection channel  142  defining an injection axis  144  with an injection septum  146  disposed in the injection channel  142 . In one embodiment, the introducer septum  136  and/or the injection septum  146  is self sealing, such that each of the septums block fluid flow through the septum after a needle has been put through the septum then removed, preventing fluid flow from the port. In this embodiment, the injection axis  144  is at an angle to and intersects with the introducer axis  134 . In one example, the delivery tube  150  is a flexible cannula and a needle hub assembly can be used to place the delivery tube  150  subcutaneously in the patient. In another example, the delivery tube  150  is a rigid needle and the delivery tube  150  can be placed subcutaneously in the patient with or without a needle hub assembly. 
       FIG. 3  is a perspective view of the injection device  100  with a needle hub assembly  170 . The needle hub assembly  170  includes a needle hub  172  and a needle  174  attached to the needle hub  172 . The needle  174  of the needle hub assembly  170  is inserted through the introducer port  130  and through the delivery tube  150  along the introducer axis  134 . The needle hub assembly  170  can be used to add rigidity to the delivery tube  150  during implantation when the delivery tube  150  is a flexible cannula. 
       FIG. 4  is an exploded perspective view of the injection device with a needle hub assembly. A needle guard  176  disposed around the needle  174  can be used to protect the needle  174  and the delivery tube  150  when the injection device and needle hub assembly are assembled for shipping. The various parts of the injection device and needle hub assembly can be connected by interference fit, adhesive, welding, and/or any other method of attachment suitable for a particular application. 
       FIGS. 5A-5C  are perspective views of various applications of the injection device made in accordance with the invention. Referring to  FIG. 5A , a syringe  190  can be used to deliver a therapeutic agent through the injection port  140  of the injection device  100 . The syringe can be a conventional syringe, a standard insulin pen, or a needleless syringe. The needle length of a conventional syringe or standard insulin pen can be of any length because the injection axis is non-collinear with the introducer axis, such that a longer needle does not damage the injection device. In one embodiment, the injection port  140  is adapted to be mateable with the syringe  190 , with a socket, fitting, or the like, to increase ease of use. In one example, the injection port  140  is a socket with a socket needle which pierces a foil front end of a needleless syringe when the needleless syringe is seated in the socket. The needleless syringe itself has no needle in this example. 
     Referring to  FIG. 5B , an on-body injector  192  is mateable with the injection port  140  of the injection device  100  and can be used to deliver a therapeutic agent through the injection port  140 . The on-body injector  192  can include a reservoir to hold the therapeutic agent. In one embodiment, the on-body injector  192  can deliver a basal and/or bolus dose of the therapeutic agent. 
     Referring to  FIG. 5C , an extendable tube  194  can be used to deliver a therapeutic agent through the injection port  140 . The extendable tube  194  includes a port connector  195 , a tube  196 , and an external device fitting  197 , all being in fluid communication. The port connector  195  is in fluid communication with the injection port  140  with a needle or mateable fitting to deliver the therapeutic agent through the injection port  140 . The external device fitting  197  is connectable to an external device, such as a wearable insulin pump or an infusion tubing line to a gravity fed container. 
       FIG. 6  is a section perspective view of one embodiment of an injection device made in accordance with the invention. In this embodiment, an upper body portion is rotatable about the introducer axis independent of a lower body portion, so that the injection axis can be positioned at a desired rotary angle regardless of the initial placement of the patch on the patient. This allows the patient to select a rotary position for the injection port that is convenient for injection of the therapeutic agent. 
     The body of the injection device can have a first body portion including the port face and a second body portion including the patient face, the first body portion and the second body portion being rotatably connected with a flange, the first body portion and the second body portion being independently rotatable about the introducer axis. 
     The body  210  of the injection device  200  includes an upper body portion  202  and a lower body portion  204 . The upper body portion  202  and lower body portion  204  are rotatably connected with a flange  206  so that the upper body portion  202  and the lower body portion  204  can rotate independently about the introducer axis  234  defined by the delivery tube  250  along the introducer channel  232 . The upper body portion  202  has a port face  212  and the lower body portion  204  has a patient face  214 . A patch  220  is attached to the patient face  214  and is operable to adhesively attach the injection device  100  to a patient (not shown). 
     The delivery tube  250  for subcutaneous delivery of a therapeutic agent projects from and is generally perpendicular to the patient face  214 . The delivery tube  250  is operably connected to the introducer port  230 , the delivery tube  250  being in fluid communication with the injection port  240 . The introducer port  230  includes an introducer channel  232 , with an introducer septum  236  disposed in the introducer channel  232 . The injection port  240  includes an injection channel  242  defining an injection axis  244  with an injection septum  246  disposed in the injection channel  242 . 
     The injection axis  244  is non-collinear with the introducer axis  234 . In this embodiment, the injection axis  244  is at an angle to and intersects with the introducer axis  234 . In one example, the delivery tube  250  is a flexible cannula and a needle hub assembly can be used to place the delivery tube  250  subcutaneously in the patient. In another example, the delivery tube  250  is a rigid needle and the delivery tube  250  can be placed subcutaneously in the patient with or without a needle hub assembly. 
     In operation, the patch  220  is attached to the patient and the delivery tube  250  inserted in the patient for subcutaneous delivery of a therapeutic agent. The injection port  240  in the upper body portion  202  can be rotated about the introducer axis  234  even though the lower body portion  204  is at a fixed position on the patient since the lower body portion  204  is attached to the patient by the patch  220 . 
       FIGS. 7-11 , in which like elements share like reference numbers, are various views of one embodiment of an injection device made in accordance with the invention. The injection device includes an introducer port along an introducer axis and an injection port along an injection axis, with the injection axis being non-collinear with the introducer axis. In this embodiment, the injection axis is parallel to and does not intersect with the introducer axis. 
     The injection device for delivering a therapeutic agent to a patient can include a body, the body having a patient face and a port face opposite the patient face, the port face having an introducer port including an introducer channel and an injection port including an injection channel, the introducer channel being in fluid communication with the injection channel through a cross channel, the injection channel defining an injection axis; a delivery tube for subcutaneous delivery of the therapeutic agent to the patient, the delivery tube projecting from and being generally perpendicular to the patient face, the delivery tube defining an introducer axis and being in fluid communication with the injection port; and a patch, the patch being attached to the patient face and being operable to adhesively attach to the patient; wherein the injection axis is parallel to the introducer axis. 
       FIG. 7  is a perspective view of the injection device  300  including a body  310  and a patch  320  attached to the body  310 . The patch  320  is operable to adhesively attach the injection device  300  to a patient (not shown). The body  310  has a port face  312 , with an introducer port  330  on the port face  312 . The introducer port  330  is used to place a delivery tube subcutaneously in the patient. In this example, an optional injection cap  302  secured to the body  310  to protect an injection port, which is used by the patient to inject a therapeutic agent. 
       FIG. 8  is a perspective view of the injection device  300  with the optional injection cap removed to expose the injection port  340 . In this example, the body  312  includes threads  306  to secure the optional injection cap to the body and an optional O-ring  304  to seal the area around the injection port  340  when the optional injection cap is secured to the body. 
       FIG. 9  is a section view of the injection device  300 , the section bisecting the introducer port  330  and the injection port  340  and including the introducer axis  334  and injection axis  344 . The body  310  has a port face  312  and a patient face  314 . A delivery tube  350  for subcutaneous delivery of the therapeutic agent projects from and is generally perpendicular to the patient face  314 . The delivery tube  350  is operably connected to the introducer port  330  and defines an introducer axis  334  along the introducer channel  332 , the delivery tube  350  being in fluid communication with the injection port  340 . The introducer port  330  includes an introducer channel  332 , with an introducer septum  336  disposed in the introducer channel  332 . The injection port  340  includes an injection channel  342  defining an injection axis  344  with an injection septum  346  disposed over the injection channel  342 . In this embodiment, the injection axis  344  is parallel to and does not intersect with the introducer axis  334 . A cross channel  343  connects the injection channel  342  to the introducer channel  332 . In one example, the delivery tube  350  is a flexible cannula and a needle hub assembly can be used to place the delivery tube  350  subcutaneously in the patient. In another example, the delivery tube  350  is a rigid needle and the delivery tube  350  can be placed subcutaneously in the patient with or without a needle hub assembly. 
       FIG. 10  is a section view of the injection device  300  with a needle hub assembly  370  and a needle guard  376 . The needle hub assembly  370  includes a needle hub  372  and a needle  374  attached to the needle hub  372 . The needle  374  of the needle hub assembly  370  is inserted through the introducer port  330  and through the delivery tube  350  along the introducer axis  334 . The needle hub assembly  370  can be used to add rigidity to the delivery tube  350  when the delivery tube  350  is a flexible cannula. The needle hub assembly  370  can optionally be used when the delivery tube  350  is a rigid needle. A needle guard  376  disposed around the needle  374  can be used to protect the needle  374  and the delivery tube  350  when the injection device and needle hub assembly are assembled for shipping. 
       FIG. 11  is a perspective section view of the injection device with an injection adapter assembly. For clarity of illustration, the cross section cut of the injection device  300  in the illustration bisects the introducer port  330  and the injection port  340 , and includes the introducer axis  334  and injection axis  344 . The cross section cut of the injection adapter assembly  400  in the illustration includes the injection axis  344  and is perpendicular to the section of the injection device  300 . The injection adapter assembly  400  screws onto the injection device  300  using the threads  306  on the body  310  to secure the needleless pen injector to the body  310 , with the O-ring  304  sealing around the interface between the adapter septum  420  and the injector septum  346 . Those skilled in the art will appreciate that the mateable connection securing the needleless pen injector to the body is not limited to threads and can be any mateable connection desired for a particular application. 
     In this embodiment, the injection adapter assembly  400  is adapted to receive a needleless pen injector (not shown). The adapter body  410  defines a recess  412  adapted to receive a tip of the needleless pen injector. In this example, the needleless pen injector includes threads on its outer diameter complementary to the adapter threads  414  on the inner diameter of the adapter body  410 . The tip of the needleless pen injector is screwed into the recess  412  so that the adapter needle  416  is received in the needleless pen injector, accessing the therapeutic agent contained within the needleless pen injector by piercing a foil on the tip of the needleless pen injector or accessing a pen injector port adapted to receive the adapter needle  416 . With the needleless pen injector secured in the injection adapter assembly  400 , pressure applied to the therapeutic agent enclosed in the needleless pen injector forces the therapeutic agent through the adapter needle  416  and the adapter septum  420  into the injection device  300 , where the therapeutic agent passes through the injector septum  346  into the injection port  340 , through the injection channel  342 , the cross channel  343 , and the delivery tube  350 , and into the patient. 
     Those skilled in the art will appreciate that a variety of interfaces can be used between the needleless pen injector, the injection adapter assembly  400 , and the injection device  300 . In the embodiment of  FIG. 11 , the adapter septum  420  and the injector septum  346  are permeable so that the therapeutic agent passes through the adapter septum  420  and the injector septum  346 . The septums can be hydrophilic when used with the needleless pen injector to allow the therapeutic agent to pass through. In another embodiment, the injector septum can include a slit valve operable to open on receiving a stub tube at the tip of the needleless pen injector. In yet another embodiment, the injector septum can include a slit valve which is open by a mechanical lever that pushes open and spread the slit valve when the needleless pen injector is received in the injection adapter assembly. In yet another embodiment, the needleless pen injector is interlocked with the injection adapter assembly so that no therapeutic agent can be dispensed from the needleless pen injector until the needleless pen injector is fully engaged with the injection adapter assembly. 
       FIGS. 12A-12D  are various views of needleless pen injectors for use with an injection device made in accordance with the invention. Each of the needleless pen injectors is provided with a manual or automatic pressurization to force the therapeutic agent held within the needleless pen injector into the injection device and patient, once the needleless pen injector has been fully engaged with an injection adapter assembly. 
       FIG. 12A  is a side view of the tip of a needleless pen injector  500  having a barrel  502  to contain a therapeutic agent and optional threads  504  for use with an adapter body having threads on the inner diameter. The end  506  of the needleless pen injector  500  can be adapted to accommodate the particular design of an injection adapter assembly for a particular application.  FIG. 12B  is a section view of the tip of a needleless pen injector  510  having a barrel  512  to contain a therapeutic agent and a foil  516  across the end of the needleless pen injector  510 . The foil  516  can be pierced by an adapter needle in the injection adapter assembly (shown in  FIG. 11 ) to provide fluid communication between the needleless pen injector  510  and the injection device through the injection adapter assembly.  FIG. 12C  is a section view of the tip of a needleless pen injector  520  having a barrel  522  to contain a therapeutic agent and a pen port  526  at the end of the needleless pen injector  520 . The pen port  526  can receive an adapter needle in the injection adapter assembly (shown in  FIG. 11 ) to open the pen port  526  and provide fluid communication between the needleless pen injector  520  and the injection device through the injection adapter assembly.  FIG. 12D  is a section view of the tip of a needleless pen injector  530  having a barrel  532  to contain a therapeutic agent and a stub tube  536  at the end of the needleless pen injector  530 . The stub tube  536  is operable to open a slit valve on the injector septum of the injection device. 
       FIGS. 13A-13F , in which like elements share like reference numbers, are section views of pop-up indicator ports for use with an injection device made in accordance with the invention. Because the introducer port and the injection port of the injection device are both in fluid communication with the delivery tube, flow blockage in the delivery tube can cause an increase in pressure at both ports when the patient attempts to inject a therapeutic agent. The flow blockage/pressure increase can be detected by the patient, indicating that the therapeutic agent is not being delivered, with a pop-up indicator port in the port not being used for injection. During injection, the membrane of the pop-up indicator port is close to the body of the injection device under normal conditions, and extends from the body of the injection device when the delivery tube is blocked and the pressure increases above a predetermined pressure. 
     The pop-up indicator can be disposed in the introducer channel, the pop-up indicator having a normal state when pressure in the introducer channel is normal and an alarm state when pressure in the introducer channel exceeds a predetermined value. 
       FIGS. 13A &amp; 13B  are section views of a pop-up indicator port  600  with a folded membrane  602  installed as the introducer port. The pop-up indicator port  600  is installed in the introducer channel  632  of the body  610  along the introducer axis  634 , and is in fluid communication with the injection channel. A self-closing port  604  in the membrane  602  allows a needle of a needle hub assembly to pass through the membrane  602  when a needle hub assembly is used to implant the injection device. No self-closing port is required if a needle hub assembly is not used to implant the injection device. Referring to  FIG. 13A , the pop-up indicator port  600  is in the normal state with normal pressure in the introducer channel  632 , with the membrane  602  folded on itself. Referring to  FIG. 13B , the pop-up indicator port  600  is in the alarm state due to pressure in the introducer channel  632  exceeding a predetermined value. The pressure occurs when a therapeutic agent is being injected into the injection port, which is in fluid communication with the introducer channel  632 , while the delivery tube is blocked. In the alarm state, the membrane  602  unfolds to extend from the body  610 . 
       FIGS. 13C &amp; 13D  are section views of a pop-up indicator port  600  with an accordion membrane  612  installed as the introducer port. Referring to  FIG. 13C , the pop-up indicator port  600  is in the normal state with normal pressure in the introducer channel  632 , with the membrane  612  pleated like an accordion. Referring to  FIG. 13D , the pop-up indicator port  600  is in the alarm state due to pressure in the introducer channel  632  exceeding a predetermined value. The pressure occurs when a therapeutic agent is being injected into the injection port, which is in fluid communication with the introducer channel  632 , while the delivery tube is blocked. In the alarm state, the membrane  612  uncompresses the pleats to extend from the body  610 . 
       FIGS. 13E &amp; 13F  are section views of a pop-up indicator port  600  with a deformable membrane  622  installed as the introducer port. Referring to  FIG. 13E , the pop-up indicator port  600  is in the normal state with normal pressure in the introducer channel  632 , with the membrane  622  extending across the introducer channel  632 . Referring to  FIG. 13F , the pop-up indicator port  600  is in the alarm state due to pressure in the introducer channel  632  exceeding a predetermined value. The pressure occurs when a therapeutic agent is being injected into the injection port, which is in fluid communication with the introducer channel  632 , while the delivery tube is blocked. In the alarm state, the material of the membrane  622  deforms under pressure to extend from the body  610 . In another embodiment, the material of the membrane  622  can deforms sufficiently to allow the therapeutic agent to leak through the membrane  622 , providing additional indication of the high pressure and delivery tube blockage. 
     Those skilled in the art will appreciate that the material and dimensions of the parts of the membrane (folds and/or pleats) can be selected as desired for a particular application. In one embodiment, the material is resilient, so that the membrane returns to the normal state after being in the alarm state. In another embodiment, the material is deformable so that the membrane remains extending from the body after the pressure is relieved and the alarm state clears. The extended membrane reminds the patient of the delivery tube blockage and the need to replace the injection device. Exemplary materials for the membrane include silicone rubber or the like. 
       FIGS. 14A &amp; 14B , in which like elements share like reference numbers, are perspective views of one embodiment of an injection device made in accordance with the invention. In this embodiment, the injection device includes a tube with an external device fitting, so that the injection device can be placed in a remote location and attached to an injection pump. 
       FIG. 14A  is a perspective view of the injection device  700  in a stored configuration, the injection device  700  including a body  710  and a patch  720  attached to the body  710 . The patch  720  is operable to adhesively attach the injection device  700  to a patient (not shown). The body  710  has a groove  702  around its outer circumference operable to receive tube  794  in the stored configuration. One end of the tube  794  is in fluid communication with an injection port (not shown) of the injection device  700  to deliver a therapeutic agent into the body of a patient. The other end of the tube  794  is in fluid communication with the external device fitting  797 , which can be extended to a convenient location when the injection device  700  is in a difficult to access location or which can be connected to an injection pump (not shown). In this example, the body  710  includes a fitting receiver  704  operable to receive and store the external device fitting  797  when the injection device  700  is in the stored configuration with the tube  794  wrapped around the body  710 .  FIG. 14B  is a perspective view of the injection device  700  in a deployed configuration, with the external device fitting  797  uncoupled from the fitting receiver  704  and the tube  794  uncoiled from the groove  702  in the body  710 . In operation, the injection device  700  can be placed on a remote location on the body of the patient, such as a remote location not normally accessible for injection by conventional means, and the tube  794  extended to allow convenient connection to an injection pump. 
       FIGS. 15-20 , in which like elements share like reference numbers, are various views of one embodiment of a body for an injection device made in accordance with the invention. The body includes cutouts to provide inspection and ventilation at the attachment point of the injection device to the patient. 
     The single piece body for an injection device can include a planar deck having a patient face, the planar deck having cutouts around and through the planar deck, the planar deck including a delivery tube port on the patient face; a port segment attached opposite the patient face of the planar deck, the port segment including an introducer port including an introducer channel and an injection port including an injection channel the introducer channel being in fluid communication with the injection channel and the delivery tube port; and attachment projections protruding from the patient face. In one embodiment, the attachment projections are operable for plastic welding. 
     The single piece body can be used with an injection device for delivering a therapeutic agent to a patient including the single piece body. The injection device further includes a delivery tube for subcutaneous delivery of the therapeutic agent to the patient, the delivery tube projecting from and being generally perpendicular to the patient face, the delivery tube being in fluid communication with the injection port; and a patch, the patch being plastically welded to the attachment projections and being operable to adhesively attach to the patient. 
       FIGS. 15 &amp; 16  are a front perspective view and a top side view, respectively, of a body  810  including a port face  812 . The port face  812  includes an introducer port  830  and an injection port  840 . The body  810  has a generally planar deck  804  with cutouts  860  spaced around and passing through the planar deck  804 . The body  810  also has a port segment  806  rising above the planar deck  804  and including the introducer port  830  and an injection port  840 . The body  810  is a single piece body, which is defined herein as a body formed as a single piece and is not a group of separate pieces assembled to form the body. 
       FIG. 17  is a left side view of the body  810 . The patient face  814  is opposite the port face  812  on the planar deck  804  and is operable to connect the body  810  to a patch (not shown) to adhesively attach the injection device to a patient. In this embodiment, the patient face  814  of the planar deck  804  includes a number of attachment projections  820  (in this example, the attachment projections  820  being bumps) protruding from the planar deck  804  to allow a patch to be plastically welded to the body  810 . Those skilled in the art will appreciate that different attachment projections, such as truncated pyramids, bumps, radial lines, concentric rings, or the like, can be selected as desired for a particular application. In yet another embodiment, the patch can be attached to the body  810  with an adhesive. 
       FIGS. 18 &amp; 19  are a bottom side view and a bottom perspective view, respectively, of the body  810 . The attachment projections  820  are arranged around the outer circumference  823  of the patient face  814 , around an inner circle  822  about a delivery tube port  825  on the introducer axis  834 , and along diameter segments  824  between the outer circumference  823  and the inner circle  822  which follow the length of the port segment. In this example, the attachment projections  820  are truncated pyramids. 
       FIG. 20  is a section view of the planar deck  804  of the body  810  along the outer circumference through the attachment projections  820 . In this example, the body  810  is plastically welded to a patch  830 , which is attached to the skin  832  of a patient. The attachment projections  820  are deformed from the truncated pyramid to a flattened, rounded shape from welding the attachment projections  820  to the patch  830  at each fixation point  836 . In this example, the tips of the attachment projections  820  are welded into the patch  830 , i.e., the tips of the attachment projections rest below the surface of the patch at the fixation points  836  where the attachment projections  820  join the patch  830 . In cross section through adjacent attachment projections  820 , the patient face  814  and the patch  830  define a ventilation gap  838  to provide ventilation and air circulation between the planar deck  804  and the patch  830 , cooling the skin  832  across the patch  830  from the ventilation gap  838 . 
     Those skilled in the art will appreciate that the design of the patch  830  can be selected as desired for a particular application. The patch can be made of any biocompatible material with biocompatible adhesive operable to hold the weight of the injection device to the skin for a predetermined number of days. The patch design also needs to account for ventilation and circulation between the patch and the skin. In one example, the patch is a continuous sheet of adhesive material. In another example, the patch is a mesh sheet of adhesive material including perforations. In yet another example, the patch is a continuous sheet of adhesive material with holes cut into the continuous sheet. The holes can align with features of the body of the injection device, such as the cutouts, as desired. The holes can optionally be the same size as the cutouts. In yet another example, the patch is a continuous sheet of adhesive material with holes cut into the continuous sheet, and mesh applied across the holes. In yet another example, the patch can be made of a transparent material to allow the condition of the skin around and below the injection device to be monitored. In one example, adhesive patches are constructed of pressure sensitive acrylic-based adhesives with non-woven polyester backings. 
     Those skilled in the art will further appreciate that the design of the body of the injection device can be selected as desired for a particular application. In one example, the number and position of the cutouts in the planar deck can be selected to provide ventilation to the skin while maintaining sufficient rigidity for the planar deck. In another example, the number and position of the cutouts can be selected to allow observation of the condition of the skin around and below the injection device. In yet another example, the body of the injection device can be made of a transparent material to allow the condition of the skin around and below the injection device to be monitored. This is particularly useful when the patch includes holes or is made from a transparent material. Exemplary materials for the body of the injection device include polycarbonate, acrylic, or the like. In one embodiment, one or more optical elements can be molded into the body of the injection device to magnify the area or areas of interest. 
       FIGS. 21-24  are various embodiments of septums for use in an injection device. The septums can be disposed in the injection device channels. In one embodiment, the septum is self sealing to block fluid flow through the septum after a needle has been put through the septum then removed, preventing fluid flow through the port connected to the channel. 
       FIG. 21  is a perspective view of one embodiment of an introducer septum for use in an injection device made in accordance with the invention. In this embodiment, the introducer septum is irregular-shaped, i.e., the introducer septum has an irregular shape. The introducer septum  900  includes a number of legs  902  to secure the introducer septum  900  in the introducer channel. 
       FIG. 22  is a section view of an injection device made in accordance with the invention including the introducer septum of  FIG. 20 . The section bisects the introducer port  930  and the injection port  940 , and includes the introducer axis  934  and injection axis  944 . The delivery tube  950  is operably connected to the introducer port  930  and defines an introducer axis  934 , the delivery tube  950  being in fluid communication with the injection port  940 . The introducer port  930  includes an introducer channel  932 , with an introducer port cover  935  and the introducer septum  900  disposed in the introducer channel  932 . The introducer septum  900  is secured in the introducer channel  932  of the injection device  901  by legs  902 . The injection port  940  includes an injection channel  942  defining an injection axis  944  with an injection septum  946  disposed in the injection channel  942 . The injection channel  942  is in fluid communication with the delivery tube  950  through a septum connection channel  904  in the introducer septum  900 . The introducer septum  900  both connects the injection port  940  to the delivery tube  950  and fills extra space within the introducer channel  932  to avoid an unnecessary amount of therapeutic agent from collecting in the introducer channel  932 . 
       FIG. 23  is a perspective view of one embodiment of a septum for use in an injection device made in accordance with the invention. In this embodiment, the septum is barrel-shaped. The barrel-shape septum  980  can be used as an introducer septum or an injection septum as desired for a particular application. 
       FIGS. 24A &amp; 24B  are top side and A-A section views, respectively, of one embodiment of a septum for use in an injection device made in accordance with the invention. In this embodiment, the septum is dome-shaped. The dome septum  990  can be used as an introducer septum or an injection septum as desired for a particular application. 
       FIGS. 25-30  illustrate an on-body injector for use with an injection device made in accordance with the invention. Referring to  FIG. 5B , an on-body injector  192  is mateable with the injection port  140  of the injection device  100  and can be used to deliver a therapeutic agent through the injection port  140 . The on-body injector  192  can include a reservoir to hold the therapeutic agent. In one embodiment, the on-body injector  192  can deliver a basal and/or bolus dose of the therapeutic agent. 
       FIG. 25  is a perspective view of one embodiment of an on-body injector for use with an injection device made in accordance with the invention. The on-body injector  192  includes a housing  1010  to contain the internal components of the on-body injector, a lock  1020  to secure the on-body injector  192  to the injection device, and a fill port  1050  for filling or refilling the on-body injector  192  with a therapeutic agent for bolus and/or basal injection. 
     The on-body injector  192  also includes a button  1030  which can be used to administer a bolus injection. A gap in the bolus injection flow path prevents bolus injection unless the button  1030  is depressed. The button  1030  is operably connected to the bolus injection needle  1040  to slide the bolus injection needle  1040  along the injection axis. When the button  1030  is depressed, the button  1030  advances the bolus injection needle tip to close a gap between the bolus injection needle tip and the injection port of the injection device and to form an injection flow path to deliver a bolus injection to the patient. The button  1030  also advances a plunger through the bolus reservoir to deliver a predetermined bolus volume to the patient through the injection flow path once the gap is closed and the injection flow path is complete. Those skilled in the art will appreciate that the button  1030  as defined herein can be any mechanism or combination of mechanisms operable to advance the bolus injection needle through the gap and deliver the bolus injection. In one example, the button slides in a track or similar guiding geometry. In another example, the button is a lever that moves the bolus injection needle and plunger. Those skilled in the art will appreciate that the button can be activated by secondary devices, such as solenoids, motors, pneumatic activators, or the like. 
       FIG. 26 , in which like elements share like reference numbers with  FIG. 25 , is a partial perspective view of portions of one embodiment of an on-body injector for use with an injection device made in accordance with the invention. In  FIG. 26 , the top portion of the housing  1010  has been removed to reveal the interior components. In this embodiment, basal injection is provided by a pressurized reservoir  1070 , which is at least partially filled with a therapeutic agent. The pressurized reservoir  1070  in this example is a spring coil that at least partially uncoils within an interior track  1080  within the housing  1010  when the pressurized reservoir  1070  is pressurized, i.e., when the pressurized reservoir is at least partially filled with a therapeutic agent. The pressurized reservoir  1070  can be filled through the fill port  1050 . For basal injection, the therapeutic agent is delivered through the introducer port of the injection device, which is in fluid communication with the delivery tube of the injection device. The therapeutic agent passes from the pressurized reservoir  1070 , through the flow restrictor  1060 , and into the patient through the injection device. The flow restrictor  1060  in this example is tubing having a length and interior diameter selected to provide a desired pressure drop, supported by tubing support structure  1062 . Those skilled in the art will appreciate that the flow restrictor can be any device providing a pressure drop between the pressurized reservoir and the delivery tube as desired for a particular application. In another example, the flow restrictor can be an orifice. In another example, the flow restrictor can be a bypass channel that re-directs access to medication. In one embodiment, the flow restrictor can be selected to provide a predetermined basal flow rate, such as a basal flow rate of 20 units of insulin per 24 hours, 30 units of insulin per 24 hours, or 40 units of insulin per 24 hours. Those skilled in the art will further appreciate that the pressurized reservoir can be any device pressurizing the therapeutic agent as desired for a particular application. In other examples, the pressurized reservoir can be an elastic bladder, a spring-loaded inelastic bladder, a fluid (gas or liquid) pressurized bladder, or the like. 
       FIG. 27 , in which like elements share like reference numbers with  FIGS. 25 &amp; 26 , is a partial perspective view of portions of one embodiment of an on-body injector for use with an injection device made in accordance with the invention. A button spring  1090  provides a bias force to the button  1030 , to bias the bolus injection needle  1040  away from the injection port of the injection device and provide the gap between the bolus injection needle tip and the injection port when the button is not depressed. 
       FIG. 28 , in which like elements share like reference numbers with  FIGS. 25-27 , is a section view of one embodiment of an injection device and on-body injector for use with an injection device made in accordance with the invention.  FIG. 28  illustrates the cross-section of the on-body injector  192  and the injection device  100  divided along the bolus injection needle  1040 . 
     The bolus injection needle tip  1042  is aligned with the injection septum  146  of the injection port  140  along the injection axis  144 . The button spring  1090  biases the bolus injection needle tip  1042  away from the injection septum  146  to create a gap  1120  between the bolus injection needle tip  1042  and the injection port  140  when the button  1030  is not depressed. When the button  1030  is depressed, the bolus injection needle  1040  slides along the injection axis  144 , closing the gap  1120  and inserting the bolus injection needle tip  1042  through the injection septum  146 . In this example, the bolus injection needle tip  1042  also passes through a needle tip septum  1122 . Once the bolus injection needle tip  1042  has passed through the injection septum  146 , and injection flow path for bolus injection is formed from the bolus reservoir  1100 , through the bolus injection needle  1040 , through the delivery tube  150 , and into the patient. When the button  1030  is released, the bolus injection needle  1040  slides back to the initial position and the gap  1120  is restored. The bolus injection needle tip  1042  is always embedded within a septum (the needle tip septum  1122  or the injection septum  146 ) to keep the bolus injection needle tip  1042  clean, and to keep the bolus injection needle tip  1042  capped so no therapeutic agent will leak out of the bolus injection needle tip  1042 . 
     The on-body injector  192  includes a bolus reservoir  1100  with a plunger  1110  slideably disposed within the bolus reservoir  1100  and a bolus stop  1114  fixed at one end of the bolus reservoir  1100 . A bolus spring  1112  biases the plunger  1110  away from the bolus stop  1114 . The plunger  1110  is coupled to the button  1030  so that the plunger  1110  slides through the bolus reservoir  1100  when the button  1030  is depressed. The plunger  1110  includes a central passage  1116  to allow fluid from the bolus reservoir  1100  to flow through the plunger  1110  into the bolus injection needle  1040  and to the patient through the bolus injection needle  1040 . The volume of the bolus reservoir  1100  can be selected to provide a predetermined bolus volume to the patient. In one embodiment, the predetermined bolus volume is 2 units of insulin. 
     When the plunger  1110  reaches a final position at the end of the bolus reservoir  1100  and contacts the bolus stop  1114 , the bolus stop  1114  blocks the central passage  1116  in the plunger  1110 . Thus, the plunger  1110  blocks the injection flow path after the predetermined bolus volume has been delivered. This prevents additional undesired delivery of a therapeutic agent should the injection flow path remains in place from a failure, such as the bolus injection needle  1040  becoming stuck in the injection port  140  of the injection device  100 , a failure of the button  1030  or related mechanism, or the like. 
       FIG. 29  is a block diagram of one embodiment of an injection device and on-body injector made in accordance with the invention.  FIG. 29  illustrates the flow paths through the injection device and on-body injector, which can be used for a bolus injection and/or a basal injection. 
     Both the bolus injection and basal injection flow paths include an optional syringe  1302 , an optional fill port  1304 , a pressure reservoir  1306 , a delivery tube  1320 , supplying the patient  1322 . The basal injection flow path also includes a flow restrictor  1308  and an introducer port  1310  between the pressure reservoir  1306  and the delivery tube  1320 . The bolus injection flow path also includes a bolus reservoir  1312 , a bolus injection needle  1314 , a gap  1316 , an injection port  1318  between the pressure reservoir  1306  and the delivery tube  1320 . 
     The optional syringe  1302  can be inserted in the optional fill port  1304  to fill or refill the pressure reservoir  1306 . As illustrated by the dashed line between the optional syringe  1302  and the optional fill port  1304 , the optional syringe  1302  is not permanently attached to the optional fill port  1304  and can be removed. In one embodiment, the pressure reservoir  1306  can be pre-filled with a therapeutic agent when the on-body injector is delivered to the patient, so that the fill port  1304  is used for refilling the pressure reservoir  1306 . In another embodiment, the pressure reservoir  1306  is empty when the on-body injector is delivered to the patient, so that the fill port  1304  is used for initially filling the pressure reservoir  1306 . In yet another embodiment, the optional fill port  1304  is omitted and the on-body injector is a single use device with the pressure reservoir  1306  pre-filled with a therapeutic agent. Those skilled in the art will appreciate that the optional syringe  1302  can be any device operable to deliver a therapeutic agent into the fill port  1304  as desired for a particular application. 
     For basal injection, the pressure reservoir  1306  of the on-body injector provides the therapeutic agent through the flow restrictor  1308  of the on-body injector to the introducer port  1310  of the injection device. The delivery tube  1320  of the injection device applies the therapeutic agent to the patient  1322 . The flow restrictor  1308  can be any device providing a pressure drop between the pressurized reservoir and the delivery tube as desired for a particular application. In one example, the flow restrictor can be tubing having a length and interior diameter selected to provide a desired pressure drop. In another example, the flow restrictor can be an orifice. In another example, the flow restrictor can be a bypass channel that re-directs access to medication. In one embodiment, the flow restrictor can be selected to provide a predetermined basal flow rate, such as a basal flow rate of 20 units of insulin per 24 hours, 30 units of insulin per 24 hours, or 40 units of insulin per 24 hours. 
     For bolus injection, the pressure reservoir  1306  of the on-body injector fills the bolus reservoir  1312  of the on-body injector with therapeutic agent. The on-body injector delivers a predetermined bolus volume (the volume of the pressure reservoir  1306 ) when the patient depresses a button. When the button is depressed, the tip of the bolus injection needle  1314  closes the gap  1316  between the bolus injection needle  1314  of the on-body injector and enters the injection port  1318  of the injection device to complete the bolus injection flow path. The gap  1316  as illustrated by the dashed lines between the bolus injection needle  1314  of the on-body injector and the injection port  1318  of the injection device is present when the button is not depressed to prevent bolus injection unless the button is depressed. Depressing the button also delivers the therapeutic agent from the bolus reservoir  1312 , through the bolus injection needle  1314 , through the injection port  1318 , through the delivery tube  1320 , and into the patient  1322 . In one embodiment, the predetermined bolus volume is 2 units of insulin. The bolus injection flow path can optionally include a flow blocker (such as the bolus stop  1114  of  FIG. 28 , for example) which blocks the bolus injection flow path after the predetermined bolus volume has been delivered. 
     Referring to  FIG. 29 , for one embodiment of an on-body injector for a bolus injection, the injection device has an injection port  1318  in fluid communication with a delivery tube  1320  with the injection port  1318  lying on an injection axis. The on-body injector includes a bolus reservoir  1312 ; a bolus injection needle  1314  in fluid communication with the bolus reservoir  1312 , the bolus injection needle  1314  having a bolus injection needle tip aligned with the injection port  1318 , the bolus injection needle  1314  being slideably biased away from the injection port to define a gap  1316  between the bolus injection needle tip and the injection port  1318 ; and a button operably connected to the bolus injection needle  1314  to slide the bolus injection needle  1314  along the injection axis. The button is operable to advance the bolus injection needle tip to close the gap  1316  and advance the bolus injection needle tip into the injection port  1318  to form an injection flow path from the bolus reservoir  1312 , through the bolus injection needle  1314 , through the delivery tube  1320 , and into the patient  1322 . The button is further operable to advance a plunger through the bolus reservoir  1312  to deliver a predetermined bolus volume to the patient  1322  through the injection flow path. 
     For one embodiment of an on-body injector for a basal injection, the injection device has an introducer port  1310  in fluid communication with a delivery tube  1320 . The on-body injector includes a pressurized reservoir  1306 ; a flow restrictor  1308  disposed between the pressurized reservoir  1306  and the delivery tube  1320 , the flow restrictor  1308  being tubing having a length and interior diameter selected to provide a desired pressure drop; and a fill port  1304  in fluid communication with the pressurized reservoir. 
       FIG. 30  is a flow chart of a method of use for an on-body injector in accordance with the invention. The method  1400  is a method of use for an on-body injector with an injection device for delivering a predetermined bolus volume to a patient. The method  1400  includes deploying the injection device  1410  in the patient, the injection device having a delivery tube placed in the patient and an injection port in fluid communication with the delivery tube; securing the on-body injector to the injection device  1420 , the on-body injector having a bolus injection needle aligned with and spaced apart from the injection port; depressing a button on the on-body injector to advance the bolus injection needle  1430  into the injection port; and further depressing the button to deliver the predetermined bolus volume  1440  from the on-body injector through the bolus injection needle, through the delivery tube, and into the patient. The method  1400  can further include releasing the button to retract the bolus injection needle from the injection port. 
     The method  1400  can also include delivering a basal injection. In this embodiment, the injection device further includes an introducer port in fluid communication with the delivery tube, and the on-body injector further includes a pressurized reservoir in fluid communication with a basal injection needle inserted in the introducer port. The method  1400  further includes delivering a basal injection from the pressurized reservoir through the basal injection needle, through the delivery tube, and into the patient. the on-body injector can further include a fill port in fluid communication with the pressurized reservoir, in which case the method  1400  can further include delivering a therapeutic agent thorough the fill port into the pressurized reservoir. 
       FIGS. 31-38  illustrate an electronic injector for use with an injection device or for independent use. The electronic injector uses a Micro-Electro-Mechanical System (MEMS) pump to deliver a therapeutic agent from a reservoir to a patient. 
       FIG. 31  is a block diagram of one embodiment of an injection device and electronic on-body injector made in accordance with the invention.  FIG. 31  illustrates the flow paths through and electrical signals for the injection device and electronic on-body injector, which can be used for a bolus injection and/or a basal injection. The injection device is deployed in the patient with a delivery tube placed subcutaneously and the electronic on-body injector is secured to the injection device. 
     The basal injection flow path includes a fluid reservoir  1602 , a MEMS pump  1604 , and a delivery tube  1606  supplying the patient  1608 . The bolus injection flow path includes the fluid reservoir  1602 , the MEMS pump  1604 , a bolus injection needle  1610 , a gap  1612 , an injection port  1614 , and the delivery tube  1606  supplying the patient  1608 . The bolus injection mechanism also includes a bolus needle button  1616  operable to advance the bolus injection needle  1610  and to activate the MEMS pump  1604  to deliver a predetermined bolus volume. 
     The electronic portion of the electronic on-body injector includes a battery  1620 , a regulator  1622 , and a microcontroller  1624 . The battery  1620  has a DC power output  1621  which is provided to the regulator  1622 . The battery  1620  is also operably connected (not shown) to provide power to the microcontroller  1624 . The regulator  1622  is operably connected to the battery  1620  to convert the DC power output  1621  to a pump drive signal  1623  in response to a regulator control signal  1625  from the microcontroller  1624 . The regulator  1622  provides the pump drive signal  1623  to the MEMS pump  1604 . The pump drive signal  1623  can be a basal pump drive signal or a bolus pump drive signal as required. The MEMS pump  1604  is responsive to the pump drive signal  1623  to control flow of the fluid from the fluid reservoir  1602 , through the MEMS pump  1604 , through the delivery tube  1606 , and into the patient  1608 . 
     The microcontroller  1624  controls the electronic on-body injector. The microcontroller  1624  receives a bolus needle button signal  1617  from the bolus needle button  1616 , which activates MEMS pump  1604  to deliver a predetermined bolus volume to the patient through the bolus injection flow path. The microcontroller  1624  provides the regulator control signal  1625  to the regulator  1622 , controlling the pump drive signal  1623 . The microcontroller  1624  can also optionally be responsive to a control switch signal  1627  from a control switch  1626  and/or can provide a display signal  1629  to a display  1628 . The control switch  1626  and the display  1628  can be used to provide input and output, respectively, to the electronic on-body injector. For example, the display  1628  can be used to display injection options, such as the basal injection rate, and control switch  1626  can be used to select one of the injection options. The microcontroller  1624  can also include or be associated with memory to store data and/or instructions. The microcontroller  1624  can also be operably connected to one or more sensors to monitor the patient  1608  and/or a wireless interface to communicate with one or more external sensors monitoring the patient  1608  or external communication and/or control systems, such as the internet, a continuous glucose monitoring system, a mobile device, or the like. Exemplary uses for a wireless interface providing communication between the electronic injector and an external system/device include calculating/setting dosages, tracking injection times and volumes, and/or sending reminders to a paired device (computer, phone, tablet, mobile device, or the like). 
     For basal injection, the fluid reservoir  1602  of the on-body injector provides the therapeutic agent to the patient  1608  through the basal injection flow path (the fluid reservoir  1602 , MEMS pump  1604 , and delivery tube  1606 ). In one embodiment, the patient  1608  initiates the basal injection by pressing the control switch  1626 , which provides the control switch signal  1627  to the microcontroller  1624 , which provides the regulator control signal  1625  to the regulator  1622 . In this case, the regulator control signal  1625  is a basal regulator control signal and the regulator  1622  generates the pump drive signal  1623  as a basal pump drive signal. The MEMS pump  1604  delivers the desired basal injection to the patient  1608  in response to the basal pump drive signal. In another embodiment, the patient  1608  selects a desired basal flow rate using the control switch  1626  and the display  1628  before initiating the basal injection. Exemplary basal flow rates can include 20 units of insulin per 24 hours, 30 units of insulin per 24 hours, 40 units of insulin per 24 hours, or the like. 
     For bolus injection, the fluid reservoir  1602  of the on-body injector provides the therapeutic agent to the patient  1608  through the bolus injection flow path (the fluid reservoir  1602 , MEMS pump  1604 , bolus injection needle  1610 , gap  1612 , injection port  1614 , and delivery tube  1606 ). The on-body injector delivers a predetermined bolus volume when the patient depresses the bolus needle button  1616  by activating the MEMS pump  1604  at a predetermined flow rate for a predetermined duration. When the bolus needle button  1616  is depressed, the tip of the bolus injection needle  1610  closes the gap  1612  between the bolus injection needle  1610  of the on-body injector and enters the injection port  1614  of the injection device to complete the bolus injection flow path. The gap  1612  as illustrated by the dashed lines between the bolus injection needle  1610  of the on-body injector and the injection port  1614  of the injection device is present when the bolus needle button  1616  is not depressed to prevent bolus injection unless the bolus needle button  1616  is depressed. Depressing the bolus needle button  1616  also delivers the bolus needle button signal  1617  to the microcontroller  1624 , which provides the regulator control signal  1625  to the regulator  1622 . In this case, the regulator control signal  1625  is a bolus regulator control signal and the regulator  1622  generates the pump drive signal  1623  as a bolus pump drive signal. The MEMS pump  1604  delivers the predetermined bolus volume to the patient  1608  in response to the bolus pump drive signal. In one embodiment, the bolus needle button  1616  triggers a switch in the path of button mechanism travel which starts the bolus injection when the bolus injection flow path is complete. In one example, the predetermined bolus volume is 2 units of insulin. In another embodiment, the patient  1608  selects a desired predetermined bolus volume using the control switch  1626  and the display  1628  before initiating the bolus injection. In this example, the basal and bolus drugs are the same drug, coming from the same fluid reservoir  1602  and going through the same flow path, but administered at different rates. The basal injection flows constantly at a very low rate. When a bolus injection is requested, the regulator  1622  changes the pump drive signal  1623  from the basal pump drive signal to a bolus delivery signal. When the bolus delivery is complete, the regulator  1622  changes the pump drive signal  1623  from the bolus pump drive signal to the basal delivery signal and basal injection resumes. In other embodiments, the basal injection flow path can include an orifice, check valve, or be sized so that the fluid does not flow forward or backward through the basal injection flow path during bolus injection. 
     The electronic on-body injector can optionally include a fill port (not shown) to fill or refill the fluid reservoir  1602 . In one embodiment, the fluid reservoir  1602  can be pre-filled with a therapeutic agent when the on-body injector is delivered to the patient, so that the fill port is used for refilling the fluid reservoir  1602 . In another embodiment, the fluid reservoir  1602  is empty when the electronic on-body injector is delivered to the patient, so that the fill port is used for initially filling the fluid reservoir  1602 . In yet another embodiment, the fill port is omitted and the electronic on-body injector is a single use device with the fluid reservoir  1602  pre-filled with a therapeutic agent. 
     For one embodiment of an electronic on-body injector for a bolus injection for use with a patient  1608  to deliver a fluid through an injection device, the injection device has an injection port  1614  in fluid communication with a delivery tube  1606  with the injection port  1614  lying on an injection axis. The electronic on-body injector includes a fluid reservoir  1602  operable to hold the fluid; a MEMS pump  1604  in fluid communication with the fluid reservoir  1602 ; a bolus injection needle  1610  in fluid communication with the MEMS pump  1604 , the bolus injection needle  1610  having a bolus injection needle tip aligned with the injection port, the bolus injection needle  1610  being slideably biased away from the injection port to define a gap  1612  between the bolus injection needle tip and the injection port; and a bolus needle button  1616  operably connected to the bolus injection needle  1610  to slide the bolus injection needle  1610  along the injection axis. the bolus needle button  1616  is operable to advance the bolus injection needle tip to close the gap  1612  and advance the bolus injection needle tip into the injection port to form a bolus injection flow path from the fluid reservoir  1602 , through the MEMS pump  1604 , through the bolus injection needle  1610 , through the delivery tube  1606 , and into the patient  1608 . The bolus needle button  1616  is further operable to activate the MEMS pump  1604  to deliver a predetermined bolus volume to the patient  1608  through the bolus injection flow path in response to a bolus pump drive signal. 
     The electronic on-body injector for bolus injection can also include a battery  1620  having a DC power output  1621 ; a regulator  1622  operably connected to the battery  1620  to convert the DC power output  1621  to the bolus pump drive signal in response to a regulator control signal  1625 ; and a microcontroller  1624  operably connected to the regulator  1622  to provide the regulator control signal  1625 . The MEMS pump  1604  is responsive to the bolus pump drive signal to control flow of the fluid from the MEMS pump  1604  through the bolus injection flow path. 
     For one embodiment of an electronic on-body injector for a basal injection for use with a patient  1608  to deliver a fluid through an injection device, the injection device has a delivery tube  1606 . The electronic on-body injector includes a fluid reservoir  1602  operable to hold the fluid; and a MEMS pump  1604  in fluid communication with the fluid reservoir  1602  and the delivery tube  1606  to form a basal injection flow path from the fluid reservoir  1602 , through the MEMS pump  1604 , through the delivery tube  1606 , and into the patient  1608 . The MEMS pump  1604  is operable to deliver a basal injection to the patient  1608  through the basal injection flow path in response to a basal pump drive signal. 
     The electronic on-body injector for basal injection can also include a battery  1620  having a DC power output  1621 ; a regulator  1622  operably connected to the battery  1620  to convert the DC power output  1621  to the basal pump drive signal in response to a regulator control signal  1625 ; and a microcontroller  1624  operably connected to the regulator  1622  to provide the regulator control signal  1625 . The MEMS pump  1604  is responsive to the basal pump drive signal to control flow of the fluid from the MEMS pump  1604  through the basal injection flow path. Exemplary batteries  1620  include non-rechargeable alkaline batteries rechargeable lithium-ion batteries, rechargeable lithium ion polymer batteries, and the like. In one example, the battery capacity is in the range of 200-500 mAh, In one example, the battery dimensions are 15×40×5 mm. Those skilled in the art will appreciate that the battery type, capacity, and size can be selected as desired for a particular application. Exemplary microcontrollers  1624  include the CC2541 (Bluetooth/microprocessor combination) from Texas Instruments, PSoC®4 (microcontroller) from Cypress Semiconductor Corporation, or the like. Those skilled in the art will appreciate that the microcontrollers can be selected as desired for a particular application. 
       FIGS. 32A-32C  are wave form diagrams of bolus, basal, and basal pump drive signals, respectively, for an electronic injector made in accordance with the invention. The frequency, amplitude, and duration of the AC portion of the pump drive signal determine the amount of fluid which is injected. 
     The bolus pump drive signal is selected to provide a predetermined bolus volume from the MEMS pump in response to a single bolus injection request from a patient. Referring to the example of  FIG. 32A , the bolus pump drive signal  1700  includes an AC power signal  1710  for a predetermined duration  1720  between time T1 when the patient requests a bolus injection until the time T2 when the predetermined bolus volume has been delivered. The bolus pump drive signal  1700  has a value of 0 V DC before and after the AC power signal  1710 . The MEMS pump moves the fluid when the AC power signal  1710  is active. In this example, the AC power signal  1710  is a sine wave. Those skilled in the art will appreciate that the pump drive signal can have any AC waveform as desired for a particular application. For example, the AC waveform can be a sine wave, a saw tooth wave, a square wave, or the like. 
     The basal pump drive signal is selected to provide a desired basal flow rate from the MEMS pump. Referring to the example of  FIG. 32B , the basal pump drive signal  1730  includes a series of AC power signals  1740  of AC power duration  1742  alternating with zero volt power signals  1750  of zero volt power duration  1752 . The time of AC power duration  1742  and/or 0 V power duration  1752  can be selected to provide the desired basal flow rate. The MEMS pump moves the fluid when each of the AC power signals  1740  is active. In this example, the AC power signal  1740  is a sine wave. Those skilled in the art will appreciate that the pump drive signal can have any AC waveform as desired for a particular application. For example, the AC waveform can be a sine wave, a saw tooth wave, a square wave, or the like. 
       FIG. 32C  is an example of a continuous basal pump drive signal, which provides a continuous AC waveform. The basal pump drive signal  1760  has a frequency and/or amplitude which is substantially less than the AC power signal of  FIG. 32A  or  FIG. 32B , so that the basal pump drive signal  1760  is continuously applied to the MEMS pump to provide a desired basal flow rate from the MEMS pump. In this example of  FIG. 32C , the basal pump drive signal  1760  is a sine wave. Those skilled in the art will appreciate that the basal pump drive signal can have any AC waveform as desired for a particular application. For example, the basal pump drive signal can be a sine wave, a saw tooth wave, a square wave, or the like. 
       FIGS. 33A-33C , in which like elements share like reference numbers, are schematic diagrams of a piezoelectric MEMS pump for use in an electronic injector made in accordance with the invention.  FIG. 33A  illustrates the MEMS pump at rest,  FIG. 33B  illustrates the MEMS pump during fluid intake, and  FIG. 33C  illustrates the MEMS pump during fluid output. 
     Referring to  FIG. 33A  illustrating the MEMS pump at rest, the piezoelectric MEMS pump  1800  includes a case  1810  defining a working chamber  1820 , the working chamber  1820  having a piezoelectric wall  1830  responsive to a first pump drive signal voltage and a second pump drive signal voltage; a one way inlet valve  1840  operable to permit flow of the fluid into the working chamber  1820  and to block reverse flow of the fluid from the working chamber  1820 ; and a one way outlet valve  1850  operable to permit flow of the fluid from the working chamber  1820  and to block reverse flow of the fluid into the working chamber  1820 . The one way inlet valve  1840  is in fluid communication with the fluid reservoir (not shown). When the piezoelectric MEMS pump  1800  is used for bolus injection, the one way outlet valve  1850  is in fluid communication with the bolus injection needle (not shown). When the piezoelectric MEMS pump  1800  is used for basal injection, the one way outlet valve  1850  is in fluid communication with the delivery tube (not shown). In one embodiment, the piezoelectric wall  1830  includes a piezoelectric disk  1832  with a membrane  1834  sealing the working chamber  1820 . The working chamber  1820  can be etched directly out of the silicon base material. The flexible membrane  1834  can be a thin layer of silicon or silicon dioxide. The piezoelectric disk  1832  can be attached to the flexible membrane  1834 . 
     Referring to  FIG. 33B  illustrating the MEMS pump during fluid intake, the piezoelectric wall  1830  flexes outward to increase volume of the working chamber  1820  in response to the first pump drive signal voltage (+V to ground across the piezoelectric wall  1830 ) to draw the fluid through the one way inlet valve to the working chamber  1820  as indicated by the arrow  1842 . 
     Referring to  FIG. 33C  illustrating the MEMS pump during fluid output, the piezoelectric wall  1830  flexes inward to decrease the volume of the working chamber  1820  in response to the second pump drive signal voltage (−V to ground across the piezoelectric wall  1830 ) to force the fluid from the working chamber  1820  through the one way outlet valve  1850  as indicated by the arrow  1852 . 
     Alternately applying the first pump drive signal voltage and the second pump drive signal voltage causes the piezoelectric wall  1830  to oscillate, pumping fluid through the piezoelectric MEMS pump  1800 . In one embodiment, the first pump drive signal voltage and the second pump drive signal voltage are applied as a pump drive signal as a square wave. The piezoelectric MEMS pump  1800  can be fabricated using standard semiconductor techniques, resulting in a pump of reduced size and improved accuracy compared to standard mechanical pumps. In one example, the piezoelectric MEMS pump  1800  can deliver flow rates up to 3 milliliters per minute, which is the equivalent of 300 units of insulin per minute or 5 units of insulin per second. Those skilled in the art will appreciate that the MEMS pump is not limited to a piezoelectric MEMS pump, but can be a bimetallic pump, an electrostatic pump, a thermopneumatic pump, an electromagnetic pump, a phase change pump, or the like, as desired for a particular application. 
       FIGS. 34A-34C , in which like elements share like reference numbers, are an exploded perspective view, a partial perspective view, and a partial perspective view of an injection device and electronic on-body injector made in accordance with the invention. In this embodiment, the electronic on-body injector is the electronic injector. 
     Referring to  FIG. 34A , the electronic on-body injector  1900  is illustrated separated from the injection device  1910 . The electronic on-body injector  1900  has a housing  1902  to contain the internal components of the electronic on-body injector  1900 . The injection device  1910  has an injection port  1912  lying on an injection axis  1914  as illustrated by the dashed line. The injection device  1910  in this example also has an introducer port  1916 . 
     Referring to  FIG. 34B , which illustrates the electronic on-body injector  1900  with the top of the housing  1902  removed, the interior of the housing  1902  of the electronic on-body injector  1900  encloses the battery  1920 , the regulator  1922 , the microcontroller  1924 , the fluid reservoir  1926 , and the MEMS pump  1928 . The bolus injection needle  1930  is partially enclosed within the housing  1902  with the bolus injection needle tip  1932  extending from the housing  1902  to access the injection device. Various controls and indicators (not shown), such as the bolus needle button, control switches, displays, and the like, can extend through and/or be positioned upon the housing  1902 .  FIG. 34C  illustrates the electronic on-body injector  1900  in place on the injection device  1910 . The bolus injection needle (not shown) is aligned with the injection axis  1914  of the injection device  1910 . 
       FIG. 35  is a block diagram of one embodiment of an electronic injector made in accordance with the invention.  FIG. 35  illustrates the flow paths through and electrical signals for the electronic injector, which can be used for injection of a therapeutic agent. 
     The basal injection flow path includes a fluid reservoir  2002 , a MEMS pump  2004 , a needle fitting  2006 , and an injection needle  2007  supplying the patient  2008 . In one embodiment, the injection needle  2007  is detachable from the needle fitting  2006  so that the injection needle  2007  can be replaced at a desired frequency, e.g., after each injection. In another embodiment, the injection needle  2007  is permanently attached to the needle fitting  2006 . In yet another embodiment, no injection needle is used, but the tip of the electronic injector is adapted for use as a needleless pen injector as described in conjunction with  FIGS. 11 &amp; 12  above. 
     Referring to  FIG. 35 , the electronic portion of the electronic injector includes a battery  2020 , a regulator  2022 , and a microcontroller  2024 . The battery  2020  has a DC power output  2021  which is provided to the regulator  2022 . The battery  2020  is also operably connected (not shown) to provide power to the microcontroller  2024 . The regulator  2022  is operably connected to the battery  2020  to convert the DC power output  2021  to a pump drive signal  2023  in response to a regulator control signal  2025  from the microcontroller  2024 . The regulator  2022  provides the pump drive signal  2023  to the MEMS pump  2004 . The MEMS pump  2004  is responsive to the pump drive signal  2023  to control flow of the fluid from the fluid reservoir  2002 , through the MEMS pump  2004 , through the needle fitting  2006 , through the needle  2007 , and into the patient  2008 . In one embodiment, the MEMS pump  2004  is a piezoelectric MEMS pump as described in conjunction with  FIGS. 33A-33C  above. In other embodiments, the MEMS pump  2004  can be a bimetallic pump, an electrostatic pump, a thermopneumatic pump, an electromagnetic pump, a phase change pump, or the like, as desired for a particular application. 
     Referring to  FIG. 35 , the microcontroller  2024  controls the electronic injector. The microcontroller  2024  provides the regulator control signal  2025  to the regulator  2022 , controlling the pump drive signal  2023 . The microcontroller  2024  can be responsive to a control switch signal  2027  from a control switch  2026  and/or can provide a display signal  2029  to a display  2028 . The control switch  2026  and the display  2028  can be used to provide input and output, respectively, to the electronic injector. For example, the display  2028  can be used to display injection options, such as the bolus injection volume, and control switch  2026  can be used to select one of the injection options. The microcontroller  2024  can also include or be associated with memory to store data and/or instructions. The microcontroller  2024  can also be operably connected to one or more sensors to monitor the patient  2008  and/or a wireless interface to communicate with one or more external sensors monitoring the patient  2008  or external communication and/or control systems, such as the internet, a continuous glucose monitoring system, a mobile device, or the like. Exemplary uses for a wireless interface providing communication between the electronic injector and an external system/device include calculating/setting dosages, tracking injection times and volumes, and/or sending reminders to a paired device (computer, phone, tablet, mobile device, or the like). 
     For bolus injection, the fluid reservoir  2002  of the on-body injector provides the therapeutic agent to the patient  2008  through the injection flow path (the fluid reservoir  2002 , MEMS pump  2004 , needle fitting  2006 , and injection needle  2007 ). In one embodiment, the patient  2008  initiates a bolus injection by pressing the control switch  2026 , which provides the control switch signal  2027  to the microcontroller  2024 , which provides the regulator control signal  2025  to the regulator  2022 . In this case, the regulator control signal  2025  is a bolus regulator control signal and the regulator  2022  generates the pump drive signal  2023  as a bolus pump drive signal. The MEMS pump  2004  delivers the desired bolus injection to the patient  2008  in response to the bolus pump drive signal. In another embodiment, the patient  2008  selects a predetermined bolus volume using the control switch  2026  and the display  2028  before initiating the bolus injection. In one example, the predetermined bolus volume is 2 units of insulin. 
     The electronic injector can optionally include a fill port (not shown) to fill or refill the fluid reservoir  2002 . In one embodiment, the fluid reservoir  2002  can be pre-filled with a therapeutic agent when the on-body injector is delivered to the patient, so that the fill port is used for refilling the fluid reservoir  2002 . In another embodiment, the fluid reservoir  2002  is empty when the electronic injector is delivered to the patient, so that the fill port is used for initially filling the fluid reservoir  2002 . In yet another embodiment, the fill port is omitted and the electronic injector is a single use device with the fluid reservoir  2002  pre-filled with a therapeutic agent. 
     For one embodiment of an electronic injector for use with a patient  2008  to deliver a fluid, the electronic injector includes a fluid reservoir  2002  operable to hold the fluid; a MEMS pump  2004  in fluid communication with the fluid reservoir  2002 ; a needle fitting  2006  adapted to receive an injection needle, the needle fitting  2006  being in fluid communication with the MEMS pump  2004 ; a battery  2020  having a DC power output  2021 ; a regulator  2022  operably connected to the battery  2020  to convert the DC power output  2021  to a pump drive signal  2023  in response to a regulator control signal  2025 ; a microcontroller  2024  operably connected to the regulator  2022  to provide the regulator control signal  2025 ; and a housing to enclose the battery  2020 , the regulator  2022 , the microcontroller  2024 , the fluid reservoir  2002 , and the MEMS pump  2004 . The MEMS pump  2004  is responsive to the pump drive signal  2023  to control flow of the fluid from the fluid reservoir  2002 , through the MEMS pump  2004 , through the injection needle  2007 , and into the patient  2008 . 
       FIGS. 36A-36D , in which like elements share like reference numbers, are a perspective view, a top view, a side view, and a partial perspective view of an electronic injector made in accordance with the invention. In this example, the electronic injector has a pen form factor, which in this example has a length less than or equal to 125 mm, a width less than or equal to 20 mm, and a height less than or equal to 9 mm. 
     Referring to  FIGS. 36A-36C , the electronic injector  2100  has a housing  2102  to contain the internal components of the electronic injector  2100 . The injection needle  2130  is attached to the electronic injector  2100  at the needle fitting  2132 . In this example, the electronic injector  2100  also includes a cap  2104  removeable from the housing  2102 . In one embodiment, the housing  2102  can include a control switch (not shown) which can be used to initiate an injection. 
     Referring to  FIG. 36D , which illustrates the electronic injector  2100  with a portion of the housing  2102  removed, the interior of the housing  2102  of the electronic injector  2100  encloses the battery  2120 , the regulator  2122 , the microcontroller  2124 , the fluid reservoir  2126 , and the MEMS pump  2128 . Various controls and indicators (not shown), such as control switches, displays, and the like, can extend through and/or be positioned upon the housing  2102 . 
       FIGS. 37A-37E , in which like elements share like reference numbers, are a perspective view, a top view, a side view, an exploded perspective view, and a partial top view of an electronic injector made in accordance with the invention. In this example, the electronic injector has a card form factor, which in this example has a length less than or equal to 85 mm, a width less than or equal to 55 mm, and a height less than or equal to 8 mm. 
     Referring to  FIGS. 37A-37C , the electronic injector  2200  has a housing  2202  to contain the internal components of the electronic injector  2200 . The injection needle  2230  can be attached to the electronic injector  2200  at the needle fitting  2232 . 
     Referring to  FIGS. 37D &amp; 37E , which illustrate the electronic injector  2200  with a top portion of the housing  2202  removed, the interior of the housing  2202  of the electronic injector  2200  encloses the battery  2220 , the regulator  2222 , the microcontroller  2224 , the fluid reservoir  2226 , and the MEMS pump  2228 . Various controls and indicators (not shown), such as control switches, displays, and the like, can extend through and/or be positioned upon the housing  2202 . 
       FIG. 38  is a schematic cross section view of an electronic injector made in accordance with the invention. The electronic injector includes an adhesive patch operable to secure the housing to the patient. 
     The electronic injector  2300  has a housing  2302  to contain the internal components of the electronic injector  2300 . The injection needle  2330  protrudes through the adhesive strip  2304 , which forms the bottom of the housing  2302  for adhesively attaching the electronic injector  2300  to the patient. The interior of the housing  2302  of the electronic injector  2300  encloses the battery  2320 , the regulator  2322 , the microcontroller  2324 , the fluid reservoir  2326 , and the MEMS pump  2328 . Various controls and indicators (not shown), such as control switches, displays, and the like, can extend through and/or be positioned upon the housing  2302 . In one embodiment, the electronic injector  2300  includes a push button  2332  which can be used to initiate delivery of a therapeutic agent to the patient. 
     The electronic injector as described in conjunction with  FIGS. 31-38  above can be extended to include additional features for convenience, ease-of-use, and safety. 
     The electronic injector can include wireless functionality, allowing communication with local or remote communication devices. Examples of wireless connections include Bluetooth, Bluetooth Low Energy, Near Field Communication or 802.11 Wi-Fi, and the like. This wireless communication can be used to pull injection data from the electronic injector and to interface with the electronic injector, including inputting data to calculate injection dosages, directly inputting injection dosages, setting timers, reminders, and safety lockouts. In one embodiment, the electronic injector can be paired with an on-body continuous glucose monitor to calculate the desired bolus injection volume for the electronic injector and avoid manual entry. In this embodiment, both the Continuous Glucose Monitor (CGM) and the injector can be paired with a wireless device running a control application. The wireless device can read in the current glucose level of the patient from the CGM and the patient can manually enter their weight/insulin resistance information (which can be saved for future use and updated as needed) along with their intended sugar intake. the mobile device control application can then calculate the injection volume and send that information back to the electronic injector. In this embodiment, neither the electronic injector nor the CGM has the computational capability to do this calculation. In another embodiment, the CGM can connect directly to the electronic injector. The patient can perform an initial step of loading in their weight and treatment resistance information. During normal use, the patient would only enter the amount of food they plan to consume. The electronic injector can then calculate the correct dosage for the patient. In another embodiment, the electronic injector can wirelessly connect to the CGM to read the patient&#39;s current glucose levels, then can take direct patient input on incoming sugars. The electronic injector can then perform the dosage calculation with no other wireless device involved. In another embodiment, the electronic injector can be paired with a communication device (computer, phone, tablet, etc.) which tracks usage data obtained by the electronic injector. Exemplary data include tracking of injection times and injection amounts, which can be used to establish trends and/or to verify that proper injections occurred at proper times. Such tracking could be particularly useful in caring for the young and the elderly. In yet another embodiment, the electronic injector can obtain and/or provide data to remote medical databases, such as the Medtronic CareLink Network, to provide an easy and quick interface between the patient and physician in an effort to continuously manage the patient&#39;s treatment. This would be particularly useful for new patients that need to make frequent adjustments to their dosage until the patient and doctor determine the correct dosages to use. 
     The electronic injector can also include safety features. In one embodiment, the electronic injector can remind the patient when it is the proper time for a basal injection by use of a vibration, auditory, and/or visual signal at a preset or predetermined time. The electronic injector can also verify that injections occur at the proper injection time with the proper injection amount, and provide the data to remote medical databases or control applications over a paired communication device. In another embodiment, the electronic injector can provide a warning or injection lockout when a second injection is attempted within a certain time period, preventing accidental double injections. In yet another embodiment when the therapeutic agent is provided in a replaceable reservoir, the electronic injector can detect the type of replaceable reservoir and/or recognize the type of insulin or other therapeutic agent being used, and adjust the operation of the electronic injector automatically. Each reservoir can have a unique ID tag, which can take the form of an RFID tag, EEPROM, a variable resistance, a small optical tag, or the like, that the electronic injector can scan to identify the specific reservoir type, contents, and/or expiration date. 
     The electronic injector can also include device monitoring features. In one embodiment, the electronic injector can verify the flow rate of the therapeutic agent using a MEMS flow meter to assure that it is correct. When the flow rate is too high, the electronic injector can stop the injection to avoid an excessive delivery of the therapeutic agent. When the flow rate is too low, the electronic injector can stop the pump to avoid build up of excessive delivery pressure due to an obstruction in the flowpath, such as a kink in the tubing. In either situation, the electronic injector can send a warning to the patient via a vibration, auditory signal, and/or visual signal through either the electronic injector or paired mobile device indicating that the injection has stopped. In another embodiment, the electronic injector can have a temperature sensor that monitors the temperature of the therapeutic agent within the reservoir. When the therapeutic agent temperature rises above or falls below recommended thresholds, the electronic injector can warn the patient via a vibration, auditory signal, and/or visual signal that the therapeutic agent may no longer be safe to use. In another embodiment, the electronic injector can provide a low battery warning to warn the patient that the electronic injector may not be available for service. This warning can be a vibration, auditory signal, and/or visual signal. This warning can also pop up as a warning, such as a vibration, auditory signal, and/or visual signal, on a wirelessly connected mobile device. In yet another embodiment, the electronic injector can check the identity and/or the expiration date of the therapeutic agent when the therapeutic agent is provided in a replaceable reservoir. This information can be included in the unique ID tag described above. 
     The electronic injector can also include green technology features. In one embodiment, the electronic injector can harvest energy to recharge or replace the battery. The electronic injector can turn mechanical motion (button press, body motions) into electrical energy through a piezo energy harvesting module. In another embodiment, the electronic injector can use rechargeable batteries that can be recharged via an AC wall adapter, or a USB, mini USB or micro USB connector. 
     The electronic injector can also include therapeutic agent flexibility features. The electronic injector can work with existing therapeutic agents and new therapeutic agent coming onto the market. Along with insulin for diabetes treatment, the electronic injector can work with glucagon-like peptide-1 (GLP-1) or Amylin pancreatic hormone. The electronic injector can also be used with other therapeutic agents such as injectable pain medication, steroids, Botox, or the like. In one embodiment, the electronic injector can adapt operation to provide a maximum flow rate and/or lockout timer through internal control valves and utilizing a clock timer within the electronic injector to prevent abuse of the therapeutic agent. In one embodiment, the electronic injector can include dual reservoirs so that one electronic injector can provide different therapeutic agents to a patient requiring more than one type of therapeutic agent. In one example, one reservoir can house fast acting bolus insulin, e.g., Novolog, and the other reservoir can house slow acting basal insulin, e.g., Lantix. 
     The electronic injector can include convenience features to encourage the patient to use the device. In one embodiment, the electronic injector would be disposable with all the parts being prepackaged (including the therapeutic agent in the reservoir) and would be tossed away as soon as the therapeutic agent is used up or expires. In another embodiment, the electronic injector would be durable with a replaceable cartridge containing just the reservoir and MEMS micropump, which would snap into place and would require only an electrical connection to the durable parts of the pump. In this embodiment, the entire flow path (reservoir, MEMS pump, and injection needle port) for the therapeutic agent can be contained within the disposable cartridge, so that only an external electrical signal from the durable portion of the electronic injector is required to control the pump. In yet another embodiment, the electronic injector would be durable and only a replaceable cartridge including the therapeutic agent would be replaced. In this embodiment, the cartridge can make a mechanical connection to create the fluid flow path from the reservoir to the MEMS pump. 
     It is important to note that  FIGS. 1-38  illustrate specific applications and embodiments of the invention, and are not intended to limit the scope of the present disclosure or claims to that which is presented therein. Upon reading the specification and reviewing the drawings hereof, it will become immediately obvious to those skilled in the art that myriad other embodiments of the invention are possible, and that such embodiments are contemplated and fall within the scope of the presently claimed invention. 
     While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.