Patent Publication Number: US-9415173-B2

Title: Externally triggerable cannula assembly

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 12/951,151, filed Nov. 22, 2010 which claims priority to European Patent Application No. EP09177194.9 filed Nov. 26, 2009. 
    
    
     TECHNICAL FIELD 
     The embodiments described herein relate to methods, assemblies, systems and devices for administering a fluid or liquid such as a medical product or liquid insulin. More particularly, the embodiments described herein relate to methods, assemblies, systems and devices for administering a fluid or liquid via an externally triggerable cannula. 
     BACKGROUND 
     A fluid product may be continuously delivered to a body using a cannula that is inserted into the body and remains in place for a period of time such as, for example, several days. Diabetes patients may use a subcutaneously positioned cannula for a continuous delivery of insulin via a drug infusion pump or for monitoring glucose levels using a sensor. Frequently, the patient initially applies a subcutaneous insertion device which includes a cannula device for subsequently delivering insulin by means of the pump. Older and/or weakened patients may encounter difficulties in correctly administering the drug due to impaired manual dexterity or lack of motor skills needed to properly handle the cannula device. Such difficulties may give rise to a risk that an incorrect dose is administered or that the cannula device is unintentionally and/or inappropriately triggered. 
     The subcutaneous insertion device may be a separate, reusable device. However the use of such an additional device may be perceived as being complicated to handle. Alternatively, disposable insertion devices are available. Disposable insertion devices are supplied with an attached infusion cannula. Once insertion is complete, the insertion device can be removed from the cannula and disposed. 
     The use of disposable insertion devices may be more expensive compared to reusable devices due to an increase in consumption of disposable insertion devices and an increased volume of sterile packing for each infusion set. 
     U.S. 2007/0142776 A9 discloses an insertion device and insertion set. The insertion device for inserting at least a portion of at least one piercing member of an insertion set through the skin of a patient includes a device housing, a carrier body and a driver. The carrier body is slidably received within the device housing for movement between an advanced position and a retracted position. The driver is operatively coupled between the device housing and the carrier body to urge the carrier body from the retracted position toward the advanced position to place at least a portion of the at least one piercing member of the insertion set through the skin of the patient to install the insertion set to the patient. The receiving structure of the carrier body is removable from the insertion set while maintaining the installation of the insertion set to the patient. 
     US 2008/0319414 A1 discloses an insertion apparatus and a method for use with a device for delivery of a therapeutic fluid into a body of a patient and/or for sensing of a bodily analyte. The apparatus includes a housing adapted for loading therein at least one cannula cartridge unit having a protective member. The protective member accommodates at least one penetrating cartridge having a subcutaneously insertable element and a penetrating member. The apparatus includes a displacement mechanism capable of protracting the penetrating cartridge towards the body of the patient, where protraction of the penetrating cartridge results in insertion of the subcutaneously insertable element into the body of the patient. 
     US 2009/0198191 discloses patches for medical devices, wherein in various embodiments, an adhesive patch of a medical device may have selective areas with adhesive material of varying adhesion strengths. In other embodiments, an adhesive patch of a medical device may include adhesive material that may be activated by a catalyst to increase or decrease the adhesion strength of the adhesive material. In further embodiments, a medical device may include a pierceable membrane containing an agent, the pierceable membrane being positioned to be pierced by a needle and to cause some of the agent to be carried to the user-patient. 
     U.S. Pat. No. 7,455,663 B2 discloses an infusion medium delivery system, a device and method for delivering an infusion medium to a patient-user, including a needle inserter device, and a method for inserting a needle and/or cannula into a patient-user to convey the infusion medium to the patient-user. 
     WO 2009/004026 A1 discloses an inserter for an infusion set for intermittent or continuous administration of a therapeutic substance, such as for example insulin. The inserter comprises means for insertion and retraction of an introducer needle. With the inserter of this document, it is possible to introduce an insertion needle when placing a medical device subcutaneously or transcutaneously. 
     SUMMARY 
     According to one embodiment, a cannula assembly may include a cannula module and an inserter module. The cannula module may include a skin-contacting surface for placing on an outer surface and a cannula having a pre-operational state and an operational state. In the pre-operational state the cannula is retracted with respect to the skin-contacting surface. In operational state the cannula projects beyond the skin-contacting surface. The inserter module is coupled to the cannula module in the pre-operational state. The inserter module may include an energy store and an activation mechanism. The energy store includes stored potential energy. When the energy store is at least partially discharged, the stored potential energy is transformed to kinetic energy that moves the cannula from the pre-operational state to the operational state. The activation mechanism is triggerable from outside the cannula assembly with a trigger device. The activation mechanism prevents the energy store from being discharged before it is triggered by the trigger device, and enables the energy store to be discharged after it is triggered by the trigger device to force the cannula from the pre-operational state into the operational state. 
     In another embodiment, a cannula system for administering a fluid is provided. The cannula system may include a disposable cannula assembly including an energy store and a cannula. The cannula moves from a pre-operational state to an operational state using energy supplied by the energy store. A movement is triggered from outside the disposable cannula assembly. A reusable trigger device is connected to and removable from a cannula assembly. The reusable trigger device triggers the movement of the cannula. 
     In a further embodiment, a method for delivering fluid to a cannula is provided. The method may include: receiving a trigger device with a cannula assembly comprising a cannula module and an inserter module, wherein the inserter module includes an energy store and an activation mechanism; receiving an input with the trigger device; transforming the input into a trigger of the activation mechanism of the inserter module, wherein the energy store becomes dischargeable; discharging at least in part the energy store; and moving the cannula from a pre-operational state into an operational state using energy of the energy store. 
     It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically depicts a cannula assembly according to one or more embodiments shown and described herein; 
         FIG. 2  schematically depicts a cannula module according to one or more embodiments shown and described herein; 
         FIG. 3  schematically depicts an inserter module according to one or more embodiments shown and described herein; 
         FIG. 4  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein a mechanical activating effect is exerted by a shiftable pin which can be moved using an electromagnet according to one or more embodiments shown and described herein; 
         FIG. 5  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein a mechanical activating effect is exerted by a shiftable pin which can be moved manually using a push button according to one or more embodiments shown and described herein; 
         FIG. 6  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein a mechanical activating effect is exerted by an element which can be moved vertically and is wedge-shaped on one side according to one or more embodiments shown and described herein; 
         FIG. 7  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein a mechanical activating effect is exerted by a wedge-shaped element which can be moved vertically according to one or more embodiments shown and described herein; 
         FIG. 8  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein a magnetic activating effect is exerted by a magnet which can be moved according to one or more embodiments shown and described herein; 
         FIG. 9  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein a mechanical activating effect is exerted by a motor-driven shiftable pin according to one or more embodiments shown and described herein; 
         FIG. 10  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein an electric field which activates an ignition device is applied in order to trigger a pyrotechnic device according to one or more embodiments shown and described herein; 
         FIG. 11  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein the trigger device comprises key elements which match a security mechanism of the cannula assembly and wherein a mechanical activating effect is exerted by a wedge-shaped element which can be moved vertically according to one or more embodiments shown and described herein; 
         FIGS. 11A to 11F  schematically depict an insertion sequence using the cannula system shown in  FIG. 11  according to one or more embodiments shown and described herein; 
         FIG. 12A  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein the triggering effect is exerted via a mechanical interface according to one or more embodiments shown and described herein; 
         FIG. 12B  schematically depicts a cannula system comprising a trigger device integrated in a medical or diabetes therapy device, wherein the triggering effect is exerted via a radio interface according to one or more embodiments shown and described herein; 
         FIG. 13  schematically depicts a cannula system comprising a trigger device integrated in a fluid connector according to one or more embodiments shown and described herein; 
         FIGS. 13A to 13E  schematically depict an insertion sequence using the cannula system shown in  FIG. 13  according to one or more embodiments shown and described herein; 
         FIG. 14A  schematically depicts a cannula system in a pre-operational state, wherein triggering is effected by a fluid or liquid acting on a spongy element according to one or more embodiments shown and described herein; 
         FIG. 14B  schematically depicts the cannula system of  FIG. 14A  in an operational state according to one or more embodiments shown and described herein; 
         FIG. 15A  schematically depicts a cannula system in a pre-operational state, wherein triggering is effected by a fluid or liquid acting on an elastic element according to one or more embodiments shown and described herein; 
         FIG. 15B  schematically depicts the cannula system of  FIG. 15A  in an operational state according to one or more embodiments shown and described herein; 
         FIG. 16A  schematically depicts a cannula system in a pre-operational state, wherein triggering is effected by a fluid or liquid acting on a shiftable plug according to one or more embodiments shown and described herein; 
         FIG. 16B  schematically depicts the cannula system of  FIG. 16A  in an operational state according to one or more embodiments shown and described herein; 
         FIG. 17A  schematically depicts a cannula system in a pre-operational state, wherein triggering is effected by a fluid or liquid acting on a shiftable plug according to one or more embodiments shown and described herein; and 
         FIG. 17B  schematically depicts the cannula system of  FIG. 17A  in an operational state according to one or more embodiments shown and described herein. 
     
    
    
     DETAILED DESCRIPTION 
     User-friendly cannula assemblies for reducing inadvertent activation are described herein. 
     In accordance with one embodiment, a cannula assembly for transcutaneous fluid or liquid transport may be used with a trigger device for triggering an activation mechanism of the cannula assembly. The cannula assembly comprises a cannula module and an inserter module which may be disposable. 
     The cannula module may include a skin-contacting surface such as, for example, an adhesive layer, or an attachment to be placed or stably fixed to an outer surface of an object or the skin of a body (e.g., the skin of a user). The cannula module also may include a cannula having a hollow structural element adapted to protrude forward through the skin of the user and remain in the tissue for the duration of use. A fluid or drug can be administered through the structural element. The structural element can be a hollow steel cannula with a pointed tip or a soft, flexible tube (e.g., made of Teflon), which may be inserted by a guiding needle. The cannula comprises a fluid inlet at a distal end relative to the skin-contacting surface, and a fluid outlet at a proximal end relative to the skin-contacting surface. The cannula is adapted to be inserted through the outer surface of the object or the skin of the user, wherein the fluid inlet is in fluid communication with the proximal end portion and with the fluid outlet. 
     The cannula may be configured to assume two states: a pre-operational or initial state and an operational or final state. In the pre-operational state, the cannula is retracted relative to the skin-contacting surface such that it does not project from the skin-contacting surface. In the operational state, the cannula is advanced relative to the skin-contacting surface and projects from the skin-contacting surface. In accordance with one embodiment, the needle is adapted to pierce the user&#39;s skin, thus enabling a fluid or liquid to be transported from the fluid inlet into the body of the user. 
     The disposable inserter module can be designed to be coupled to the cannula module in the pre-operational state of the cannula. In the operational or piercing state, the cannula can be adapted to penetrate the skin and/or tissue of the body, thus allowing a fluid or liquid to be transported into the body. 
     In accordance with one embodiment, the inserter module is designed to be releasably coupled to the cannula module and to be separated from the cannula module in the operational state of the cannula. 
     The inserter module may include an energy store having stored potential energy and the activation mechanism. The energy store is designed as an energized or energizable actuating means such as a biased spring member that transforms stored or potential energy into kinetic energy when discharged, a pyrotechnic material that undergoes an exothermic chemical reaction in order to produce kinetic energy when ignited, a gas which is adapted to expand when heated, an electromagnetic device which is adapted to move when triggered and/or when an electric current is passed through it, or a magnetic device which is adapted to move when triggered. 
     If the energy store acts as an energized actuating means, it can be prevented from being discharged by blocking means, and when the blocking means is released the energy store may be discharged and the cannula may be moved. If the energy store acts as an energizable actuating means, it can be adapted to be discharged by an activating means, wherein activating, firing or triggering the activating means can enable the energy store to be discharged. 
     The inserter module may be configured to move the cannula from the pre-operational state to the operational state using the energy of the energy store or by at least partially discharging the energy store. In accordance with one embodiment, the inserter module is designed to bear the cannula module and to position the cannula at a desired location on the surface of the object such as, for example, at a desired angle to the skin. 
     The activation mechanism may include the blocking or activating means in order to prevent the energy store from being discharged and maintain the pre-operational state of the cannula, or to enable the energy store to be discharged and force the cannula into the operational state. As used herein, the phrase “force the cannula” means to move, to shift, to advance, to push, or to press the cannula axially along a casing or body of the inserter module. 
     The activation mechanism can be triggered from outside the cannula assembly by the trigger device. Triggering can, for example, involve transferring a force, movement, or mechanical impulse from the trigger device to the activation mechanism in order to release the blocking means or initiate the activating means in order to advance the cannula. In accordance with one embodiment, the activation mechanism is designed such that it can only be triggered by a trigger device which matches the activation mechanism (e.g., fulfilling a dedicated match criterion). 
     Triggering is possible from outside the cannula assembly. In accordance with one embodiment, triggering is only possible from outside the cannula assembly. The trigger device can be assembled together with a medical device or diabetes therapy device such as a glucose meter or a fluid supply or an infusion pump, wherein the trigger device and the medical or diabetes therapy device forms a single physical entity. A reusable triggering medical or diabetes therapy device can be cost-efficient to the user. For example, the complexity of the cannula assembly (e.g., the disposable modules) can be reduced by relocating the trigger device outside the cannula assembly. 
     The energy store can be a coil spring or a gas spring, for example a compression or extension spring supported on one side by being axially fixed to the body and on the other side by being axially fixed to a plunger. 
     The energy store can also be a pyrotechnic device which is adapted to ignite a pyrotechnic material or to expand a gas when exogenously triggered, for example by an ignition device in order to axially advance the plunger and/or the cannula. 
     In one embodiment, the activation mechanism comprises a trigger interface which is adapted to receive an exogenous or external trigger signal or trigger effect and to convert the trigger signal or trigger effect into a mechanical activating effect, magnetic activating effect, electric activating effect, electromagnetic activating effect, hydraulic activating effect, thermal activating effect, pneumatic activating effect, pyrotechnic activating effect, or combinations thereof. A trigger effect can be a trigger signal, such as a force, a voltage, an electric field, or a magnetic field. The activating effect can be a force or momentum which is exerted on a blocking means or blocking element. The blocking element can be designed to prevent the energy store from being discharged, until the blocking element is released from a blocking position in order to discharge the energy store and move the cannula. 
     A mechanical activating effect can be a force which is exerted, for example by a moving or shifting actuator on a pivoting retaining hook. Pivoting the retaining hook can release the retaining hook from an engagement with a retaining element, thus enabling the energy store such as, for example, a biased coil spring or gas spring coupled to the retaining hook, to be discharged. 
     A magnetic activating effect can be a magnetic force which is exerted by a permanent magnet or an electromagnet on a blocking element such as, for example, a pivoting retaining hook comprising a top which includes a permanent magnet or an electromagnet. 
     A pneumatic activating effect can be a pneumatic force exerted, for example, by releasing a gas spring integrated in the trigger device and fluidly connected to the activating mechanism, which exerts a force or momentum on the activating mechanism. 
     A thermal activating effect can be achieved by heating a gas contained in the cannula assembly, in order to generate a mechanical force or momentum. 
     A hydraulic activating effect can be achieved by a fluid or liquid such as, for example, insulin which is supplied from outside the cannula assembly. In accordance with one embodiment, the liquid can be supplied from the trigger device, a medical device, or a diabetes therapy device which is coupled to or integrated with the trigger device. For example a liquid can be supplied in order to wet a spongy element of the activating mechanism. The liquid changes the consistency of the spongy element and consequently moves a blocking element supported by the spongy element. 
     An electric activating effect can be an electric field which acts on an activating element, such as an ignition device, in order to enable the energy store, such as a pyrotechnic device, to be discharged. The activating means can be designed to enable the energy store to be discharged when triggered, activated, fired, or released. 
     In one embodiment, the activation mechanism comprises a security mechanism designed to help prevent the energy store from being accidentally discharged without having been triggered. An accidental discharge could be caused by inadvertent mechanical shocks acting on the cannula assembly initiated by a user before triggering. 
     The security mechanism can be adapted to switch from a blocking state in which the security mechanism prevents the energy store from being discharged (e.g., when the trigger device is detached from the cannula assembly), to a releasing state in which the energy store can be discharged. The security mechanism can be adapted to interact with key elements of the trigger device, wherein it is only possible to switch from the blocking state to the releasing state if the key elements of the trigger device and the security mechanism of the activation mechanism fulfill corresponding criteria. 
     A matching criterion can be that a shape of the key elements of the trigger device fit or match correspondingly shaped elements of the security mechanism in order to allow the security mechanism to enter the releasing state. The security mechanism can comprise a retaining pin which is levered on a fulcrum from the blocking state, in which the retaining pin prevents the retaining hook from pivoting, to the releasing state, in which the retaining pin is released in order to be pivoted. In accordance with one embodiment, an opening in the trigger device, a medical, or diabetes therapy device comprising the trigger device is designed to receive a bar-shaped inserter module. A wall enclosing the opening can comprise a key element such as a release buckle, which is adapted to release a levered retaining pin of the security mechanism. The security mechanism is adapted to engage with the release buckle when the inserter module is inserted into the opening of the trigger device, medical, or diabetes therapy device. 
     In some embodiments, a reed switch configured to be closed by a magnet in the triggering device is provided in the cannula assembly. For example, a reed switch may be provided in cannula assembly that cooperates with an electric trigger and a pyrotechnic device. Alternatively, it is possible to provide an RF transmitter in the triggering device and a corresponding receiver in the cannula assembly. In this case, the matching criterion can be a code which is transmitted from the triggering device. In another embodiment, triggering is only possible when the inserter module is inserted into the opening of the trigger device. The release buckle of the trigger device levers the retaining pin of the inserter module when the inserter module is advanced into the opening of the trigger device, medical, or diabetes therapy device. 
     If triggering is dependent on an external trigger device and an activation mechanism fulfilling certain matching criteria, the operating security of the cannula assembly can be improved by reducing the risk of the cannula assembly being inadvertently or accidentally activated. 
     In one embodiment, the activation mechanism comprises or operates as a blocking mechanism which prevents the energy store from being discharged such as, for example, when utilizing a mechanical, magnetic, electromagnetic, hydraulic, thermal, or pneumatic activating effect. The blocking mechanism can be triggered from outside the cannula assembly to be released, thus enabling the energy store to be discharged or resulting in the energy store being discharged. 
     In one embodiment, the activation mechanism is adapted to be triggered by moving a blocking element. In accordance with another embodiment, the blocking element forms part of the trigger interface. Thus, the blocking mechanism can simultaneously receive an activating effect and control the discharge of the energy store. The blocking element can be releasably attached to a retaining element in order to prevent the energy store from being discharged, and can be adapted to be detached from the retaining element by the activating effect in order to discharge the energy store. 
     Accordingly, security features can be incorporated in order to make handling the cannula assembly more secure such as, for example: the activation mechanism comprises a blocking element and a retaining element; the blocking element is releasably attached to the retaining element in order to prevent the energy store from being discharged; the blocking element is adapted to be detached from the retaining element by the activating effect; detaching the blocking element from the retaining element causes the energy store to be discharged; the activation mechanism can be triggered by moving the blocking element; and/or the blocking element optionally forms part of the trigger interface. 
     The inserter module can comprise an elongated cylindrical body. The cannula module can comprise a plunger mounted in it for a longitudinal shifting movement within the body of the inserter module between a retracted position and an advanced position. The energy store may engage with the plunger in order to advance the plunger when the energy store is discharged. The cannula can be axially fixed to the plunger such that advancing the plunger from the retracted position to the advanced position moves the cannula from the non-operational to the operational state. 
     The retaining elements of the activation mechanism can comprise a retaining hook and a retaining bearing or bearing element which are designed to assume a blocking state and a releasing state. When in the blocking state, the retaining hook is releasably engaged with the retaining bearing and the energy store is prevented from being discharged in the blocking state. When in the releasing state, the retaining hook is released from the retaining bearing and the energy store is allowed to be discharged. 
     The retaining hook can be a pivoting retaining hook comprising a hooked end releasably engaged with the retaining bearing, and an opposite, straight end, which pivots on and is axially fixed to the plunger. The pivoting retaining hook can be released from the retaining bearing by a lateral force which pushes against the hooked end of the retaining hook and moves the retaining hook from the blocking state to the releasing state. 
     The retaining hook can be an axially shiftable retaining hook comprising a hooked end releasably engaged with the plunger and an opposite end, which is connected to a bistable elastic element and axially fixed such that it can be separated. The bistable elastic element has two equilibrium states. The transition of the bistable elastic element from a blocking state to a releasing state enables the retaining hook to transition from the blocking state to the releasing state. 
     The bistable elastic element can be configured such that a transition from the blocking state to the releasing state is enabled by feeding a triggering fluid or liquid to the spongy element. For example, the bistable elastic element may be supported by a spongy element having a higher consistency in a dry state and a lower consistency in a moist state. 
     The retaining hook can be a laterally shiftable retaining hook comprising a first hooked end which is releasably engaged with the plunger, and a second hooked end which is connected to the bistable elastic element and laterally fixed such that it can be separated. The bistable elastic element may prevent the retaining hook from laterally shifting in the blocking state and enable the retaining hook to laterally shift in the releasing state. 
     The retaining hook can be a levered retaining hook comprising a hooked end which is releasably engaged with the plunger, and an opposite end which can be moved by an exogenously applied lateral force. The lateral force may lever the hook on a fulcrum and switch from the blocking state to the releasing state. 
     The embodiments described herein relate to a trigger device for triggering an activation mechanism of a cannula assembly. The trigger device may comprise an actuator which is adapted to trigger, i.e., move, the activation mechanism of the cannula assembly and a control element. In accordance with one embodiment, the control element is gripped by a user and manually operated by the user in order to initiate a triggering process for the actuator. 
     In accordance with one embodiment, the control element is adapted to be manually gripped by the user or to receive an operating effect from, for example, a medical or diabetes therapy device which is coupled to or integrated into or with the trigger device. The actuator may be coupled to the control element in order to exert an activating effect when the control element is operated. 
     In one embodiment, the trigger device is adapted to convert a user operation (i.e., a received input) such as, for example, touching, pushing, pulling or rotating the control element, into an externally supplied activating effect exerted on a blocking element of the activation mechanism. The activating effect triggers, i.e., moves, the blocking element and may be a mechanical activating effect, electromagnetic activating effect, thermal activating effect, hydraulic activating effect, pneumatic activating effect, or combinations thereof. 
     The actuator may comprise a release element adapted to be advanced outside the trigger device to interact with a retaining element of the activation mechanism. The interaction transfers or exerts a mechanical effect such as a shifting force on the retaining element. 
     The release element can comprise any of the following: a shiftable trigger pin or shiftable release plug adapted to exert an outward linear force; a shiftable wedge-shaped element adapted to exert an outward lateral force; a magnet which can be moved and/or activated and is adapted to exert an outward, variable magnetic force; and/or an electrical circuit, if for example a pyrotechnic device is used. 
     The trigger device can comprise a trigger body or housing for a control element and an actuator. The trigger body and control element can be designed to be substantially identical. For example, the trigger body may be a parallelepiped, a cuboid, or a cylindrical body comprising an opening for accommodating the inserter module. The actuator can be embodied by one or more bar-shaped elements which protrude onto, into or contact the inserter module for exerting an activation effect, such as a pushing effect on a blocking element of the activation mechanism. 
     Alternatively, the trigger body, control element and actuator can be designed to be substantially identical. For example, a fluid connector of a fluid source or infusion pump may be connected or attached to the inserter module. The fluid connector can be adapted such that attaching or connecting the fluid connector to the inserter module exerts an activation effect in order to trigger the activation mechanism of the cannula assembly. The activation effect may be, for example, a pushing effect on a blocking element of the activation mechanism. 
     The trigger device may comprise a trigger interface which is adapted to transfer the activation effect or triggering information to the activation mechanism. In accordance with one embodiment, the trigger interface is a mechanical interface comprising the actuator for transferring the activation effect, or an electrical or radio interface for transferring the triggering information. 
     The actuator and/or the control element can be included or integrated in a medical or diabetes therapy device such as, for example, a glucose meter, or a fluid pump (e.g., an infusion pump or an insulin pump). Optionally, the actuator and/or the control element can comprise the medical or diabetes therapy device. 
     The trigger device can comprise key elements for interacting with a security mechanism of the cannula assembly which is adapted to be switched from a blocking state to a releasing state. When in the blocking state, the security mechanism prevents an energy store from being discharged. When in the releasing state, the energy store can be discharged. In certain embodiments, the key elements or the security mechanism can only interact if the key elements or the security mechanism fulfill matching criteria. 
     In accordance with one embodiment, the security mechanism and the blocking mechanism of the cannula assembly are adapted to be cascaded or to operate in succession. The security mechanism can block the blocking mechanism against being released for as long as the matching criteria between the key elements and the security mechanism are not fulfilled. 
     The embodiments described herein relate to a medical or diabetes therapy device such as a glucose meter, an infusion pump or fluid connector comprising a trigger device. The medical or diabetes therapy device can be shaped as a cylinder or a box with a cross-section adapted to match a corresponding means of the activation mechanism. In accordance with one embodiment, the activation mechanism can only be triggered by a trigger device which matches the activation mechanism, thus fulfilling matching criteria. For example the physical form of the medical or diabetes therapy device may be adapted to fit a correspondingly shaped inserter module. 
     The trigger device or the medical or diabetes therapy device can comprise a security mechanism designed to match a security mechanism of an activation mechanism of a cannula assembly. 
     Optionally, an opening in the medical or diabetes therapy device which has a specific cross-section or profile can be designed such that it can only receive a corresponding or complementary shape such as, for example, a bar-shaped inserter module having a suitably shaped cross-sectional profile. In one embodiment, triggering is only possible when the inserter module is inserted into the opening of the medical or diabetes therapy device. 
     If matching criteria have to be fulfilled prior to triggering, the operating security of the cannula assembly may be improved by reducing the risk of the cannula assembly being inadvertently or accidentally activated. 
     The embodiments described herein relate to a cannula system comprising a cannula assembly and a trigger device. 
     In one embodiment, a cannula system which is to be used with a fluid source, liquid supply or a pump for delivering a fluid or liquid to the cannula, such as an infusion pump. The cannula system comprises a disposable cannula assembly and/or a reusable trigger device. 
     In one embodiment, the cannula assembly comprises an energy store and a cannula, wherein the cannula can be moved from a pre-operational state to an operational state using the energy of the energy store and the movement is triggered from outside the cannula assembly. The trigger device can be connected, such that it can be separated, to the cannula assembly or energy store in order to trigger the movement of the cannula. 
     In one embodiment, the trigger device is distinct from the cannula assembly and/or from the energy store. 
     A trigger device may comprise a trigger interface of the having an actuator. The trigger device can be designed to interact with a trigger interface of the cannula assembly in order to transfer and/or convert a trigger into an activating effect. The activating effect may trigger an activation mechanism of the trigger device and may be a mechanical activating effect, an electromagnetic activating effect, a thermal activating effect, a hydraulic activating effect, a pneumatic activating effect or a combination thereof. 
     A release element of the trigger device designed to interact with a retaining element of the activation mechanism may comprise one of the following elements: a shiftable trigger pin; a shiftable wedge-shaped element; a magnet which can be moved and/or activated; and a movable release plug. 
     The shiftable trigger pin can be adapted to laterally push a box-shaped cap which is fixed to a retaining hook, and pivot the retaining hook in order to release it from the engagement with a bearing element. 
     The shiftable wedge-shaped element can be adapted to engage with a wedge-shaped cap which is fixed to a retaining hook. In one embodiment, the wedge-shaped element is adapted to be complementary to the wedge-shaped cap, and pivot the retaining hook in order to release it from the engagement with a bearing element. 
     A magnet can be adapted to engage with a ferromagnetic cap which is fixed to a retaining hook. The magnet can be moved and/or activated to pivot the retaining hook and release it from the engagement with a bearing element. 
     The movable release plug can be fixed to a fluid connector and adapted to engage with a levered retaining hook in order to switch from the blocking state to the releasing state. 
     Embodiments of the present disclosure relate to methods for delivering a fluid or liquid to a cannula. In one embodiment, the method is applied to a cannula assembly comprising a cannula module, an inserter module and a trigger device which can be connected, such that it can be separated, to the cannula assembly. The inserter module comprises an energy store and an activation mechanism. 
     In one embodiment the method comprises: triggering the activation mechanism of the inserter module; moving the cannula from a pre-operational state to an operational state; and separating the trigger device from the cannula assembly. The activation mechanism is triggered by the trigger device, and enables the energy store to be discharged. The cannula is moved to an operational state using the energy of the energy store, for example, by at least partially discharging the energy store. 
     In accordance with one embodiment, the cannula system is suitably positioned on the surface or skin of an object or body before the triggering step is performed. Suitable positions for the cannula system include a desired inclination towards the surface of the object or body. 
     Methods according to the embodiments described herein can be performed without piercing the skin of a human or animal or can be performed in the absence of a human or animal body. Such methods can also be performed for the purpose of piercing the skin of a human or an animal. 
     In one embodiment, the energy store can be prevented from being discharged when the trigger device or a medical or diabetes therapy device comprising the trigger device is detached from the cannula assembly. Attaching the trigger device or the medical or diabetes therapy device comprising the trigger device to the cannula assembly enables the activation mechanism to be triggered, in order to discharge the energy store. 
     In accordance with one embodiment, the activation mechanism can only be triggered if matching criteria between key elements of the trigger device and a security mechanism of the cannula assembly are fulfilled. 
     In one embodiment, performing a triggering process of the trigger device can trigger the activation mechanism such as by exerting a force. The triggering process of the trigger device can also enable the activation mechanism to be triggered such as, for example, by attaching the medical or diabetes therapy device to the cannula assembly or by transferring triggering information from the trigger device to the cannula assembly via an electrical or radio interface. 
     In accordance with one embodiment, the activation mechanism can be triggered by enabling the security mechanism of the cannula assembly to switch from a blocking state to a releasing state. For example, the matching criteria between the key elements of the trigger device and the security mechanism of the cannula assembly have to be fulfilled in order to permit the energy store to be discharged. 
     In one embodiment, a triggering process of the trigger device induces an activating effect of the trigger device which is adapted to initialize the discharge of the energy store or to release at least one retaining element of the activation mechanism such as a security mechanism, in order to enable the energy store to be discharged. 
     In accordance with the embodiments described herein, the discharge can be enabled by switching the security mechanism from a blocking state to a releasing state. In one embodiment, it is only possible to discharge the energy store or to initialize the discharge in the releasing state of the security mechanism. 
     In one embodiment, triggering the activation mechanism involves at least one of the following: attaching the trigger device, such that it can be separated, to the cannula assembly; attaching a fluid connector or a medical or diabetes therapy device comprising the trigger device, such that it can be separated, to the cannula assembly; operating a control element of the trigger device; or channeling a fluid or liquid into the cannula assembly. 
     In one embodiment, discharging the energy store is enabled by at least one of the following: shifting an actuator of the trigger device; activating a motor in order to shift an actuator of the trigger device; activating a magnetic field in order to shift a plunger of the trigger device; wetting a spongy element of the activation mechanism in order to move at least one retaining element by lowering the consistency of the spongy element; or igniting a pyrotechnic device. 
     In one embodiment a method for delivering a fluid or liquid to a cannula utilizes: a cannula assembly comprising a cannula module and an inserter module, wherein the inserter module comprises an energy store and an activation mechanism; and a trigger device which can be connected, such that it can be separated, to the cannula assembly. The method includes: triggering the activation mechanism of the inserter module using the trigger device, thus enabling the energy store to be discharged; moving the cannula into an operational state using the energy of the energy store; and separating the trigger device from the cannula assembly. 
     In one embodiment, the energy store is prevented from being discharged when the trigger device is detached from the cannula assembly, and attaching the trigger device to the cannula assembly enables the activation mechanism to be triggered, in order to discharge the energy store. 
     In one embodiment, performing a triggering process of the trigger device triggers the activation mechanism or enables the activation mechanism to be triggered. 
     In one embodiment, a triggering process of the trigger device initializes the discharge of the energy store or releases at least one blocking element of the activation mechanism in order to enable the energy store to be discharged. 
     In one embodiment, triggering the activation mechanism includes at least one of the following: attaching the trigger device to the cannula assembly or energy store; attaching a fluid connector or a medical device or diabetes therapy device comprising the trigger device to the cannula assembly; operating a control element of the trigger device; and/or channeling a fluid or liquid into the cannula assembly. Discharging the energy store may be enabled or initiated by at least one of the following: shifting an actuator of the trigger device, manually or motor-driven, in order to exert a releasing force on a blocking element; wetting a spongy element of the activation mechanism in order to move at least one blocking element by lowering the consistency or structural strength of the spongy element; activating an ignition device in order to ignite a pyrotechnic device. 
     Referring collectively to  FIGS. 1 to 3 , a cannula assembly  1  according to the embodiments described herein is schematically depicted. In one embodiment, the cannula assembly  1  comprises a cannula module  100  and an inserter module  200 , which may be disposable. 
     As depicted in  FIG. 2 , the cannula module  100  comprises an adhesive layer disposed on the skin-contacting surface  140  which may be placed on a user&#39;s skin. The cannula module  100  also comprises a cannula  120  having a hollow structural element which remains in the tissue for the duration of use and through which a drug can be administered. The hollow structural element can be a hollow steel cannula with a pointed tip or a flexible cannula tube, which may be made of Teflon. In the latter case, a guidance needle is provided inside the cannula tube. The guidance needle has a pointed tip and is slightly longer than the flexible cannula tube, but is generally not hollow. The guiding needle pierces the skin and stabilizes the flexible cannula tube during insertion. Once insertion is complete, the guiding needle may be retracted and removed manually or by a spring. 
     The cannula  120  can be configured to assume two states: a pre-operational or initial state and an operational or final state. In the pre-operational state, depicted in  FIG. 1 , the cannula  120  is retracted relative to a skin-contacting surface  140 , i.e., the pointed tip is above (higher on the page) the skin-contacting surface  140 . In the operational state, depicted in  FIG. 2 , the cannula is advanced relative to the skin-contacting surface  140  and projects beyond the skin-contacting surface  140 , i.e., the pointed tip is below (lower on the page) the skin-contacting surface  140 . 
     Referring collectively to  FIGS. 1 to 3 , the inserter module  200  may be releasably coupled to the cannula module  100  in the pre-operational state of the cannula  120 , depicted in  FIG. 1 , and may be separated from the cannula module  100  in the operational state of the cannula  120 , depicted in  FIG. 2 . The inserter module  200  comprises an energy store such as a biased spring  220 , which is adapted to transform stored energy into kinetic energy when discharged, and an activation mechanism. In the depicted embodiment, the activation mechanism comprises a pivoting retaining hook  341 , a bearing element  350 , and a box-shaped cap  361 . 
     The biased spring  220  can be prevented from being discharged by blocking means comprising a pivoting retaining hook  341  and a bearing element  350 . The release of the blocking means can enable the biased spring  220  to be discharged and the cannula  120  to be moved. The activation mechanism can be triggered from outside the cannula assembly by a trigger device, as described herein. Triggering involves transferring a force from a trigger device to the activation mechanism in order to release the blocking means in order to advance the cannula  120 . 
     In one embodiment, the blocking means comprise a pivoting retaining hook  341  and a bearing element  350 . When in a blocking state, the pivoting retaining hook  341  is releasably engaged with the bearing element  350 . When in a releasing state, the pivoting retaining hook  341  is released or disengaged from the bearing element  350 . The biased spring  220  is prevented from being discharged in the blocking state, and allowed to be discharged in the releasing state. In another embodiment, the energy store may be a tensioned spring which is prevented from being relaxed in the blocking state, and allowed to be relaxed in the releasing state. 
     As depicted in  FIGS. 1 and 3 , the pivoting retaining hook  341  comprises a hooked end having a box-shaped cap  361  releasably engaged with the bearing element  350 , and an opposite, straight end which pivots on and is axially fixed to a plunger  130 . The pivoting retaining hook  341  can be released from the bearing element  350  by a lateral force which pushes against the box-shaped cap  361  on the hooked end of the pivoting retaining hook  341  and moves the pivoting retaining hook  341  from the blocking state to the releasing state. 
     Referring now to  FIGS. 4 to 12 , embodiments of a cannula system may comprise a trigger device integrated in a medical therapy device  450  such as a diabetes therapy device. The medical therapy device  450  may trigger or initiate the movement of the cannula  120 . Alternatively, the cannula assembly  1  can be controlled and/or operated with or without mechanical contact between the cannula assembly  1  and the trigger device. As used herein, the phrase “diabetes therapy device” means a device used by a person in diabetes therapy such as a glucose meter or an insulin pump. 
     As depicted in  FIG. 4 , the trigger device comprises a shiftable pin  413  and an electromagnet  412  that cooperate via electromagnetism to trigger the insertion of the cannula  120 . In one embodiment, the electromagnet  412  is energized by a current which causes the shiftable pin  413  to move laterally (to the right as depicted in  FIG. 4 ). As the shiftable pin  413  is urged into the box-shaped cap  361  by the electromagnet  412 , the shiftable pin  413  interacts with the box-shaped cap  361  on the pivoting retaining hook  341 . The interaction causes the pivoting retaining hook  341  to deflect. When the box-shaped cap  361  is deflected beyond the bearing element  350 , the biased spring  220  is released and acts on the plunger  130  attached to the cannula  120 . Upon being released, the plunger  130  and the biased spring  220  move downwards. For example, if a patient&#39;s skin were beneath the cannula  120 , the triggering would cause the cannula  120  to be inserted into the patient&#39;s skin. It is noted that, the shiftable pin  413  may be moved back into its initial position by another spring (not depicted) in the trigger device. 
     In the embodiment depicted in  FIG. 4 , the movement of the cannula  120  is limited when the plunger  130  contacts a cannula hub  150 . The cannula  120  is fully inserted when the plunger  130  is in contact with the cannula hub  150 . The cannula hub  150  is attached to the skin-contacting surface  140  and also comprises a fluid connector to the medical therapy device (not depicted in  FIG. 4 ). 
     Additionally it is noted that once insertion is complete, the trigger device can be removed and followed by an inserter module  200 . 
     Various modifications to the embodiments described herein are contemplated. For example, the shiftable pin  413 , depicted in  FIG. 4 , could also be operated via a push button  420  included in the trigger device, as depicted in  FIG. 5 . For example, the push button  420  may receive a manually generated force and cause the box-shaped cap  361  to be deflected beyond the bearing element  350 . 
     In the embodiments depicted in  FIGS. 4 to 11 , the medical therapy device  450  is attached to the cannula assembly  1  in order to initiate an insertion of the cannula. Insertion is triggered by a control element (e.g., the push button  420  depicted in  FIG. 5 ). 
     Referring back to  FIG. 4 , a ferrite rod  414  or piston rod coupled to the shiftable pin  413  may be moved by an electromagnet  412 . The movement of the ferrite rod  414  can move the pivoting retaining hook  341  until it is completely released and the cannula  120  is injected. In the embodiment depicted in  FIG. 4 , the energy store is a biased spring  220  which is held in a compressed state and released in order to insert the cannula  120 . The pivoting retaining hook  341  interacts, prior to the insertion of the cannula  120 , with a corresponding element (not depicted) of the inserter module  200  in order to hold the biased spring  220  in a compressed state and the cannula  120  in the pre-operational state. 
     Referring back to  FIG. 5 , movement of the push button  420  moves the pivoting retaining hook  341  until it is released. In further embodiments, it is also possible to use more than one push button  420  and more than one pivoting retaining hook  341 , such as two of each. For example, the insertion of the cannula  120  may be triggered only if both buttons are pushed. 
     In the embodiment depicted in  FIG. 6 , the pivoting retaining hook  341  is moved laterally by an inclined wedge-shaped surface on one side of a wedge-shaped element  415 . For example, insertion of the cannula  120  may be triggered as the wedge-shaped element  415  moves downward until the pivoting retaining hook  341  is released. 
     In the embodiment depicted in  FIG. 7 , triggering occurs when a prism-shaped or wedge-shaped element  416  is moved towards the pivoting retaining hook  341  until the pivoting retaining hook  341  is released and the cannula  120  is injected. In one embodiment, the wedge-shaped element  416  pierces an initially sterile barrier such as a septum  162  which covers the trigger device. 
     In one embodiment, depicted in  FIG. 8 , a cannula assembly  1  comprises a pivoting retaining hook  341  having a snapping element such as a metal element or a ferromagnetic cap  363 . The ferromagnetic cap holds the biased spring  220  in its biased state. A permanent magnet  410  integrated into the medical therapy device  450  may be moved towards the pivoting retaining hook  341  until the pivoting retaining hook  341  is released and the cannula  120  is injected, i.e., triggering occurs. 
     In the embodiment depicted in  FIG. 9 , the trigger device is a motor-driven gear rack  411  that moves the activation mechanism, i.e., the pivoting retaining hook  341 . The cannula  120  is injected when the pivoting retaining hook  341  is moved beyond the bearing element  350 . 
     Referring to  FIG. 10 , an embodiment of the cannula assembly  1  comprises an energy store. In the depicted embodiment, the energy store is a pyrotechnic device  417  which releases stored chemical energy in a controlled “explosion” upon receiving an electrical trigger signal via trigger contacts in the trigger device. The corresponding control and power circuitry for triggering the pyrotechnic device  417  may be included in the trigger device. 
     Referring to  FIG. 11 , in one embodiment the trigger device is a wedge-shaped element  416  (e.g., prism-shaped) that is moved towards the activation mechanism, which is a pivoting retaining hook  341  in the depicted embodiment. For example, triggering occurs when the pivoting retaining hook  341  is released by the wedge-shaped element  416  and the cannula  120  is then injected. 
     The cannula assembly  1  depicted in  FIG. 11  comprises a security mechanism  364  which is adapted to switch from a blocking state to a releasing state. When the security mechanism  364  is in the blocking state the energy store is prevented from being discharged. For example, when the trigger device is detached from the cannula assembly  1 , a biased spring  220  can be prevented from discharging by a retaining pin. When the security mechanism  364  is in the releasing state the energy store can be discharged. Specifically, in the depicted embodiment, the security mechanism  364  is a retaining pin which can be levered on a fulcrum from the blocking state, in which the security mechanism  364  (e.g., retaining pin) prevents the pivoting retaining hook  341  from pivoting, to the releasing state in which the pivoting retaining hook  341  is released for pivoting. 
     In the embodiment depicted in  FIG. 11 , the top of the pivoting retaining hook  341  comprises a wedge-shaped cap  362  designed to facilitate an engagement between the retaining pin and the pivoting retaining hook  341  in the blocking state. The wedge-shaped cap  362  enables an engagement between a wedge-shaped element  416  and the pivoting retaining hook  341  to release the pivoting retaining hook  341  from its engagement with a bearing element  350 . Once the pivoting retaining hook  341  is released the biased spring  220  can be discharged. The retaining pin can be levered on a fulcrum from the blocking state to the releasing state by a release buckle  418  of the trigger device. The release buckle  418  and the retaining pin are designed to match such that advancing the trigger device or the medical therapy device  450  comprising the trigger device from a distal position with respect to the skin-contacting surface  140  enables the retaining pin to be levered. 
     The security mechanism  364  is designed in a similar way to a locking device. For example, the medical therapy device  450  may comprise the release buckle  418  that operates as a key that can unlock the security mechanism  364 . This “locking” ensures that the pivoting retaining hook  341  is not inadvertently released. Accordingly, the security mechanism  364  can be designed in a similar way to a mechanical lock. Thusly, the security mechanism  364  can prevent an insertion of the cannula  120  from being triggered inadvertently or through deliberate misuse. Triggering may be limited such that triggering is only possible using the corresponding counterpart or key such as, for example, a release buckle  418  in a medical therapy device  450 . 
     Referring collectively to  FIGS. 11A to 11F , an insertion sequence using the embodiment of the cannula system  10  shown in  FIG. 11  is depicted. 
     In  FIG. 11A , the inserter module  200  has been introduced into a corresponding opening of the medical therapy device  450 . The pivoting retaining hook  341  is engaged with the bearing element  350 , and the security mechanism  364  is engaged with the wedge-shaped cap  362  of the pivoting retaining hook  341 . 
     In  FIG. 11B , the release buckle  418 , which is part of the opening of the medical therapy device  450  (e.g., curved profile), tilts the security mechanism  364  (e.g., locking lever or levered retaining pin). The pivoting retaining hook  341  is no longer blocked or secured by the security mechanism  364 . 
     In  FIG. 11C  depicts the inserter module  200  being passed upwards and further into the corresponding opening. The pivoting retaining hook  341  is displaced by the wedge-shaped element  416  and released. 
     As depicted in  FIG. 11D , releasing the pivoting retaining hook  341  frees the lock on the cannula  120  (e.g., needle assembly). The biased spring  220  can relax and move the cannula  120  towards the skin-contacting surface  140 . 
     In  FIG. 11E , the cannula  120  is advanced downward into contact with the cannula hub  150 , i.e., its final position. In the final position, the cannula  120  snaps into the cannula hub  150 . The inserter module  200  is also released from the cannula hub  150  (not depicted). 
       FIG. 11F  depicts the cannula module  100  after the inserter module  200  has been removed. The cannula module  100  is ready to be attached to a fluid or liquid tube of a fluid source such as an infusion pump. 
       FIG. 12A  schematically depicts an embodiment of a cannula system  10  comprising a cannula assembly  1  and a medical therapy device  450  such as a glucose meter comprising an integrated trigger device. Alternatively, the trigger device can be integrated into an insulin pump or other diabetes therapy device. Inserting the cannula assembly  1  into a slot  453  of the medical therapy device  450  triggers the cannula assembly  1 . The medical therapy device  450  may further comprise an electrical trigger interface  454 . It is noted that in some embodiments the slot  453  and the electrical trigger interface may be integral. 
       FIG. 12B  depicts a further embodiment of the cannula system  10 , wherein the cannula assembly  1  is triggered via a radio trigger interface  455  of the medical therapy device  450 . 
     Referring collectively to  FIGS. 4 to 12 , the mechanical components that are susceptible to abrasive wear may be integrated into the inserter module  200  rather than the medical therapy device  450 . The inserter module  200  can be designed for a small number of applications or for only one application, thus permitting the inserter module  200  to be disposable. Furthermore, the probability that the inserter module  200  malfunctions due to abrasive wear can be reduced. 
     In the embodiments described herein, the medical therapy device  450  may comprise the trigger device, which can be small in volume for integration. 
     In some embodiments, the inserter module  200  may be made disposable without any controls. 
     Software functions can be integrated with the embodiments described herein. For example, a function whereby the insertion of the cannula  120  is triggered at a point in time that is determined using a random number generator within a several-second period or e.g. 10-second period, such that the patient is surprised and feels less pain. 
     Each triggering or insertion procedure can be recorded together with time and date stamps with the medical therapy device  450  such as a glucose meter or an insulin pump. 
     Additional data such as, for example, the insertion location, can also be recorded by the medical therapy device  450  for each triggering or insertion procedure. 
     The embodiments described herein may comprise a mechanical interface, a non-contact interface, inductive interface or magnetic interface for integrating the trigger device into a medical therapy device  450 . 
       FIG. 13  depicts an inserter module  200  that is triggered without using control elements, but rather by connecting a fluid connector  440  to the cannula hub  150 . 
     For example, the embodiment depicted in  FIG. 13  may be utilized to administer insulin into a patient. The patient may position a cannula assembly  1  comprising an inserter module  200  on the patient&#39;s skin. A fluid connector  440 , which has been filled with insulin beforehand, may then be attached to the cannula hub  150 . The coupling of the fluid connector  440  to the cannula hub triggers the insertion of the cannula  120 . The inserter module  200  then may be decoupled and/or detached from the cannula hub  150 . The user can then dispose the inserter module  200  and begin an insulin infusion procedure. In a further embodiment, the inserter module  200  is integrated with the cannula assembly  1  such that the inserter module  200  can be removed after triggering. 
     The inserter module  200  may be disposable and comprise a biased spring  220 . The biased spring  220  can be integrated into the inserter module  200 . In the embodiments described herein, the biased spring  220  may be in tension or compression. Furthermore, the energy stores described herein, (e.g., biased spring  220 ) may be energized and/or discharged automatically and/or manually. 
     As depicted in  FIG. 13 , the inserter module  200  has a mechanical locking/releasing mechanism which initially holds the biased spring  220  securely in a tensioned state. Once a fluid connector  440  is connected to the cannula assembly  1 , the locking/releasing mechanism is triggered and the cannula  120  is released. The locking/releasing mechanism comprises a release plug  419  that can slide and a tilting device such as a levered retaining hook  342 . Linear movement of the fluid connector  440 , as it is connected with the cannula hub  150 , is converted into a mechanical movement that releases a blocking element. The movement of the blocking element thus causes the biased spring  220  to be discharged. In the embodiment depicted in  FIG. 13 , a levered retaining hook  342  is the locking/releasing mechanism. The interaction between the release plug  419  and the levered retaining hook  342  causes the levered retaining hook  342  to tilt or pivot. When the levered retaining hook  342  is sufficiently tilted the biased spring  220  is discharged. 
     In the embodiment depicted in  FIG. 13 , the trigger device is the fluid connector  440  which may fluidically connect the cannula  120  to an infusion pump. For example, the fluid connector  440  may be connected to the cannula assembly  1  via a tubing connection after the cannula assembly  1  has been attached to the skin of a patient. The fluid connector  440  further comprises a connector cannula for piercing a septum  462 . 
     Referring collectively to  FIGS. 13A to 13F , an insertion sequence using the cannula system  10  shown in  FIG. 13  is depicted. 
     In  FIG. 13A , the biased spring  220  is held in a compressed state by a levered retaining hook  342 . The levered retaining hook  342  also holds the plunger  130 , together with the cannula  120 , in a pre-operational (retracted) state. The fluid connector  440  is not engaged with the cannula assembly  1 . The release plug  419  of the fluid connector  440  is moved linearly (e.g., to the right) and comes into contact with the levered retaining hook  342 . 
     In  FIG. 13B , the movement of the fluid connector  440  is depicted. The fluid connector  440  causes the levered retaining hook  342  to be levered in a counter-clockwise direction about its levering point. The engagement between the levered retaining hook  342  and the plunger  130  is released. Accordingly, the plunger  130  together with the cannula  120  is moved downwards by the biased spring  220 . 
     Referring now to  FIG. 13C , the plunger  130  comes into contact with the cannula hub  150 , and the cannula  120  is in the operational state. The plunger  130  comprises a septum  462  that is integrated for fluidically connecting the cannula  120 . In the operational state, the septum  462  is aligned with the fluid connector  440  and the cannula  120 , and the biased spring  220  is in an end position (e.g., the biased spring is relaxed). The cannula  120  is secured on the cannula hub  150  by means of a snapping mechanism (not depicted). 
     In  FIG. 13D , the linear movement of the fluid connector  440  is depicted. The connector cannula pierces the septum  462  and establishes a fluidic connection between the fluid connector  440  and the cannula  120  for infusion. The fluid connector  440  and the cannula hub  150  may engage via a latching mechanism (not depicted). 
     In  FIG. 13E , the cannula module  100  is depicted with the inserter module  200  removed. Upon removal of the inserter module  200 , the delivery of insulin can be started. 
     In the embodiments described herein the cannula  120  may be a hollow steel needle with a pointed tip. The cannula  120  may also be a flexible tube. Specifically, the flexible tube may be mechanically supported during insertion by a guiding needle. In embodiments in which a guiding needle is provided, the guiding needle may be retracted once insertion is complete manually or mechanically (e.g., by a second spring). 
       FIGS. 14 to 17  depict a cannula system  10  in which the cannula assembly is triggered by the flow of a medical product or liquid such as insulin into the activation mechanism. 
     A priming procedure may be performed. In one embodiment, the fluid connector  440  and the connection tube to the pump are filled with fluid. The cannula hub  150  comprising an inserter module  200  is attached to the fluid connector  440  and the connection tube. Individual insulin dose amount may be set such that when the cannula assembly  1  is activated an insulin pump dispenses insulin. For example, a user may place the cannula assembly  1  onto the skin of a patient. An “Insert” function may be activated on the insulin pump and the desired individual insulin dose may be set. A few seconds after activating the “Insert” function, the cannula  120  is inserted. It is noted that the individual insulin dose amount may be set before or after insertion of the cannula  120 . Insulin pumps are typically pre-programmed such that the pump merely has to be started in order to initiate insulin dispensation, i.e., performed automatically at the end of the priming procedure. 
       FIGS. 14A and 14B  depict an embodiment in which the cannula assembly  1  is triggered by a fluid acting on the activation mechanism (a spongy element  330 ). An inserter module  200  comprises a biased spring  220 .  FIG. 14A  depicts a pre-operational state of the cannula  120 , and  FIG. 14B  depicts an operational state of the cannula  120 . 
     In the depicted embodiment, a retaining hook  343  is laterally provided and holds the biased spring  220  in a biased state. Inserting the fluid connector  440  levers the retaining hook  343 , and the cannula  120  is then injected. The fluid connector  440  also locks the cannula  120  in place. 
     When fluid such as insulin is supplied, the fluid acts on the spongy element  330 . The spongy element  330  becomes soft and a biased elastic element  320  such as, for example, a flexible seal made of a material such as silicone rubber, is inverted. The inversion triggers the activation or insertion mechanism. The retaining hook  343  and the inserter body  240  are chamfered. The inserter body bends the retaining hook  343  (to the left in  FIG. 14A ) and allows the plunger  130  to move downwards and pass the retaining hook  343  without being blocked. 
     The cannula assembly  1  may be integral with the inserter module  200  and placed on an administration site such as the skin of a patient. The fluid connector  440 , which has been filled with insulin beforehand, may be attached to the cannula hub  150 . The insulin delivery device or pump may be activated to start insulin flow. The insulin flow triggers the insertion of the cannula  120 . After the insertion of the cannula  120 , the inserter module  200  can be decoupled from the cannula hub  150 . The inserter module  200  can be disposed at the start of an insulin infusion procedure. 
     In practice, the priming procedure can be carried out in three steps: (i) the tubing and the fluid connector  440  are primed, in a detached state, in a first priming step; (ii) the fluid connector  440  is attached; (iii) a second priming procedure is carried out in order to fill the cannula with insulin e.g. after activating the “Insert” function of the insulin pump. Only in step (iii) is the spongy element  330  wetted and the insertion of the cannula  120  triggered. The amount of insulin employed in the second priming procedure should not exceed the amount needed to fill the cannula, in order to prevent additional insulin being unintentionally administered to the patient. 
     In this embodiment, the insertion of the cannula  120  is triggered by the insulin which flows into the cannula assembly  1  from the insulin pump, wherein the insulin pump serves as the trigger device. 
     In the pre-operational state, the biased spring  220  is held in a compressed state by a retaining hook  343 , as described above. The retaining hook  343  is supported by the biased elastic element  320  connected to the spongy element  330  in the fluid connector  440 . When insulin flows into the fluid connector  440  of the cannula module  100 , the spongy element  330  is structurally weakened such that it can no longer support the biased elastic element  320 . Accordingly, the spongy element  330  causes the biased elastic element  320  to change its state, such that the engagement between the plunger  130  and the retaining hook  343  is released. 
       FIGS. 15A and 15B  depicts another embodiment wherein the cannula assembly  1  is triggered by a fluid or liquid acting on a biased elastic element  320  such as a bistable elastic element. Once insulin has been transferred into the cannula hub  150  and a certain pressure has accumulated, the biased elastic element  320  is inverted outwards and triggers the inserter module  200 .  FIG. 15A  depicts the pre-operational state of the cannula  120 , and  FIG. 15B  depicts the operational state of the cannula  120 . 
       FIGS. 16 and 17  depict additional embodiments wherein the cannula assembly  1  is triggered by a fluid or liquid acting on a shiftable plug  365 . For example, when insulin is transferred into the cannula hub  150 , the shiftable plug  365  is moved and triggers the inserter module  200 . The triggering releases the lock on the biased spring  220 , and moves the cannula  120 . In one embodiment, the quantity of insulin which is transferred in the course of the “Insert” function corresponds to the filling volume of the fluid channel and cannula  120 . 
       FIGS. 16A and 17A  depict a pre-operational state of the cannula  120 , and  FIGS. 16B and 17B  depict the operational state of the cannula  120 . 
     As depicted in  FIGS. 14 to 17 , embodiments of the cannula  120  comprise a lateral opening  121  which in the operational state of the cannula  120  is positioned so as to be in fluid communication with the fluid connector  440 . When the lateral opening  121  is in fluid communication with the fluid connector  440 , fluid or liquid can flow through the fluid connector  440 , via the lateral opening  121  into the cannula  120 . 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and the scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modifications and variations come within the scope of the appended claims and their equivalents.