Memory wire terminator with spring contacts

A container for use in a dispensing system is disclosed. The container comprises a body, a linkage element movably attached to the body, a control module, and an actuator comprising a memory wire having a length and a terminator that is attached to the memory wire. The linkage element has a first position and a second position, and the actuator is mechanically coupled to the linkage element. The control module is attached to the body and comprises a contact element. The terminator is attached to the body and electrically coupled to the contact element, wherein the electrical coupling between the memory wire and the contact element is mechanically compliant such that the position of the terminator relative to the body is invariant when the position of the control module relative to the body varies.

BACKGROUND

The present disclosure generally relates to systems and methods for dispensing items and, in particular, systems having individually actuated lidded compartments.

2. Description of the Related Art

Dispensing of medications using Automated Dispensing Machines (ADMs) has become common in hospitals around the world. The benefits include a reduction in the amount of pharmacist labor required to access the medications as well as enabling nurses to obtain the medications faster as many ADMs are located at the nursing stations. ADMs also provide secure storage of medications, particularly controlled substances, as users must typically identify themselves and the patient to whom the medication will be administered before the ADM will allow access to the medication.

One of the challenges of ADMs is providing controlled access in a space-efficient manner. Providing access to a single item, whether in quantity or to only a single dose, reduces the risk that the user might select the incorrect item. Single-dose access is particularly desirable when the item is valuable or has a potential for abuse, such as a controlled substance. Minimizing the volume occupied by the mechanisms of the ADM maximizes the volume available for storage of the items themselves.

The technology of ADMs is applicable to a wide range of non-medical applications, such as dispensing of consumable cutting tools in a machine shop or tracking of tools while working on an aircraft engine where it is critical to ensure that no tool has been left in the engine. Applications where inventory control is a concern or where the identity of the user must be authenticated prior to allowing access to the contents of the storage system are candidates for the use of ADM technology.

Memory wire, also known as “muscle wire”, can be made from a range of alloys generally known as “shape memory alloy.” Memory wire has been used in a wide variety of applications including medical devices and dispensing technology. Medical devices that incorporate shape memory alloy include stents, specialty guidewires, and laparoscopic surgical sub-assemblies. The Pyxis CUBIE® pockets from CareFusion use a memory wire actuator to release the lid of the pockets as disclosed in U.S. Pat. No. 6,116,461.

SUMMARY

Containers having a memory wire actuator disclosed herein provide an elegant and secure method of dispensing items such as medications. The container may be loaded at a remote location such as a pharmacy and securely transported to the ADM by a non-pharmacist and quickly loaded into the ADM, saving pharmacist time and improving the availability of the ADM to nurses. As a memory wire actuator is small compared to a solenoid and other electric actuators, the container provides single-dose dispensing capability in a space-efficient manner.

A container is disclosed according to certain embodiments. The container comprises a body, a linkage element that is movably attached to the body, a control module that comprises a contact element, and an actuator comprising a memory wire having a length and a terminator that is attached to the memory wire. The linkage element has a first position and a second position. The actuator is mechanically coupled to the linkage element. The control module is attached to the body. The terminator is attached to the body and electrically coupled to the contact element. The electrical coupling between the memory wire and the contact element is mechanically compliant such that variation in the position of the control module relative to the body does not cause variation in the position of the terminator relative to the body.

A container is disclosed according to certain embodiments. The container comprises a body, a linkage element attached to the body, a memory wire having a length, and a biasing element configured to apply a tensile force to the memory wire. The linkage element has a first position and a second position. The memory wire is configured such that a reduction in the length of the memory wire causes the linkage element to move away from the first position towards the second position. The force applied by the biasing element is reduced as the linkage element moves from the first position towards the second position.

A container is disclosed according to certain embodiments. The container comprises a body, a linkage element rotatably attached to the body, the linkage element having a first position and a second position, a sliding element slidably attached to the body along an axis fixed relative to the body, the sliding element coupled to the linkage element, and an actuator comprising a memory wire having a length and a terminator attached to the wire. The actuator is mechanically coupled to the sliding element. The terminator is attached to the body. The memory wire is substantially parallel to the axis of motion of the sliding element. A reduction in the length of the memory wire will cause the linkage element to move from the first position to the second position.

An ADM is disclosed according to certain embodiments. The ADM comprises a container and a dispensing machine. The container comprises a body, a linkage element movably attached to the body, a control module attached to the body, and an actuator comprising a memory wire having a length and a terminator that is attached to the memory wire. The linkage element has a first position and a second position. The actuator is mechanically coupled to the linkage element. The control module comprises a connector and a contact element. The terminator is attached to the body and electrically coupled to the contact element. The electrical coupling between the memory wire and the contact element is mechanically compliant such that motion of the control module does not cause motion of the terminator. The actuator is configured such that a reduction in the length of the memory wire will cause the linkage element to move from the first position to the second position. The control module is configured to accept a control signal through the connector and cause the linkage element to move to the second position in response to the control signal. The dispensing machine comprises a housing, a drawer mounted within the housing, the drawer configured to receive the container, the drawer comprising a docking connector that mates to the connector of the container when the container is received in the drawer assembly, and a processor coupled to the docking connector, the processor configured to transmit the control signal to the container via the docking connector.

A method of dispensing items is disclosed according to certain embodiments. The method comprises the steps of loading at least one item into a container comprising a body having an internal volume with an opening and a lid that is moveably attached to the body and releasably secured over the opening by a linkage element coupled to an actuator that comprises a memory wire, loading the container into a drawer of an automatic dispensing machine (ADM), requesting the item to be accessed from the ADM; and opening the lid of the container that contains the item.

DETAILED DESCRIPTION

Pharmacists are under increasing pressure to better manage the medications that are provided to nurses and other caregivers in a medical facility. There is an increasing level of regulation, particularly for controlled substances, related to the handling and tracking of medications. Many of these regulations require a pharmacist to perform certain checks on medications, increasing the workload of a pharmacist. Controlled substances, which may include medications listed on Schedules I-V of the Controlled Substances Act, are a particular focus of regulatory requirements for monitoring and control. In addition, many hospitals cannot find pharmacists to fill open positions, placing greater burdens on the pharmacists that are on the hospital staff. There is therefore a need to manage medications with a reduced amount of pharmacist time.

Memory wire actuators are well suited to use in small dispensing systems. The memory wire actuators are small compared to alternate actuators such as solenoids and motors, and simple to operate. A common method of energizing a memory wire actuator is to pass a current through the memory wire. The energy dissipated by the electrical resistance of the memory wire heats the wire and induces the phase change that causes the memory wire to contract. Removal of current allows the memory wire to expand to its original length. Current applications of memory wire actuators have a number of challenges including low output force, low actuation travel, and sensitivity to tolerances in the installation.

Memory wire is sensitive to the conditions under which it is used. To achieve the full potential force, travel, and cycle life of the memory wire requires careful attention to, among other factors, the type of motion and preload force. Bending of the memory wire during an operational cycle may lead to early failure of the memory wire. Existing memory wire actuators that are used as part of a mechanism are terminated to printed circuit board assemblies (PCBAs). The PCBAs are then attached to the same structure to which the other elements of the mechanism are attached, adding tolerances in the relative positioning of the PCBA to the elements of the mechanism. If multiple memory wire actuators are attached to a single PCBA, the system is further constrained resulting in additional tolerances added to multiple parts of the mechanism. Existing memory wire designs frequently are configured to induce bending of the memory wire as it contracts, resulting in fatigue and a reduced operational life. In addition, the tension applied to the memory wire over the operational stroke of actuation can vary significantly, varying from a zero-tension condition to conditions where the preload consumes most of the available actuation force of the memory wire.

The disclosed container and ADM provide a reliable and secure system and method of storing and dispensing items especially medications. Certain exemplary embodiments of the present disclosure include a container having an actuator that comprises a memory wire and a terminator, wherein the terminator is attached to the body of the container rather than the drive electronics.

While the discussion of the system and method is directed to the dispensing of medications in a hospital, the disclosed methods and apparatus are applicable to dispensing of medications in other environments as well as the dispensing of other types of items in a variety of fields. For example, machine shops frequently have a tool crib staffed by an individual to provide cutters, drills, and other consumable supplies to the machinists without providing uncontrolled access to the stock of tools and parts. An ADM may be stocked with these consumables and used in place of the tool crib to provide these items to the machinists in a controlled and traceable manner. Similarly, items such as an expensive specialty tool may be removed by an individual for use and returned to the same compartment after use, enabling the tool to be tracked and making a single tool available to multiple people.

FIG. 1is a drawing of an ADM for use in medical facilities. This example ADM10includes a plurality of drawers12, some of which may be configured to receive dispensing cartridges (not shown). This configuration of an ADM10is often referred to as a cabinet, which includes a housing11, multiple drawers12, a variety of electronics and controls (not shown), and the user interface. The user interface of the ADM10includes a display16and a keyboard14so that a user, such as a nurse, may identify which medication they wish to remove from the ADM10. The embodiments of the present disclosure may be employed with an otherwise conventional ADM10, with a change in the drawer configuration.

FIG. 2illustrates a drawer of an ADM configured to accept secure lidded containers according to certain embodiments of the present disclosure. The drawer12is shown installed in housing11. A container20is shown separate from the drawer12, wherein the space18is configured to accept container20. Other containers20of various sizes are shown installed in drawer12.

FIG. 3depicts an example configuration of the internal construction of a secure lidded container20according to certain embodiments of the present disclosure. Container20comprises a body24with a lid22that, in this example, is hingedly attached to the body24. Lid22includes a fastening element that, in this example, is a hook23. When lid22is closed, hook23protrudes downward and is engaged by linkage element34that, in this example, is a latch. Torsion spring36applies a counterclockwise torque, in this example, to linkage element34that rotates linkage element34towards the closed position wherein the tip of linkage element34engages the hook23and keeps lid22closed and secured.

Container20also includes a sliding element38that engages linkage element34such that a right-to-left movement of sliding element38will, in this example, cause a clockwise rotation of linkage element34thereby releasing the hook23. Sliding element38is attached to body24by sleeve40which constrains sliding element38to move only along a single axis that, in this example, is horizontal and parallel to the front face of the body24.

Actuator25comprises a memory wire26that wraps around a portion of sliding element38and is terminated at each end by a terminator28. In this example, the lengths of memory wire26between the sliding element38and the respective terminators28are approximately parallel to the direction of motion of sliding element38such that contraction of the memory wire26does not cause a bending of the memory wire between the terminators28and the sliding element38. A second biasing element42is attached to the body24and applies a force to sliding element38in the direction that places the memory wire26in tension. It is desirable to maintain memory wire26in tension over the entire cycle of operation to provide the maximum operational life.

Memory wire, also know as muscle wire, is made from a shape memory alloy (SMA). The three main types of shape memory alloys are the copper-zinc-aluminum-nickel, copper-aluminum-nickel, and nickel-titanium (NiTi) alloys although SMAs can also be created by alloying zinc, copper, gold, and iron. NiTi alloys are generally more expensive and change from austenite to martensite upon cooling. The transition from the martensite phase to the austenite phase is only dependent on temperature and stress, not time as most phase changes are, as there is no diffusion involved. It is the reversible diffusionless transition between these two phases that allow the special properties to arise. Use of memory wire as an actuator is very space efficient.

Heating of the memory wire26is induced, in this example, by passing electrical current through the memory wire26itself The container20includes a control module32that, in this example, is a PCBA. The control module32controls the flow of current through the memory wire26. The terminators28are mechanically captured in a socket30that is part of body24while the electrical connection between terminators28and control module32is accomplished through spring elements that are part of the terminators and which will be discussed in more detail below. The control module32is attached to the body24and a cover (not shown) is attached over the control module32to protect the control module32and the other components.

Memory wire will typically exhibit a length change of under 5% when heated. Because this working motion is so small, it is important to minimize tolerances in the assembly of the actuator and the mechanism to which the actuator is coupled. for example, a one-inch length of memory wire will only produce 0.050 inches of motion. This working range would be effectively eliminated if there are five +/−0.005 tolerances between the terminators of the memory wire and the portion of the mechanism to which the memory wire actuator is attached. In the example similar to that ofFIG. 3, if the terminators28are mechanically attached to PCBA32, and PCBA32is then attached to the body24of the container20, at least three tolerances (terminator attach point to mounting hole on the PCBA32, variation in the mounting hole, and position of the mounting hole to the attachment point on the body24). Thus, the direct and fixed attachment of the terminators28to the body24reduces the total variation between the actuator25and linkage element34, increasing the stroke and force available to secure and release the lid22.

In operation, container20is placed in drawer12as shown inFIG. 2, whereupon a control signal and power connection are made between the control module32and the electronics of the ADM10. When it is desired to provide access to the contents of container10, a signal is transmitted from the electronics of ADM10to the control module32, which then causes electrical current to pass through the memory wire26. As the temperature of the memory wire26increases, the length of the memory wire26is decreased. This decrease causes the sliding element38to move to the left, which in turn pushes on the lower portion of linkage element34causing linkage element34to rotate clockwise. At some point, the linkage element will release hook23and lid22is free to open. Upon receipt of a signal that the lid is open or after a fixed amount of time, the control module32will stop the current from flowing through memory wire26, causing the memory wire26to cool and therefore increase in length. As the length of memory wire26increases, biasing elements42and36will take up the slack and cause sliding element38and linkage element34to return to their original positions.

FIG. 4Adepict a partially exposed perspective view of a multi-lidded cartridge50having individual actuators according to certain embodiments of the present disclosure Cartridge50has multiple bins, each bin having a lid22. In this example, each lid is associated with an individual memory wire actuator25.

FIG. 4Bdepicts an enlarged side view of a portion of the cartridge ofFIG. 4Aaccording to certain embodiments of the present disclosure. In this configuration of cartridge50, terminators28are attached to the memory wire26at an angle to the memory wires26. This angled attachment enables a more compact arrangement of the various components of container50. The linkage element34and sliding element38are substantially similar to the embodiment ofFIG. 3, although sleeve40has been omitted for clarity inFIG. 4B. The mechanism sets are overlapped between adjacent bins to allow the use of a longer memory wire26than would be possible if the length of memory wire26were restricted to the length of a single bin. A longer memory wire26may provide a higher actuation force, a greater range of motion, or a longer operational life, depending on the specific design.

FIG. 5illustrates an example configuration of the memory wire terminator28and the mating contact element52of the control module32according to certain embodiments of the present disclosure. In this perspective view of the side of cartridge50, a portion of control module32has been cut away to show the connection between actuator25and control module32. Control module32has two pins that form the contact elements52. As can be seen inFIG. 5, these contact elements are forced between the spring elements of terminators28when the control module32is mounted over the mechanism and attached to body24.

FIG. 6Aillustrates an example configuration of a memory wire actuator25according to certain embodiments of the present disclosure. It can be seen that, in this example, terminators28are crimped onto each end of memory wire26. Each terminator28includes two terminal pads54located on conductive elastic elements56that are mechanically compliant in a direction perpendicular to the plane of the main portion of terminator28.

FIG. 6Bdepicts a partially exposed view of the memory wire actuator25ofFIG. 6Ainstalled in a secure lidded container, illustrating the compliant coupling between the actuator terminator28that is fixedly attached to the body24of the container and a flat mating contact element56of the control module32according to certain embodiments of the present disclosure. The main portions of terminators28are mechanically captured in socket30on the body24. This direct and fixed attachment of the terminators28to the body24of the container reduces the variation in the position of the memory wire actuator25relative to the other elements of the release mechanism to which the memory wire actuator25is coupled. The electrical connection between the memory wire26and control module32is established when control module32is attached to body24. The contact pads64, which are flat plated areas on the surface of control module32that are visible at the edge of the cut-away area, contact the terminal pads54and deform the conductive elastic elements56. The stress induced by the deformation of elastic conductive elements56creates contact force between the terminal pads54and the contacts pads64on control module32. The position of terminators28is invariant when the position of control module32varies due to manufacturing and assembly tolerances.

FIGS. 7A-7Billustrate an example configuration of a memory wire actuator25used to retain a cartridge20of the type shown inFIG. 3in a drawer12according to certain embodiments of the present disclosure.FIG. 7Adepicts a drawer12having a plurality of trays58lining the bottom interior. These trays are configured with holes60(shown only for the position58A corresponding to the cartridge20for clarity) that are configured to accept legs21of cartridge20.FIG. 7Bis a view of the underside of position58A of tray58fromFIG. 7A. The four holes60accept the four legs21(not shown) to align the cartridge20(not shown) with the position58A. A latch62engages the retention feature (not shown) of cartridge20when in place. Memory metal actuator25is attached to the tray58, wherein the terminators28are secured in sockets30similar to the configuration shown inFIG. 3. The memory wire26wraps around a sliding element38similar to that ofFIG. 6, wherein contraction of the memory wire26will pull the sliding element38upwards, in the orientation of this view, pushing latch62upwards and releasing the retention feature of cartridge20. Spring element64provides a downward force, in the orientation of this view, to return the latch to the engaged position. In this embodiment, additional spring elements65provide a downward force on sliding element38A independent of spring element64. This enables latch62to slide upward, in the orientation of this view, when the retention feature of cartridge20is introduced through hole66without releasing the tension on memory wire26. A PCBA (removed for clarity) covers this area, wherein the position of contact pads64are shown in outline for reference. As discussed relative toFIG. 6B, the sliding contact between the terminators28and contact pads64decouples the position variation of the PCBA from the position of the memory wire actuator25, reducing the tolerance accumulation and improving the range and force available to actuate the latch62.

FIG. 8is a flowchart describing the method of using a container20with a memory metal actuator25to access an item using an ADM10according to certain embodiments of the present disclosure. In step105, the item is loaded into a container20having a body24with an internal volume and a lid22movably attached and releasably secured over the opening of the internal volume, wherein the lid22is secured by a linkage element34coupled to a memory wire actuator25having a terminator28that is attached to the body24of the container20. Container20ofFIG. 3is an example of such a container. In step110, this container20is transported to an ADM10and loaded into a drawer12that is configured to receive the container20. In step115, a user who desires to remove the item comes to the ADM10and requests the item. In a hospital environment, this request may include identification of the user, identification of the patient, and other safety checks and protocols that are known to those of skill in the art. Upon the satisfactory completion of the request process, the ADM10transmits a control signal to the container20in step120to open the lid22of the container20. The container20will energize the memory wire26in the memory wire actuator25by, in this example, passing electric current through the memory wire26. This causes the memory wire26to shrink, reducing the length of the memory wire26and exerting a force on the linkage element34to which the memory wire actuator25is coupled. This force causes the linkage element34to move from a first position, where the linkage element secures lid22, to a second position, where the linkage element releases lid22as shown in step130. In step135, the lid22is opened, which may be accomplished by either by the user or by a spring. After the lid22is opened, the current to the memory wire26is stopped, de-energizing the memory wire26and allowing the memory wire26to expand to its original length and returning the linkage element34to its original position. The opening of the lid22may be detected directly by a sensor or a timer may be used to stop the current after the maximum expected delay time for the user to open the lid22. In step145, the user removes the item and, in step150, closes lid22.

It can be seen that the disclosed embodiments of memory wire actuator provide an elegant and space-efficient actuation system that is particularly suited for controlled dispensing of items. Attachment of the memory wire terminators to the body of the container while providing compliant electrical connection to the control module eliminates several sources of variation in the construction of an actuation mechanism, increasing the available force and stroke of the actuator while also improving the operational life. Reduction in the bending of the memory wire during operation also will improve the operational life of the actuator.

While the disclosed configuration of an ADM has been directed to a drawer into which a container is placed, this same technique of design can be applied to any actuator that comprises a memory wire. The drawer may be replaced by a flat mounting surface, a portable attachment surface, or other operationally equivalent surfaces that provide for a power and communication connection to the container. This same method of terminating and attaching memory wires may also be employed in a battery-powered system that communicate wirelessly such that the container is fully functional while unconnected.

A phrase such as an “aspect” does not imply that such aspect is essential to the subject technology or that such aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. A phrase such as an aspect may refer to one or more aspects and vice versa. A phrase such as an “embodiment” does not imply that such embodiment is essential to the subject technology or that such embodiment applies to all configurations of the subject technology. A disclosure relating to an embodiment may apply to all embodiments, or one or more embodiments. A phrase such an embodiment may refer to one or more embodiments and vice versa.