Patent Description:
Moving small quantities of fluid in ambulatory devices is challenging due to the limited feedback on the fluid that is received after the motors have turned. When pushing fluid with a syringe type of disposable pump system, for instance, although the motion of the motor can be determined, friction between a rubber plunger and a barrel of a syringe may create problems where the entire drive unit tightens but the plunger does not move thereby no fluid is delivered to the patient. This effect, commonly called stiction, can be minimized with silicon oil. However, this oil may infuse into patients such as people with diabetes. Such diabetes patients are continuously on such pumps creating unknown potential health issues. In addition, the use of such oil has been shown in some studies to compromise the stability and storage life of insulin. Lead screws and gearboxes of such plunger based pumps must have clearances between mating parts creating backlash that contributes to variability in the system as it attempts to consistently deliver liquid down to the microliter level even though the pump could be in very different positions due to the motion of the person. Mini peristaltic motors have been developed as well but the variability in the flexible tubing and affects from changes in ambient conditions may also make accurate microfluidic delivery difficult. Although a reciprocating piston pump was developed by <CIT> to minimize these effects with a small bore syringe that refills from time to time, the cost of this approach has been high making commercial viability difficult.

In high liquid volume pumping applications, check valves open at its cracking pressure, deliver fluid, then close when pressure is reduced are often used. Dispensing a minimum amount of liquid required for micro delivery has been a persistent problem within the industry when using such standard check valves because the minimum amount of liquid delivered upon achieving the cracking pressure may be too much volume for micro delivery applications. Peristaltic type of delivery, pressing on tubing and pulling fluid from the container when the tubing returns to round and alternately pushing it towards the patient has also been used but variability in tubing both in manufacturing and during delivery has plagued the accuracy of this approach.

Small orifice restrictors often made of glass or rubies are often used where the fluid pressure is kept relatively constant and the small orifice controls the flow rate of the liquid. There is a linear relationship between the pressure and the flow rate making the control of flow relatively straightforward. Controlling pressure however is a difficult task as is the case of rubber balloon devices where the rubber contracts with variable pressure. Also these small orifice restrictors are expensive and may be plagued with blockage from particulate and air bubbles. What have been needed are methods and devices for accurately pumping microliter size quantities of liquid to a patient with a broad range of flow rate and low cost.

<CIT> discloses a dosing pump that can be worn on the body of a patient for subcutaneously delivering liquid with centi-micro liter accuracy to his/her body. The dosing pump comprises a pump unit, an internal control unit; and a reservoir containing the liquid. The pump unit comprises a pump block comprising a pump chamber with a pump diaphragm stretched across its entrance and a pump pin cylinder extending from the exterior of the pump block to the entrance to the pump chamber; a pump pin that is located in the pump pin cylinder and a motor unit comprising a motor and gear system. When the motor is activated, the rotational motion of the motor and the gears in the gear system is transformed into cyclic back and forth linear motion of the pump pin in the pin cylinder pumping the liquid from the reservoir into the patient. Unlike standard piston pumps, the pump diaphragm is not attached to the pump pin and the only force required to be exerted by the motor is to move the pin back and forth and not to pull the diaphragm back, i.e. in the present invention the force required to create the suction is provided by the internal energy stored in the stretched diaphragm and not by the mechanism that moves the piston.

<CIT> discloses a method of dispensing a therapeutic fluid from a line includes providing an inlet line connectable to an upstream fluid source. The inlet line is in downstream fluid communication with a pumping chamber. The pumping chamber has a pump outlet. The method also includes actuating a force application assembly so as to restrict retrograde flow of fluid through the inlet while pressurizing the pumping chamber to urge flow through the pump outlet. A corresponding system employs the method.

<CIT> discloses a fill adapter for filling a reservoir. The fill adapter includes a button assembly actuator and a pump chamber plunger actuator hingably attached to the button assembly actuator, wherein the actuation of the button assembly actuator actuates the pump chamber plunger actuator and wherein the pump chamber plunger actuator actuates a pump chamber membrane before the at least one button assembly is actuated.

The invention is set out in appended claim <NUM>.

Some embodiments (non-claimed) of a medical pump for delivering fluid to a patient may include a pump cavity which is surrounded by a rigid wall and which includes a diaphragm opening. A diaphragm may be disposed over and sealed to the diaphragm opening of the pump cavity. The medical pump may also include a pump chamber defined by an inside surface of the rigid wall of the pump cavity and an inside surface of the diaphragm which disposed over and sealed to the pump cavity. A pressure actuator may include a piston with a distal end that is operatively coupled to the diaphragm. In addition an inlet conduit may also be disposed in fluid communication with the pump chamber. A check valve may be operatively coupled to the inlet conduit and may also be oriented to allow a flow of liquid to the pump chamber but prevent a flow of liquid from the pump chamber back towards the check valve. An outlet conduit may be disposed in fluid communication with the pump chamber and an outlet port disposed in fluid communication with the outlet conduit. The medical pump may optionally further include a flow control valve which is operatively coupled to the outlet conduit between the pump chamber and the outlet port. Embodiments of the flow control valve may further include a rigid base having a top surface with an upstream orifice and a downstream orifice and a distensible membrane secured to the top surface of the rigid base in sealed relation relative to the upstream orifice and the downstream orifice so as to be in close approximation with the top surface of the rigid base forming a sealed distensible channel between the upstream and downstream orifices that is normally closed.

Some embodiments (non-claimed) of a method of pumping a liquid from a medical pump to a patient may include actuating a motor of a pressure actuator and advancing a piston of the pressure actuator into a diaphragm of a pump chamber of the medical pump such that an inside surface of the diaphragm intrudes into the pump chamber thereby increasing an internal pressure within an interior volume of the pump chamber and expelling liquid from the pump chamber through an outlet conduit. The method may also include flowing the liquid expelled from the pump chamber through the outlet conduit and into a distensible channel of a flow control valve which is normally closed. The flowing of the liquid into the distensible channel results in stretching a distensible membrane of the flow control valve and expanding the distensible channel to allow a flow of the liquid through the flow control valve and out of an outlet port of the outlet conduit.

According to the invention a medical pump for delivering fluid to a patient includes a pump cavity which is surrounded by a rigid wall, the pump cavity further including a diaphragm opening. A diaphragm is disposed over and sealed to the diaphragm opening of the pump cavity forming a pump chamber which is defined by an inside surface of the rigid wall of the pump cavity and an inside surface of the diaphragm which disposed over and sealed to the pump cavity. A pressure actuator includes a piston with a distal end that is operatively coupled to the diaphragm. The medical pump further includes an outlet conduit which is in fluid communication with the pump chamber and an outlet port which is in fluid communication with the outlet conduit. A flow control valve is operatively coupled to the outlet conduit between the pump chamber and the outlet port, the flow control valve further including a rigid base having a top surface with an upstream orifice and a downstream orifice and a distensible membrane secured to the top surface of the rigid base in sealed relation relative to the upstream orifice and the downstream orifice so as to be in close approximation with the top surface of the rigid base forming a sealed distensible channel between the upstream and downstream orifices that is normally closed and being created by joining the distensible membrane film to the top surface of the rigid base.

Some embodiments (non-claimed) of a method of pumping a liquid from a medical pump to a patient may include actuating a motor of a pressure actuator and advancing a piston of the pressure actuator into a diaphragm of a pump chamber of the medical pump such that an inside surface of the diaphragm extends into the pump chamber and intrudes into the interior volume of the pump chamber so as to increase a pressure within an interior volume of the pump chamber and expel liquid from the pump chamber into an outlet conduit. The method may also include flowing the liquid expelled from the pump chamber into the outlet conduit and into a distensible channel of a flow control valve which is normally closed. The flowing of the liquid into the distensible channel results in stretching a distensible membrane of the flow control valve and expanding the distensible channel to allow a flow of the liquid through the flow control valve and out of an outlet port of the outlet conduit.

Some embodiments (non-claimed) of a method of welding a distensible membrane to a rigid base of a pump cavity may include positioning the distensible membrane onto a top surface of the rigid base such that an inside surface of the distensible membrane is in contact with the top surface of the rigid base. Thereafter, a layer of rigid material, that may optionally include a rigid material, may be positioned onto an outside surface of the distensible membrane over an area between the distensible membrane and rigid base to be welded. The method may further include applying pressure to the distensible membrane in a direction towards the rigid base thereby approximating the inside surface of the distensible membrane with the top surface of the rigid base and transmitting electromagnetic energy through the layer of rigid material and onto the distensible membrane until the distensible membrane and rigid base melt and form a fluid tight weld zone. In some cases, the layer of material may be positioned so as to provide a predetermined minimum pressure on the distensible membrane prior to welding so as to adjust the pressure required to open the distensible membrane and thereby the cracking pressure and minimal dispensed volume of liquid.

Certain embodiments are described further in the following description, examples, claims and drawings. These features of embodiments will become more apparent from the following detailed description when taken in conjunction with the accompanying exemplary drawings.

The drawings are intended to illustrate certain exemplary embodiments and are not limiting. For clarity and ease of illustration, the drawings may not be made to scale and, in some instances, various aspects may be shown exaggerated or enlarged to facilitate an understanding of particular embodiments.

In some cases, medical pump embodiments discussed herein may include the use of a flow control valve that combines the functions of a check valve opened by pressure applied to the check valve and a flow restrictor where a flow rate may be determined by the liquid pressure differential across each of the sides of a restriction caused by the flow restrictor. Since the flow restrictor may be flexible in this case, the flow rate may also be determined by the elastic properties of the material used to create the flow restrictor. By simply creating air pressure against a flexible liquid chamber filled with a fluid and measuring the air pressure response to the change in liquid volume, flow feedback may be achieved. Such a device and process may have significant safety and cost advantages over the present art since the control may easily be done by measuring and controlling an air pressure response to a pressure influence through a flow restrictor/check valve in the liquid chamber. The air chamber may optionally be open to the atmosphere to provide altitude feedback and replace a volume of liquid that has been displaced. By combining these two techniques of simple pressure pumping and using low cost materials, such a configuration may have significant cost and performance advantages over the present art.

Methods of creating low cost medical pump embodiments <NUM> are discussed herein that may allow, for instance, a bioactive material such as a medicament or any other desired liquid <NUM>, to be delivered to a patient with precision. In general, the medical pump embodiments discussed herein may be used to administer liquids to a patient such as insulin, antibiotics, saline, dextrose or any other useful liquid used to treat or otherwise assist a patient. Any of the medical pump embodiments discussed herein may be adapted for use as portable insulin pumps such as patch pumps or the like for use by diabetic patients. For some embodiments, a rigid liquid pump chamber <NUM> with a flexible film diaphragm <NUM> on a least one side of the fluid is envisioned having an air space of a pump chamber <NUM> between the liquid chamber and the flexible film as shown in <FIG>. Operating a motor <NUM> of a pressure actuator <NUM> such as by displacing an airtight diaphragm <NUM> of a speaker, as an example, may be used to create this air pressure.

The amount of air displacement may be varied as a function of the voltage that is applied to the coil <NUM> of the speaker <NUM>. As this liquid flows under pressure though the check valve/variable flow restrictor which is exemplified in the embodiment of <FIG> as a flow control valve <NUM>, the quantity of liquid displaced may be replaced by the reduction in the air and thereby the pressure. For short bursts of air pressure the check valve may be used to displace a very small quantity of liquid. In some cases, the amount of liquid that is delivered may be selected by the magnitude of displacement of the speaker <NUM> and the amount of time the speaker is displaced. The air pressure may be measured with a pressure sensor <NUM> which is in fluid communication with the liquid chamber <NUM> and using Boyles Law the quantity of liquid displaced may be calculated. Upon reaching a point of sufficient or desired liquid displacement, power to the coil <NUM> of the speaker <NUM> may be terminated and the system returns to equilibrium.

To replace the displaced liquid <NUM> and bring the air pressure back to room level with outside ambient air pressure, a standard currently available flexible check valve <NUM> may be added with a known cracking pressure. When the air pressure become sufficiently low, this check valve <NUM> will open and allow air to return into the pump chamber <NUM> replacing the liquid <NUM> that has been displaced. Actuating the coil <NUM> of the speaker in reverse may be used to create a further level of vacuum to controllably let air in so this doesn't occur during the liquid flow part of the cycle.

Some embodiments of a medical pump as shown in <FIG> for delivering fluid <NUM> to a patient <NUM> (see <FIG>) may include a pump cavity <NUM> which is surrounded by a rigid wall <NUM>, the pump cavity further including a diaphragm opening <NUM>. The diaphragm <NUM> may be disposed over and sealed to the diaphragm opening <NUM> of the pump cavity forming the pump chamber <NUM> which is defined by an inside surface <NUM> of the rigid wall <NUM> of the pump cavity <NUM> and an inside surface <NUM> of the diaphragm <NUM> which disposed over and sealed to the pump cavity. The pressure actuator <NUM> may include a piston <NUM> with a distal end <NUM> that is operatively coupled to the diaphragm <NUM>. The medical pump <NUM> may further include an outlet conduit <NUM> which is in fluid communication with the pump chamber <NUM> and an outlet port <NUM> which is in fluid communication with the outlet conduit <NUM>. The flow control valve <NUM> may be operatively coupled to the outlet conduit <NUM> between the pump chamber <NUM> and the outlet port <NUM>, the flow control valve <NUM> further including a rigid base <NUM> having a top surface <NUM> with an upstream orifice <NUM> and a downstream orifice <NUM> and a distensible membrane <NUM> secured to the top surface <NUM> of the rigid base <NUM> in sealed relation relative to the upstream orifice <NUM> and the downstream orifice <NUM> so as to be in close approximation with the top surface <NUM> of the rigid base <NUM> forming a sealed distensible channel <NUM> between the upstream and downstream orifices <NUM>, <NUM> that is normally closed.

<FIG> illustrates a medical pump embodiment <NUM>' that may have the same or similar features, dimensions and materials as those of the medical pump embodiment <NUM> of <FIG>. However, pressure actuator <NUM>' has a different configuration and the diaphragm <NUM>' of the medical pump of <FIG> extends completely across the pump chamber <NUM> and makes direct contact with the liquid <NUM> disposed within the pump chamber. As such, there is no air cushion disposed between the liquid <NUM> and the diaphragm <NUM>' and the piston <NUM>' of the motor extends substantially to the level of the liquid <NUM> so as to effectively apply pressure directly onto the liquid through the diaphragm <NUM>'. The flow control valve <NUM> of the medical pump <NUM>' of <FIG> may be the same as the flow control valve <NUM> of the medical pump <NUM> of <FIG>. The valve <NUM> in fluid communication with the air space disposed between the diaphragm <NUM>' and a bulkhead <NUM> which seals the top opening <NUM> of the pump chamber and an ambient atmosphere <NUM> outside the medical pump structure. The bulkhead <NUM> also serves as a mount for the motor of the pressure actuator <NUM>'. Such a valve <NUM> may be used to vent the air space in the pump chamber <NUM> and replace a volume of liquid <NUM> which has been dispensed from the pump chamber <NUM>. The pressure sensor <NUM> is also in operative communication with the air space within the pump chamber <NUM> and may provide pressure measurements that are used to determine the amount of liquid <NUM> which has been dispensed from the pump chamber <NUM>.

Some embodiments of a method of pumping a liquid as shown in <FIG> from the medical pump <NUM> as shown in <FIG> to a patient <NUM> may include actuating the motor of the pressure actuator <NUM> and advancing the piston <NUM> of the pressure actuator <NUM> into the diaphragm <NUM> of a pump chamber <NUM> of the medical pump <NUM> such that an inside surface <NUM> of the diaphragm <NUM> extends into the pump chamber <NUM> and intrudes into the interior volume of the pump chamber <NUM> so as to reduce an interior volume of the pump chamber, increase a pressure within the interior volume of the pump chamber <NUM> and expel liquid <NUM> from the pump chamber <NUM> into the outlet conduit <NUM>. The method may also include flowing the liquid <NUM> expelled from the pump chamber <NUM> into the outlet conduit <NUM> and into the distensible channel <NUM> of a flow control valve <NUM> which is normally closed. The flowing of the liquid <NUM> into the distensible channel <NUM>, as shown in <FIG>, results in stretching a distensible membrane, as shown in <FIG>, of the flow control valve <NUM> and expanding the distensible channel <NUM> to allow a flow of the liquid <NUM> through the flow control valve <NUM> and out of the outlet port <NUM> of the outlet conduit <NUM>.

For some embodiments, a speaker, solenoid, piezo disk, motor, heating coil or any other suitable means may be used as a pressure actuator <NUM> to push on the air creating an increase in pressure within the interior volume to push on the air which then pushes on the liquid <NUM> so as to flow the liquid <NUM> through a distensible channel <NUM> of the flow control valve <NUM> and thereby open the distensible channel <NUM> of the flow control valve <NUM> and allow flow of liquid <NUM> through the distensible channel <NUM>. For some embodiments, a quantity of pressure applied to the liquid <NUM> may be controlled by the displacement of the diaphragm <NUM> shown in <FIG> of the pressure actuator speaker <NUM> by varying the voltage applied to the coil <NUM> of the speaker. By measuring this pressure change the quantity of displacement and liquid flow may be calculated to allow for calibration of the displacing means and verification of proper liquid flow.

Such intermittent actuated liquid flow may be highly variable as a function of the characteristics of a distensible membrane <NUM> of the flow control valve <NUM> versus pressure and the pressure producing capabilities of the speaker <NUM>. At slow flow rates the speaker may actuate slightly to raise the pressure a small amount before the liquid would flow through the distensible channel <NUM> of the flow control valve <NUM>. At higher rates more motion of the speaker cone would allow the speaker to push more liquid <NUM> at a higher rate. By measuring the flow of liquid through measurement of a pressure response preprogramming the size of the cavity and other chambers, the entire system and quantity of liquid flow to a patient's body <NUM> may be calibrated. Further calibration may occur at point where the quantity of fluid <NUM> is known such as when the liquid pump chamber <NUM> is empty of liquid <NUM>, full or when the known amount of liquid <NUM> is entered.

Another embodiment of returning air to the liquid pump chamber <NUM> may include use of a small orifice as the valve <NUM> that is always open between the air-filled portion of the liquid pump chamber <NUM> and the ambient atmosphere <NUM>. A pressure change due to displacement of air may be measured and controllably decay over time. By using Pouiselle's law of flow through the small orifice <NUM>, the amount of liquid displaced may be determined as a function of the pressure differential. This may then be subtracted from the pressure decay during flow to determine the air displacement and thereby the quantity of liquid that has been dispensed out of the pump to a patient's body <NUM>. The small orifice <NUM> may be factory calibrated or by blocking the distensible channel <NUM> using an alternative pressure actuator so that the orifice can be calibrated with an actuation of the speaker <NUM> and subsequently subtracted from the flow to the liquid when the distensible channel <NUM> is opened. This calibration and redundancy phase is essential to creating a fail-safe product. For other embodiments, this alternative pressure actuator <NUM> such as a vibrator motor for example, may be added to a product for redundant control of flow and calibration of every new set that is added to the hardware.

For a medical pump embodiment <NUM> using a vibrator motor, each pressure wave generated by the motor <NUM> may send air and liquid out of the system, each return of the diaphragm <NUM> may thus return both to the system. In some cases, the characteristics of the check valve of the flow control valve <NUM> may prevent this return allowing the system to return only air to the liquid pump chamber <NUM>. Therefore, the pressure sensor <NUM> may be measuring flow and air leakage for a known liquid pump chamber size and a known air volume. All that is needed is to characterize the speaker properties with a known volume of air. This can be done, for example with an empty liquid pump chamber <NUM> to verify calibration either at the factory or with a known empty liquid chamber as verification at the end of each usage or with a liquid pump chamber <NUM> with a known quantity of liquid <NUM>.

Distensible membrane based flow control valve embodiments <NUM>, as shown in <FIG>, may be closed under low pressure but flex as a function of the pressure applied to the distensible membrane <NUM> from within the distensible channel <NUM> allowing it open until the pressure is reduced by the passing of the fluid <NUM> or the reduction of air pressure. Furthermore, as the pressure increases the distensible channel <NUM> continues to open further allowing the flow rate to increase as shown in <FIG> illustrates a relationship between pressure of liquid on an embodiment of the distensible channel <NUM> and resulting flow of liquid <NUM> through the distensible channel <NUM>. A dashed line <NUM> is shown indicating a flow for a maximum bolus of fluid <NUM> and a dashed line <NUM> is shown indicating a level corresponding to a minimum safe leak level. Since the flow control valve <NUM> includes a distensible membrane <NUM> that may be made from a thin film of a polymer that is welded to plastic, such a configuration may offer significant size and cost advantages over alternative designs.

In some cases, an important part of heat welding of plastic, and laser welding technology as an example, may require that one part is impregnated with a colorant to allow the laser to warm the plastic. By pressing a clear plastic part against the light absorbing plastic part the energy of the laser may pass through the clear plastic and be absorbed by the dark plastic. Applying pressure to these plastic components with clear glass over the top, it will cause the plastic components to heat and bond. One application of this process may include joining plastic distensible membrane to plastic parts. Specifically, as shown in <FIG>, the distensible membrane film <NUM> may be pressed against a colored semi-rigid plastic or rigid plastic base <NUM> with clear glass plate <NUM>. The laser energy <NUM> from a laser <NUM> passes through the glass plate <NUM> and distensible plastic membrane <NUM>, hits the dark surface of the dark plastic rigid base <NUM> and heats the plastic. The combination of heat and expansion of the heated plastic against the distensible membrane <NUM> causes a thermal bond between the distensible membrane <NUM> and rigid dark plastic base. More importantly, this heating and subsequent cooling of both the dark part and distensible membrane <NUM> causes, for example, two close laser welded lines <NUM> to tighten the distensible membrane film <NUM> towards where the laser weld bonds <NUM> took place. If this occurs between two parallel laser weld bonding lines <NUM> this tightening may restrict flow along the distensible channel <NUM> created by this bonding as a function of the distance between the two bonds <NUM> creating the distensible flow channel <NUM>. For some embodiments, the distensible membrane <NUM> may be secured to the rigid base <NUM> by other suitable methods including ultrasonic welding, solvent welding, adhesive bonding, or the like.

The tightened distensible membrane film <NUM> now works to block the majority of flow of liquid <NUM> attempting to traverse this distensible channel <NUM> created by joining the distensible membrane film <NUM> to the rigid plastic base <NUM>. As the liquid pressure is increased the elastic properties of the distensible membrane film <NUM> begin to stretch allowing liquid flow to occur. The liquid flow through the distensible channel <NUM> is not linear as a function of pressure as is classically done with orifice flow through a rigid small channel, but instead may be exponential allowing a relatively small amount of pressure to flow considerable liquid <NUM>. At low pressure such as the pressure due to the movement of the system on the patient's body <NUM> for instance it fails to create sufficient pressure to open and the small head height differential between the liquid <NUM> and the flow control valve <NUM> and the distensible membrane film <NUM> is able to resist pressure and open. By adding a means of creating pressure on the liquid <NUM>, the pressure within the liquid pump chamber <NUM> may be controllably varied to achieve a desired liquid flow rate or an aliquot of fluid <NUM> requested by varying the amount of pressure and the time the pressure is applied.

Such a medical pump embodiment may provide a low cost, easy to manufacture combination of a check valve and variable flow and cracking volume orifice to the flow of liquid <NUM>. By varying the pressure on the liquid <NUM> the amount of liquid <NUM> passing through the distensible channel <NUM> versus time can be varied. Feedback of the liquid movement occurs by measuring the pressure. By knowing the air volume and pressure created along with Boyles law of flow, a predictable quantity of liquid <NUM> may be dispensed.

Another medical pump embodiment <NUM> and/or measure of safety may include use of a second liquid pump chamber <NUM>, much smaller than the pump chamber <NUM>, that is filled between the liquid chamber and the patient as shown in <FIG>. The smaller second liquid pump chamber <NUM> may then be emptied by actuation of a second pressure actuator <NUM>' similar to the first pressure actuator <NUM>, which may include, for example a second speaker. Upon filling the second liquid pump chamber <NUM> through a check valve <NUM>, the second pressure actuator <NUM>' may push the liquid <NUM> forward through yet another flow control valve <NUM> with the distensible channel <NUM> to the patient <NUM> as shown in <FIG>. In some cases, the check valve <NUM> may include either a passive check valve or active check valve that may be controlled by the transmission of a signal or energy source to the check valve. Failure of the second flow control valve <NUM> may only expose the patient <NUM> to the small quantity of liquid <NUM> versus the liquid contents of the entire liquid chamber <NUM>. This would, for example, allow for much higher pressure in the delivery of the liquids <NUM> may allow the liquid to overcome and flow through an obstruction in the outlet conduit <NUM> which may include a cannula that is kinked, body fluid pressure, capillary effects in small bore tubing and tissues against the end of the cannula.

Other medical pump embodiments may include use of a redundant on/off valve <NUM> as shown in <FIG>, pressing against the distensible membrane <NUM> for example, in line with the distensible membrane <NUM> of the distensible channel <NUM> that may be used for flow control. This might allow the distensible channel <NUM> to be opened or closed as required for flow safety and calibration. It also may create redundancy and verification of the workings of the medical pump system. This redundancy, although adding complexity to the medical pump embodiment <NUM>, may be useful to improve failsafe operation.

Other medical pump embodiments may be configured to displace air with the speaker <NUM> with a known voltage and displacement characteristics against a flexible liquid pump chamber <NUM> allowing liquid <NUM> to flow controllably through the distensible channel <NUM> of the flow control valve <NUM> or not, to push liquid <NUM> to the patient <NUM> in an open loop type of control system. This system may controllably burp an aliquot of fluid into the patient <NUM> with a very simple and low cost means of actuation. Redundant controls and feedback may be added if necessary to add features as appropriate. Examples may include, for example, oncology drug delivery, saline delivery and dextrose delivery where accuracy isn't as important as consistent flow over time.

In <FIG>, a medical pump embodiment <NUM> having a plurality of pump chambers <NUM> is shown where the respective liquids <NUM> of each pump chamber <NUM> each have a control speaker <NUM> and a flow control valve <NUM> and where the liquids <NUM> pass to a common outlet conduit <NUM> which may terminate in a common needle or cannula (not shown). The flow control valves <NUM> may be placed in the center of the medical pump <NUM> near the common needle for each liquid <NUM> to pass through, minimizing mixing of the liquids <NUM> of each of the four liquid pump chambers <NUM>. A flush of saline or other diluent from one of the four chambers could be used to empty or otherwise flush the needle if appropriate.

Some embodiments of a medical pump as shown in <FIG> for delivering fluid <NUM> to a patient <NUM> may include a pump cavity <NUM> which is surrounded by a rigid wall <NUM> and which includes a diaphragm opening <NUM> at a top portion of the pump cavity <NUM>. A diaphragm <NUM> may be disposed over and sealed to the diaphragm opening <NUM> of the pump cavity <NUM>. The medical pump <NUM> may also include a pump chamber <NUM> defined by an inside surface of the rigid wall <NUM> of the pump cavity <NUM> and an inside surface of the diaphragm <NUM> which disposed over and sealed to the pump cavity <NUM>. For some embodiments, the diaphragm <NUM> may include flexible materials such as flexible thermoset polymer, thermoplastic, nylon, silicone, polyvinylchloride (PVC), polypropylene, polyisoprene, polyester or rubber. In some cases, it may be useful for the pump chamber <NUM> to have an aspect wherein a transverse width of the pump chamber <NUM> along a direction parallel to the diaphragm <NUM> is greater than a depth of the pump chamber <NUM> measured perpendicular to the plane of the diaphragm <NUM>. For some embodiments, the pump chamber <NUM> may have a width that is about <NUM> times to about <NUM> times the depth of the pump chamber <NUM>. In some cases, the pump chamber <NUM> may include an interior volume of about <NUM> nanoliters to about <NUM>,<NUM> nanoliters and be configured to pump aliquots of liquid <NUM> in volumes of about <NUM> nanoliter to about <NUM> microliter or more.

A pressure actuator <NUM>, which is generally directed to a device that is configured to impose a force or multiple forces on the diaphragm <NUM>, may include a piston <NUM> with a distal end that is operatively coupled to the diaphragm <NUM>. In addition, an inlet conduit <NUM> may also be disposed in fluid communication with the pump chamber <NUM>. A check valve <NUM> may be operatively coupled to the inlet conduit <NUM> and may also be oriented to allow a flow of liquid <NUM> to the pump chamber <NUM> but prevent a flow of liquid <NUM> from the pump chamber <NUM> back towards the check valve <NUM>. Active controllable embodiments of the check valve <NUM> may be coupled to and operated by a controller such as controller <NUM> discussed below. Such a check valve <NUM> may include a passive check valve, an active controllable check valve that may be activated by a signal or energy transmitted to the active check valve or any other suitable form of check valve <NUM>. An outlet conduit <NUM> may be disposed in fluid communication with the pump chamber <NUM> and an outlet port <NUM> disposed in fluid communication with the outlet conduit <NUM>.

The medical pump <NUM> may further include a flow control valve <NUM> which is operatively coupled to the outlet conduit <NUM> between the pump chamber <NUM> and the outlet port <NUM>. Embodiments of the flow control valve <NUM> may have the same or similar features, dimensions or materials as those of the flow control valve embodiments <NUM> discussed above. In particular, embodiments of the flow control valve <NUM> may serve to act both as a check valve and as a variable flow restrictor with flow characteristics that may be represented generally by the graph shown in <FIG> and discussed above. Embodiments of the flow control valve <NUM> may further include a rigid base <NUM> having a top surface <NUM> with an orifice <NUM> and a distensible membrane <NUM> secured to the top surface <NUM> of the rigid base <NUM> in sealed relation relative to the orifice so as to be in close approximation with the top surface <NUM> of the rigid base <NUM>. This structure forms a sealed distensible channel <NUM> between the orifice <NUM> including the structure surrounding the orifice <NUM> and an inside surface <NUM> of the distensible membrane <NUM>, the distensible channel <NUM> being normally closed. For some embodiments, the outlet conduit <NUM> may terminate with a tissue interface <NUM> having an inner lumen <NUM> in fluid communication with the outlet conduit <NUM>, which in some instances may include a hollow hypodermic needle or cannula <NUM> configured to be inserted into a patient's tissue <NUM> such as a patient's dermis, sub-dermis or muscle tissue beneath the patient's skin.

The components of the medical pump embodiment <NUM> discussed above may be disposed within or otherwise operatively coupled to a pump housing <NUM> that includes an upper housing <NUM>, a lower housing <NUM> and a pump chassis <NUM> as shown in the exploded view of the medical pump <NUM> in <FIG>. The pump housing <NUM> may be made from any suitable high strength rigid material including polymers such as polycarbonate, acrylonitrile butadiene styrene (ABS) plastic or the like. The pump cavity <NUM>, check valve <NUM> and flow control valve <NUM> of the medical pump embodiment <NUM> may all be formed in whole or at least partially into the structure of the pump chassis <NUM>.

For such embodiments, the flow control valve <NUM> may further include a raised boss <NUM> disposed about the orifice <NUM>, the raised boss <NUM> including a seal surface <NUM> which is disposed at a level above the top surface <NUM> of the rigid base <NUM> and which forms a releasable seal with the distensible membrane <NUM> as shown in <FIG>. For some embodiments <NUM>, the distensible channel <NUM> may include a structure wherein the distensible membrane <NUM> is secured to the rigid base <NUM> while the distensible membrane <NUM> is under some tension in a plane of the distensible membrane <NUM>. In some cases, the distensible membrane <NUM> may be secured to the rigid base <NUM> with a weld such as a laser weld <NUM>. The distensible membrane <NUM> may also be secured to the rigid base <NUM> by any other suitable means such as ultrasonic welding, solvent welding, heat sealing, adhesive bonding or mechanical capture.

For some embodiments, the distensible membrane <NUM> of the flow control valve <NUM> may include a thin polymer or elastomeric material with a thickness of about <NUM> to about <NUM>. For some embodiments, the distensible membrane <NUM> may include materials such as a thermoset polymer, thermoplastic, polyester, polypropylene, PVC, nylon or the like which may be compatible for welding or other forms of bonding to corresponding materials of the rigid base <NUM> which may include ABS plastic, PC/ABS, cyclic olefin copolymer (COC) or the like.

A reservoir <NUM> having an interior volume <NUM> for storing liquids <NUM> to be delivered to a patient <NUM> is disposed within the pump housing <NUM> of the medical pump <NUM>. The interior volume <NUM> of the reservoir <NUM> being in fluid communication with the inlet conduit <NUM>. In addition, the check valve <NUM> is operatively coupled to the inlet conduit <NUM> between the reservoir <NUM> and the pump chamber <NUM> for some embodiments as shown. In some cases, the reservoir <NUM> may be disposed within an interior volume of a rigid reservoir chamber <NUM> which may be formed by the pump housing <NUM> and which may be fluidly sealed from an ambient atmosphere <NUM>.

A pressure sensor <NUM> that is positioned and configured to measure pressure within the interior volume <NUM> of the rigid reservoir chamber <NUM> may be disposed within the rigid reservoir chamber <NUM> and may be coupled to a processor <NUM> of a controller <NUM>, which may include a micro controller <NUM>, as shown in <FIG>. For some embodiments, the pressure sensor <NUM> may be operatively coupled to the controller <NUM> and configured to measure pressure within the interior volume of the rigid reservoir chamber <NUM>. The controller <NUM> may further be configured to analyze a pressure profile received from the pressure sensor <NUM> and calculate an appropriate amount of fluid delivered to a patient based on the pressure profile of pressure change over time and knowledge of the size or volume of the chamber being measured. In some instances, the processor <NUM> may include software instructions which are configured to process pressure data received from the pressure sensor <NUM> and determine an amount of fluid <NUM> delivered to a patient <NUM> based on pressure change profiles. Such a controller embodiment <NUM> may also be operatively coupled, such as by electrical wires <NUM> or the like, to the motor <NUM> of the pressure actuator <NUM> and a battery <NUM> that may be used to store electrical energy for operation of the processor <NUM>, controller <NUM>, motor <NUM> or any other appropriate element that requires electrical energy for proper operation.

For certain embodiments, such as the medical pump embodiment <NUM> illustrated in <FIG>, the pressure actuator <NUM> may include a motor <NUM> which has a magnet <NUM> and a conducting coil <NUM> with the conducting coil <NUM> being operatively coupled to the piston <NUM> and the magnet <NUM> secured in a fixed relation to the pump chassis <NUM> and diaphragm <NUM>. For this configuration, the conducting coil <NUM> and piston <NUM> translate towards and away from the diaphragm <NUM> due to electromagnetic forces between the conducting coil <NUM> and the magnet <NUM> when electrical current is conducted through the conducting coil <NUM>. In other embodiments, the magnet <NUM> may be operatively coupled to the piston <NUM> instead of the conducting coil <NUM> and the conducting coil <NUM> secured in fixed relation to the pump chassis <NUM> and diaphragm <NUM>.

Another valve <NUM> may be disposed in operative communication between the interior volume <NUM> of the rigid reservoir chamber <NUM> and the ambient atmosphere <NUM> that surrounds the pump housing <NUM>. Embodiments of such a valve <NUM> may include an active controllable valve that may be operated or controlled by the controller <NUM> to open and close at appropriate intervals. For some embodiments, the valve <NUM> may include a passive small orifice in fluid communication between the interior volume <NUM> of the rigid reservoir chamber <NUM> and the ambient atmosphere <NUM>. In some cases, a transverse dimension of such a small orifice opening may be about <NUM> to about <NUM>. In other embodiments, the valve <NUM> may include a check valve disposed in fluid communication between the interior volume <NUM> of the rigid reservoir chamber <NUM> and the ambient atmosphere <NUM>. Such a check valve <NUM> being oriented to allow ambient air into the interior volume <NUM> of the rigid reservoir chamber <NUM>.

As discussed above, the interior volume <NUM> of the reservoir <NUM> may be used to store any suitable liquid <NUM> for delivery to the body of a patient <NUM>, including non-bioactive liquids such as saline, dextrose and the like, or bioactive liquids including medicaments such as insulin, antibiotics, peptides, pain medication, and the like. For some embodiments, the interior volume <NUM> of the reservoir <NUM> may be about <NUM> milliliters to about <NUM> milliliters, more specifically, about <NUM> milliliter to about <NUM> milliliters.

Some embodiments of a method of pumping a liquid <NUM> from a medical pump <NUM> to the patient as shown in <FIG> may include actuating the motor <NUM> of the pressure actuator <NUM> and advancing the piston <NUM> of the pressure actuator <NUM> into the diaphragm <NUM> of a pump chamber <NUM>. The piston <NUM> may continue to be advanced until an inside surface of the diaphragm <NUM> intrudes into an interior volume of the pump chamber <NUM> thereby reducing the interior volume of the pump chamber <NUM>, increasing an internal pressure within an interior volume of the pump chamber <NUM> and expelling the liquid <NUM> from the pump chamber <NUM> and into the outlet conduit <NUM> as shown in <FIG>. The method may also include flowing the liquid expelled from the pump chamber <NUM> through the outlet conduit <NUM> and into the distensible channel <NUM> of the flow control valve <NUM> which is normally closed. For some embodiments, the flow control valve <NUM> that is normally closed is closed sufficiently in order to prevent a clinically significant amount of liquid <NUM> from being dispensed from the medical pump <NUM>. For some embodiments, the distensible channel <NUM> may function as a check valve wherein flow from the pump chamber <NUM> through the flow control valve <NUM> does not begin until a cracking pressure of the distensible channel <NUM> is reached and overcome and the distensible channel <NUM> opens from the normally closed state.

The flowing of the liquid <NUM> into the distensible channel <NUM>, as shown in <FIG>, results in stretching the distensible membrane <NUM> of the flow control valve <NUM> and expanding the distensible channel <NUM> to allow a flow of the liquid <NUM> through the flow control valve <NUM> and out of an outlet port <NUM> of the outlet conduit <NUM>. Such stretching or compliance of the distensible membrane <NUM> may result in a non-linear flow response as a function of pressure change such as is exemplified in the flow graph of <FIG>. For some embodiments, the distensible channel <NUM> may include a distensible membrane <NUM> under tension disposed over the orifice <NUM> of the raised boss <NUM> of the flow control valve <NUM> with the distensible membrane <NUM> sealing the orifice <NUM>. For such embodiments, expanding the distensible channel <NUM> to allow a flow of the liquid <NUM> through the flow control valve <NUM> may include pressurizing liquid <NUM> within a lumen <NUM> of the raised boss <NUM> and pushing the distensible membrane <NUM> away from the orifice <NUM> thereby opening the orifice <NUM> as shown in <FIG>. For such a method, the amount of liquid <NUM> that is pumped may be controlled by selecting the amount of pressure applied by the piston <NUM> to the diaphragm <NUM> and the amount of time the pressure is applied by the piston <NUM>. For electromagnetic conducting coil embodiments of the motor <NUM>, these parameters may be controlled by adjusting the voltage and dwell of the electrical current conducted through the coil <NUM>.

Such a method of pumping a liquid <NUM> from the medical pump <NUM> may further include withdrawing the piston <NUM> of the pressure actuator <NUM> away from the diaphragm <NUM> as shown in <FIG> by reversing or reducing the current applied to the coil <NUM> of the motor <NUM> and thereby contracting the diaphragm <NUM> from a stretched state and increasing the interior volume of the pump chamber <NUM>. Withdrawing the piston <NUM> in this manner has the effect of reducing liquid pressure on the distensible membrane <NUM> of the flow control valve <NUM>. This reduced fluid pressure may then allow the distensible channel <NUM> to assume the normally closed state while also drawing liquid through the inlet conduit <NUM> and a check valve <NUM> disposed in fluid communication with the inlet conduit <NUM> into the pump chamber <NUM> thereby refilling the pump chamber <NUM> as shown in <FIG> and <FIG>.

In some cases, drawing liquid <NUM> through the inlet conduit <NUM> may also include drawing liquid <NUM> from within the interior volume <NUM> of the reservoir <NUM> which is disposed within the sealed rigid reservoir chamber <NUM> of the medical pump housing <NUM>. For such a process, pressure may be measured within the interior volume <NUM> of the rigid reservoir chamber <NUM> before and after drawing the liquid <NUM> through the inlet conduit <NUM>. Information regarding a measured pressure drop over time may be used by the processor <NUM> of the controller <NUM> to determine an amount of liquid <NUM> dispensed. In addition, in some cases, the electrical current conducted through the conducting coil <NUM> may be controlled by the controller <NUM> permitting precise displacement of the piston <NUM> and precise control of a force exerted by the piston <NUM> on the diaphragm <NUM>. For such embodiments, a measured potential voltage may be used to determine a resistance value of electrical current through the conducting coil <NUM> and thereafter determining whether inefficiencies in performance are present which may be indicative of an occlusion of the outlet conduit <NUM>.

Some embodiments of a method of welding a distensible membrane <NUM> to the rigid base <NUM> of the pump cavity <NUM> as shown generally in <FIG> and <FIG> may include positioning the distensible membrane <NUM> onto a top surface <NUM> of the rigid base <NUM> such that an inside surface of the distensible membrane <NUM> is in contact with the top surface <NUM> of the rigid base <NUM> as shown in <FIG>. Thereafter, a layer of rigid material <NUM> may be positioned onto an outside surface <NUM> of the distensible membrane <NUM> over an area between the distensible membrane <NUM> and rigid base <NUM> to be welded. The layer of rigid material <NUM> may optionally include rigid transparent material <NUM>. The method may further include applying pressure to the distensible membrane <NUM> in a direction towards the rigid base <NUM> thereby approximating the inside surface of the distensible membrane <NUM> with the top surface <NUM> of the rigid base <NUM> and transmitting electromagnetic energy <NUM> through the layer of rigid material <NUM> and onto the distensible membrane <NUM> until the distensible membrane <NUM> and rigid base <NUM> melt and form a fluid tight weld zone <NUM>. In some cases, the layer of material <NUM> may be positioned so as to provide a predetermined minimum pressure on the distensible membrane <NUM> prior to welding.

In some cases, positioning the layer of rigid material <NUM> onto the outside surface <NUM> of the distensible membrane <NUM> may include positioning a glass plate <NUM> onto the outside surface <NUM> of the distensible membrane <NUM> over an area between the distensible membrane <NUM> and rigid base <NUM> to be welded. In addition, in some instances, transmitting electromagnetic energy <NUM> through the layer of rigid material <NUM> and onto the distensible membrane <NUM> includes transmitting laser energy <NUM> through the layer of rigid material <NUM> and onto and at least partially through the distensible membrane <NUM>. For some flow control valve embodiments <NUM>, positioning the distensible membrane <NUM> onto a top surface <NUM> of the rigid base <NUM> includes positioning a distensible membrane <NUM> that includes thin polymer film over a pump cavity <NUM> of a rigid base <NUM> made of a polymer. In some cases, positioning the distensible membrane <NUM> onto a top surface <NUM> of the rigid base <NUM> includes positioning the distensible membrane <NUM> over a flat planar surface <NUM> of the rigid base <NUM> and welding a perimeter configuration of weld lines <NUM> so as to form a sealed distensible channel <NUM> between the inside surface of the distensible membrane <NUM> and top surface <NUM> of the rigid base <NUM> within the weld perimeter. For the medical pump embodiment <NUM>, the process of welding the diaphragm <NUM> over the pump cavity <NUM> disposed in the pump chassis <NUM> in order to form the pump chamber <NUM> as shown in <FIG> may be the same as or similar to the method discussed above with regard to the welding of the distensible membrane <NUM> to the rigid base <NUM> including laser welding. Such methods may also include heat sealing, ultrasonic welding, solvent welding, adhesive bonding, mechanical capture or the like.

For some embodiments, heat may be applied to the distensible membrane <NUM> after the distensible membrane <NUM> has been welded to the rigid base <NUM> in order to increase tension one the distensible membrane <NUM> and increase an equivalent spring rate of the distensible membrane <NUM>. Such a post processing heat treatment may be used to adjust fluid flow characteristics of a distensible channel produced by the method. In addition, in some cases, negative air pressure may be applied between the distensible membrane <NUM> and the rigid base <NUM> to tightly form the distensible membrane <NUM> onto the rigid base <NUM> providing a preset position on the material of the distensible membrane <NUM> of the features of the rigid base <NUM>. In some instances, the distensible membrane <NUM> may be preformed prior to positioning the distensible membrane <NUM> onto the top surface of the rigid base <NUM>.

Embodiments illustratively described herein suitably may be practiced in the absence of any element(s) not specifically disclosed herein. Thus, for example, in each instance herein any of the terms "comprising," "consisting essentially of," and "consisting of" may be replaced with either of the other two terms. The terms and expressions, which have been employed, are used as terms of description and not of limitation and use of such terms and expressions do not exclude any equivalents of the features shown and described or portions thereof, and various modifications are possible. The term "a" or "an" can refer to one of or a plurality of the elements it modifies (e.g., "a reagent" can mean one or more reagents) unless it is contextually clear either one of the elements or more than one of the elements is described.

Claim 1:
A medical pump (<NUM>) for delivering fluid (<NUM>) to a patient (<NUM>), comprising:
a pump cavity (<NUM>) which is surrounded by a rigid wall (<NUM>) and which includes a diaphragm opening (<NUM>);
a diaphragm (<NUM>) disposed over and sealed to the diaphragm opening (<NUM>) of the pump cavity (<NUM>);
a pump chamber (<NUM>) defined by an inside surface (<NUM>) of the rigid wall of the pump cavity (<NUM>) and an inside surface (<NUM>) of the diaphragm (<NUM>) which disposed over and sealed to the pump cavity (<NUM>);
a pressure actuator (<NUM>) including a piston (<NUM>) with a distal end (<NUM>) that is operatively coupled to the diaphragm (<NUM>);
an outlet conduit (<NUM>) which is in fluid communication with the pump chamber (<NUM>);
an outlet port (<NUM>) which is in fluid communication with the outlet conduit (<NUM>);
a flow control valve (<NUM>) which is operatively coupled to the outlet conduit (<NUM>) between the pump chamber (<NUM>) and the outlet port (<NUM>),
characterized by
the flow control valve (<NUM>) comprising:
a rigid base (<NUM>) having a top surface (<NUM>) with an upstream orifice (<NUM>) and a downstream orifice (<NUM>), and
a distensible membrane (<NUM>) secured to the top surface (<NUM>) of the rigid base (<NUM>) in sealed relation relative to the upstream orifice (<NUM>) and the downstream orifice (<NUM>) so as to be in approximation with the top surface (<NUM>) of the rigid base (<NUM>) forming a sealed distensible channel (<NUM>) between the upstream and downstream orifices (<NUM>, <NUM>), the distensible channel (<NUM>) being normally closed and being created by joining the distensible membrane film (<NUM>) to the top surface (<NUM>) of the rigid base (<NUM>).