Flow Control Device

Abstract

An apparatus for controlling a flow of a fluid comprising: a first valve having: a selectively openable and closable inlet; an opening; and a selectively openable and closable outlet, the first valve being arranged such that a fluid can enter the first valve through the inlet, exit the first valve through the opening, enter the first valve through the opening, and exit the first valve through the outlet; a first sensor for detecting a fluid; and a second sensor for detecting a fluid, the first sensor and the second sensor being in fluid communication with the first valve via the opening; a control device for receiving a signal from the first sensor and the second sensor and controlling the opening and closing of the inlet and the outlet in response to receiving the signal, wherein the device is configured such that, in use, fluid can flow through the device by: - ​​entering the first valve through the inlet of the first valve; - exiting the first valve through the opening of the first valve; - passing the first sensor for detecting fluid; - flowing to the second sensor for detecting fluid; - entering the first valve through the opening of the first valve; - exiting the first valve through the outlet of the first valve.

Description

[Technical field]

[0001] (Field) FIELD OF THE DISCLOSURE This application relates generally to devices for controlling fluid flow, and more particularly to a system for delivering a volume of fluid connected to a fluid reservoir. [Background technology]

[0002] (background) Accurate delivery of volumes of fluids is important in many fields. Syringe pumps and the like are common laboratory devices for precisely delivering a predetermined volume of fluid. Syringe pumps can be operated to gradually deliver small amounts of fluid. Pumps can be operated to regulate the delivery of fluid and controlled to deliver specific flow rates and volumes. A typical syringe pump can hold about 60 mL of fluid and deliver at a pump flow rate of about 1000 mL / hour.

[0003] Some known disadvantages associated with syringe pumps are: response time, which can vary from a few seconds to several hours depending on the resistance and compatibility of the fluid; the inability to know the flow rate during transient periods without a flow meter; and the associated difficulties in fine tuning.

[0004] It is an aim of at least certain embodiments to address one or more of these problems. Summary of the Invention [Means for solving the problem]

[0005] (overview) According to a first aspect of the present invention, there is provided an apparatus for controlling a flow of a fluid, the apparatus comprising: a first valve having: a selectively openable and closable inlet; an opening; and a selectively openable and closable outlet, arranged such that fluid can enter the first valve through the inlet, exit the first valve through the opening, enter the first valve through the opening, and exit the first valve through the outlet; a first sensor for detecting a fluid; and a second sensor for detecting a fluid, wherein the first sensor and the second sensor are in fluid communication with the first valve via the opening. and a control device for receiving signals from the first sensor and the second sensor and controlling the opening and closing of the inlet and the outlet in response to receiving the signals, wherein the device is arranged such that, in use, fluid can flow through the device by:- entering the first valve through the inlet of the first valve;- exiting the first valve through the opening of the first valve;- passing the first sensor for detecting fluid;- flowing to the second sensor for detecting fluid;- entering the first valve through the opening of the first valve;- exiting the first valve through the outlet of the first valve.

[0006] The valves of the device allow the flow rate of the fluid to be controlled to a desired value. The arrangement of the device allows for very accurate delivery of fluid from the device. Such accuracy can be attributed to the arrangement of mechanisms, particularly the interaction between the inlets, outlets, sensors and controls. Benefits of such a device include the ability to maintain the flow rate from the device even as fluid conditions change. Additionally, the device can ensure the same flow rate for multiple outlets.

[0007] In one embodiment, the control device is configured to: close the inlet in response to receiving a signal from the second sensor, the signal being transmitted in response to the second sensor detecting a fluid; and close the outlet in response to receiving a signal from the first sensor, the signal being transmitted in response to the first sensor detecting a fluid after the signal from the second sensor is transmitted.

[0008] The device can reliably deliver a specific fluid volume over multiple repetitions.

[0009] In one embodiment, the signal transmitted in response to the second sensor detecting fluid is a signal to close the inlet; and the signal transmitted in response to the first sensor detecting fluid is a signal to close the outlet.

[0010] In one embodiment, detecting the fluid includes at least one of: detecting fluid adjacent to the sensor; detecting fluid passing through the sensor; detecting a change in the fluid adjacent to the sensor from a first fluid to a second fluid; and detecting a change in the fluid passing through the sensor from the first fluid to a second fluid.

[0011] The sensor of the device is capable of reliably detecting fluid, and reliable detection helps the device deliver reproducible amounts of fluid from the device.

[0012] In one embodiment, the apparatus further comprises a second valve, the second valve being disposed downstream of the outlet of the first valve.

[0013] The second valve of the device can aid in the controllable delivery of a predetermined amount of fluid. The second valve allows a certain amount to be held for a period of time before delivery. This can be advantageous in situations where immediate delivery is not desired. The second valve also provides failure tolerance to the device.

[0014] In one embodiment, the device comprises a flow path configured to transport a fluid between a first valve and a first sensor and a second sensor, the flow path configured to hold a volume of fluid between the first valve and the second sensor of about 10 μl to about 1000 μl.

[0015] The device is capable of delivering fluid at a specific flow rate that is repeatable and durable over small changes in fluid conditions. Typically, it is durable at flow rates that cannot be delivered accurately using current technology. Durability means that the flow rate is precisely maintained even as fluid conditions or resistance change. Such maintenance of flow rates is not possible with current technology.

[0016] In one embodiment, the device further comprises a fluid reservoir fluidly connected to the valve via an inlet, and the control device is configured to control the flow of fluid held in the fluid reservoir from the inlet to the valve during use.

[0017] The device may allow for the controllable delivery of a predetermined amount of fluid from a fluid reservoir, the reservoir being capable of holding a large amount of fluid such that the device can operate for a relatively long period of time without the user having to reconfigure the device, thereby improving ease of use for the user of the device.

[0018] In one embodiment, the opening is a selectively openable and closable opening.

[0019] The selectively openable openings in the device allow the user increased control over the operation of the device. Selectively opening openings in the device allows the user an increased level of control over certain steps in the operation of the device. Any increase in the complexity of the device is offset by the increased level of control provided to the user.

[0020] In one embodiment, the fluid is a liquid.

[0021] According to a second aspect of the present invention, there is provided a method of controlling fluid flow comprising: filling a flow path with fluid to a first predetermined level; detecting that the flow path has been filled to the first predetermined level; in response to said detection, draining the flow path to a second predetermined level, the second predetermined level being lower than the first predetermined level; and detecting that the flow path has been drained to the second predetermined level.

[0022] The method can be implemented to control the flow rate to a desired amount. The steps of the method result in highly accurate delivery of fluid from the flow path. Such accuracy can result from the sequence of steps, particularly the interplay between filling, draining, and detecting. Benefits of such a method include maintaining the flow rate from the flow path even if fluid conditions change.

[0023] According to a third aspect of the present invention, there is provided a method of controlling fluid flow comprising the steps of: opening an inlet of a valve to allow fluid to flow into the valve; passing the fluid through an opening of the valve; detecting the fluid by a second sensor; in response to detection of the fluid by the second sensor, closing the inlet of the valve to prevent the fluid from flowing into the valve; after closing the inlet of the valve, opening an outlet of the valve to allow fluid to drain from the valve; detecting fluid by a first sensor; and in response to detection of fluid by the first sensor, closing the outlet of the valve to prevent fluid from flowing out of the valve, wherein detection by the second sensor requires a greater volume of fluid to flow into the valve than detection by the first sensor.

[0024] The method can be implemented to control the flow rate to a desired volume. The steps of the method result in highly accurate delivery of fluid from the valve. Such accuracy can be attributed to the sequence of steps, particularly the interactions between the inlet, outlet, orifice, and sensor. Benefits of such a method include maintaining the flow rate from the flow path even as fluid conditions change.

[0025] In one embodiment, the method further includes, in response to detection of fluid by the second sensor, transmitting a message from the second sensor to a controller that fluid has been detected, and, in response to receiving the message from the second sensor by the controller, transmitting a message to the valve to close the inlet of the valve to prevent fluid from flowing into the valve.

[0026] Detection of fluid by the second sensor and transmission of a message to the controller which acts in response to the received message increases the reliability of delivery of a predetermined amount of fluid. The controller also makes the device easier to operate by eliminating the need for a user to assist with certain stages of operation of the valve.

[0027] In one embodiment, the method further includes, in response to detection of fluid by the first sensor, transmitting a message from the first sensor to a control device that fluid has been detected, and, in response to receiving the message from the first sensor by the control device, transmitting a message to the valve to close an outlet of the valve to prevent fluid from flowing out of the valve.

[0028] This method can be implemented to improve the reliability of delivery of a predetermined amount of fluid, and the control device can make the device easier to operate by eliminating the need for user assistance with certain steps of the valve operation.

[0029] In one embodiment, the method further includes sending a message to a fluid delivery system of a fluid reservoir to initiate delivery of fluid from the reservoir to the valve.

[0030] The method can be implemented to allow for controllable delivery of a predetermined amount of fluid from a reservoir of fluid. Because the reservoir can hold a large amount of fluid, the method can be used for a relatively long period of time without the user having to modify the method, such as by repeatedly introducing fluid or a source of fluid, thereby making the method easier for the user to use.

[0031] In one embodiment, the method further comprises the step of delivering a predetermined volume of fluid through the valve, the predetermined volume being between about 2 μl and 100 μl of fluid.

[0032] The device is capable of delivering fluids at a specific flow rate that is repeatable and durable to small changes in the resistance of the fluid, typically at flow rates that cannot be accurately delivered using current technology, and that is maintained even as fluid conditions and resistance change, unlike current technology.

[0033] In one embodiment, the fluid is a liquid.

[0034] In one embodiment, the method further includes the step of holding fluid between the valve and a second sensor for a predetermined period of time before opening an outlet of the valve to allow fluid to flow out of the valve.

[0035] The method can be implemented to controllably deliver a predetermined amount of fluid. The method allows for a volume of fluid to be held for a period of time before delivery, which can be advantageous in situations where immediate delivery is not desired. The method also provides fault tolerance by providing operational checks for a predetermined period of time to ensure normal, i.e. error-free, operation of the method. [Brief description of the drawings]

[0036] BRIEF DESCRIPTION OF THE DRAWINGS Specific embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0037] [Figure 1] FIG. 1 shows a schematic cross-sectional view of an apparatus for controlling fluid flow according to a first example. [Diagram 2] FIG. 2 shows a schematic cross-sectional view of an instrument comprising a device for controlling fluid flow according to a second example. [Diagram 3] FIG. 3 shows a schematic cross-sectional view of a part of an instrument comprising a device for controlling fluid flow according to a third example. [Figure 4]FIG. 4 shows a schematic cross-sectional view of a part of an apparatus for controlling fluid flow according to a first example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] DETAILED DESCRIPTION OF CERTAIN EXEMPLARY EMBODIMENTS 1 shows a schematic cross-sectional view of an apparatus 100 for controlling the flow of a fluid. The apparatus 100 includes a valve 110, a first sensor 120, and a second sensor 130. The valve 110 has an inlet 112 that can be selectively opened and closed. The valve 110 has an opening 114. The valve 110 has an outlet 116 that can be selectively opened and closed. The valve 110 is arranged such that fluid can enter the valve 110 through the inlet 112, exit the valve 110 through the opening 114, enter the valve 110 through the opening 114, and exit the valve 110 through the outlet 116.

[0039] The apparatus 100 also includes a controller (not shown) that receives signals from the first sensor 120 and the second sensor 130 and controls the opening and closing of the inlet 112 and the outlet 116 in response to receiving the signals.

[0040] The device 100 operates to control the flow of fluid by allowing fluid to flow into the valve 110 through the inlet 112 of the valve 110. The fluid can flow out of the valve 110 through the opening 114. Fluid flowing out of the valve 110 through the opening 114 can pass through a first sensor 120. As more fluid flows out of the valve 110 through the opening 114, it can flow to a second sensor 130. Fluid can re-enter the valve 110 through the opening 114 and flow out of the valve 110 through the outlet 116.

[0041] Prior to use, the device 100 is closed and the inlet 112 is closed so that no fluid can flow into the valve 110. The outlet 116 can also be closed before the device 100 is used. Upon actuation, the controller of the device 100 sends an open signal to the inlet 112. The inlet 112 opens and fluid can flow into the valve 110. If the outlet 116 is open before the fluid flows into the valve 100, the outlet 116 is closed before the inlet 112 is opened. As fluid enters the valve 110 and more fluid flows into the valve 110, it passes through the open opening 114. The fluid flows through the opening 114 along the flow path 140. After a certain volume of fluid passes through the inlet 112 and exits the opening 114, the fluid passes through the first sensor 120. After a second certain volume of fluid passes through the inlet 112 and exits the opening 114, the fluid reaches the second sensor 130. The first sensor 120 and the second sensor 130 are positioned such that a greater amount of fluid must be present in the flow path 140 to activate the second sensor 130 than to activate the first sensor 120.

[0042] The second sensor 130 sends a signal to the controller when fluid is detected. The controller can then close the inlet 112 to prevent further fluid from entering the valve 110. At this point, the volume of fluid held within the device 100 is a predetermined amount. This fluid can be held within the device 100 for a relatively long period of time if necessary. If fluid needs to be drained, the controller sends a signal to the outlet 116 to open. Fluid then flows from the flow path 140 through the opening 114 and out of the valve 110 through the outlet 116. When the fluid surface (fluid boundary) passes the first sensor 120, the first sensor 120 sends a message to the controller. The controller can then close the outlet 116 so that no further fluid can exit the device 100.

[0043] The sensors 120, 130 detect fluid. The sensors 120, 130 detect the presence or absence of fluid. In response to an initial detection of fluid, such as the second sensor 130, a signal can be sent to close the inlet 112. In response to a lack of detection of fluid, such as the first sensor 120, a signal can be sent to close the outlet 116. In this manner, the movement of the fluid level within the flow path 140 can be tracked by the sensors 120, 130. The sensors 120, 130 can detect fluid by any suitable method, including differences in light absorption, light diffraction, the use of variable capacitors, and the like. The fluids used in the flow path 140 preferably exhibit distinct interfaces with one another to allow for accurate measurements taken by the sensors 120, 130.

[0044] The device 100 can then be refilled with fluid flowing in through the inlet 112. The device 100 can be supplied from a fluid source, such as, for example, a fluid reservoir. The fluid source is in fluid communication with the valve 110. The fluid source can be pressurized to supply fluid to the device 100. The device 100 can advantageously be arranged such that, during the second operation, fluid present within the device 100 does not flow out of the device 100 towards the fluid source through the reopened inlet 112.

[0045] In this manner, a predetermined and carefully controlled volume of fluid can be delivered each time by the device 100. Moreover, this predetermined volume of fluid can be delivered repeatedly. The volume delivered will be the volume retained by the device 100 in the flow path 140 between the first sensor 120 and the second sensor 130. This amount can be carefully controlled by the size of the flow path between the sensors 120 and 130 and the sensitivity of the sensors.

[0046] Prior to the ejection of the fluid, pressure may be applied to a volume of fluid contained within device 100 to force the fluid out of outlet 116. This may be particularly advantageous under certain atmospheric conditions, etc., where the fluid contained within device 100 would benefit from additional motive force to eject the fluid from device 100. This pressure may be applied by another fluid (which may or may not be miscible with the fluid entering valve 100 through inlet 112), a plunger, etc.

[0047] The cycling of opening and closing of the inlet 112 and outlet 116 can control the two-stage process (described above) and thus the overall flow rate. Thus, the device 100 can maintain a controlled flow rate even as fluid conditions, such as flow resistance, change.

[0048] Figure 2 shows a schematic cross-sectional view of an instrument 200 including a device 100 for controlling fluid flow. Features of Figure 2 previously described in relation to Figure 1 are numbered the same and may not be described in detail here for ease of reading. In particular, previously described features of device 100 will not be repeated here.

[0049] The instrument 200 includes a fluid source 210, a pressure source 220, and a delivery manifold 230. The fluid source 210 supplies fluid that flows into the device 100 through the inlet 112. The pressure source 220 provides a pressure P1 to the fluid source 210 to force the fluid into the conduit 212 and through the inlet 112 into the device 100. The pressure source 220 can also provide a pressure P2 to the flow passage 140 of the device 100. Thus, the pressure source 220 controls the respective pressure ΔP between the fluid source 210 and the flow passage 140 (ΔP=P1-P2). Thus, the pressure source 220 can control the direction of fluid flow when the inlet 112 is open. The pressure source 220 can be controlled by a controller of the device 100 or by other means, such as an integrated controller (not shown) for the pressure source 220.

[0050] The example device 100 shown in FIG. 2 includes a second valve 150 in fluid communication with the outlet 116. The second valve 150 allows a volume of fluid to be held between the first valve 110 and the second valve 150 for a desired period of time. The second valve 150 can introduce an additional level of control over the fluid exiting the first valve 110. The second valve 150 may have an inlet and an outlet, or may simply be a movable shutoff element that blocks the passage of fluid. The second valve 150 may be actuated (opened or closed) by a controller, or may be pressure actuated such that fluid pressure above a predetermined fluid pressure level forces the second valve 150 open.

[0051] The instrument 200 includes a delivery manifold 230. The delivery manifold 230 may have a single fluid inlet and multiple fluid outlets. The manifold 230 may have multiple outlet channels connecting the multiple outlets to the inlet. The multiple outlet channels may branch off from a central inlet channel in fluid communication with the inlet. The manifold 230 may have openable and closable valves configured to allow controllable distribution of fluid from the device 100 along specific outlet channels and out of specific ones of the multiple fluid outlets. The multiple channels within the manifold may not have the same resistance to fluid flow. Thus, the device 100 advantageously allows for controllable fluid delivery rates from the manifold 230 with different resistances to fluid flow.

[0052] In practice, the volume delivered by the device 100 to the manifold 230 may be slightly larger than the volume contained between the first sensor 120 and the second sensor 130 due to the reaction times associated with the detection of the fluid (or fluid level) by the sensors 120, 130, sending a message to the controller, and then completely closing the inlet 112 or outlet 116 (as appropriate depending on the stage of the process). In any event, these reaction times can be calculated accordingly to allow for a predetermined and desired amount of fluid to be delivered to the manifold 230. The location of the sensors 120, 130 can be moveable along the flow path 140 so that the constant volume of delivered fluid can be altered.

[0053] A user may adjust the flow rate controllably delivered by the device 100 by adjusting the pressure P1 supplied by the pressure source 220 to the fluid source 210 along the conduit 222; the pressure P2 supplied by the pressure source 220 to the device 100 along the conduit 224; and the periodic opening and closing of the valves 110, 150.

[0054] The period is calculated taking into account the volume of fluid delivered by the device 100 in one repeated use. To ensure reproducibility over multiple times, the pressures P1, P2 supplied along the conduits 222, 224 can be provided at set values. If there is a pressure loss along the conduits 222, 224, this should be taken into account accordingly to ensure that the loss along one conduit does not disturb the balance of pressures required to maintain the flow of fluid through the device 100 in the desired manner.

[0055] Figure 3 shows a schematic cross-sectional view of a portion of an instrument 200 comprising a device 100 for controlling fluid flow according to a third embodiment. Features of Figure 3 previously described in relation to Figures 1 or 2 are numbered the same and may not be described in detail here for ease of reading. In particular, previously described features of the device 100 will not be repeated here.

[0056] Figure 3 illustrates a portion of the instrument 200 shown in Figure 3, which includes a manifold 230 connected to a series of fluid outlets 240. In one example, the fluid outlets 240 can be a series of nozzles or outlets, etc., for controlled delivery of fluid from the manifold 230. The manifold 230 has an inlet flow passage 232 connected to multiple outlet flow passages 234. In the example shown, there are as many outlet flow passages 234 as there are fluid outlets 240.

[0057] The device 100 operates as previously described to repeatedly deliver set volumes of fluid to the manifold 230. The manifold 230 can route specific volumes of fluid to specific fluid outlets 240A, 240B, etc. In this manner, the instrument 200 can controllably deliver specific set volumes of fluid from a fluid source (not shown in FIG. 3). As shown by the timeline 250, fluid delivery points 252, 254, 256, 258 occur at regular intervals. Each fluid delivery point 252, 254, 256, 258 results from the delivery of fluid through outlets 240A, 240B, 240C, etc.

[0058] 4 shows a schematic cross-sectional view of a portion of an apparatus 100 for controlling a fluid flow according to a first embodiment. FIG. 4 shows a first sensor 120, a second sensor 130, and a flow path 140 of the apparatus 100.

[0059] Figure 4 shows two stages of operation of the device 100. The filling stage is shown in Figure 4B, and the draining stage is shown in Figure 4A. Pressures P1, P2 supplied by pressure source 220 to the fluid source 210 and device 100 respectively are each shown as operating in their associated stages. The draining stage shown in Figure 4A is acted upon by pressure P2 applied along conduit 224 connecting pressure source 220 to device 100. The filling stage shown in Figure 4B is acted upon by pressure P1 applied along conduit 222 connecting pressure source 220 to fluid source 210.

[0060] 4 highlights three portions 140A, 140B, 140C of the flow path 140. The top portion 140A represents the volume V of fluid contained in the flow path 140 above the second sensor 130. e 0, V f2, and this volume V e 0, V f 2 results from the reaction time associated with fluid passing the second sensor 130 and closing the inlet 112 of the valve 110 to prevent further fluid from entering the device 100. Because this reaction time is non-zero, there is a volume of fluid retained in the flow path 140 above the second sensor 130.

[0061] The intermediate portion 140B is a volume V of fluid contained in the flow path 140 between the first sensor 120 and the second sensor 130. e 1. V f 1. In a preferred embodiment, this volume V e 1. V f 1 is the volume V held in the upper portion 140A of the second sensor 130. e 0, V f The volume V held in the lower portion 140C of the second and first sensors 140 e 2. V f 0. This results in a volume V held in these portions 140A, 140C. e 0, V f 2. V e 2. V f The error to be corrected by 0 is the volume V held in the intermediate portion 140B. e 1. V f It is guaranteed to be insignificant compared to 1.

[0062] The bottom 140C is a volume V of fluid discharged from the flow path 140 below the first sensor 120. e 2. V f 0, and this volume V e 2. V f The zero occurs as a result of the reaction time associated with the fluid (fluid level) passing the first sensor 120 and closing the outlet 116 of the valve 110 to prevent further fluid discharge from the device 100.

[0063] The volumes of the three sections 140A, 140B, 140C in Figures 4A and 4B are the same despite their respective representations in Figure 4, because the size of the flow channel 140 does not change during the drain phase (Figure 4A) or during the fill phase (Figure 4B). e 0 is the volume V of the portion 140A of FIG. f 2, which also applies to the middle portion 140B and the bottom portion 140C.

[0064] 4A, the draining (or evacuation) phase is shown. A pressure P2 is applied to the fluid contained within the flow path 140. The time it takes for the fluid to drain from the flow path 140 until it has a fluid level at the second sensor 130 is T e 0. The time it takes for the fluid to exit the flow path 140 until it has a fluid level at the first sensor 120 is T e 1. The reaction time required for the first sensor 120 to send a signal that results in the outlet 116 of the valve 110 closing to prevent further fluid from being discharged from the flow path 140 is then T e 2. The final fluid level FFL is shown below the first sensor 120. The flow of fluid from the flow channel 140 during the ejection phase is indicated by the arrow f e As shown in the figure.

[0065] With particular reference to FIG. 4B, the filling stage is shown. The filling stage shown is the stage that follows the drain stage, so that some fluid is already present in the flow channel 140 before filling. The initial fluid level IFL is the fluid level of the fluid remaining in the flow channel 140 after the drain stage (shown in FIG. 4A). The initial fluid level IFL is shown in FIG. 4B. The initial fluid level IFL of the filling stage is at the same level as the final fluid level FFL of the drain stage shown in FIG. 4A. A pressure P1 can be applied to the fluid contained in the fluid source 210 to force the fluid into the device 100 as previously described. The time it takes for the fluid to flow into the flow channel 140 until the fluid level moves from the initial fluid level IFL to the first sensor 120 is T f 0. The time it takes for the fluid to enter the flow path 140 until the fluid level moves to the second sensor 130 is then Tf 1. The reaction time required for the second sensor 130 to send a signal that results in the inlet 112 of the valve 110 closing to prevent further fluid from the fluid source 210 is T f 2. T f 2 is T f It depends on the same parameters as 1, but cannot be measured directly. Therefore, T f By controlling 1, T f 2, thereby ensuring that the volume above the second sensor 130 remains constant. The flow of fluid into the channel 140 during the filling phase is indicated by the arrow f f As shown in the figure.

[0066] Volume at both ends V f 2 and V f 0 is kept constant, and the volume V between the sensors 120 and 130 f If 1 is kept constant, the total volume delivered by device 100 remains constant.

[0067] The device 100 disclosed herein can accommodate changes in fluid conditions, such as resistance of the fluid or the tube through which the fluid is delivered, for example, by adjusting the refill pressure P1 applied to the fluid source 210.

[0068] When refilling, the volume V f 0 needs to be refilled, this volume V f 0 depends on the pressure and the flow resistance during the discharge phase. As mentioned above, this volume V f 0(V e 2) can be evacuated from the device 100 during the “reaction time” of the first sensor 120 during the evacuating process. f To keep 0 constant, time T e 2 can be adjusted by a controller in the device 100. This can then be used to ensure that the volume under the first sensor 120 is constant.

[0069] In the case of a pressure loss, the pressure P1 supplied to the fluid source 210 can be adjusted. This adjustment is performed when the fluid is in the volume V between both sensors 120 and 130. f The time T required to satisfy 1 f 1. This time should be kept constant. As the flow resistance increases, the volume V f The same time T as 1 is satisfied f Pressure P1 should be increased to maintain the pressure at 1. That is, time T f 1 is controlled by pressure P1. f 1 also has a volume V f 1, but if the dimensions of the flow channel 140 are constant, this volume V f 1 is a constant.

[0070] The relationship between the pressure P1 applied to the fluid source 210 and the pressure P2 through the conduit 224 is f 1 is managed to be constant over multiple repetitions of fluid delivery because the pressure difference experienced across the flow channel 140 is the controlling factor for fluid delivery to and from the flow channel 140.

[0071] Fluid herein may refer to gas or liquid. Fluid detection relates to detection of fluid flowing into the device 100, such as from a reservoir. The device 100 ideally does not include a vacuum, and therefore a secondary fluid is present within the device 100, which is replaced by a primary fluid flowing into the device 100, such as from a fluid source 210. This fluid is temporarily present within the device 100 and is detected by the first and second sensors 120, 130. Such sensors may operate using IR spectroscopy, magnetism (along with magnetic floats), conductivity sensors, or air pressure sensors to detect the fluid.

[0072] The phrase "detecting a fluid" may be used herein to refer to at least one of the following: detecting a fluid adjacent to a sensor; detecting a fluid passing through a sensor; detecting a change in a fluid adjacent to a sensor from a first fluid to a second fluid; and detecting a change in a fluid passing through a sensor from a first fluid to a second fluid. "Adjacent" may be used herein to mean near or in the vicinity of a sensor, and is not necessarily limited to being directly adjacent to a sensor.

[0073] During use, the fluid being displaced in flow path 140 may be evacuated from device 100 via a one-way valve, such as a pressure relief valve, or may be pressurized elsewhere in device 100. This may be useful for overfilling device 100 with fluid, as the incoming fluid must act against the pressure of the fluid being displaced.

[0074] In any of the above examples, rather than using a controller to control the opening and closing of the valve inlet 112 and valve outlet 116, the inlet 112 and outlet 116 can be pressure actuated. In this manner, fluid can enter the valve 100 when pressure P1 through conduit 222 is great enough to overcome the resistance to the fluid pressure at the inlet 112, and can exit the valve 100 when pressure P2 through conduit 224 is great enough to overcome the resistance to the fluid pressure at the outlet 116. In this manner, a less complex device 100 can be manufactured that does not require a controller.

Claims

1. 1. An apparatus for controlling a flow of a fluid, comprising: A first valve comprising: selectively openable and closable entrances; An opening; and A selectively openable and closable outlet is provided, the first valve arranged such that fluid can enter the first valve through the inlet, exit the first valve through the opening, enter the first valve through the opening, and exit the first valve through the outlet; a first sensor for detecting a fluid; a second sensor for detecting a fluid, wherein the first sensor and the second sensor are in fluid communication with the first valve through the opening; a control device that receives signals from the first sensor and the second sensor and controls opening and closing of the inlet and the outlet in response to the reception of the signals; During use, the fluid: flowing into the first valve through the inlet of the first valve; exiting the first valve through the opening in the first valve; passing a fluid through the first sensor to detect the fluid; flowing the fluid to the second sensor for detecting the fluid; flowing into the first valve through the opening in the first valve; The device is configured to allow flow through the device by exiting the first valve through the outlet of the first valve.

2. The control device: closing the inlet in response to receiving a signal from the second sensor transmitted in response to the second sensor detecting fluid; and 2. The device of claim 1, wherein the signal is transmitted in response to the first sensor detecting fluid after the signal from the second sensor is transmitted, and the device is configured to close the outlet in response to receiving a signal from the first sensor.

3. the signal transmitted in response to the second sensor detecting fluid is a signal to close the inlet; and 3. The apparatus of claim 2, wherein the signal transmitted in response to the first sensor detecting fluid is a signal to close the outlet.

4. The fluid can be detected by: detecting a fluid adjacent to the sensor; detecting fluid passing through the sensor; detecting a change in a fluid adjacent to the sensor from a first fluid to a second fluid; and 4. The apparatus of claim 2 or claim 3, further comprising at least one of detecting a change in fluid passing through the sensor from a first fluid to a second fluid.

5. 5. The apparatus of claim 1, further comprising a second valve, the second valve being disposed downstream of the outlet of the first valve.

6. a flow path configured to transport a fluid between the first valve, the first sensor, and the second sensor; 6. The device of claim 1, wherein the flow path is configured to hold a volume of fluid between the first valve and the second sensor of about 10 μl to about 1000 μl.

7. a fluid reservoir in fluid communication with the valve through the inlet; 7. Apparatus according to any one of claims 1 to 6, wherein the control device is configured to, in use, control the flow of fluid held in the fluid reservoir from the inlet to the valve.

8. The device of any one of claims 1 to 7, wherein the opening is a selectively openable and closable opening.

9. The device according to any one of claims 1 to 8, wherein the fluid is a liquid.

10. 1. A method for controlling a flow of a fluid, comprising: filling the flow channel with fluid to a first predetermined level; detecting when the flow path is filled to the first predetermined level; in response to said detecting, draining said flow path to a second predetermined level, said second predetermined level being less than said first predetermined level; detecting when the flow path is evacuated to the second predetermined level.

11. 1. A method for controlling a flow of a fluid, comprising: opening an inlet of the valve to allow fluid to enter the valve; passing the fluid through an opening in the valve; detecting the fluid with a second sensor; in response to detection of the fluid by the second sensor, closing an inlet of the valve to prevent the fluid from entering the valve; after the step of closing the inlet of the valve, opening an outlet of the valve to allow drainage of fluid from the valve; detecting a fluid with a first sensor; in response to detection of fluid by the first sensor, closing the outlet of the valve to prevent fluid from flowing out of the valve; The method, wherein detection by the second sensor requires a greater volume of fluid to enter the valve than detection by the first sensor.

12. in response to detecting the fluid by a second sensor, transmitting a fluid detected message from the second sensor to a controller; and in response to the controller receiving the message from the second sensor, sending a message to the valve to close the inlet of the valve to prevent fluid from entering the valve.

13. in response to detecting the fluid by the first sensor, transmitting a fluid detected message from the first sensor to a controller; and in response to receipt by the controller of the message from the first sensor, sending a message to the valve to close the outlet of the valve to prevent fluid from flowing out of the valve.

14. 14. The method of any one of claims 11 to 13, further comprising the step of sending a message to a fluid delivery system of a fluid reservoir to initiate delivery of fluid from the reservoir to the valve.

15. 15. The method of any one of claims 11 to 14, further comprising the step of delivering a predetermined volume of fluid from said valve, said predetermined volume being between about 2 μl and 100 μl.

16. The method of any one of claims 11 to 15, wherein the fluid is a liquid.

17. 17. The method of claim 11, further comprising the step of holding fluid between the valve and the second sensor for a predetermined period of time before opening an outlet of the valve to allow fluid to flow out of the valve.

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