Syringe pump

A syringe pump including a syringe including a plunger that slides in a body which has a discharge port, a driving mechanism coupled to the syringe, including a cylinder in which a piston slides, and a plurality of biasing devices arranged about the piston operative to apply urging forces on the piston to drive the piston distally in the cylinder and thereby cause the plunger to slide in the body and discharge a substance found in the body through the discharge port, wherein if one of the biasing devices fails another of the biasing devices continues to apply a force on the piston to drive the piston distally in the cylinder, and a safety catch that initially prevents the biasing device from moving the piston, the safety catch being removable to permit the biasing device to move the piston.

FIELD OF THE INVENTION

The present invention relates generally to syringe pumps, and particularly to a disposable syringe pump for sperm delivery, such as in slow-release insemination.

BACKGROUND OF THE INVENTION

Microfluidic pumping devices are used in numerous applications, such as administration of medicine and biological and pharmaceutical research. Such pumping devices include mechanical pumps, such as syringe-type pumps and micromechanical pumps, and non-mechanical pumps, such as electrohydrodynamic pumps, electro-osmotic flow pumps, electrowetting pumps, and thermocapillary pumps.

There are drawbacks to different pumping devices. For example, a steady flow rate is difficult to achieve. Moreover, many mechanical pumps require an electrical power source, as do pumps that operate based on electrical properties. Many of these pumps are costly and often have slow response times.

Conventional syringe pumps are typically employed with either a syringe or a vial and plunger system for administering a liquid to a patient. In such conventional systems, a syringe or vial of the liquid is oriented vertically in a fixed position on the syringe pump. The bottom of the syringe or vial defines a discharge port connected to a flexible, hollow tubing which extends to the patient. The plunger or piston of the apparatus is engaged with the moving pusher plate or drive member of the syringe pump and is driven downwardly into the syringe body or vial to force the liquid agent from the syringe body or vial through the tubing and into the patient.

An example of such a syringe pump is described in a system of PCT published patent application WO03008102. The system employs a microchannel and a gravity driven pump comprising horizontally oriented fluid supply reservoirs. The pump supplies fluid to the microchannel at a substantially constant rate. The device may be used, among other things, for motile sperm sorting.

SUMMARY OF THE INVENTION

The present invention seeks to provide a novel, disposable syringe pump for sperm delivery, such as in slow-release insemination, as described more in detail hereinbelow. The invention may have other applications and is not limited just to slow-release insemination. For example, the invention may be used in the laboratory or other research area for pumping sperm and other fluids.

There is thus provided in accordance with an embodiment of the present invention a pump including a syringe including a plunger that slides in a body which has a discharge port, a driving mechanism coupled to the syringe, including a cylinder in which a piston slides, and a plurality of biasing devices arranged (e.g., symmetrically arranged) about the piston operative to apply urging forces on the piston to drive the piston distally in the cylinder and thereby cause the plunger to slide in the body and discharge a substance found in the body through the discharge port, wherein if one of the biasing devices fails another of the biasing devices continues to apply a force on the piston to drive the piston distally in the cylinder, and a safety catch that initially prevents the biasing device from moving the piston, the safety catch being removable to permit the biasing device to move the piston.

The safety catch may be initially held in place by a breakable element, and an actuator may be provided, which when actuated breaks the breakable element and releases the safety catch to allow the piston to start traveling in the cylinder by the force of the biasing devices.

In accordance with an embodiment of the present invention the cylinder is at least partially filled with a hydraulic fluid, and as the piston slides in the cylinder, the hydraulic fluid flows from in front of the piston to behind the piston, whereupon the hydraulic fluid continues to flow through a tube out a needle. The biasing forces of the biasing devices and hydraulic damping of the hydraulic fluid provide a close-to-linear pumping force.

The tip of the needle may be covered with a sponge, which does not interfere with flow of the hydraulic fluid therethrough and yet prevents dehydration of the hydraulic fluid when the syringe pump is in long storage.

A finishing button may be arranged to push a portion of the tube against a knife, so as to cut the tube, whereupon cutting the tube, the hydraulic fluid suddenly flows through the tube instead of the needle.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made toFIG. 1, which illustrates a syringe pump10, constructed and operative in accordance with an embodiment of the present invention.

The syringe pump10may include an outer casing12, in which are housed a driving mechanism14coupled to a syringe16. The casing12is illustrated as being constructed of two halves joined together (e.g., by screws, bonding, sonic welding or any other suitable method of connection), but may be constructed of one part or many parts as well. The syringe pump10may have any size and shape, which may depend, among other things, on the size and shape of the syringe16and the required flow rate. In one non-limiting embodiment of the invention, syringe pump10may be about 5-9 cm long, 5 cm wide and 3 cm thick.

The syringe16may include a body18in which a plunger20slides. The body18may hold any suitable volume of sperm22, such as but not limited to, about 0.3-1.5 cc. The syringe16may have a discharge port24, which may be connected to suitable tubing and a filter (not shown) for sperm delivery, such as in slow-release insemination. The syringe16and its parts may be made of any medically safe material, such as but not limited to, polycarbonate, and may be completely disposable.

The driving mechanism14may be coupled to a head26of plunger20, such as by means of a clasp28or any other suitable link or connection. The driving mechanism14may include a cylinder30in which a piston32slides. The travel of piston32inside cylinder30may be bounded by end caps34. Piston32may be mounted on a shaft36, which is connected to clasp28.

Reference is now made additionally toFIGS. 3 and 4. The driving mechanism14may include a biasing device38, such as but not limited to, a coil spring, disposed on a portion of shaft36proximal to the piston32. The biasing device38is operative to apply an urging force on piston32to drive piston32distally (in the direction of an arrow40) in cylinder30. Initially, a safety catch35may arrest movement of shaft36and piston32. For example, the safety catch35may initially abut against one of the end caps34and sit in a notch33formed in shaft36, thereby preventing biasing device38from expanding and moving piston32.

Cylinder30may be at least partially filled with a hydraulic fluid42, such as but not limited to, glycerin. Piston32may be formed with a relatively tiny vent hole44(such as but not limited to, a diameter of 0.1 mm) that passes through the thickness of piston32and is in fluid communication with a port45in shaft36on the proximal side of piston32(seeFIG. 4). The combination of vent hole44and port45permit flow of hydraulic fluid42from a distal portion46of cylinder30(that is, in front of piston32) to a proximal portion48of cylinder30(that is, behind piston32) (seeFIG. 3). Accordingly, after removal of safety catch35, biasing device38pushes piston32distally in the direction of arrow40, and hydraulic fluid42is transferred between the distal portion46to the proximal portion48of cylinder30(located at the posterior end of the moving plunger) via vent hole44and port45. The combination of the biasing force of biasing device38and the hydraulic damping of the hydraulic fluid42may provide a close-to-linear pumping force.

As seen inFIG. 3, a regulator valve49may be disposed in the vent hole44that regulates the transfer of hydraulic fluid42between the distal portion46to the proximal portion48of cylinder30. The regulator valve49may include a threaded screw shaft that may be turned (e.g., with a screwdriver) to regulate the size of the opening for passage therethrough of hydraulic fluid42.

Referring again toFIG. 1, it is seen that the casing12may be provided with a window50through which the travel and forward progress of driving mechanism14may be observed. For example, the widow50may expose a tab52formed on shaft36, which easily allows observation of the movement of shaft36.

The flow or pumping rate of syringe pump10may be adjusted by adjusting or selecting different operating parameters, such as but not limited to, the spring coefficient of biasing device38, sizes and shapes of vent hole44and port45, the position of regulator valve49, the cross sectional area of cylinder30and of body18, and/or the viscosity of hydraulic fluid42(e.g., in the range of 50-1000 centipoise at 20° C.).

Reference is now made toFIGS. 5A and 5B, which illustrate a disposable syringe pump70, constructed and operative in accordance with another embodiment of the present invention.

As in the previous embodiment, the syringe pump70may include an outer casing72, in which are housed a driving mechanism74coupled to syringe16. As before, syringe16includes body18in which plunger20slides, and body18may hold any suitable volume of sperm22for discharging through discharge port24. Outer casing72may be provided with a strap73for attaching to a person or some object.

Reference is now made toFIGS. 7A and 7B. Driving mechanism74includes a piston76(also called plunger or plunger rod) which slides in a syringe cylinder78which is sealed by a cap79(seen inFIG. 5A). Driving mechanism74includes a plurality of biasing devices80, such as but not limited to, three coil springs symmetrically arranged about piston76(i.e., 120° apart). The coil springs are mounted on spring guides82. Piston76is capped by a sealing cap84at a distal end thereof. A tube86is fluidly connected to a vent tube88at the distal end of piston76. The other end of tube86is connected to a needle90via a male Luer lock92. A lever arm93is mounted on the proximal end of piston76for pushing plunger20of syringe16.

A safety catch94is mounted on the proximal end of piston76. Safety catch94is initially held in place by a breakable element96. An actuator, herein referred to as push button98, (FIG. 5A) is provided, which when actuated (pushed) breaks breakable element96and thereby releases safety catch94to allow piston76to start traveling in syringe cylinder78by the force of biasing devices80. The movement of piston76(via lever arm93) causes plunger20to move in syringe16and discharge sperm therefrom. It is noted that push button98is designed in such a way that it can not be activated unintentionally. The shape of push button98is flat and it has to be intentionally pressed in order to activate it.

As with the previous embodiment, cylinder78may be at least partially filled with a hydraulic fluid42, such as but not limited to, glycerin gel. Piston76may be formed with a relatively tiny vent hole as above that passes through the thickness of piston76to vent tube88. As piston76slides in cylinder78, hydraulic fluid42flows from the distal portion of cylinder78(that is, in front of piston76) to the proximal portion of cylinder78(that is, behind piston76), whereupon hydraulic fluid42continues to flow through tube86out needle90. Accordingly, after removal of safety catch94, the biasing devices80push piston76distally in cylinder78. The combination of the biasing force of biasing devices80and the hydraulic damping of the hydraulic fluid42may provide a close-to-linear pumping force.

The tip of needle90may be covered with a sponge, such as a polymer (closed cell polyurethane) sponge89, which does not interfere with the flow of hydraulic fluid42therethrough and yet prevents dehydration of hydraulic fluid42when syringe pump70is in long storage.

It is noted that in this embodiment, more than one biasing device is used and the biasing devices are arranged about the piston. The significance of this is twofold. First, since there is more than one biasing device, even if one of them fails the other biasing device(s) continues to apply a force on the piston to drive the piston distally in the cylinder and thus ensures proper operation of the pump. Second, the positioning of the biasing devices inside the plunger rod (piston) ensures that the biasing force is directly applied on the plunger rod and not on lever arm93, thus avoiding deformation and seizing of the driving mechanism.

Syringe pump70is provided with a finishing button100(FIG. 5A), which can be used to change the pump activity from continuous mode to an immediate bolus activity, as is now explained.

Finishing button100is arranged to push a portion of tube86against a knife102(FIG. 6). Pressing button100pushes tube86(which may be made, without limitation, from silicone or other cuttable material) against knife102which cuts tube86. Prior to cutting tube86, hydraulic fluid42was forced to flow out the very small tip of needle90. By cutting tube86, hydraulic fluid42suddenly can flow through a much larger area, that is, through the diameter of severed tube86. Thus, hydraulic fluid42suddenly flows through a larger diameter orifice, meaning the flow is much faster and biasing devices80push plunger76towards its distal end very quickly.

There are applications where there is a need to finish each pump cycle with a bolus shot to make sure that there is no sperm left in the syringe and catheter which is connected to the sperm container. Finishing button100may be used to make this bolus shot by rapidly ejecting the remaining sperm.