Constant Force Syringe

Abstract

Various syringe systems are disclosed. One such syringe system may include a body having a hollow lumen and a distal end, a vacuum chamber disposed within the hollow lumen of the syringe body, a first plunger connected to a distal portion of the vacuum chamber, the first plunger forming a first seal against an inner surface of the syringe body and defining a fluid volume between the first plunger and the distal end of the syringe body, a second plunger disposed within the vacuum chamber, the second plunger forming a second seal against an inner surface of the vacuum chamber and defining proximal and distal volume compartments within the vacuum chamber, and a piston affixed to the second plunger, the piston configured to move the second plunger within the vacuum chamber, thereby altering a volume of the proximal volume compartment and a volume of the distal volume compartment.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. application Ser. No. 13/797,959, filed Mar. 12, 2013, entitled "Constant Force Syringe", the disclosure of which is hereby incorporated by reference it its entirety.

BACKGROUND OF THE DISCLOSURE

[0002] 1. Field of the Disclosure

[0003] The present application relates, in general, to a syringe, and, in particular, to a constant force syringe for administration and aspiration of medications, supplements, fluids, contrast media, and/or the like at a constant rate.

[0004] 2. Description of the Related Art

[0005] During various medical procedures, it may be necessary to administer and/or aspirate medications, supplements, fluids, contrast media, saline, and/or the like to and from a patient or a fluid container. In general, administration and aspiration may occur subcutaneously, intramuscularly, intraperitoneally, and/or intravenously. In some instances, administration may be accomplished with the use of a manually activated syringe. In other instances, administration and/or aspiration may occur to and from a fluid container.

[0006] Occasionally, a constant rate of administration or aspiration may be of particular concern to the medical services provider and/or the patient. In an illustrative example, biological cells included in some treatments may be susceptible to damage if the pressure (or vacuum) and/or the flow rate of the injection/aspiration is too high. Furthermore, damage to the biological cells may reduce the efficacy of treatment. In another illustrative example, the rate of delivery/aspiration may be important to ensure proper uptake of an agent. Even the most skilled medical services provider may struggle with the process of smoothly administering/aspirating at a constant rate.

[0007] Cells are sensitive to shear forces and turbulence generated during a collection procedure. Non-constant rate or a rate above a cell lysis threshold can cause the rupture or the destruction of the cells. When the cell structure is compromised in this manner, a collected fluid specimen may not be identical to the fluid in the environment from which it is collected.

[0008] Previous attempts to ensure smooth administration and/or aspiration of medications, supplements, fluids, contrast media, and/or the like at a constant rate have resulted in injector systems that are used to administer and/or aspirate a fluid at a constant rate that are complicated and expensive to use and implement.

SUMMARY OF THE DISCLOSURE

[0009] In an embodiment, a syringe system may include a syringe body having a hollow lumen and a distal end. The syringe body may be configured to receive a fluid therein. A vacuum chamber may be disposed within the hollow lumen of the syringe body. A first plunger may be connected to a distal portion of the vacuum chamber within the hollow lumen of the syringe body. The first plunger may form a first seal against an inner surface of the syringe body and define a fluid volume between the first plunger and the distal end of the syringe body. A second plunger may be disposed within the vacuum chamber. The second plunger may form a second seal against an inner surface of the vacuum chamber and define a proximal volume compartment and a distal volume compartment within the vacuum chamber. A vent may be provided within one of the proximal volume compartment and the distal volume compartment of the vacuum chamber. The vent may be configured to allow communication of air between an area outside the syringe system and one of the proximal volume compartment and the distal volume compartment. A piston may be affixed to the second plunger and extend proximally out of the vacuum chamber. The piston may be configured to move the second plunger within the vacuum chamber, thereby altering a volume of the proximal volume compartment and a volume of the distal volume compartment.

[0010] In another embodiment, the vent may include a bore extending therethrough the piston and the second plunger, where the bore is configured to allow communication of air between an area outside the syringe system and one of the proximal volume compartment and the distal volume compartment. A valve may be provided to regulate an amount of the air communicated between the area outside the syringe system and one of the proximal volume compartment and the distal volume compartment. The vent may include a side vent extending through a wall in one of the proximal volume compartment and the distal volume compartment of the vacuum chamber. The side vent may be configured to allow communication of air between an area outside the syringe system and one of the proximal volume compartment and the distal volume compartment.

[0011] In another embodiment, a tip may be provided at the distal end of the syringe body. The tip may be configured to allow fluid from the fluid volume to pass therethrough upon movement of the first plunger. The tip may be further configured to attach to one or more tubes, needles, or nozzles for delivery of the fluid to a patient. The piston may extend proximally out of the vacuum chamber through a proximal wall, forming a third seal between the piston and the proximal wall.

[0012] In another embodiment, a force exacted upon the piston in a substantially distal direction may be configured to cause the second plunger to move distally within the vacuum chamber, thereby increasing the volume of the proximal volume compartment and decreasing the volume of the distal volume compartment, creating a pressure difference between the proximal volume compartment and the distal volume compartment, which causes the vacuum chamber and the first plunger to move in a distal direction, thereby expelling the fluid located in the fluid volume out of a tip in the distal end of the syringe body. Alternatively, a force exacted upon the piston in a substantially proximal direction may be configured to cause the second plunger to move proximally within the vacuum chamber, thereby increasing the volume of the distal volume compartment and decreasing the volume of the proximal volume compartment, creating a pressure difference between the proximal volume compartment and the distal volume compartment, which causes the vacuum chamber and the first plunger to move in a proximal direction, thereby aspirating the fluid into the fluid volume through a tip in the distal end of the syringe body.

[0013] In another embodiment, a syringe system may include a syringe body having a hollow lumen and a distal end. The syringe body may be configured to receive a fluid therein. A vacuum chamber may be at least partially disposed within the hollow lumen of the syringe body. A first plunger may be disposed distally to the vacuum chamber within the hollow lumen of the syringe body. The first plunger may form a seal against an inner surface of the syringe body and define a fluid volume between the first plunger and the distal end of the syringe body. A second plunger may be disposed within the vacuum chamber to define a proximal volume compartment and a distal volume compartment within the vacuum chamber. A side vent may extend through a wall in one of the distal volume compartment and the proximal volume compartment of the vacuum chamber. The side vent may be configured to allow communication of air between an area outside the syringe system and one of the proximal volume compartment and the distal volume compartment. A piston may extend distally out of the vacuum chamber and connect to the first plunger and the second plunger. The piston may be configured to move the second plunger within the vacuum chamber and the first plunger within the syringe body.

[0014] In another embodiment, a tip may be provided at the distal end of the syringe body. The tip may be configured to allow fluid from the fluid volume to pass therethrough upon movement of the first plunger. The tip may be further configured to attach to one or more tubes, needles, or nozzles for delivery of the fluid to a patient.

[0015] In another embodiment, a force exacted upon the vacuum chamber in a substantially distal direction may be configured to cause the vacuum chamber to move distally within the syringe body, thereby decreasing the volume of the proximal volume compartment and increasing the volume of the distal volume compartment, creating a pressure difference between the proximal volume compartment and the distal volume compartment, which causes the second plunger, the piston, and the first plunger to move in a distal direction, thereby expelling the fluid located in the fluid volume out of a tip in the distal end of the syringe body. Alternatively, a force exacted upon the piston in a substantially proximal direction may be configured to cause the second plunger to move proximally within the vacuum chamber, thereby increasing the volume of the distal volume compartment and decreasing the volume of the proximal volume compartment, creating a pressure difference between the proximal volume compartment and the distal volume compartment, which causes the vacuum chamber and the first plunger to move in a proximal direction, thereby aspirating the fluid into the fluid volume through a tip in the distal end of the syringe body.

[0016] In yet another embodiment, a syringe system may include a syringe body having a hollow lumen and a distal end having a tip. The syringe body may be configured to receive a fluid therein. A vacuum chamber may be at least partially disposed within the hollow lumen of the syringe body. A first plunger may be disposed distally to the vacuum chamber within the hollow lumen of the syringe body and form a seal against an inner surface of the syringe body, thereby defining a fluid volume between the first plunger and the distal end of the syringe body. A second plunger may be disposed within the vacuum chamber, the second plunger defining a proximal volume compartment and a distal volume compartment within the vacuum chamber. A piston may extend distally out of the vacuum chamber and be connected to the first plunger and the second plunger. The piston may be configured to move the second plunger within the vacuum chamber and the first plunger within the syringe body.

[0017] In another embodiment, a thumb piece may be removably attached to a proximal portion of the vacuum chamber. The thumb piece may be configured to provide a surface for a user to apply a force in a substantially axial direction. The thumb piece may be further configured to increase and decrease a volume of one of the distal volume compartment and the proximal volume compartment. The thumb piece may be configured to increase and decrease the volume of one of the distal volume compartment and the proximal volume compartment by screwing into at least a portion of the vacuum chamber. The thumb piece may be configured to move in a distal direction, wherein the vacuum chamber is configured to move within the syringe body in response to movement of the thumb piece. The second plunger, the piston, and the first plunger may be configured to move in response to the vacuum chamber moving within the syringe body.

[0018] In another embodiment, a syringe system may include a syringe body having a hollow lumen and a distal end having a tip. The syringe body may be configured to receive a fluid therein. A vacuum chamber may be at least partially disposed within the hollow lumen of the syringe body. A first plunger may be disposed distally to the vacuum chamber within the hollow lumen of the syringe body. The first plunger may form a seal against an inner surface of the syringe body and define a fluid volume between the first plunger and the distal end of the syringe body. A second plunger may be disposed within the vacuum chamber. The second plunger may define a proximal volume compartment and a distal volume compartment within the vacuum chamber. A thumb piece may be configured to screw into a proximal portion of the vacuum chamber. The thumb piece may be configured to increase and decrease a volume of one of the distal volume compartment and the proximal volume compartment. A piston may extend distally out of the vacuum chamber and be connected to the first plunger and the second plunger. The piston may be configured to move the second plunger within the vacuum chamber and the first plunger within the syringe body. A guide may be provided on an outside surface of the vacuum chamber, such that the guide is configured to assist a user of the syringe system to screw the thumb piece to a desired depth in the vacuum chamber to ensure a desired volume of one of the distal volume compartment and the proximal volume compartment. The thumb piece may be further configured to increase and decrease a flow rate of the fluid out of the syringe system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1A depicts a side view of a syringe having a vent according to an embodiment.

[0020] FIG. 1B depicts a side view of a syringe having an angled bore according to an embodiment.

[0021] FIG. 1C depicts a side view of a syringe having a bore that extends through the thumb piece according to an embodiment.

[0022] FIG. 2A depicts a side view of an alternative syringe having a side vent according to an embodiment.

[0023] FIG. 2B depicts a side view of an alternative syringe having a screw-on thumb piece according to an embodiment.

[0024] FIGS. 3A-3B depict movement of the various components of the syringe depicted in FIG. 1A according to an embodiment.

[0025] FIGS. 4A-4C depict movement of the various components of the syringe depicted in FIG. 2A according to an embodiment.

[0026] FIGS. 5A-5C depict movement of the various components of the syringe depicted in FIG. 2B according to an embodiment.

[0027] FIG. 6A depicts a side view of a syringe having a vent according to an embodiment.

[0028] FIG. 6B depicts a side view of a syringe having an angled bore according to an embodiment.

[0029] FIG. 6C depicts a side view of a syringe having a bore that extends through the thumb piece according to an embodiment.

[0030] FIG. 7A depicts a side view of an alternative syringe having a side vent according to an embodiment.

[0031] FIG. 7B depicts a side view of an alternative syringe having a screw-on thumb piece according to an embodiment.

[0032] FIGS. 8A-8B depict movement of the various components of the syringe depicted in FIG. 6A according to an embodiment.

[0033] FIGS. 9A-9C depict movement of the various components of the syringe depicted in FIG. 7A according to an embodiment.

[0034] FIGS. 10A-10C depict movement of the various components of the syringe depicted in FIG. 7B according to an embodiment.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0035] This disclosure is not limited to the particular systems, devices and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope.

[0036] As used in this document, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior disclosure. As used in this document, the term "comprising" means "including, but not limited to."

[0037] For purposes of the description hereinafter, the terms "upper," "lower," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and derivatives thereof shall relate to the orientation of embodiments disclosed in the figures. However, embodiments may assume alternative variations and step sequences, except where expressly specified to the contrary. The specific devices and processes illustrated in the attached drawings and described in the following specification, are exemplary embodiments. Hence, physical characteristics related to the embodiments disclosed herein are not to be considered as limiting.

[0038] The word "proximal" refers to a direction relatively closer to a clinician or operator using the device described herein, and the word "distal" refers to a direction relatively further from the clinician or operator. For example, the end of a syringe placed nearest the body of a patient is considered a distal end of the syringe, while the end closes to the clinician is a proximal end of the syringe. The terms "axial" or "axially" refer generally to an axis around which the particular objects being referred to are preferably formed (although not necessarily symmetrically therearound). The term "radial" refers generally to a direction normal to the axis or along a radius of an object having a circular cross-section.

[0039] Various embodiments of the present disclosure may be directed to syringes, particularly those used for manual fluid delivery and aspiration, that may rely on a transient vacuum induced within one or more compartments of the syringe. In some embodiments, the fluid may be delivered from the syringe at a uniform rate because the vacuum itself powers the fluid delivery or aspiration, as applicable, instead of the person or device pressing on the thumb piece of the syringe.

[0040] FIG. 1A depicts a side view of a syringe, generally designated 100, having a vent 135 according to an embodiment. The syringe 100 may generally include a syringe body 105 having a hollow lumen 107, a proximal end 101, and a distal end 102 having a tip 110. The syringe body 105 is not limited in shape or size by this disclosure, and may be any shape or size, particularly shapes and sizes of syringe bodies commonly known by those skilled in the art. In various embodiments, the syringe body 105 may be substantially cylindrical. In various embodiments, the syringe body 105 may be about 4 ml to about 20 ml in volume. In particular embodiments, the volume of the syringe body 105 may be about 4 ml, about 5 ml, about 10 ml, about 15 ml, about 20 ml, or any value or range between any two of these values. In various embodiments, the syringe 100 may be made of glass, a polymer, and/or the like.

[0041] In various embodiments, the hollow lumen 107 may include a plurality of plungers disposed therein. For example, in the present embodiment, the hollow lumen 107 may have a first plunger 125 and a second plunger 150. However, those skilled in the art will recognize that more than two plungers may be used without departing from the scope of this disclosure. In some embodiments, a vacuum chamber 120 may be disposed within the syringe body 105 in contact with the first plunger 125. In various embodiments, the first plunger 125 may form a seal against the interior of the syringe body 105 by means of a first seal 130. In some embodiments, the first seal 130 may be a separate component from the first plunger 125, such as, for example, an added O-ring and/or the like. In these embodiments, the first seal 130 may be fixedly attached to the first plunger 125 by any means of attachment, including attachment apparatuses, adhesives, and/or the like, or the first seal may removably attached to the first plunger. In other embodiments, the first seal 130 may be fabricated as a portion of the first plunger 125. In some embodiments, the first seal 130 may be associated with a distal portion of the vacuum chamber 120.

[0042] In various embodiments, the second plunger 150 may be disposed within the vacuum chamber 120. In some embodiments, the second plunger 150 may be mechanically activated by a piston 155. The second plunger 150 may be attached to the piston 155 by any means of attachment, including, but not limited to, any number of clips, fasteners, hooks, adhesives, and/or the like. In some embodiments, the second plunger 150 may be molded as a portion of the piston 155. In some embodiments, the piston 155 may at least partially extend out of an opening of the proximal end 101 of the syringe body 105. In some embodiments, the piston 155 may generally extend out of the vacuum chamber 120 through a proximal wall 140. The opening in the proximal wall 140 may be sealed with a second seal 145 to the piston 155. The second seal 145 may be an air-tight seal around the shaft of the piston 155. In some embodiments, in lieu of the vent 135, the piston 155 may contain a bore therethrough, such as 180 in FIG. 1B or 180' in FIG. 1C, as described in greater detail herein.

[0043] In various embodiments, a proximal portion of the piston 155 may be connected to a thumb piece 160. The thumb piece 160 may generally provide a surface upon which a user's digits or another device applies a force to move the piston 155 in either a distal or proximal direction. The thumb piece 160 depicted herein is a generally flat surface; however, those skilled in the art will recognize that the shape and size of the thumb piece is not limited by this disclosure, and may include any number of rings, openings, contoured surfaces, and/or the like without departing from the scope of the present disclosure. Persons skilled in the art will also note that the term `thumb piece` is not intended to be limiting; while a thumb may be a preferred digit for manipulating the thumb piece 160, the user may use any object to manipulate the thumb piece as described herein. In an illustrative example, a user may press his/her thumb against the thumb piece 160 to effect distal movement of the piston 155 and/or other components of the syringe 100, as described in greater detail herein.

[0044] Similar to the first plunger 125 described herein, in various embodiments, the second plunger 150 may form an airtight seal against an interior surface of the vacuum chamber 120, thereby dividing the vacuum chamber into two volume compartments. A distal volume compartment 165 may be created by the space between a distal surface of the second plunger 150 and a proximal end of the first plunger 125. A proximal volume compartment 170 may be created by the space between a proximal surface of the second plunger 150 and a distal surface of the proximal wall 140 of the vacuum chamber 120.

[0045] In various embodiments, the vacuum chamber 120 may be detachable from the first plunger 125. The ability to detach the vacuum chamber 120 from the first plunger 125 may allow for use of vacuum chambers that vary in size and shape, thereby increasing compatibility with a wide range of forces to allow for varying pressures and flow rates, as described in greater detail herein.

[0046] In various embodiments, the vacuum chamber 120 may include a vent 135. The vent 135 may generally be an opening within the vacuum chamber to allow fluid communication of air between the distal volume compartment 165 and an area outside the syringe body 105. In some embodiments, the communication between the vent 135 and the area outside the syringe body 105 may be along a path bounded by the inner surface of the syringe body and the outer surface of the vacuum chamber 120.

[0047] In various embodiments, a fluid delivery volume 175 may be defined within the syringe body 105. In some embodiments, the fluid delivery volume 175 may be defined as the space that is located distally to the first plunger 125. In some embodiments, the fluid delivery volume 175 may contain a fluid therein. Examples of fluids are not limited by this disclosure, and may include, for example, medications, supplements, bodily fluids, contrast media, saline, and/or the like. In some embodiments, fluid contained within the fluid delivery volume 175 may be delivered through the tip 110. The tip 110 may further be configured to be connected to additional elements, such as, for example, needles, tubes, nozzles, and/or the like for delivery of the fluid. It may be appreciated that the first seal 130 may be configured to prevent air transfer from either outside the syringe body 105 or the vacuum chamber 165 from entering the delivery volume 175. Similarly, the first seal 130 may be configured to prevent air and/or fluid from escaping the delivery volume 175 into the vacuum chamber 165 and/or the remainder of the syringe body 105. The volume of the delivery volume 175 may be determined by the distance between the first plunger 125 and the distal end 102 of the syringe body 105, as well as the circumference of the syringe body.

[0048] In various embodiments, one or more finger guards 115 may be positioned at a location that is generally located at or near the proximal end 101 of the syringe body 105. In some embodiments, the finger guards 115 may generally be located on an outside surface of the syringe body 105 and may generally extend from the outside surface of the syringe body. In some embodiments, the finger guards 115 may act to provide stability to the syringe 100 during operation. In some embodiments, a user may use the finger guards 115 to prevent movement of the syringe 100 during operation. In some embodiments, the user may use the finger guards 115 to prevent the syringe 100 from slipping out of the user's hand. In some embodiments, the user may use the finger guards 115 to protect the user's fingers. In some embodiments, the finger guards 115 may act as a stopping device to prevent the piston 155 from moving further distally inside the syringe body 105. The shape and size of the finger guards 115 are not limited by this disclosure, and may be any shape and/or size known in the art. Specific examples of shapes may be ring shaped, wedge shaped, and/or the like.

[0049] In various embodiments, as depicted in FIGS. 1B and 1C, the bore 180, 180' may be used in lieu of the vent 135 (FIG. 1A). In some embodiments, the bore 180, 180' may extend through at least a portion of the piston 155 and/or the second plunger 150. In some embodiments, the bore 180, 180' may be configured to allow air from outside the syringe 100 to enter and/or escape the vacuum chamber 120, effectively regulating by increasing and/or decreasing the pressure of air inside the vacuum chamber. In some embodiments, the bore 180 may include a bore outlet 181 containing a valve and/or the like to assist in regulation of air pressure inside the vacuum chamber 120. In some embodiments, the valve may be incorporated within the thumb piece 160. In other embodiments, the valve may be a separate element, such as a one way check valve or the like. In yet other embodiments, a user may use his/her finger to block the bore 180 in a manner similar to that of a valve. In some embodiments, such as the syringe shown in FIG. 1B, the bore 180 may be curved or angled so that the bore outlet 181 is located substantially on a side of the piston 155, such as, for example, a top side, a bottom side, or the like. In other embodiments, such as the syringe shown in FIG. 1C, the bore 180' may be substantially straight and/or linear with the piston 155. Such a configuration may allow for the bore outlet 181' to be located at or near the thumb piece 160. In some embodiments with this configuration, the thumb piece 160 may act as the valve to block the bore outlet 181', as previously described herein. In other embodiments with this configuration, a user may block the bore outlet 181' with an external apparatus, a thumb, and/or the like while manipulating the thumb piece 160 at the same time.

[0050] FIG. 2A depicts a side view of an alternative syringe, generally designated 200, according to an embodiment. Similar to the syringe 100 disclosed with respect to FIGS. 1A-1C above, the syringe 200 may include a syringe body 205 having a proximal end 201 and a distal end 202. In some embodiments, the syringe body 205 may include a first plunger 225 disposed therein, the plunger incorporating a first seal 230, as previously described herein. A delivery volume 275 may be formed between the distal surface of the first plunger 225 and the tip, as previously described herein.

[0051] In various embodiments, a vacuum chamber 220 may be disposed within the syringe body 205. In some embodiments, the vacuum chamber 220 may be bounded by a distal wall 240 and a proximal thumb piece 260. In some embodiments, at least a portion of the vacuum chamber 220 may contain air that is pressurized to a pressure at or above standard atmospheric air pressure at sea level, as described in greater detail herein. In other embodiments, at least a portion of the vacuum chamber 220 may contain air that is pressurized to a pressure below standard atmospheric air pressure at sea level, as described in greater detail herein.

[0052] In various embodiments, the first plunger 225 may be mechanically coupled via a piston 255 to the second plunger 250. The first plunger 225 may generally be disposed at a location inside the syringe body 205, as previously described herein, and further disposed at a location that is distal to the vacuum chamber 220. In some embodiments, the positioning of the first plunger 225 and the vacuum chamber 220 may define a medial compartment 285 therebetween. Particularly, the medial compartment 285 may be formed between the proximal surface of the first plunger 225 and the distal surface of the distal wall 240. In some embodiments, the piston 255 may traverse the medial compartment 285 and extend into the vacuum chamber 220 through the distal wall 240. In some embodiments, the piston 255 may be attached by any means of attachment to the first plunger 225 and/or the second plunger 250. In some embodiments, the piston 255 may be molded as a portion of the first plunger 225 and/or the second plunger 250. In some embodiments, the piston 255 may be detachable from the first plunger 225 and/or the second plunger 250. The ability to detach the piston 255 from the plungers 225, 250 may allow for the piston to be used with varying plungers, thereby increasing compatibility with a wide range of syringes of different sizes and shapes, lowering operating costs, lowering manufacturing costs, enabling the use pre-filled syringes, and/or the like.

[0053] In various embodiments, the second plunger 250 may be located within the vacuum chamber 220. As in the embodiments depicted herein with respect to FIGS. 1A-1C, the second plunger 250 may be configured to form an airtight seal against an interior surface of the vacuum chamber 220, thereby dividing the vacuum chamber into two compartments. A distal volume compartment 265 may be created by the space between a distal surface of the second plunger 250 and the distal wall 240 of the vacuum chamber 220. A proximal volume compartment 270 may be created by the space between a proximal surface of the second plunger 250 and a distal surface of the thumb piece 260.

[0054] In various embodiments, a second seal 245 may be positioned within the distal wall 240 around the piston 255 to form an airtight seal around the piston. In some embodiments, the second seal 245 may prevent air from entering and/or escaping from the distal volume compartment 265 when the piston 255 is actuated. In some embodiments, the distal volume compartment 265 may be sealed and/or evacuated before the syringe 200 is used.

[0055] In optional embodiments, the vacuum chamber 220 may include a vent 235. The vent 235 may generally be an opening within the vacuum chamber 220 configured to allow fluid communication of air between an area outside the syringe body 205 and the proximal volume compartment 270. The vent 235 may be further configured to equalize air pressure within the proximal volume compartment 270 with the outside air pressure, as described in greater detail herein. In some embodiments, the outside air pressure may be about 14.7 psi, or standard atmospheric pressure at sea level.

[0056] As depicted in FIG. 2B, a movable thumb piece 260' may be used instead of a vent according to some embodiments. The movable thumb piece 260' may be moved generally distally and/or proximally by any means of movement, and is not limited by this disclosure. By way of example only, the movable thumb piece 260' in the present embodiment may contain a plurality of threads 290 that allow the thumb piece to be screwed into the vacuum chamber 220. In some embodiments, the thumb piece 260' may be screwed over the vacuum chamber 220. In other embodiments, the thumb piece 260' may be screwed inside the vacuum chamber 220. The thumb piece 260' may be screwed into a specific depth to obtain a desired pressure inside the proximal volume compartment 270, as will be described in greater detail herein. To aid in determining the pressure inside the proximal volume compartment 270 a guide 295 may be located on the syringe 200 to aid a user in determining where to position the thumb piece 260'. For example, the guide 295 may be a plurality of hash marks printed on an outside surface of the vacuum chamber 220, wherein each hash mark is labeled with the pressure that will be achieved by moving the thumb piece 260' to that hash mark. In some embodiments, the thumb piece 260 may incorporate a display that indicates the amount of adjusted pressure inside the proximal volume chamber 270.

[0057] In various embodiments, the syringe 200 may further include any number of shock absorbing devices (not shown). Specific examples of shock absorbing devices may include, for example, springs, air cushions, absorbing materials, and/or the like. The shock absorbing devices may generally function to ensure a smooth distribution of fluid out of the tip 210 at a constant rate that acts supplementary to the driving force cause by the difference in pressure, as described in greater detail herein.

[0058] FIGS. 3A-3B depict movement of the various components of the syringe 100 depicted in FIGS. 1A-1C according to an embodiment. More particularly, FIG. 3A depicts an initial state of the syringe 100. As previously described herein, a force F may be applied to the thumb piece 160 to force the piston 155 in a distal direction into the syringe body 105. As a result, the piston 155 may mechanically force the second plunger 150 to move in a distal direction within the vacuum chamber 120.

[0059] As described in greater detail herein, the second seal 145 and the second plunger 150 may be configured to prevent air from entering the proximal volume compartment 170. In addition, the movement of the second plunger 150 in a distal direction may increase the volume of the proximal volume compartment 170. In some instances, this combination may result in a decrease in pressure in the proximal volume compartment 170 where the proximal volume compartment has a pressure greater than or equal to zero. However, in instances where the proximal volume compartment 170 is a vacuum (thereby having a zero pressure), this combination will not change the pressure within the proximal volume compartment 170. This is due to the ideal gas law, which is represented by Equation (1):

PV=nRT (1)

where P is the pressure of the gas, V is the volume of the gas, n is the amount of substance of gas (also known as number of moles), T is the temperature of the gas and R is the ideal, or universal, gas constant, equal to the product of the Boltzmann constant and the Avogadro constant. To compare different volumes, Equation (1) can be written to reflect the different volumes as follows: P.sub.--1V.sub.--1=nR.sub.--1T.sub.--1 and P.sub.--2V.sub.--2=nR.sub.--2T.sub.--2. If P1 and P2 are both zero because of the vacuum (zero pressure), then a change in either volume V1, V2 will not change the results.

[0060] Furthermore, the pressure can be written as a function of force, as represented by Equation (2):

.DELTA.P=F/A (2)

where .DELTA.P is the change in pressure, F is the normal force, and A is the area of the surface on contact. Thus, in an illustrative example, if the pressure P is zero (0 psi), such as in a vacuum, then according to Equation (1), the pressure will not change when other variables change, such as, for example, the volume V. Since the pressure remains the same, the force F that is exerted by the pressure will also remain constant according to Equation (2), which allows for a smooth distribution of the fluid from within the delivery volume 175.

[0061] Similarly, the movement of the second plunger 150 in a distal direction may decrease the volume of the distal volume compartment 165. However, due to the location of the vent 135 (or in some embodiments, the bore 180), the pressure of the distal volume compartment may equalize with the outside air pressure (i.e., moving towards about 14.7 psi). As a result the force F may be active on the second plunger 150 due to the unequal pressure between the pressure of the distal volume compartment 165 and the pressure of the proximal volume compartment 170. In some embodiments, the pressure of the distal volume compartment 165 may be greater than the pressure of the proximal volume compartment 170. In other embodiments, such as those where it is desired to add fluid to the syringe 100, the pressure of the distal volume compartment 165 may be less than the pressure of the proximal volume compartment 170. In some embodiments, to ensure that the proximal volume compartment has a lower pressure than the distal volume compartment 165, the proximal volume compartment may be pre-evacuated prior to movement of the piston 155. The pre-evacuation process may be completed, for example, by attaching a vacuum pump or the like to the proximal volume compartment 170 through a sealable valve and port (not shown).

[0062] In various embodiments, because of the unequal pressure between the distal volume compartment 165 and the proximal volume compartment 170, a driving force F' may be active on the vacuum chamber 120. However, since the user may maintain force on the thumb piece 160 to keep it in a depressed state, the second plunger 150 may be fixed relative to the syringe body 105. Accordingly, the pressure difference between the distal volume compartment 165 and the proximal volume compartment 170 may force the vacuum chamber 120 to shift in the distal direction, thereby driving the first plunger 125 in a distal direction towards the distal end 102 of the syringe body 105. The resulting motion of the first plunger 125 may reduce the delivery volume 175, causing the fluid in the delivery volume to exit out the tip 110 at a steady rate. Those skilled in the art may appreciate that the driving force F' on the first plunger 125 may be due to the pressure difference developed between the proximal volume compartment 170 and the distal volume compartment 165, and may not depend on the user's force on the thumb piece 160. Those skilled in the art may also appreciate that the driving force F' on the first plunger 125 may not be due to the position of the second plunger 150 relative to the vacuum chamber 120 and/or the syringe body 105, as long as the second plunger is not located at the proximal end 101 or the distal end 102 of the syringe body. Furthermore, the driving force F' on the first plunger 125 may not be due to the velocity of the second plunger 150 in moving towards the distal end 102 of the syringe body 105 provided that there is only a small amount of friction between the second plunger and the vacuum chamber 120. Accordingly, the rate of motion of the first plunger 125 may be smooth and may not reflect any possible unsteady movement from the user. Furthermore, the rate of delivery of the fluid from the delivery volume 175 may be adjusted by the user prior to applying force on the thumb piece 160 by increasing or decreasing the pressure of the distal volume compartment 165, as described in greater detail herein.

[0063] FIGS. 4A-4C depict the effect on the syringe of FIG. 2A when a force F is applied to the thumb piece 260 according to various embodiments. In some embodiments, the force F may cause the thumb piece 260 to move in a generally distal direction. This movement of the thumb piece 260 may cause the vacuum chamber 220 to also travel in a generally distal direction within the syringe body 205. In some embodiments, the various volume compartments 265, 270 may change volume as a result of the movement while the pressure remains the same (i.e., about 14.7 psi in the proximal volume compartment and zero in the distal volume compartment), as previously described herein. In some embodiments, the force F applied to the thumb piece 260 may cause the vacuum chamber 220 to move relative to the second plunger 250. The movement of the vacuum chamber 220 may therefore result in an increase in the volume of the distal volume compartment 265 and a decrease in volume of the proximal volume compartment 270. In various embodiments, a driving force F' that pushes the first plunger 225 towards the distal end 202 of the syringe body 205 may result from the difference of pressure of the proximal volume compartment 270 (where the pressure is at or near atmospheric pressure, or about 14.7 psi) and the distal volume compartment 265 (where the pressure is zero) as described herein. Accordingly, if a user of the syringe 200 provides a sharp force on the thumb piece 260, it will have no effect on the rate of ejection of fluid from the tip 210 because the difference in pressures in the distal volume compartment 265 and the proximal volume compartment 270 will continue to remain the same, even with the distal volume compartment increasing in volume. In addition, if a faster rate of ejection of fluid from the tip 210 is desired, the vent 235 can be covered with a valve or a user's finger while a force is exacted upon the thumb piece 260 to increase the pressure of the proximal volume compartment 270 and alter the driving force F' accordingly.

[0064] FIGS. 5A-5C depict the effect on the syringe of FIG. 2B when a force F is applied to the thumb piece 260' according to various embodiments. The movement of the various components of the syringe 200 is substantially the same as previously described herein with respect to FIGS. 4A-4C; however, instead of regulating the pressure of the proximal volume compartment 270 with a vent to increase the rate of distribution of fluid, the thumb piece 260' may be moved to adjust the pressure of the proximal volume compartment. For example, the thumb piece 260' may be moved in a proximal direction to decrease the pressure of the proximal volume compartment 270. Similarly, the thumb piece 260' may be moved in a distal direction to increase the pressure of the proximal volume compartment 270. In some embodiments, the thumb piece 260' may be moved in either direction by twisting the thumb piece in a clockwise direction T or in a counterclockwise direction (not shown). In some embodiments, adjusting the thumb piece 260' to decrease the pressure in the proximal volume compartment 270 may decrease the difference in pressure between the proximal volume compartment and the distal volume compartment 265, thereby causing the force on the second plunger 250 to decrease, which may cause a slower movement of the second plunger in the distal direction. Similarly, in some embodiments, adjusting the thumb piece 260' to increase the pressure in the proximal volume compartment 270 may increase the difference in pressure between the proximal volume compartment and the distal volume compartment 265, thereby causing the force on the second plunger 250 to increase, which may cause a faster movement of the second plunger in the distal direction.

[0065] FIG. 6A depicts a side view of a syringe, generally designated 300, having a vent 335 according to an embodiment. The syringe 300 may generally include a syringe body 305 having a hollow lumen 307, a proximal end 301, and a distal end 302 having a tip 310. The syringe body 305 is not limited in shape or size by this disclosure, and may be any shape or size, particularly shapes and sizes of syringe bodies commonly known by those skilled in the art. In various embodiments, the syringe body 305 may be substantially cylindrical. In various embodiments, the syringe body 305 may be about 4 ml to about 20 ml in volume. In particular embodiments, the volume of the syringe body 305 may be about 4 ml, about 5 ml, about 10 ml, about 15 ml, about 20 ml, or any value or range between any two of these values. In various embodiments, the syringe 300 may be made of glass, a polymer, a metal, a composite, and/or the like.

[0066] In various embodiments, the hollow lumen 307 may include a plurality of plungers disposed therein. For example, in the present embodiment, the hollow lumen 307 may have a first plunger 325 and a second plunger 350. However, those skilled in the art will recognize that more than two plungers may be used without departing from the scope of this disclosure. In some embodiments, a vacuum chamber 320 may be disposed within the syringe body 305 in contact with the first plunger 325. In various embodiments, the first plunger 325 may form a seal against the interior of the syringe body 305 by means of a first seal 330. In some embodiments, the first seal 330 may be a separate component from the first plunger 325, such as, for example, an added O-ring and/or the like. In these embodiments, the first seal 330 may be fixedly attached to the first plunger 325 by any means of attachment, including attachment apparatuses, adhesives, and/or the like, or the first seal may removably attached to the first plunger. In other embodiments, the first seal 330 may be fabricated as a portion of the first plunger 325. In some embodiments, the first seal 330 may be associated with a distal portion of the vacuum chamber 320.

[0067] In various embodiments, the second plunger 350 may be disposed within the first plunger 325. In some embodiments, the second plunger 350 may be mechanically activated by a piston 355. The second plunger 350 may be attached to the piston 355 by any means of attachment, including, but not limited to, any number of clips, fasteners, hooks, adhesives, and/or the like. In some embodiments, the second plunger 350 may be molded as a portion of the piston 355. In some embodiments, the piston 355 may at least partially extend out of an opening of the proximal end 301 of the syringe body 305. In some embodiments, the piston 355 may generally extend out of the first plunger 325 through a proximal wall 340. The opening in the proximal wall 340 may be sealed with a second seal 345 to the piston 355. The second seal 345 may be an air-tight seal around the shaft of the piston 355. In some embodiments, the piston 355 may contain a bore therethrough, such as 380 in FIG. 6B or 380' in FIG. 6C, as described in greater detail herein.

[0068] In various embodiments, a proximal portion of the piston 355 may be connected to a thumb piece 360. The thumb piece 360 may generally provide a surface upon which a user's digits or another device applies a force to move the piston 355 in either a distal or proximal direction. The thumb piece 360 is depicted herein as a generally flat surface; however, those skilled in the art will recognize that the shape and size of the thumb piece is not limited by this disclosure, and may include any number of rings, openings, contoured surfaces, and/or the like without departing from the scope of the present disclosure. Persons skilled in the art will also note that the term `thumb piece` is not intended to be limiting; while a thumb may be a preferred digit for manipulating the thumb piece 360, the user may use any digit(s), body extremity (such as heel of a hand), or object to manipulate the thumb piece as described herein. In an illustrative example, a user may press his/her thumb against the thumb piece 360 to effect distal movement of the piston 355 and/or other components of the syringe 300, as described in greater detail herein. In another illustrative example, a user may grasp thumb piece 360 with his/her thumb and one or more additional digits on his/her hand to proximally draw piston 355 and/or other components the syringe 300.

[0069] Similar to the first plunger 325 described herein, in various embodiments, the second plunger 350 may form an airtight seal against an interior surface of the vacuum chamber 320, thereby dividing the vacuum chamber into two volume compartments. A distal volume compartment 365 may be created by the space between a distal surface of the second plunger 350 and a distal end of the vacuum chamber 320. A proximal volume compartment 370 may be created by the space between a proximal surface of the second plunger 350 and a distal surface of the proximal wall 340 of the vacuum chamber 320.

[0070] In various embodiments, the vacuum chamber 320 may be detachable from the first plunger 325. The ability to detach the vacuum chamber 320 from the first plunger 325 may allow for use of vacuum chambers that vary in size and shape, thereby increasing compatibility with a wide range of forces to allow for varying pressures and flow rates, as described in greater detail herein.

[0071] In various embodiments, the vacuum chamber 320 may include a vent 335. The vent 335 may generally be an opening within the vacuum chamber 320 and/or a bore through the shaft of piston 355 to allow fluid communication of air between the proximal volume compartment 370 and an area outside the syringe body 305. In some embodiments, the communication between the vent 335 and the area outside the syringe body 305 may be along a path extending through the proximal wall 340.

[0072] In various embodiments, a fluid aspiration volume 375 may be defined within the syringe body 305. In some embodiments, the fluid aspiration volume 375 may be defined as the space that is located distally to the first plunger 325. In some embodiments, the fluid aspiration volume 375 may contain a fluid therein. Examples of fluids are not limited by this disclosure, and may include, for example, medications, supplements, bodily fluids, contrast media, saline, suspensions of biological cells, and/or the like. In some embodiments, fluid contained within the fluid aspiration volume 375 may be aspirated through the tip 310. The tip 310 may further be configured to be connected to additional elements, such as, for example, needles, tubes, nozzles, and/or the like for aspiration of the fluid. It may be appreciated that the first seal 330 may be configured to prevent air transfer from either outside the syringe body 305 or the vacuum chamber 320 from entering the aspiration volume 375. Similarly, the first seal 330 may be configured to prevent air and/or fluid from escaping the aspiration volume 375 into the vacuum chamber 320 and/or the remainder of the syringe body 305. The volume of the aspiration volume 375 may be determined by the distance between the first plunger 325 and the distal end 302 of the syringe body 305, as well as the circumference of the syringe body 305.

[0073] In various embodiments, one or more finger guards 315 may be positioned at a location that is generally located at or near the proximal end 301 of the syringe body 305. In some embodiments, the finger guards 315 may generally be located on an outside surface of the syringe body 305 and may generally extend from the outside surface of the syringe body. In some embodiments, the finger guards 315 may act to provide stability to the syringe 300 during operation. In some embodiments, a user may use the finger guards 315 to prevent movement of the syringe 300 during operation. In some embodiments, the user may use the finger guards 315 to prevent the syringe 300 from slipping out of the user's hand. In some embodiments, the user may use the finger guards 315 to protect the user's fingers. In some embodiments, the finger guards 315 may act as a stopping device to prevent the piston 355 from moving further distally inside the syringe body 305. The shape and size of the finger guards 315 are not limited by this disclosure, and may be any shape and/or size known in the art. Specific examples of shapes may be ring shaped, wedge shaped, and/or the like.

[0074] In various embodiments, as depicted in FIGS. 6B and 6C, the bore 380, 380' may be used in lieu of the vent 335 (FIG. 6A). In some embodiments, the bore 380, 380' may extend through at least a portion of the piston 355 and/or the second plunger 350. In some embodiments, the bore 380, 380' may be configured to allow air from outside the syringe 300 to enter and/or escape the vacuum chamber 320, such as proximal volume compartment 370, effectively regulating by increasing and/or decreasing the pressure of air inside the vacuum chamber 320. In some embodiments, the bore 380 may include a bore outlet 381 containing a valve and/or the like to assist in regulation of air pressure inside the vacuum chamber 320. In some embodiments, the valve may be incorporated within the thumb piece 360. In other embodiments, the valve may be a separate element, such as a one way check valve or the like. In yet other embodiments, a user may use his/her finger to block the bore 380 in a manner similar to that of a valve. In some embodiments, such as the syringe shown in FIG. 6B, the bore 380 may be curved or angled so that the bore outlet 381 is located substantially on a side of the piston 355, such as, for example, a top side, a bottom side, or the like. In other embodiments, such as the syringe shown in FIG. 6C, the bore 380' may be substantially straight and/or linear with the piston 355. Such a configuration may allow for the bore outlet 381' to be located at or near the thumb piece 360. In some embodiments with this configuration, the thumb piece 360 may act as the valve to block the bore outlet 381', as previously described herein. In other embodiments with this configuration, a user may block the bore outlet 381' with an external apparatus, a thumb, and/or the like while manipulating the thumb piece 360 at the same time.

[0075] FIG. 7A depicts a side view of an alternative syringe, generally designated 400, according to an embodiment. Similar to the syringe 300 disclosed with respect to FIGS. 6A-6C above, the syringe 400 may include a syringe body 405 having a proximal end 401 and a distal end 402. In some embodiments, the syringe body 405 may include a first plunger 425 disposed therein, the plunger incorporating a first seal 430. An aspiration volume 475 may be formed between the distal surface of the first plunger 425 and the tip 410.

[0076] In various embodiments, a vacuum chamber 420 may be disposed within the syringe body 405. In some embodiments, the vacuum chamber 420 may be bounded by a distal wall 440 and a proximal thumb piece 460. In some embodiments, at least a portion of the vacuum chamber 420 may contain air that is pressurized to a pressure at or above standard atmospheric air pressure at sea level, as described in greater detail herein. In other embodiments, at least a portion of the vacuum chamber 420 may contain air that is pressurized to a pressure below standard atmospheric air pressure at sea level (i.e., a full or partial vacuum), as described in greater detail herein.

[0077] In various embodiments, the first plunger 425 may be mechanically coupled via a piston 455 to a second plunger 450. The first plunger 425 may generally be disposed at a location inside the syringe body 405, as previously described herein, and further disposed at a location that is distal to the vacuum chamber 420. In some embodiments, the positioning of the first plunger 425 and the vacuum chamber 420 may define a medial compartment 485 therebetween. Particularly, the medial compartment 485 may be formed between the proximal surface of the first plunger 425 and the distal surface of the distal wall 440. In some embodiments, the piston 455 may traverse the medial compartment 485 and extend into the vacuum chamber 420 through the distal wall 440. In some embodiments, the piston 455 may be attached by any means of attachment to the first plunger 425 and/or the second plunger 450. In some embodiments, the piston 455 may be molded as a portion of the first plunger 425 and/or the second plunger 450. In some embodiments, the piston 455 may be detachable from the first plunger 425 and/or the second plunger 450. The ability to detach the piston 455 from one or both of the plungers 425, 450 may allow for the piston to be used with varying plungers, thereby increasing compatibility with a wide range of syringes of different sizes and shapes, lowering operating costs, lowering manufacturing costs, enabling the use pre-filled syringes, and/or the like.

[0078] In various embodiments, the second plunger 450 may be located within the first plunger 425. As in the embodiments depicted herein with respect to FIGS. 6A-6C, the second plunger 450 may be configured to form an airtight seal against an interior surface of the vacuum chamber 420, thereby dividing the vacuum chamber into two compartments. A distal volume compartment 465 may be created by the space between a distal surface of the second plunger 450 and the distal wall 440 of the vacuum chamber 420. A proximal volume compartment 470 may be created by the space between a proximal surface of the second plunger 450 and a distal surface of the thumb piece 260.

[0079] In various embodiments, a second seal 445 may be positioned within the distal wall 440 around the piston 455 to form an airtight seal around the piston. In some embodiments, the second seal 445 may prevent air from entering and/or escaping from the proximal volume compartment 470 when the piston 455 is actuated. In some embodiments, the proximal volume compartment 470 may be sealed and/or evacuated before the syringe 400 is used.

[0080] In optional embodiments, the vacuum chamber 420 may include a vent 435. The vent 435 may generally be an opening within the vacuum chamber 420 configured to allow fluid communication of air between an area outside the syringe body 405 and the distal volume compartment 465. The vent 435 may be further configured to equalize air pressure within the distal volume compartment 465 with the outside air pressure through a second vent 436 extending through the syringe body 405. In some embodiments, the outside air pressure may be about 14.7 psi, or standard atmospheric pressure at sea level.

[0081] As depicted in FIG. 7B, a movable thumb piece 460' may be used instead of a vent according to some embodiments. The movable thumb piece 460' may be moved generally distally and/or proximally by any means of movement, and is not limited by this disclosure. By way of example only, the movable thumb piece 460' in the present embodiment may contain a plurality of threads 490 that allow the thumb piece to be screwed into the vacuum chamber 420. In some embodiments, the thumb piece 460' may be screwed over the vacuum chamber 420. In other embodiments, the thumb piece 460' may be screwed inside the vacuum chamber 420. The thumb piece 460' may be screwed into a specific depth to obtain a desired pressure inside the distal volume compartment 465, as will be described in greater detail herein. To aid in determining the pressure inside the distal volume compartment 465, a guide 495 may be located on the syringe 400 to aid a user in determining where to position the thumb piece 460'. For example, the guide 495 may be a plurality of indicia, such as hash marks, printed on an outside surface of the vacuum chamber 420, wherein each hash mark is labeled with the vacuum that will be achieved during aspiration by moving the thumb piece 460' to that hash mark. In some embodiments, the thumb piece 460 may incorporate a display that indicates the amount of adjusted vacuum inside the proximal volume chamber 470.

[0082] In various embodiments, the syringe 400 may further include any number of shock absorbing devices 500. Specific examples of shock absorbing devices 500 may include, for example, springs, air cushions, absorbing materials, and/or the like. The shock absorbing devices 500 may generally function to ensure a smooth distribution of fluid out of the tip 410 at a constant rate that acts supplementary to the driving force cause by the difference in pressure, as described in greater detail herein. According to various embodiments, such as illustrated in FIGS. 7A-7B, piston 455 may further include one or more indicator markings 505, such as hash marks or rings, on the shaft located within medial compartment 485. The indicator markings 505 may allow a user to know when the draw force on shock absorbing device 500, and therefore the rate at which the first plunger 425 is withdrawn, exceeds a critical infusion rate. Examples of critical infusion rates may correspond to, for example, the maximum reduced pressure that certain biological cells can withstand before lysing. Thus, for example, the user may proximally withdraw thumb piece 460' while monitoring the reduced pressure within aspiration volume 475 by observing the indicator markings 505 to ensure that the reduced pressure does not exceed the pressure at which the biological cells may lyse.

[0083] FIGS. 8A-8B depict movement of the various components of the syringe 300 depicted in FIGS. 6A-6C according to an embodiment during an aspiration process. More particularly, FIG. 8A depicts an initial state of the syringe 300. As previously described herein, a force F may be applied to the thumb piece 360 to force the piston 355 in a proximal direction away from the syringe body 305. As a result, the piston 355 may mechanically force the second plunger 350 to move in a proximal direction within the vacuum chamber 320.

[0084] As described in greater detail herein, the movement of the second plunger 350 in a proximal direction may increase the volume of the distal volume compartment 365 while decreasing the volume of the proximal volume compartment 370. In some instances, this combination may result in a decrease in pressure in the distal volume compartment 365 where the distal volume compartment 365 has a pressure greater than or equal to zero. However, in instances where the distal volume compartment 365 is a vacuum (thereby having a zero pressure), this combination will not change the pressure within the distal volume compartment 365. This is due to the ideal gas law, which is represented by Equation (1):

PV=nRT (1)

where P is the pressure of the gas, V is the volume of the gas, n is the amount of substance of gas (also known as number of moles), T is the temperature of the gas and R is the ideal, or universal, gas constant, equal to the product of the Boltzmann constant and the Avogadro constant. To compare different volumes, Equation (1) can be written to reflect the different volumes as follows: P.sub.1V.sub.1=nR.sub.1T.sub.1 and P.sub.2V.sub.2=nR.sub.2T.sub.2. If P.sub.1 and P.sub.2 are both zero because of the vacuum (zero pressure), then a change in either volume V.sub.1, V.sub.2 won't change the results.

[0085] Furthermore, the pressure can be written as a function of force, as represented by Equation (2):

.DELTA.P=F/A (2)

where .DELTA.P is the change in pressure, F is the normal force, and A is the area of the surface on contact. Thus, in an illustrative example, if the pressure P is zero (0 psi), such as in a vacuum, then according to Equation (1), the pressure will not change when other variables change, such as, for example, the volume V. Since the pressure remains the same, the force F that is exerted by the pressure will also remain constant according to Equation (2), which allows for a smooth aspiration of the fluid into the aspiration volume 375.

[0086] Similarly, the movement of the second plunger 350 in a proximal direction may decrease the volume of the proximal volume compartment 370. However, due to the location of the vent 335 (or in some embodiments, the bore 380), the pressure of the proximal volume compartment 370 may equalize with the outside air pressure (i.e., moving towards about 14.7 psi). As a result the force F may be active on the second plunger 350 due to the unequal pressure between the pressure of the distal volume compartment 365 and the pressure of the proximal volume compartment 370. In some embodiments, the pressure of the proximal volume compartment 370 may be greater than the pressure of the distal volume compartment 365. In other embodiments, such as those where it is desired to expel fluid from the syringe 300, the pressure of the proximal volume compartment 370 may be less than the pressure of the distal volume compartment 365. In some embodiments, to ensure that the proximal volume compartment has a higher pressure than the distal volume compartment 365, the distal volume compartment 365 may be pre-evacuated prior to movement of the piston 355. The pre-evacuation process may be completed, for example, by attaching a vacuum pump or the like to the distal volume compartment 365 through a sealable valve and port (not shown). According to these embodiments, the second plunger 350 may be located adjacent to the inner distal wall of vacuum chamber 320.

[0087] In various embodiments, because of the unequal pressure between the distal volume compartment 365 and the proximal volume compartment 370, a driving force F' may be active on the vacuum chamber 320. However, since the user may maintain force on the thumb piece 360 to keep it in a withdrawn state, the second plunger 350 may be fixed relative to the syringe body 305. Accordingly, the pressure difference between the distal volume compartment 365 and the proximal volume compartment 370 may force the vacuum chamber 320 to shift in the proximal direction, thereby driving the first plunger 325 in a proximal direction toward the proximal end 301 of the syringe body 305. The resulting motion of the first plunger 325 may increase the aspiration volume 375, causing the fluid to be aspirated into the aspiration volume 325 through the tip 310 at a steady rate. Those skilled in the art may appreciate that the driving force F' on the first plunger 325 may be due to the pressure difference developed between the proximal volume compartment 370 and the distal volume compartment 365, and may not depend on the user's force on the thumb piece 360. Those skilled in the art may also appreciate that the driving force F' on the first plunger 325 may not be due to the position of the second plunger 350 relative to the vacuum chamber 320 and/or the syringe body 305, as long as the second plunger is not located at the proximal end 301 or the distal end 302 of the syringe body 305. Furthermore, the driving force F' on the first plunger 325 may not be due to the velocity of the second plunger 350 in moving towards the proximal end 301 of the syringe body 305 provided that there is only a small amount of friction between the second plunger and the vacuum chamber 320. Accordingly, the rate of motion of the first plunger 325 may be smooth and constant since the force on the first plunger 350 is determined by the pressure differential between the distal and proximal compartments of vacuum chamber 329 and not on the rate at which the second plunger is withdrawn, and thus may not reflect any possible unsteady movement from the user. Furthermore, the rate of aspiration of the fluid into the aspiration volume 375 may be adjusted by the user prior to applying force on the thumb piece 360 by increasing or decreasing the pressure of the proximal volume compartment 370, as described in greater detail herein.

[0088] FIGS. 9A-9C depict the effect on the syringe of FIG. 7A when a force F is applied to the thumb piece 460 according to various embodiments. In some embodiments, the force F may cause the thumb piece 460 to move in a generally proximal direction. This movement of the thumb piece 460 may cause the vacuum chamber 420 to also travel in a generally proximal direction within the syringe body 405. In some embodiments, the various volume compartments 465, 470 may change volume as a result of the movement while the pressure remains the same (i.e., about 14.7 psi in the distal volume compartment 465 and substantially zero psi in the proximal volume compartment 470), as previously described herein. In some embodiments, the force F applied to the thumb piece 460 may cause the vacuum chamber 420 to move relative to the second plunger 450. The movement of the vacuum chamber 420 may therefore result in an increase in the volume of the proximal volume compartment 470 and a decrease in volume of the distal volume compartment 465. In various embodiments, a driving force F' that pulls the first plunger 425 towards the proximal end 401 of the syringe body 405 may result from the difference of pressure of the distal volume compartment 465 (where the pressure is at or near atmospheric pressure, or about 14.7 psi) and the proximal volume compartment 470 (where the pressure is zero psi) as described herein. Accordingly, if a user of the syringe 400 provides a sharp force on the thumb piece 460 in the proximal direction, it will have no effect on the rate of aspiration of fluid through the tip 410 because the difference in pressures in the distal volume compartment 465 and the proximal volume compartment 470 will continue to remain the same, even with the proximal volume compartment 470 increasing in volume. In addition, if a faster rate of aspiration of fluid through the tip 410 is desired, the vent 435 and/or 436 can be covered with a valve or a user's finger while a force is exacted upon the thumb piece 460 to increase the pressure of the distal volume compartment 470 and alter the driving force F' accordingly. After a desired volume of fluid is aspirated into the aspiration volume 475, the syringe 400 is ready for fluid delivery. The fluid delivery may be effected by driving the thumb piece 460 in a distal direction such that the proximal volume compartment 470 is reduced in volume relative to the distal volume compartment 465 and the fluid is expelled through the tip 410.

[0089] FIGS. 10A-10C depict the effect on the syringe of FIG. 7B when a force F is applied to the thumb piece 460' according to various embodiments. The movement of the various components of the syringe 400 is substantially the same as previously described herein with respect to FIGS. 9A-9C; however, instead of regulating the pressure of the distal volume compartment 465 with a vent to increase the rate of distribution of fluid, distal volume compartment 465 contains a gas and is sealed to the atmosphere; and the thumb piece 460' may be moved to adjust the volume and the pressure of the distal volume compartment 465. For example, the thumb piece 460' may have a rod extending in the distal direction that contacts the second plunger 450 and urges the second plunger in the proximal or distal direction depending on the position of the thumb piece 460'. For example, the thumb piece 460' may be moved in a proximal direction relative to the vacuum chamber 420 to decrease the pressure of the distal volume compartment 465. Because the distal volume compartment 465 is at a higher pressure relative to the proximal volume compartment 470, the second plunger 450 will move in a proximal direction with the movement of the thumb piece 460'. For example, thumb piece 460' may be connected to vacuum chamber 420 by a threaded mechanism where the distal/proximal position of thumb piece 460' may be adjusted. In some embodiments, the thumb piece 460' may be moved in either a proximal or a distal direction by twisting the thumb piece 460' in a clockwise direction T (FIG. 10B) or in a counterclockwise direction (not shown). In some embodiments, adjusting the thumb piece 460' to decrease the pressure in the distal volume compartment 465 may decrease the difference in pressure between the proximal volume compartment 470 and the distal volume compartment 465, thereby causing the force on the second plunger 450 to decrease, which may cause a slower but uniform movement of the first plunger 425 in the proximal direction. Similarly, in some embodiments, adjusting the thumb piece 460' move the second plunger 450 in a distal direction will increase the pressure in the distal volume compartment 465 and may increase the difference in pressure between the proximal volume compartment 470 and the distal volume compartment 465. The force on the second plunger 450 increases correspondingly, which may cause a faster but uniform movement of the first plunger 425 in the proximal direction.

[0090] In another embodiment, the thumb piece 460' may be sealed to the vacuum chamber 420 and may comprise a threaded rod, or an equivalent connection means, extending through thumb piece 460' and contacting second plunger 450, where the proximal end of the threaded rod has means to rotate the threaded rod in a clockwise or counter-clockwise direction thereby moving the distal end of threaded rod in a distal or proximal direction. In this manner, the distal or proximal movement of the threaded rod results in a corresponding distal or proximal movement of the second plunger 450 relative to the vacuum chamber 420 by turning threaded rod in a clockwise or counter-clockwise direction to force second plunger 450 in a distal or proximal direction. The distal volume compartment 465 may contain a gas such that movement of the threaded rod and the second plunger 450 adjusts the volume and the pressure of the distal volume compartment 465. Because the distal volume compartment 465 is at a higher pressure relative to the proximal volume compartment 470, the second plunger 450 will move in a proximal direction when the force provided by threaded rod to the second plunger is lessened, for example by rotating threaded rod in a counter-clockwise direction. Adjusting the thumb piece 460' to decrease the pressure in the distal volume compartment 465 may decrease the difference in pressure between the proximal volume compartment 470 and the distal volume compartment 465, thereby causing the force on the second plunger 450 to decrease, which may cause a slower but uniform movement of the first plunger 425 in the proximal direction. Similarly, in some embodiments, adjusting the threaded rod to move the second plunger 450 in a distal direction, for example by rotating in a clockwise direction, will increase the pressure in the distal volume compartment 465 and may increase the difference in pressure between the proximal volume compartment 470 and the distal volume compartment 465. The force on the second plunger 450 increases correspondingly, which may cause a faster but uniform movement of the first plunger 425 in the proximal direction. It will be understood that the rotation direction of thumb piece 460' or threaded rod may be reversed by reversing the direction of the threads in either the vacuum chamber 420 or thumb piece 460'.

[0091] Although various embodiments have been described in detail for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that the disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements. For example, it is to be understood that this disclosure contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.

Claims

1. A syringe system comprising: a syringe body comprising a hollow lumen and a distal end, the syringe body being configured to receive a fluid therein; a vacuum chamber disposed within the hollow lumen of the syringe body; a first plunger connected to a distal portion of the vacuum chamber within the hollow lumen of the syringe body, the first plunger forming a first seal against an inner surface of the syringe body and defining a fluid volume between the first plunger and the distal end of the syringe body; a second plunger disposed within the vacuum chamber, the second plunger forming a second seal against an inner surface of the vacuum chamber and defining a proximal volume compartment and a distal volume compartment within the vacuum chamber; a vent within one of the proximal volume compartment and the distal volume compartment of the vacuum chamber, wherein the vent is configured to allow communication of air between an area outside the syringe system and one of the proximal volume compartment and the distal volume compartment; and a piston affixed to the second plunger and extending proximally out of the vacuum chamber, the piston configured to move the second plunger within the vacuum chamber, thereby altering a volume of the proximal volume compartment and a volume of the distal volume compartment.

2. The syringe system of claim 1, wherein the vent comprises a bore extending therethrough the piston and the second plunger, the bore configured to allow communication of air between an area outside the syringe system and one of the proximal volume compartment and the distal volume compartment.

3. The syringe system of claim 2, further comprising a valve configured to regulate an amount of the air communicated between the area outside the syringe system and one of the proximal volume compartment and the distal volume compartment.

4. The syringe system of claim 1, wherein the vent comprises a side vent extending through a wall in one of the proximal volume compartment and the distal volume compartment of the vacuum chamber, wherein the side vent is configured to allow communication of air between an area outside the syringe system and one of the proximal volume compartment and the distal volume compartment.

5. The syringe system of claim 1, further comprising a tip at the distal end of the syringe body, wherein the tip is configured to allow fluid from the fluid volume to pass therethrough upon movement of the first plunger.

6. The syringe system of claim 5, wherein the tip is further configured to attach to one or more tubes, needles, or nozzles for delivery of the fluid to a patient.

7. The syringe system of claim 1, wherein the piston extends proximally out of the vacuum chamber through a proximal wall, forming a third seal between the piston and the proximal wall.

8. The syringe system of claim 1, wherein a force exacted upon the piston in a substantially distal direction is configured to cause the second plunger to move distally within the vacuum chamber, thereby increasing the volume of the proximal volume compartment and decreasing the volume of the distal volume compartment, creating a pressure difference between the proximal volume compartment and the distal volume compartment, which causes the vacuum chamber and the first plunger to move in a distal direction, thereby expelling the fluid located in the fluid volume through a tip at the distal end of the syringe body.

9. The syringe system of claim 1, wherein a force exacted upon the piston in a substantially proximal direction is configured to cause the second plunger to move proximally within the vacuum chamber, thereby increasing the volume of the distal volume compartment and decreasing the volume of the proximal volume compartment, creating a pressure difference between the proximal volume compartment and the distal volume compartment, which causes the vacuum chamber and the first plunger to move in a proximal direction, thereby aspirating the fluid into the fluid volume through a tip at the distal end of the syringe body.

10. A syringe system comprising: a syringe body comprising a hollow lumen and a distal end, the syringe body being configured to receive a fluid therein; a vacuum chamber at least partially disposed within the hollow lumen of the syringe body; a first plunger disposed distally to the vacuum chamber within the hollow lumen of the syringe body, the first plunger forming a seal against an inner surface of the syringe body and defining a fluid volume between the first plunger and the distal end of the syringe body; a second plunger disposed within the vacuum chamber, the second plunger defining a proximal volume compartment and a distal volume compartment within the vacuum chamber; a side vent extending through a wall in one of the distal volume compartment and the proximal volume compartment of the vacuum chamber, wherein the side vent is configured to allow communication of air between an area outside the syringe system and one of the proximal volume compartment and the distal volume compartment; and a piston extending distally out of the vacuum chamber and connected to the first plunger and the second plunger, the piston configured to move the second plunger within the vacuum chamber and the first plunger within the syringe body.

11. The syringe system of claim 10, further comprising a tip at the distal end of the syringe body, wherein the tip is configured to allow fluid from the fluid volume to pass therethrough upon movement of the first plunger.

12. The syringe system of claim 11, wherein the tip is further configured to attach to one or more tubes, needles, or nozzles for delivery of the fluid to a patient.

13. The syringe system of claim 10, wherein a force exacted upon the vacuum chamber in a substantially distal direction is configured to cause the vacuum chamber to move distally within the syringe body, thereby decreasing the volume of the proximal volume compartment and increasing the volume of the distal volume compartment, creating a pressure difference between the proximal volume compartment and the distal volume compartment, which causes the second plunger, the piston, and the first plunger to move in a distal direction, thereby expelling the fluid located in the fluid volume through a tip at the distal end of the syringe body.

14. The syringe system of claim 10, wherein a force exacted upon the piston in a substantially proximal direction is configured to cause the second plunger to move proximally within the vacuum chamber, thereby increasing the volume of the distal volume compartment and decreasing the volume of the proximal volume compartment, creating a pressure difference between the proximal volume compartment and the distal volume compartment, which causes the vacuum chamber and the first plunger to move in a proximal direction, thereby aspirating the fluid into the fluid volume through a tip at the distal end of the syringe body.

15. A syringe system comprising: a syringe body comprising a hollow lumen and a distal end having a tip, the syringe body being configured to receive a fluid therein; a vacuum chamber at least partially disposed within the hollow lumen of the syringe body; a first plunger disposed distally to the vacuum chamber within the hollow lumen of the syringe body, the first plunger forming a seal against an inner surface of the syringe body and defining a fluid volume between the first plunger and the distal end of the syringe body; a second plunger disposed within the vacuum chamber, the second plunger defining a proximal volume compartment and a distal volume compartment within the vacuum chamber; a piston extending distally out of the vacuum chamber and connected to the first plunger and the second plunger, wherein the piston is configured to move the second plunger within the vacuum chamber and the first plunger within the syringe body; and a thumb piece removably attached to a proximal portion of the vacuum chamber, wherein the thumb piece is configured to provide a surface for a user to apply a force in a substantially axial direction, and wherein the thumb piece is further configured to increase and decrease a volume of one of the distal volume compartment and the proximal volume compartment.

16. The syringe system of claim 15, wherein the thumb piece is configured to increase and decrease the volume of one of the distal volume compartment and the proximal volume compartment by screwing into at least a portion of the vacuum chamber.

17. The syringe system of claim 15, wherein the thumb piece is configured to move in a distal direction, wherein the vacuum chamber is configured to move within the syringe body in response to movement of the thumb piece, wherein the second plunger, the piston, and the first plunger are configured to move in response to the vacuum chamber moving within the syringe body.

18. (canceled)

19. (canceled)

20. (canceled)