Patent Description:
This patent disclosure relates generally to syringes and, more particularly to syringes that provide tactile feedback of a dose quantity delivered.

Syringes are known for storing and transporting substances with fluid properties such as gases, liquids, pastes, slurries, and the like. A syringe may include a barrel defining a bore in communication with a port, and a piston disposed within the barrel. Translation of the piston away from the port may draw material into the barrel through the port. Alternatively, translation of the piston toward the port may expel material out of the barrel through the port.

A syringe barrel may be formed from a transparent or translucent material, such that a position of the piston within the bore is visible through the barrel. Further, the syringe barrel may include indicia disposed thereon, such that longitudinal alignment of the piston relative to the indicia may visually indicate a volume of material stored between the piston and the port.

<CIT> (hereinafter, "the "<NUM> patent") purports to describe a syringe for dispensing measured quantities of a material (e.g., a medicament). The syringe from the '<NUM> patent includes a barrel, a plunger rod having a cruciform transverse cross section, and an infinitely adjustable stop member secured to the plunger rod for positively setting the length of travel of the plunger rod to thereby control the volume of material dispensed from the syringe. However, sequential delivery of multiple doses using the syringe from the '<NUM> patent may be subject to dosage errors resulting from inaccurate displacement of the infinitely adjustable stop member between dose deliveries, undue time consumption to adjust the position of the infinitely adjustable stop member, or both.

<CIT> (hereinafter, "the "<NUM> publication") purports to describe a unit to administer medication having a plunger with non-reusable stroke stops sequentially arranged along the plunger. According to the '<NUM> patent, the stroke stops are frangible about a weakening line, such that each broken stroke stop enables the forward movement of the impelling plunger and the administration of a corresponding dose. However, the stroke stops of the '<NUM> publication may interfere with filling an empty syringe so configured, and therefore limit application to pre-filled syringes. Further, the stroke stops of the '<NUM> patent are inherently non-reusable because of their frangible nature, and the stroke stops may be complex and expensive to manufacture.

<CIT> (hereinafter, "the "<NUM> patent") purports to describe a syringe for metering predetermined volumes of fluid therefrom. The syringe of the '<NUM> patent includes a tube, a clip, and a metering plunger having stop surfaces disposed thereon, where the plunger is inserted through an opening in the clip and is slidably located within the syringe tube. However, the plunger stop surfaces of the '<NUM> patent have complex shapes that could be difficult or expensive to manufacture. Further, the stop surfaces of the '<NUM> patent may interfere with filling an empty syringe by requiring rotation of the plunger in addition to axial translation during a filling step.

<CIT> (hereinafter, "the '<NUM> patent") purports to describe a syringe with a structure that allows variation in sliding displacement of the plunger which may be accompanied by an audible sound. <CIT> (hereinafter, "the "<NUM> publication") purports to describe a syringe including physical stops or dosage administered indicators which can act to prevent hydraulic momentum from continuing to deliver fluid after thumb pressure is lifted off of the push rod. However, neither the '<NUM> patent nor the ' <NUM> publication provides asymmetric ramps for tailoring differences in deceleration and acceleration resistance forces for movement of a plunger within a dose dividing syringe.

<CIT> purports to disclose a dispensing device including a hollow cylindrical body from which a high viscosity composition is discharged in precisely metered doses by a plunger rod longitudinally movable within the body. A series of projection are formed at equispaced, longitudinal intervals from each other on the plunger rod. A pair of parallel actuating arms pivotally mounted on the body extend along opposite side of the plunger rod and are formed with a pair of teeth, respectively, projecting inward toward the rod. By depressing the arms, the teeth pivot into engagement with one of the projections to advance the plunger within the body to expel a desired amount of composition. In a preferred embodiment, advancement of the plunger rod through a precise distance is automatically controlled via contact between the teeth with stop surfaces formed on the next in-line projection.

<CIT> purports to disclose a syringe comprising an outer cylinder body equipped with a cylinder head section joining to a needle at one end and an opening at the other end, a plunger which is engaged with the inside of the outer cylinder body , and a plunder rod attached to the plunger. The plunger rod has a plurality of rib sections placed in positions extending in a longitudinal direction and having a divergine peripheral direction, and locking sections are provided while leaving spaces in the longitudinal direction, respectively, in the rib sections, a locking receiving section is prepared in the opening, the locking sections are locked with the locking receiving section by rotating the plunder rod and the dosages of the liquid medicine or the like is stepwise adjusted.

Accordingly, there is a need for apparatus and methods to address the above-identified shortcomings of conventional syringes, as well as other shortcomings in the art.

The invention is defined by a syringe according to claim <NUM>. Advantageous embodiments are the subject-matter of the dependent claims. According to the invention, a syringe comprises a barrel having an internal surface defining an internal bore therein, and a plunger disposed within the internal bore of the barrel. A distal end of the plunger is inserted into a proximal end of the barrel, and a proximal end of the plunger is opposite the distal end of the plunger along a longitudinal axis of the plunger. At least one radial projection is disposed on an external surface of the plunger, the at least one radial projection includes a proximal ramp and a distal ramp, the proximal ramp being disposed on a proximal side of the at least one radial projection, and the distal ramp being disposed on a distal side of the at least one radial projection, the distal ramp including a convex ramp. The distal ramp includes a first point being a point of incipient contact with the internal surface of the barrel, the first point being located at a first radial distance from the longitudinal axis, and the at least one radial projection having a first slope relative to the longitudinal axis at the first point. The at least one radial projection has a second slope relative to the longitudinal axis at a second point along the proximal ramp located a second radial distance from the longitudinal axis, the second radial distance being substantially equal to the first radial distance. The absolute value of the first slope is greater than the absolute value of the second slope.

According to another aspect of the disclosure, not according to the invention, a plunger for a syringe comprises a shaft extending along a longitudinal axis of the plunger; a piston disposed at a proximal end of the plunger, the piston configured to engage an internal bore of the syringe in sliding and sealing engagement, a distal end of the plunger being opposite the proximal end of the plunger; and at least one radial projection disposed on an outer surface of the shaft. The at least one radial projection includes a proximal ramp and a distal ramp, the proximal ramp being disposed on a proximal side of the at least one radial projection, and the distal ramp being disposed on a distal side of the at least one radial projection. A linear portion of the proximal ramp has a proximal slope with respect to the longitudinal axis, and a linear portion of the distal ramp has a distal slope with respect to the longitudinal axis. An absolute value of the proximal slope is different from an absolute value of the distal slope.

According to another aspect of the disclosure, not according to the invention, a plunger for a syringe comprises a shaft extending along a longitudinal axis of the plunger; a piston disposed at a proximal end of the plunger, the piston configured to engage an internal bore of the syringe in sliding and sealing engagement, a distal end of the plunger being opposite the proximal end of the plunger; and at least one radial projection disposed on an outer surface of the shaft. The at least one radial projection includes a proximal ramp and a distal ramp, the proximal ramp being disposed on a proximal side of the at least one radial projection, and the distal ramp being disposed on a distal side of the at least one radial projection. The distal ramp extends at least partly in a radial direction to a point of maximum distal ramp radial height, the radial direction being normal to the longitudinal axis, and the proximal ramp extending at least partly in the radial direction to a point of maximum proximal ramp radial height. The distal ramp is asymmetric with the proximal ramp about a plane normal to longitudinal axis and passing through a point halfway between the point of maximum proximal ramp radial height and the point of maximum distal radial height in an axial direction parallel to the longitudinal axis.

Another aspect of the disclosure not according to the invention provides a method for operating a syringe. The syringe includes a barrel having an internal surface defining an internal bore therein, a plunger disposed within the internal bore of the barrel, a distal end of the plunger being inserted into a proximal end of the barrel, a proximal end of the plunger being opposite the distal end of the plunger along a longitudinal axis of the plunger, and at least one radial projection disposed on an external surface of the plunger. The at least one radial projection includes a proximal ramp and a distal ramp, the proximal ramp being disposed on a proximal side of the at least one radial projection, and the distal ramp being disposed on a distal side of the at least one radial projection. The method comprises delivering a first dose of material from the syringe by translating the plunger relative to the barrel along the longitudinal axis of the plunger in a first direction until the proximal ramp of the plunger engages the internal surface of the barrel at a proximal point of incipient contact, the first direction extending from the proximal end of the plunger toward the distal end of the plunger; sensing an increase in translational resistance between the plunger and the barrel caused by contact between the proximal ramp and the internal surface of the barrel; ending the delivering of the first dose of material from the syringe based on the sensing the increase in translational resistance between the plunger and the barrel; and delivering a second dose of material from the syringe by translating the plunger relative to the barrel along the longitudinal axis of the plunger in the first direction through a distal point of incipient contact between the distal ramp of the plunger and the internal surface of the barrel, the at least one radial projection having a first slope relative to the longitudinal axis at the proximal point of incipient contact and a second slope relative to the longitudinal axis at the distal point of incipient contact, an absolute value of the first slope being different from the absolute value of the second slope.

Different aspects of the disclosure will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout, unless otherwise specified.

<FIG> shows a schematic view of a syringe <NUM>, according to an aspect of the disclosure. The syringe <NUM> includes a barrel <NUM>, a plunger <NUM>, and at least one radial projection <NUM> disposed on the plunger <NUM>. The barrel <NUM> has an internal surface <NUM> defining a first aperture or port <NUM>, a second aperture or port <NUM>, and an internal bore <NUM> extending therebetween. The first aperture <NUM> may be located at a distal end <NUM> of the barrel <NUM> along a longitudinal axis <NUM> of the barrel <NUM>, and the second aperture <NUM> may be located at a proximal end <NUM> of the barrel <NUM> along the longitudinal axis <NUM> of the barrel <NUM>. It will be appreciated that the first aperture <NUM> may be centered on the longitudinal axis <NUM> but need not be centered on the longitudinal axis <NUM> to be considered located at the distal end <NUM> of the barrel <NUM>. Further, it will be appreciated that the second aperture <NUM> may be centered on the longitudinal axis <NUM> but need not be centered on the longitudinal axis <NUM> to be considered located at the proximal end <NUM> of the barrel <NUM>.

The barrel <NUM> may include a flange <NUM> extending away from the barrel <NUM> at least partly in a radial direction <NUM>, where the radial direction <NUM> is perpendicular to an axial direction <NUM>. According to an aspect of the disclosure, the axial direction <NUM> is parallel to the longitudinal axis <NUM>. According to another aspect of the disclosure, the flange <NUM> extends away from the barrel <NUM> in substantially the radial direction <NUM>.

The plunger <NUM> includes a shaft <NUM> having a distal end <NUM> and a proximal end <NUM>. A piston <NUM> is coupled to the distal end <NUM> of the shaft <NUM>, and a radial projection <NUM> extends from an outer surface of the shaft <NUM> at least partly in the radial direction <NUM>. The radial projection is disposed along a longitudinal length of the shaft <NUM> between the distal end <NUM> and the proximal end <NUM> of the shaft. The plunger <NUM> may further include a flange <NUM> disposed at the proximal end <NUM> of the shaft <NUM>, where the flange <NUM> extends outward from the shaft <NUM> at least partly in the radial direction <NUM>. It will be appreciated that the shaft <NUM> could have a circular cross section, a polygonal cross section, a rectangular cross section, a cruciform cross section, or any other shaft cross section known to persons having skill in the art.

The radial projection <NUM> may include an axisymmetric surface of revolution about a longitudinal axis <NUM> of the shaft, where the radial projection <NUM> either partially or completely surrounds the shaft <NUM> in a circumferential direction <NUM> about the shaft <NUM>. Alternatively, the radial projection <NUM> may include any other structure defining a cross section in a plane including the radial direction <NUM> and the axial direction <NUM>, where the structure projects from the shaft <NUM> at least partly in the radial direction <NUM>. According to an aspect of the disclosure, the radial projection <NUM> is fixed to the shaft <NUM>, such that the radial projection <NUM> is not free to translate relative to the shaft <NUM> along a longitudinal axis <NUM> of the shaft <NUM>, and the radial projection <NUM> is not free to rotate relative to the shaft <NUM> about the longitudinal axis <NUM>.

The at least one radial projection <NUM> may include an axial array of radial projections including two or more radial projections <NUM> disposed at different axial locations along the shaft <NUM> relative to the axial direction <NUM>. Two or more radial projections <NUM> of the axial array may be located at substantially identical circumferential locations about the shaft <NUM>.

The at least one radial projection <NUM> may include a circumferential array of radial projections <NUM> disposed at different circumferential locations about the longitudinal axis <NUM> of the plunger <NUM>. Two or more radial projections <NUM> of the circumferential array may be located at substantially identical axial locations along the shaft <NUM> relative to the axial direction <NUM>.

Referring now to <FIG>, it will be appreciated that <FIG> shows a radial cross section of a plunger <NUM>, according to an aspect of the disclosure; <FIG> shows a radial cross section of a plunger <NUM>, according to an aspect of the disclosure; and <FIG> shows a radial cross section of a plunger <NUM>, according to an aspect of the disclosure.

As shown in <FIG>, the two or more radial projections <NUM> may be arranged in a circumferential array about the shaft <NUM>, such that one of the two or more radial projections <NUM> is disposed substantially opposite the other of the two or more radial projections <NUM> in the circumferential direction <NUM>.

As shown in <FIG>, the two or more radial projections <NUM> may include three radial projections <NUM> arranged at different circumferential locations about the shaft <NUM> in the circumferential direction <NUM>. According to an aspect of the disclosure, the three radial projections <NUM> may be disposed in a substantially uniform array in the circumferential direction <NUM>. According to another aspect of the disclosure, the three radial projections <NUM> may all be disposed at substantially the same axial location along the shaft <NUM>.

As shown in <FIG>, the two or more radial projections <NUM> may include four radial projections <NUM> arranged at different circumferential locations about the shaft <NUM> in the circumferential direction <NUM>. According to an aspect of the disclosure, the four radial projections <NUM> may be disposed in a substantially uniform array in the circumferential direction <NUM>. According to another aspect of the disclosure, the four radial projections <NUM> may all be disposed at substantially the same axial location along the shaft <NUM>.

Returning to <FIG>, the plunger <NUM> is configured to translate within the bore <NUM> of the barrel <NUM> along the axial direction <NUM>. Further, the piston <NUM> is configured for sliding and sealing engagement with the internal surface <NUM> of the barrel <NUM>. According to one aspect of the disclosure, the longitudinal axis <NUM> of the barrel <NUM> is substantially coaxial with the longitudinal axis <NUM> of the plunger <NUM>. However, it will be appreciated that the longitudinal axis <NUM> of the barrel <NUM> need not be substantially coaxial with the longitudinal axis <NUM> of the plunger <NUM>.

Translation of the piston <NUM> away from the first aperture <NUM> along the axial direction <NUM> may act to draw material from outside the barrel <NUM> into the internal bore <NUM> of the barrel <NUM> via the first aperture <NUM>. Conversely, translation of the piston <NUM> toward the first aperture <NUM> along the axial direction <NUM> may act to expel material out of the internal bore <NUM> of the barrel <NUM> via the first aperture <NUM>.

The internal surface <NUM> of the barrel <NUM> defines an aperture <NUM> near the proximal end <NUM> having a bore <NUM> radial dimension <NUM> from the longitudinal axis <NUM> to the portion of the internal surface <NUM> defining the aperture <NUM>. According to an aspect of the disclosure, the radial dimension <NUM> is the smallest radial dimension of the bore <NUM> between the axial location of the piston <NUM> within the bore <NUM> and the proximal end <NUM> of the barrel. According to another aspect of the disclosure, the aperture <NUM> is located at the same axial location of the aperture <NUM>. According to another aspect of the disclosure, the aperture <NUM> is defined by an undercut <NUM> projecting radially toward the longitudinal axis <NUM> of the barrel.

The radial dimension <NUM> may be smaller than a radial dimension <NUM> from the longitudinal axis <NUM> of the plunger <NUM> to an outer surface of the piston <NUM>. Further, the radial dimension <NUM> may be smaller than a radial dimension <NUM>, measured from the longitudinal axis <NUM> of the barrel to a portion of the internal surface <NUM> of the barrel <NUM> disposed between the piston <NUM> and the aperture <NUM> in the axial direction <NUM>.

The at least one radial projection <NUM> is configured to effect non-uniform resistance or force in opposition to motion of the plunger <NUM> relative to the barrel <NUM> through variation in radial interference between the outer surface of the plunger <NUM> and the internal surface <NUM> of the barrel at the minimum proximal aperture <NUM>. According to an aspect of the disclosure, a portion of the plunger shaft <NUM> may have a radial dimension <NUM>, extending from the longitudinal axis <NUM> of the plunger <NUM> to an outer surface of the shaft <NUM>, that is less than or equal to the radial dimension <NUM> of the barrel aperture <NUM>, such that there is little or no contact between the plunger shaft <NUM> and the internal surface <NUM> of the barrel at the aperture <NUM> when the piston <NUM> is disposed within the bore <NUM>. According to another aspect of the disclosure, a radial dimension <NUM> from the longitudinal axis <NUM> of the plunger <NUM> to an external surface of a radial projection <NUM> may be greater than the radial dimension <NUM> of the barrel aperture <NUM>, such that radial interference between the radial projection <NUM> and the internal surface <NUM> at the aperture <NUM> effects increased resistance to translating the plunger <NUM> relative to the barrel <NUM>. Thus, the radial profile of the plunger <NUM> may provide haptic feedback to a user of the syringe <NUM> that is indicative of a location of the plunger <NUM> relative to the barrel <NUM> in the axial direction <NUM>.

Sliding contact between an outer surface of a radial projection <NUM> and the internal surface <NUM> of the barrel at the aperture <NUM> may cause elastic deformation of the radial projection <NUM>, plastic deformation of the radial projection <NUM>, elastic deformation of the internal surface <NUM> of the barrel, plastic deformation of the internal surface <NUM> of the barrel, or combinations thereof. According to an aspect of the disclosure, an entire axial length <NUM> of a radial projection <NUM> may traverse the aperture <NUM> by translating the plunger <NUM> relative to the barrel <NUM> without breaking any portion of the radial projection <NUM> away from the plunger <NUM>. Accordingly, the at least one radial projection <NUM> may not be frangible relative to the plunger <NUM> by operation of the plunger <NUM> within the barrel <NUM>.

Referring to <FIG>, it will be appreciated that <FIG> shows a partial cross sectional view of the syringe <NUM>, according to an aspect of the disclosure; and <FIG> shows a partial cross section view of the syringe <NUM>, according to an aspect of the disclosure. As shown in <FIG>, the plunger <NUM> may be translated toward the barrel <NUM> until the radial projection <NUM> contacts the barrel <NUM> at a leading incipient point of contact <NUM>, such that the leading incipient point of contact <NUM> is spaced apart from the longitudinal axis <NUM> of the plunger <NUM>, the longitudinal axis <NUM> of the barrel <NUM>, or both, by a radial distance <NUM>.

As shown in <FIG>, the plunger <NUM> may be translated toward the barrel until the radial projection <NUM> contacts the barrel <NUM> at a trailing incipient point of contact <NUM>, such that the trailing incipient point of contact <NUM> is spaced apart from the longitudinal axis <NUM> of the plunger <NUM>, the longitudinal axis <NUM> of the barrel <NUM>, or both, by a radial distance <NUM>. It will be appreciated that the radial distance <NUM> (see <FIG>) may or may not be equal to the radial distance <NUM> (see <FIG>) depending on the profile of the internal surface <NUM> of the barrel <NUM> defining the undercut <NUM>.

<FIG> show axial cross sectional views of the plunger <NUM>, according to various aspects of the disclosure. As shown in <FIG>, the plunger <NUM> includes a radial projection <NUM> having a distal ramp <NUM> extending from the external surface of the shaft <NUM> to a point of maximum radial height <NUM>. The point of maximum radial height <NUM> of the distal ramp <NUM> is located a radial distance <NUM> from the longitudinal axis <NUM>. The distal ramp <NUM> has a slope <NUM>, with respect to the radial direction <NUM> and the axial direction <NUM>, at its point of leading incipient contact <NUM> with the barrel <NUM>.

The radial projection <NUM> also includes a proximal ramp <NUM> extending from the external surface of the shaft <NUM> to a point of maximum radial height <NUM>. The point of maximum radial height <NUM> of the proximal ramp <NUM> is located a radial distance <NUM> from the longitudinal axis <NUM>. The proximal ramp <NUM> has a slope <NUM>, with respect to the radial direction <NUM> and the axial direction <NUM>, at a point <NUM> located at the radial distance <NUM> from the longitudinal axis <NUM>.

It will be appreciated that the radial distance <NUM> to the point of maximum radial height <NUM> for the distal ramp <NUM> may or may not be equal to the radial distance <NUM> to the point of maximum radial height <NUM> for the proximal ramp <NUM>. According to an aspect of the disclosure, the point of maximum radial height <NUM> for the distal ramp <NUM> may be separated from the point of maximum radial height <NUM> for the proximal ramp in the axial direction <NUM> by a plateau surface <NUM>. According to another aspect of the disclosure, the point of radial height <NUM> for the distal ramp <NUM> may be coincident with the point of radial height <NUM> for the proximal ramp <NUM>, such that there is no plateau surface <NUM> therebetween.

It will be appreciated that the distal ramp <NUM> may be distinguished from the proximal ramp <NUM> or the plateau surface <NUM> by a discontinuity in slope therebetween. Further, it will be appreciated that such discontinuities in slope may be discerned by persons having skill in the art notwithstanding smoothed or radiused corners transitioning from either the distal ramp <NUM> or the proximal ramp <NUM> to an adjacent surface on the radial projection <NUM>.

According to an aspect of the disclosure, the absolute value of the slope <NUM> of the distal ramp <NUM> does not equal the absolute value of the slope <NUM> of the proximal ramp <NUM>. According to the invention, the absolute value of the slope <NUM> of the distal ramp <NUM> is greater than the absolute value of the slope <NUM> of the proximal ramp <NUM>. For example, the absolute value of the slope <NUM> of the distal ramp <NUM> may be greater than <NUM> degrees and the absolute value of the slope <NUM> of the proximal ramp <NUM> may be less than <NUM> degrees. According to yet another aspect of the disclosure, not according to the invention, the absolute value of the slope <NUM> of the distal ramp <NUM> is less than the absolute value of the slope <NUM> of the proximal ramp <NUM>.

It will be appreciated that the distal ramp <NUM> and the proximal ramp <NUM> may include linear profiles in the plane defined by the radial direction <NUM> and the axial direction <NUM>, such that the slope <NUM> of the distal ramp <NUM> lies on a linear profile of the distal ramp <NUM>, and such that the slope <NUM> of the proximal ramp lies on a linear profile of the proximal ramp <NUM>.

According to an aspect of the disclosure, profiles of the distal ramp <NUM> and the proximal ramp <NUM> may be non-symmetric about a plane <NUM> normal to the longitudinal axis <NUM> and located at a point <NUM> halfway between the points of maximum radial height <NUM> and <NUM> in the axial direction <NUM>. According to another aspect of the disclosure, the points of maximum radial height <NUM> and <NUM> are coincident, and the plane <NUM> passes through the points of maximum radial height <NUM> and <NUM>.

As shown in <FIG>, either the distal ramp <NUM> or the proximal ramp <NUM> may include concave profiles in the plane defined by the radial direction <NUM> and the axial direction <NUM>. As shown in <FIG>, either the distal ramp <NUM> or the proximal ramp <NUM> may include convex profiles in the plane defined by the radial direction <NUM> and the axial direction <NUM>. As shown in <FIG>, the distal ramp <NUM> may include a concave profile and the proximal ramp <NUM> may include a convex profile, both with respect to the plane defined by the radial direction <NUM> and the axial direction <NUM>. Conversely, it will be appreciated that the proximal ramp <NUM> may include a convex profile and the proximal ramp <NUM> may include a concave profile.

As shown in <FIG>, the distal ramp <NUM> may include an abutment surface <NUM>, where the abutment surface <NUM> defines the point of leading incipient contact <NUM> with the inner surface <NUM> of the barrel <NUM> (see <FIG>). The abutment surface <NUM> may have a linear profile, a concave profile, or a convex profile. According to an aspect of the disclosure, a line <NUM> tangent to the abutment surface <NUM> at the point of leading incipient contact <NUM> forms an angle <NUM> with the longitudinal axis <NUM> of approximately <NUM> degrees. According to another aspect of the disclosure, no line tangent to the proximal ramp <NUM> forms an angle <NUM> with the longitudinal axis <NUM> of approximately <NUM> degrees. Here, approximately <NUM> degrees will be understood to be an angle between about <NUM> degrees and about <NUM> degrees.

The present disclosure is applicable to syringes in general, and more particularly, to syringes that provide haptic or tactile feedback of material quantity delivered to the user. Further, the present disclosure may be applicable to syringes used in the context of medicine, manufacturing, construction, maintenance and repair, agriculture, food preparation, or any other context where syringes may be used. Accordingly, aspects of the disclosure may be applied to syringes for delivering a medication to a patient, extracting bodily fluids from a patient, or delivering other fluid materials such as air, adhesives, lubricants, food products, and the like.

Operation of the syringe <NUM> will now be described with reference to <FIG>. The plunger <NUM> translates within the bore <NUM> of the barrel <NUM> toward the port <NUM> with a relatively low resistance until the at least one radial projection <NUM> contacts the internal surface <NUM> of the barrel <NUM> at the leading point of incipient contact <NUM> (see <FIG>). After incipient contact between the radial projection <NUM> of the plunger <NUM> and the barrel <NUM>, the increased resistance provides haptic feedback to a user indicating an axial position of the plunger <NUM> relative to the barrel <NUM>.

According to an aspect of the disclosure, the location of the at least one radial projection <NUM> along the axial length of the plunger <NUM> corresponds to a stopping point against the barrel <NUM> for a swept piston <NUM> volume within the bore <NUM> for a desired dose of material discharged from the syringe <NUM>. Accordingly, the syringe <NUM> user may stop translation of the plunger <NUM> into the barrel <NUM> upon sensation of the haptic feedback caused by incipient contact between the at least one radial projection <NUM> and the internal surface <NUM> of the barrel <NUM>.

Next, the user may then proceed to deliver a second dose of material from the syringe <NUM> by applying sufficient force to translate the plunger <NUM> against the interference between the at least one radial projection <NUM> and the inner surface <NUM> of the barrel <NUM>. When the proximal ramp of the radial projection <NUM> is in trailing incipient contact with the inner surface <NUM> of the barrel <NUM>, the user may feel reduced resistance to further translation of the plunger <NUM> into the barrel <NUM>, and may continue to translate the plunger <NUM> into the barrel <NUM> until a second increase in plunger resistance is perceived. The second increase in plunger resistance may be the result of incipient contact between a distal ramp of a subsequent radial projection <NUM>, or a hard stop such as abutting contact between the piston <NUM> and the internal surface <NUM> of the barrel, or any other abutting contact between the plunger <NUM> and the barrel <NUM>.

According to aspects of the disclosure, asymmetry between the distal and proximal ramps of the radial projections <NUM> allow designers to further refine the haptic or tactile feedback by tailoring the relative resistances of leading incipient contact and trailing incipient contact between the at least one radial projection <NUM> and the internal surface <NUM> of the barrel <NUM>. For example, the slope of the distal ramp may be steeper than the slope of the proximal ramp, thereby effecting more abrupt deceleration of the plunger <NUM> relative to the barrel <NUM> upon delivering a dose, and more gradual acceleration of the plunger <NUM> relative to the barrel <NUM> upon the beginning of delivering a subsequent dose of material from the syringe <NUM>.

Thus, aspects of the present disclosure provide apparatus and methods for indicating an axial position of a plunger <NUM> within a barrel <NUM> of a syringe <NUM> through haptic feedback via variable resistance or force for motion of the plunger <NUM> relative to the barrel <NUM>. Accordingly, a user may deliver multiple doses of material from the syringe <NUM> without needing to visually observe the location of the plunger <NUM> relative to the barrel <NUM>, and potentially while operating the syringe <NUM> with just one hand, thereby freeing up the user's other hand to perform other operations in parallel with delivering material from the syringe <NUM>.

Applicants have identified a need for delivering multiple doses of medication from a single syringe using rapid plunger motion to deliver each of the multiple doses. For example, nasal administration of medications may benefit from delivery of partial doses to each nostril of a patient in quick succession and with a high degree of atomization.

The degree of atomization increases with increasing pressure drop across the atomization orifice, and therefore, increasing flow rate through the atomization orifice. Accordingly, the degree of atomization may benefit from higher velocities of the plunger <NUM> relative to the barrel <NUM> during medicine delivery. In turn, Applicants have identified that high plunger velocities for multi-dose syringes may result in repeatability and reproducibility errors, in both the amount of medicine in each dose and the degree of atomization, when dose quantity is controlled via visual feedback of a relative position of the plunger <NUM> within the barrel <NUM> of the syringe. Indeed, errors in dose quantity based on visual feedback may be exacerbated by the need for high plunger velocities at least because of difficulty in rapidly decelerating the plunger <NUM> to while simultaneously stopping precisely at the axial location corresponding to a desired dose.

Aspects of the disclosure address drawbacks of conventional approaches by providing tactile dose feedback through variable interference between the plunger <NUM> and the barrel <NUM> of a syringe, instead of conventional visual feedback. As described previously, variable interference between a plunger <NUM> and a barrel <NUM> of a syringe <NUM> may be varied according to aspects of the disclosure to provide variable degrees of tactile interference indicative of the position of the plunger <NUM> within the barrel <NUM>. Indeed, by providing tactile feedback indicative of individual dose quantities, syringe users may allocate more attention to the rate of plunger travel and the location of the aperture <NUM> relative to a patient's nose, for example, thereby improving repeatability and reproducibility of both dose quantity and the degree of atomization.

In addition, aspects of the disclosure provide a dose dividing syringe <NUM> that allows translation of the plunger <NUM> away from the barrel <NUM>, for example during filling procedures. Unlike conventional multiple-dose syringes, such as those described in the '<NUM> patent and the '<NUM> publication, discussed above, syringes according to the present disclosure may not require rotation of the plunger shaft <NUM> in order to fill the syringes with material.

The syringe <NUM> may be configured with an axial array of radial projections <NUM> such that a first dose of material, corresponding to translation of the plunger <NUM> until contact between a first radial projection <NUM> and the barrel <NUM>, may be substantially equal in quantity to a second dose of material, corresponding to translation of the plunger <NUM> until contact between a second radial projection <NUM> and the barrel <NUM> of the syringe <NUM>. However, it will be appreciated that the syringe <NUM> may also be configured such that the quantity of the first dose of material is different from the quantity of the second dose of material for other material delivery processes.

Unless specified otherwise herein, the word "substantially" shall mean "considerable in extent," or shall mean largely but not necessarily wholly that which is specified.

It will be appreciated that the foregoing description provides examples of the disclosed apparatus and method. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.

Claim 1:
A syringe (<NUM>), comprising:
a barrel (<NUM>) having an internal surface (<NUM>) defining an internal bore (<NUM>) therein;
a plunger (<NUM>) disposed within the internal bore (<NUM>) of the barrel (<NUM>), a distal end (<NUM>) of the plunger (<NUM>) being inserted into a proximal end (<NUM>) of the barrel, a proximal end <NUM>) of the plunger being opposite the distal end (<NUM>) of the plunger along a longitudinal axis (<NUM>) of the plunger; and
at least one radial projection (<NUM>) disposed on an external surface (<NUM>) of the plunger (<NUM>), the at least one radial projection (<NUM>) including a proximal ramp (<NUM>) and a distal ramp (<NUM>), the proximal ramp (<NUM>) being disposed on a proximal side of the at least one radial projection (<NUM>), and the distal ramp (<NUM>) being disposed on a distal side of the at least one radial projection (<NUM>), the distal ramp (<NUM>) including a convex ramp,
the distal ramp(<NUM>) including a first point (<NUM>) being a point of incipient contact with the internal surface (<NUM>) of the barrel (<NUM>), the first point (<NUM>) being located at a first radial distance from the longitudinal axis, the at least one radial projection (<NUM>) having a first slope relative to the longitudinal axis at the first point (<NUM>),
the at least one radial projection (<NUM>) having a second slope relative to the longitudinal axis at a second point (<NUM>) along the proximal ramp (<NUM>) located a second radial distance from the from the longitudinal axis, the second radial distance being substantially equal to the first radial distance,
characterised in that
the absolute value of the first slope is greater than the absolute value of the second slope.