TEATS FOR FEEDING BOTTLES

Abstract

A feeding teat for use with a bottle that contains a fluid includes a nipple defining an orifice at a terminal end and an interior profile shaped by multiple intersecting reverse curves that generally decreases an interior diameter of the nipple toward the orifice for directing a flow of the fluid into the orifice, a flange configured to be releasably coupled to the bottle such that the fluid can flow from the bottle into the feeding teat, an intermediate portion integrally connecting the nipple to the flange, and a pressure relief valve extending laterally from the intermediate portion and configured to admit air into an interior region formed by the feeding teat and the bottle.

Claims

1. A feeding teat for use with a bottle that contains a fluid, the feeding teat comprising: a nipple defining an orifice at a terminal end and an interior profile shaped by a plurality of intersecting reverse curves that generally decreases an interior diameter of the nipple toward the orifice for directing a flow of the fluid into the orifice; a flange configured to be releasably coupled to the bottle such that the fluid can flow from the bottle into the feeding teat; an intermediate portion integrally connecting the nipple to the flange; and a pressure relief valve extending laterally from the intermediate portion and configured to admit air into an interior region formed by the feeding teat and the bottle.

2. The feeding teat of claim 1, wherein the pressure relief valve is integrally formed with the intermediate portion.

3. The feeding teat of claim 1, wherein the pressure relief valve comprises first and second walls spaced apart from each other and extending to a terminal wall.

4. The feeding teat of claim 3, wherein the first and second walls are oriented at an angle of about 1 degrees to about 3 degrees with respect to each other.

5. The feeding teat of claim 3, wherein the first and second walls are parallel to each other.

6. The feeding teat of claim 3, wherein the pressure relief valve comprises third and fourth walls spaced apart from each other and extending to the terminal wall.

7. The feeding teat of claim 6, wherein the third and fourth walls are oriented at an angle of about 1 degree to about 5 degrees with respect to each other.

8. The feeding teat of claim 3, wherein the terminal wall defines a slit through which the air can pass into the interior region.

9. The feeding teat of claim 8, wherein the slit has a width of about 3 mm to about 5.5 mm.

10. The feeding teat of claim 3, wherein the terminal wall is a flat wall.

11. The feeding teat of claim 3, wherein the terminal wall is a curved wall.

12. The feeding teat of claim 3, wherein the terminal wall comprises a flat exterior surface and a curved interior surface.

13. The feeding teat of claim 3, wherein the terminal wall has a vertical orientation.

14. The feeding teat of claim 3, wherein the pressure relief valve comprises wall portions that define an entry zone of the pressure relief valve.

15. The feeding teat of claim 14, wherein the wall portions are thicker than the terminal wall.

16. The feeding teat of claim 14, wherein the wall portions are thicker than the first and second walls.

17. The feeding teat of claim 1, wherein the pressure relief valve extends horizontally from the intermediate portion.

18. The feeding teat of claim 1, wherein the nipple and the flange are radially symmetric about a central axis of the feeding teat.

19. The feeding teat of claim 1, wherein the plurality of reverse curves comprises: a concave curve adjacent the orifice; and a convex curve adjacent the concave curve and at which the nipple has a maximum wall thickness to stiffen the terminal end at which the orifice is located.

20. The feeding teat of claim 1, wherein the feeding teat comprises silicone.

Description

DESCRIPTION OF DRAWINGS

[0037] FIG. 1 is a cross-sectional view of one embodiment of a feeding teat.

[0038] FIG. 2 shows the teat of FIG. 1 on a bottle.

[0039] FIG. 3 is a bottom perspective view of the teat of FIG. 1 showing the construction that accomplishes a pressure relief valve.

[0040] FIG. 4 is a greatly enlarged view of the teat of FIG. 1, but with a slightly different pressure relief valve construction.

[0041] FIGS. 5A and 5B are side and cross-sectional views of a second embodiment of a feeding teat.

[0042] FIGS. 6A and 6B are different side and cross-sectional views of the second embodiment of a feeding teat.

[0043] FIGS. 7A-7D are side, cross-sectional and two partial close-up views of the second embodiment of a feeding teat.

[0044] FIGS. 8A-8C are side, cross-sectional and a partial close-up views of the second embodiment of a feeding teat.

[0045] FIGS. 9A-9C are side, cross-sectional and a partial close-up views of the second embodiment of a feeding teat.

[0046] FIGS. 10A-10C are top, side and perspective views of another embodiment of a feeding teat.

[0047] FIG. 11 is a side cross-sectional view of an embodiment of a feeding teat.

[0048] FIG. 12 is an enlarged side cross-sectional view of a pressure relief valve of the feeding teat of FIG. 11.

[0049] FIG. 13 is an enlarged top cross-sectional view of a terminal end of the pressure relief valve of FIG. 12.

[0050] FIG. 14 is a perspective view of the pressure relief valve of FIG. 12.

[0051] FIG. 15 is an enlarged perspective view of the pressure relief valve of FIG. 12.

[0052] FIG. 16 is a side cross-sectional view of an embodiment of a feeding teat.

[0053] FIG. 17 is an enlarged side cross-sectional view of a pressure relief valve of the feeding teat of FIG. 14.

[0054] FIG. 18 is an enlarged top cross-sectional view of a curved interior terminal portion of the pressure relief valve of FIG. 15.

DETAILED DESCRIPTION

[0055] Teat 40 with nipple 70, FIGS. 1-3, directs the milk/liquid in a relatively laminar flow through and out of the nipple through outlet 71. Teat 40 can be an integral molded item that is typically made from medical grade silicone of 30-40 durometer. The laminar flow into the outlet is in part accomplished by the interior profile of wall 73 that smoothly steps the diameter down to terminal portion 74 and through opening 71. The interior shape 79 of teat 40 as a whole includes concave interior surface 81 of intermediate teat portion 80 that has a convex exterior shape. Nipple proximal region 72 has a convex interior shape 78. First interior nipple portion wall curve 75 is concave, second interior wall curve 76 is convex and third interior wall curve 77 is concave. The series of two or more reverse curves accomplishes a gradual narrowing of the interior diameter, which accomplishes a more laminar flow than a typical nipple with a single concave wall that leads to the orifice/outlet. This reduces turbulence in the liquid and thus inhibits air bubble integration. This will also inhibit the contents of the liquid (e.g., foodstuffs, minerals/vitamins) from settling or being pushed away from the liquid in the solution. Also, the wall 73 proximate orifice or opening 71 that generally increases in thickness from the proximal region toward the outlet provides more stiffness proximate opening (valve) 71, thus the valve functions more effectively to inhibit leakage. Also, because neck or nipple proximal region 72 is thinner, when an infant sucks on nipple 70, region 72 can flex, which allows the stiffer nipple to be drawn into the mouth more naturally, to mimic actions that take place when an infant feeds from its mother.

[0056] FIGS. 1-3 also illustrate an embodiment of a pressure relief valve 60 incorporated into teat 40. One or more such valves can be incorporated. In this embodiment the valves are accomplished between the upper wall 52 of the bottle to which the teat is attached (which can be any standard bottle and so is not fully shown in the drawings) and the teat 40, via integral annular teat extension or skirt 62 with its distal end resting against the inside surface of wall 52. Integral annular teat flange 66 defines open undercut 64 that leaves volume 53 between the bottle and the teat open to the atmosphere. As the pressure inside the bottle drops, atmospheric pressure pushes skirt 62 at the location of open volume 53 away from the bottle to allow air to flow into the bottle. Skirt 62 is deformable (e.g., by being made from an elastomer such as silicone, and due to its mechanical design, its flexibility, and the manner in which it contacts the bottle). Air is thus channeled from outside (atmosphere) into the bottle during suck (negative pressure). This air is kept away from the feeding zone (the valves are at the end of the teat farthest from the outlet opening in the nipple), and allows the prevention of a vacuum in the bottle. This also allows for one shot molding of the teat and does not rely on post-processing (e.g., a knife slit) of the material to create the valve.

[0057] FIG. 4 depicts an alternative embodiment of the valve 60a in teat 40a, wherein extension or skirt 62a has a more parabolic shape as opposed to the straight extension 62 shown in FIGS. 1-3. This shape may create a better seal against bottle neck 52. The skirt can take other shapes and be constructed differently so as to accomplish a good liquid tight seal that will deflect slightly so as to allow air into the bottle when a sufficient negative pressure is reached inside the bottle.

[0058] In teat 40, air flows in from outside of the bottle to neutralize pressure. The bottle neck insert on the teat acts as valve. Multiple valves can be spaced around the periphery of the base or flange of the teat, typically but not necessarily evenly spaced around the periphery. For example, two valves located 180 degrees from each other or three valves located 120 degrees from one another. The one piece molded teat has a valve mechanism that is not very compression sensitive so can be coupled to the bottle like a normal teat without a valve in its flange.

[0059] FIGS. 5-9 illustrate a second embodiment. Teat 100 includes nipple portion 102 with outlet orifice 112, intermediate portion 104, flange portion 106 that is adapted to be coupled to a bottle, and pressure relief valve 110. As with the first embodiment, teat 100 is integrally molded from silicone. Feed hole 112 can be created in the molding process or can be created post-molding with a mechanical punch or a laser. For slow feed rates of 6-12 ml/minute hole 112 is typically from about 0.25 to about 0.53 mm in diameter 124. For intermediate feed rates of 9-19 ml/minute hole 112 is typically from about 0.46 to about 0.65 mm in diameter. For fast feed rates of 17-25 ml/minute hole 112 is typically from about 0.58 to about 0.77 mm in diameter. Feed rates were determined with water.

[0060] Valve 100 comprises flexible parallel walls 161 and 162 connected at their lower ends by transverse wall 163, which is slit so as to provide a path for air to enter the inside of the teat. The slit 132 in lower valve wall 163 is created by a blade and rigging fixture. The slit is nominally set to a width of 5 mm.+0.0.5 mm. The curved lower wall 163 of the valve increases its stiffness and thus decreases the chances of fluid leakage, as compared to a linear wall. Vertical wall 164 locates wall 165 sufficiently offset from teat wall 189 such that walls 165 and 166 are at the same depth. Curved (typically circular or elliptical) transverse walls 165 and 166 serve to separate the pressure-sensitive walls 161 and 162 that are part of the valve from the main body of the teat. This means that the thin, sensitive walls 161 and 162 are not affected or at least less affected by stretching or twisting of the teat in use than would be the case if walls 161 and 162 were directly connected to main wall 189 of the teat. This makes the valve function better under typical usage scenarios where the teat is stretched and twisted in use. It may be possible to change the sensitivity of the valve even more by making a valve with a different durometer, or out of a different material than the rest of the teat, in a two-shot molding process. Silicone and many other thermoplastic elastomers will stick together over time after they have been slit. This may require the user to pinch the valve before use to assure that it is open and functional. Using a different material that does not stick to this extent over time could resolve this potential issue.

[0061] As in the first embodiment, the nipple portion is designed to accomplish a relatively laminar flow into the orifice. The terminal part of the nipple portion defines interior wall 200. First curve 202 is concave. Second curve 206 is convex. Third curve 210 is concave. Fourth curve 214 (which leads directly into orifice 112) is convex. This series of four reverse curves accomplishes a smoothly-decreasing interior diameter that supports laminar flow into orifice 112. Teat wall 191 generally increases in thickness from portion 72 and along at least part of wall 206, up to where walls 210 and 214 are located. This helps to maintain the stiffness of the nipple in the portion that delivers the fluid.

[0062] In one non-limiting embodiment that illustrates the disclosure, the radii of curvature and dimensions of a teat of the type shown in FIGS. 5-9 are as follows. Note that the radii and dimensions are adjustable, subject to finite element analysis to determine that the flow is relatively laminar. On average, the radii can be defined as about +/0.5 mm for smaller radii to as much as about +/1 mm for larger radii. Distance variation can be more liberal, likely as much as plus 3 mm more.

[0063] Radius 122: 0.750 mm

[0064] Radius 131: 13.53 mm

[0065] Radius 133: 5.52 mm

[0066] Radius 134: 4.5 mm

[0067] Radius 135: 30 mm

[0068] Radius 136: 1 mm

[0069] Radius 142: 2 mm

[0070] Radius 174: 0.25 mm

[0071] Radius 182: 0.25 mm

[0072] Radius 188 (4 places): 0.500+/0.025 mm

[0073] Radius 204: 2 mm

[0074] Radius 208: 2.471 mm

[0075] Radius 212: 1.042 mm

[0076] Radius 216: 0.750 mm

[0077] Dimension 130: 5.500 mm

[0078] Dimension 132 (the width of the slit 132 in curved lower wall 163 of valve 110): 5 mm

[0079] Dimension 138: 2.134 mm

[0080] Dimension 139: 9+/0.025 mm

[0081] Dimension 140: 44+/0.127 mm

[0082] Dimension 144: 1.87 mm

[0083] Dimension 146: 60.50 mm

[0084] Dimension 150: 1 mm

[0085] Dimension 152: 2 mm

[0086] Dimension 154: 12.25 mm

[0087] Dimension 170: 3.800+/0.127 mm

[0088] Dimension 172: 1+/0.025 mm

[0089] Dimension 176: 0.600+/0.025 mm

[0090] Dimension 178: 0.500+/0.025 mm

[0091] Dimension 180: 5+/0.025 mm

[0092] Dimension 184: 5.72 mm

[0093] Dimension 186 (2 places): 0.600+/0.025 mm

[0094] Dimension 222: 1.757 mm

[0095] Dimension 224: 0.617 mm

[0096] Dimension 226: 0.633 mm

[0097] Dimension 228: 0.250 mm

[0098] Quantitative tests were run on teat 100 as compared to two standard teats with a single concave internal nipple wall leading to the orifice. For a given mass flow rate out of the teat, the required pressure vacuum to be created by the infant was at least 26% less than the other two designs, meaning that the child needs to expend less energy to obtain the same amount of milk/liquid. Also the child will experience less frustration during feeding, as flow comes easier. The two standard designs required 36% and 78% greater pressure drop to maintain the same flow rate of 2e4 kg/sec. as compared to teat 100. Standard data establish that the peak negative vacuum that can be developed in an infant's mouth is about 145+/58 mm Hg. At 145 mm Hg the subject teat delivered 16.6 cc/min as compared to 12.5 and 14.2 cc/min for the two standard designs.

[0099] FIG. 10A-10C show the optional addition of three (or morepotentially four or five) internal ribs 312-314 that run from the intermediate portion 308 of teat 300 into the nipple portion 306. Valve 304 is shown. The ribs help to maintain an open flow path even if the infant bites down on the teat. Rib portion 321 that lies along the inside wall of intermediate portion 308 is generally radial with respect to the teat centerline 330 (a vertical line running through orifice 310, coming directly out of the page in FIG. 10A, and illustrated in FIG. 10B), while inflection location 323 alters the direction of portion 322 to one that is angled along the inside of the nipple proximal portion; this configuration prevents the nipple from fully collapsing if it is bitten down on by the infant. The angle of upper portion 322 relative to the teat centerline 330 is typically between about 45 degrees and about 75 degrees; an angle of about 65 degrees is illustrated. The ribs are typically about 5 mm wide at their widest (closest to flange 302) and taper to about 2 mm-4 mm at the top. The height or protrusion of the ribs from the interior wall is typically 2 mm1 mm; at their widest point they gradually decrease in height so as to end flush with the interior wall. The ribs allow for the teat to stretch into the child's mouth during a suck, while preventing the base of the teat from collapsing or kinking inward under a stretch force as the child sucks on the nipple. This inward stretch is similar to the action of the nipple of a breast during breastfeeding.

[0100] In some embodiments, a teat may include an integral pressure relief valve extending horizontally from an intermediate portion of the teat. For example, FIG. 11 illustrates a teat 400 that includes such a valve, as will be discussed in more detail below. The teat 400 is formed as a molded component that includes a nipple 402 that directs a laminar flow of liquid (e.g., milk, water, or another liquid) out of the teat 400, a flange 404 that can be releasably coupled to a bottle, and an intermediate portion 406 that connects the nipple 402 to the flange 404.

[0101] The teat 400 defines a wall 408 that forms various sections of the teat 400. For example, the wall 408 includes a base portion 410 along the intermediate portion 406, a transition portion 412 that transitions the intermediate portion 406 to the nipple 402, and a terminal portion 414 that forms a terminal region of the nipple 402. The base portion 410 of the wall 408 provides a concave interior surface 416 and a convex exterior surface 418 along the intermediate portion 406 of the teat 400. The transition portion 412 of the wall 408 provides a convex interior surface 420 and a concave exterior surface 422 along a transition region between the intermediate portion 406 and the nipple 402 of the teat 400. Along the nipple 402 of the teat 400, the terminal portion 414 of the wall 408 provides a convex exterior surface 424 and sequentially provides a concave interior surface 426, a convex interior surface 428, and a concave interior surface 430 that surrounds an orifice 432 of the nipple 402.

[0102] The wall 408 of the teat 400 is circumferential about a central axis 434 of the teat and varies in thickness along the central axis 434 of the teat 400. The wall 408 is reduced to a minimum value at the orifice 434, which also defines a minimum internal diameter of the nipple 402. At the terminal region of the nipple 402, along the convex interior surface 428, the wall 408 has an increased thickness that increases a stiffness of the nipple 402 near the orifice 432 such that leakage of liquid out of the orifice 432 is effectively prevented. Along the concave exterior surface 422, the wall 408 has a relatively small thickness such that when an infant sucks on the nipple 402, the transition portion 412 can flex to allow the stiffer terminal region of the nipple 402 to be drawn into the mouth naturally in a manner as when an infant feeds from its mother.

[0103] The series of alternating concave and convex interior curves 416, 420, 422, 426, 428, 430 (i.e., two or more reversely shaped curves) produces a flow of liquid from the bottle to the orifice 432 that is more laminar as compared to a flow of liquid produced by teats that have only a single concave interior surface leading to an orifice. Such laminar flow within the teat 400 reduces turbulence within the liquid and accordingly prevents the formation of air bubbles within the liquid and prevents contents within the liquid from settling out of the liquid within the nipple 402.

[0104] The intermediate portion 406 of the teat 400 terminates at a neck portion 436 of the wall 408 that has a reduced diameter as compared to a maximum diameter of the base portion 410 of the wall 408. The neck portion 436 leads to the flange 404, which is formed to rest against an open wall of a bottle, as described above with respect to the flange portion 66 and the bottle 52 illustrated in FIG. 2. A circumferential skirt 454 projects downwardly from the flange 404 and is configured to be inserted within an opening of a bottle, as described above with respect to the skirts 62, 62a of the teats 40, 40a and the bottle 52 illustrated in FIG. 2.

[0105] The teat 400 also includes a pressure relief valve 438 (e.g., an atmospheric vent) that allows ambient air to flow into the teat 400 (e.g., introducing positive pressure) to counteract a vacuum pressure (e.g., a negative pressure) produced within the teat 400 as the infant sucks on the nipple 402 and extracts fluid. The pressure relief valve 438 is integrally formed and protrudes inward laterally (e.g., horizontally) from the wall 408 along the intermediate portion 406 of the teat 400. The wall 408 of the teat is symmetric about the central axis 434 of the teat 400, except within a region at which the pressure relief valve 438 is located. Referring to FIGS. 12-15, the pressure relief valve 438 is formed in part as a protrusion 440 that extends into the interior region of the teat 400. The protrusion 440 is defined by two opposing upper and lower flat walls 460, 462 and two opposing lateral flat walls 464, 466. The walls 460, 462, 464, 466 terminate at a flat terminal wall 442. The upper and lower walls 460, 462 define an interior angle that can range from about 1.0 degree to about 3.0 degrees such that the walls 460, 462 are just slightly off from parallel. In the example embodiment 400, a is about 1.5 degrees. The opposing lateral walls 464, 466 define an interior angle that can range from about 1 degree to about 5 degrees such that the walls 464, 466 are non-parallel. The flat terminal wall 442 has a slit 444 through which ambient air can flow into the teat 400. Along an interior region of the pressure relief valve 438, the pressure relief valve 438 has a profile 446 with flat sections defined by the protrusion 440, as well as an arcuate interior profile 448 defined by a thickened wall portion 470 the wall 408.

[0106] A width of the arcuate interior profile 448 gradually decreases from an outer opening 450 to an internal entry zone 452 to direct ambient air inward towards the slit 444 of the pressure relief valve 438. Owing to the angle between the upper and lower walls 460, 462 of the protrusion 440, the flat terminal wall 442 has a vertical height that is less than a vertical height at the internal entry zone 452. In some implementations, the inward angle of the protrusion 440 facilitates release of the pressure relief valve 438 from a mold used to form the pressure relief valve 438 during an injection molding process. Thickened wall portions 468, 470 of the pressure relief valve 438 prevent the valve 438 from deforming when a nipple/screw ring assembly is tightened onto the bottle. For example, a common issue with atmospheric vents built into teats is deformation and failure of the vents due to flex or strain on the teat caused from tightening onto the bottle. Wall portions 468, 470 create a stable platform for the pressure relief valve 438. This stability allows the walls 460, 462, 464, 466 of the protrusion 440 to be extra thin (e.g., about 0.35 mm to about 0.5 mm). The advantage to the extra thin walls 460, 462, 464, 466 is that the pressure relief valve 438 becomes more sensitive such that the slit 444 will crack open under a relatively low pressure difference between atmospheric pressure (i.e., outside of the bottle) and the pressure inside of the bottle. The advantage of the upper and lower walls 460, 462 being almost parallel is also related to increasing the sensitivity of the pressure relief valve 438 while maintaining an overall robust structure. For example, such a configuration reduces a pressure from liquid contained in the bottle and interior bottle forces to maintain the slit 444 in a closed configuration during use. In contrast, conventional duck valve and triangular valve structures typically result in higher cracking forces due to the pressure that liquid applies to an interior surface of the teat wall for the given system.

[0107] In some embodiments, an internal height along the flat terminal wall 442 of the pressure relief valve 438 may be in a range of about 1 mm to about 2 mm. In some embodiments, the internal height at the internal entry zone 452 of the pressure relief valve 438 may be in a range of about 1 mm to about 2 mm. In some embodiments, the flat terminal wall 442 has a thickness in a range of about 0.3 mm to about 0.6 mm. In some embodiments, the protruding wall 440 has a thickness in a range of about 0.35 mm to about 0.6 mm. In some embodiments, the slit 444 has a width in a range of about 3 mm to about 5 mm (e.g., about 4 mm). In some embodiments, the teat 400 is made of medical grade silicone that has a durometer of about 40 shore hardness A to about 60 shore hardness A.

[0108] While the teat 400 has been described and illustrated as including a pressure relief valve 438 with slightly non-parallel upper and lower walls 460, 462, in some embodiments, a teat may include a pressure relief valve that has a different sidewall configuration and/or a different end wall configuration. For example, FIG. 16 illustrates a teat 500 that includes a pressure relief valve 538 that has a protrusion 540 with parallel upper and lower flat walls 560, 562. The teat 500 is otherwise substantially similar in construction and function to the teat 400 and accordingly includes a nipple 502, a flange 504, and an intermediate portion 506 that are defined by a wall 508. Accordingly, the nipple 502, the flange 504, the intermediate portion 506 (e.g., with the exception of the pressure relief valve 538), and the wall 508 are substantially similar in construction and function to the nipple 402, the flange 404, the intermediate portion 406 (e.g., with the exception of the pressure relief valve 438), and the wall 408 as described above.

[0109] As described above with respect to the pressure relief valve 438, the pressure relief valve 538 (e.g., an atmospheric vent) allows ambient air to flow into the teat 500 (e.g., introducing positive pressure) to counteract a vacuum pressure (e.g., a negative pressure) produced within the teat 500 as the infant sucks on the nipple 502. The pressure relief valve 538 is integrally formed and protrudes inward laterally (e.g., horizontally) from the wall 508 along the intermediate portion 506 of the teat 500. Referring to FIGS. 17 and 18, the pressure relief valve 538 is formed in part as the protrusion 540 that extends into the interior region of the teat 500. The protrusion 540 is defined by the two opposing upper and lower flat walls 560, 562 and two opposing lateral flat walls. The upper and lower walls 560, 562 and the lateral walls terminate at a terminal wall 542. The upper and lower walls 560, 562 are parallel to one another. The terminal wall 542 defines a curved interior profile 556 that has a slit 544 through which ambient air can flow into the teat 500. Along an interior region of the pressure relief valve 538, the pressure relief valve 538 has a profile 546 with flat sections defined by the protrusion 540, as well as an arcuate interior profile 548 defined by a thickened wall portion 570 the wall 508. A width of the arcuate interior profile 548 gradually decreases from an outer opening 550 to an internal entry zone 552 to direct ambient air inward towards the slit 544 of the pressure relief valve 538. The protrusion 538 is strengthened by thickened wall portions 568, 570.

[0110] In some embodiments, the interior profile 546 has a height in a range of about 0.35 mm to about 0.6 mm. In some embodiments, the internal height at the internal entry zone 552 of the pressure relief valve 538 may be in a range of about 1 mm to about 2 mm. In some embodiments, the terminal wall 542 has a maximum thickness in a range of about 0.35 mm to about 0.65 mm. In some embodiments, the upper and lower walls 560, 562 and the lateral walls of the protrusion 540 have a thickness in a range of about 0.35 mm to about 0.6 mm. In some embodiments, the slit 544 has a width in a range of about 3.5 mm to about 5.5 mm. In some embodiments, the teat 500 is made of medical grade silicone that has a durometer of about 40 to about 60 shore hardness A.

[0111] Other embodiments are also within the scope of the following claims. For example, while the teats 40, 40a, 100, 300, 400, 500 have been described with respect to certain dimensions, shapes, and material formulations, in other embodiments, a teat that is substantially similar in construction and function to any of the teats 40, 40a, 100, 300, 400, 500 may include one or more similar features that have one or more dimensions, shapes, and/or material formulations that are different from those described with respect to the teats 40, 40a, 100, 300, 400, 500. In other embodiments, a teat that is substantially similar in construction and function to either of the teats 400, 500 may include more than one pressure relief valve 438, 538.