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HELMET INTEGRATED WITH MODULATED DISSIPATION FOR ENHANCED IMPACT PROTECTION, METHOD OF MAKING AND METHOD OF USING THE SAME

20250380763 ยท 2025-12-18

    Inventors

    Cpc classification

    International classification

    Abstract

    Protective headwear such as a helmet, a method of making and a method of using the same are provided. The protective headwear includes a shell having an exterior surface and an interior surface and configured to accept the head of a subject, and at least one cushioning member disposed on and at least partially covering the interior surface. The cushioning member includes a cell pack structure, which comprises a plurality of flexible cells defining a plurality of internal cavities, a plurality of channels fluidly connected with the plurality of cells to provide a network of cells, and a fluid disposed within the plurality of internal cavities and the plurality of channels. The plurality of cells comprise a first type of cells and a second type of smaller cells. The cells and the channels are made of the same or different materials.

    Claims

    1. A protective headwear, comprising: a shell having an exterior surface and an interior surface and configured to circumferentially accept the head of a subject in need thereof and cover a skull of the head from the interior surface; and at least one cushioning member disposed on and at least partially covering the interior surface, wherein: the at least one cushioning member comprises a cell pack structure, the cell pack structure comprises a plurality of cells defining a plurality of internal cavities, a plurality of channels fluidly connected with the plurality of cells to provide a network of cells, and a fluid disposed within the plurality of internal cavities and the plurality of channels, the plurality of cells comprises a first type of cells having a first dimension and a second type of cells having a second dimension, the first dimension is greater than the second dimension, the plurality of cells are flexible and made of a first material, and the plurality of channels are made of a second material.

    2. The protective headwear of claim 1, wherein the first material is the same as or different from the second material.

    3. The protective headwear of claim 1, wherein each of the first material and the second material comprises a polymer.

    4. The protective headwear of claim 1, wherein each of the first material and the second material is selected from the group consisting of a rubber, a latex, a plastic, a thermoplastic elastomer, and any combination thereof.

    5. The protective headwear of claim 1, wherein each of the first material and the second material is a silicone elastomer or polychloroprene.

    6. The protective headwear of claim 1, wherein the first material and the second material have different hardness.

    7. The protective headwear of claim 1, wherein the at least one cushioning member comprises two or more pieces of cushioning members.

    8. The protective headwear of claim 1, wherein two or more of the second type of cells are disposed around each of the first type of cells.

    9. The protective headwear of claim 8, wherein each of the plurality of cells has a circular or oval sectional shape, and more than one cell of the second type are disposed concentrically around each of the first type of cells.

    10. The protective headwear of claim 1, wherein the first type of cells and the second type of cells are connected in series in a string pattern.

    11. The protective headwear of claim 10, wherein the first type of cells and the second type of cells are in an alternating pattern.

    12. The protective headwear of claim 1, wherein the first type of cells and the second type of cells are disposed and connected with each other in an array, and each cell has a circular or oval sectional shape.

    13. The protective headwear of claim 1, wherein each of the first dimension and the second dimension is a diameter in a range of from about 0.2 cm to about 8 cm.

    14. The protective headwear of claim 1, wherein each of the plurality of channels has a length in a range of from 0.2 cm to 5 cm and a diameter in a range of from 0.2 mm to 8 mm.

    15. The protective headwear of claim 1, wherein the fluid is a Newtonian fluid.

    16. The protective headwear of claim 1, wherein the fluid is a non-Newtonian fluid.

    17. The protective headwear of claim 16, wherein the fluid is a shear-thickening fluid.

    18. The protective headwear of claim 1, wherein in the at least one cushioning member has a first side and a second side, the first side is disposed on the interior surface of the shell, the second side is configured to contact a head of a subject, and the second side has a hardness lower than that of the first side.

    19. The protective headwear of claim 1, wherein the protective headwear is a helmet.

    20. A method of making the protective headwear of claim 1, comprising steps: forming upper and lower halves of the plurality of cells; forming upper and lower halves of the plurality of channels; bonding the upper and lower halves of the plurality of cells; bonding the upper and lower halves of the plurality of channels; and attaching the plurality of the cells and the plurality of channels to provide the at least one cushioning member.

    21. The method of claim 20, wherein the plurality of cells and the plurality of channels are made of the same materials and have a unitary structure, and the steps of forming upper and lower halves of the plurality of cells, forming upper and lower halves of the plurality of channels, and attaching the plurality of the cells and the plurality of channels to provide the at least one cushioning member are preformed concurrently.

    22. The method of claim 20, further comprising: providing the shell; and attaching the at least one cushioning member onto the interior surface of the shell.

    23. The method of claim 20, wherein the upper halves and the lower halves are made of the first material having different hardness.

    24. A method of using the protective headwear of claim 1, comprising: applying the protective headwear onto the head of a subject, wherein the subject is a human subject.

    Description

    BRIEF DESCRIPTION OF THE DRAWINGS

    [0027] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not necessarily to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.

    [0028] Like reference numerals denote like features throughout specification and drawings.

    [0029] FIG. 1 is an exploded view of a cell in an exemplary cell pack structure in accordance with some embodiments.

    [0030] FIG. 2A is a plan view illustrating an exemplary cell pack structure comprising a central cell, a plurality of surrounding cells, and a plurality of connecting channels in accordance with some embodiments.

    [0031] FIG. 2B is a sectional view illustrating an exemplary headwear such as a helmet comprising the exemplary cell pack structure of FIG. 2A.

    [0032] FIG. 3A is a plan view illustrating an exemplary cell pack structure comprising a plurality of surrounding cells in a cell string and connected via a plurality of connecting channels in accordance with some embodiments.

    [0033] FIG. 3B is a sectional view illustrating an exemplary headwear such as a helmet comprising the exemplary cell pack structure of FIG. 3A.

    [0034] FIG. 4 is a side sectional view illustrating an exemplary headwear such as a helmet in accordance with some embodiments.

    [0035] FIGS. 5A-5C are schematic views showing exemplary cell pack structures in accordance with some embodiments.

    [0036] FIG. 6 is a flow chart illustrating an exemplary method of making a cushioning member comprising an exemplary cell pack structure in accordance with some embodiments.

    [0037] FIGS. 7A-7C are sectional views of the apparatus and materials illustrating the exemplary method of making an exemplary cell pack structure in accordance with some embodiments.

    [0038] FIG. 8 is a flow chart illustrating an exemplary method of making an exemplary protective headwear in accordance with some embodiments.

    [0039] FIG. 9A is a perspective view illustrating an exemplary model comprising an exemplary protective headwear such as a helmet and a 3D-printed head for testing protective capability in accordance with some embodiments.

    [0040] FIG. 9B is a perspective view illustrating an exemplary testing set-up, in which the exemplary model of FIG. 9A is freely dropped sideway from a certain height.

    [0041] FIGS. 10A-10B show impact results represented by the acceleration experienced by the 3D-printed head inside the exemplary protective headwear without and with the cell pack structures, respectively.

    DETAILED DESCRIPTION

    [0042] This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as lower, upper, horizontal, vertical,, above, below, up, down, top and bottom as well as derivative thereof (e.g., horizontally, downwardly, upwardly, etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as connected and interconnected, refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.

    [0043] The term operatively coupled is such an attachment, coupling, or connection that allows the pertinent structures to operate as intended by virtue of that relationship.

    [0044] For purposes of the description hereinafter, it is to be understood that the embodiments described below may assume alternative variations and embodiments. It is also to be understood that the specific articles, compositions, and/or processes described herein are exemplary and should not be considered as limiting.

    [0045] In the present disclosure the singular forms a, an, and the include the plural reference, and reference to a particular numerical value includes at least that particular value, unless the context clearly indicates otherwise. When values are expressed as approximations, by use of the antecedent about, it will be understood that the particular value forms another embodiment. As used herein, about X (where X is a numerical value) preferably refers to +10% of the recited value, inclusive. For example, the phrase about 8 preferably refers to a value of 7.2 to 8.8, inclusive. Where present, all ranges are inclusive and combinable. For example, when a range of 1 to 5 is recited, the recited range should be construed as including ranges 1 to 4, 1 to 3, 1-2, 1-2 & 4-5, 1-3 & 5, 2-5, and the like. In addition, when a list of alternatives is positively provided, such a listing can be interpreted to mean that any of the alternatives may be excluded, e.g., by a negative limitation in the claims. For example, when a range of 1 to 5 is recited, the recited range may be construed as including situations whereby any of 1, 2, 3, 4, or 5 are negatively excluded; thus, a recitation of 1 to 5 may be construed as 1 and 3-5, but not 2, or simply wherein 2 is not included. It is intended that any component, element, attribute, or step that is positively recited herein may be explicitly excluded in the claims, whether such components, elements, attributes, or steps are listed as alternatives or whether they are recited in isolation.

    [0046] As used herein, the term substantially denotes elements having a recited relationship (e.g., parallel, perpendicular, aligned, etc.) within acceptable manufacturing tolerances. For example, as used herein, the term substantially parallel is used to denote elements that are parallel or that vary from a parallel arrangement within an acceptable margin of error, such as +/5, although it will be recognized that greater and/or lesser deviations can exist based on manufacturing processes and/or other manufacturing requirements.

    [0047] Unless expressly indicated otherwise, references to flexible cells or cells being flexible made herein will be understood to encompass a cell having an internal cavity is deformable under a force or a pressure. For example, a flexible cell may be deformable under a pressure such as 25 KPa. The flexible cell, which is filled with a fluid, may not break under a higher pressure, for example, 5 MPa or less such as 1 MPa.

    [0048] The present disclosure provides protective headwear such as a helmet comprising a cell pack structure, a method of making and a method of using the same.

    [0049] In the drawings, like items are indicated by like reference numerals, and for brevity, descriptions of the structure, provided above with reference to the preceding figures, are not repeated. The methods described in FIGS. 6 and 8 are described with reference to the exemplary structure described in FIGS. 1-4, 5A-5C, and 7.

    [0050] In accordance with some embodiments, the present disclosure provides protective headwear or head gear such as a helmet comprising a material including a network of flexible cells (referred to herein as a cell pack) filled with, e.g., a fluid. The term fluid may include a gas such as air, a liquid, or a combination thereof. The technology with such a material comprising a network of flexible cells filled with a fluid is called the cell-pack technology.

    [0051] The cell-pack technology is developed by the primary inventors for wearable garments, and is first disclosed in an earlier patent application, U.S. application Ser. No. 18/319,107, filed May 17, 2023 and published as US 2023/0372185 on Nov. 23, 2023, which claims the priority to U.S. Provisional Patent Application No. 63/342,681, filed May 17, 2022. These applications are incorporated herein by reference in the entirety.

    [0052] In the cell-pack technology, cells made of flexible materials, and filled with a fluid that flows between them in response to external mechanical stimuli are connected in a network. Examples of the flexible materials for the cells include, but are not limited to, rubber, latex, plastic, polychloroprene, silicone elastomers, thermoplastic elastomers, any other polymeric materials, and any combination thereof. The working fluid can be either Newtonian, with viscosities ranging from that of air to pure glycerin, or non-Newtonian, such as a shear-thickening fluid, which could be especially suitable for gradual impact attenuation. The cells can be cast in 3D-printed molds of different designs or can be made using any other suitable methods.

    [0053] The cells are connected by a plurality of connecting channels. The connecting channels can either be cast in the same molds and made from the same material as that of the cells or made separately from materials of different rigidities as needed. The length of the channels and their diameters will be adjusted to achieve the desired resistance and target pressures.

    [0054] In accordance with some embodiments, the protective headwear comprises a shell and at least one cushioning member. The shell has exterior and interior surfaces and is configured to circumferentially accept the head of a subject in need thereof and cover the skull of the head from the interior surface. The at least one cushioning member is disposed on and at least partially covers the interior surface of the shell.

    [0055] The at least one cushioning member comprises a cell pack structure, which comprises a plurality of cells defining a plurality of internal cavities, a plurality of channels fluidly connected with the plurality of cells to provide a network of cells, and a fluid disposed within the plurality of internal cavities and the plurality of channels.

    [0056] In some embodiments, the plurality of cells comprise a first type of cells having a first dimension and a second type of cells having a second dimension. The first dimension is greater than the second dimension. The plurality of cells are flexible and are made of a first material, and the plurality of channels are made of a second material. The first material is the same as or different from the second material.

    [0057] Each of the first material and the second material comprises a polymer. Examples of a suitable material for each of the first material and the second material include, but are not limited to, a rubber, a latex, a plastic, a thermoplastic elastomer, and any combination thereof. In some embodiments, each of the first material and the second material is a silicone elastomer or polychloroprene.

    [0058] In some embodiments, the first material and the second material have different hardness or rigidity. They may be made from the same or different materials.

    [0059] Referring to FIG. 1, an exploded view of a cell in an exemplary cell pack structure 100 in accordance with some embodiments is illustrated.

    [0060] A cell pack structure 100 includes a plurality of cells (collectively cells 6) that each defines an internal cavity 8. The cells may be made of a first material 4. The cells 6 include an upper layer 10a, a lower layer 10b, and a perimeter wall 12 that collectively define the internal cavity 8. In some embodiments, the upper layer 10a and/or the lower layer 10b includes a material having a first (e.g., higher) elasticity and the perimeter wall 12 includes a material having a lower (e.g., lower/more rigid) elasticity. In some embodiments, the upper layer 10a and/or the lower layer 10b may be defined by a portion of the material, such as a fabric material, suitable for a material contained therein. In some embodiments, the internal cavity 8 is filled with a working fluid and/or gel. The fluid may be viscous in some embodiments.

    [0061] In some embodiments, the perimeter wall 12 may define any suitable shape, such as, for example, a hexagonal outer perimeter (as shown), a square outer perimeter, a circular perimeter, an oval perimeter, and/or any other suitable perimeter shape. Three-dimensionally, each cell may have a suitable shape such as a cube, a cuboid, a sphere, and ovoid or ellipsoid.

    [0062] Each of the cells 6 is interconnected by one or more connecting channels 16 (collectively connecting channels 16 or channels 16). The cells and the connecting channels are fluidly connected. The channels may be fibrous in some embodiments. The connecting channels 16 may be formed of the same material (described below) as that of the perimeter wall 12 of each of the cells 6. In some embodiments, the connecting channels interlink, or knit together, the plurality of cells 6. When one or more of the cells 6 are compressed (e.g., squeezed). A pressure build-up may displace the fluid into adjacent cells 6 through the connecting channels 16. The force displacement/build-up of the working material provides compression and conformity.

    [0063] Due to the elastic nature of each cell 6, e.g., the elastic nature of the upper layer 10a and/or the lower layer 10b, the extra working material that is received in each of the cells 6 will raise pressure in those cells, while depressurizing another cell, for example, a central cell or a larger cell. The combined pressurization/depressurization is configured to propagate pressure. When the pressure is relaxed, the pressure build-up in the adjacent cells 6 pushes the extra working fluid back into a central, depressurized cell 6 (or a larger cell), restoring initial equilibrium.

    [0064] In some embodiments, the flow throughout the entire material 2, e.g., throughout the entire network of cell packs 100, may be simulated using computational fluid dynamics and/or as a first order approximation treating the network of cell packs 100 as a hemodynamic circuit where cells 6 act as capacitors, and the connecting channels 16 as resistors.

    [0065] In some embodiments, each cell pack 100 may include one or more elastomeric materials, such as, for example, PDMS (polydimethysilicone) Sylgard 184, Ecoflex, etc. PDMS Sylgard 184, a silicone elastomer, is available from Dow of the United States, and Ecoflex is available from Smooth-on, Inc. of the United States. All types of Ecoflex, e.g., Ecoflex 00-10, 00-20, 00-30, 00-31, etc., may be suitable. Ecoflex is a platinum-catalyzed silicone rubber. Sylgard 184 may consist of different mixing ratios by weight or volume in various embodiments, such as 10:1, 15:1, or 30:1 (elastomer base: curing agent) of when forming the elastomer. In some embodiments, the Sylgard 184 may have an elasticity modulus of between 1.3-3 MPa. In some embodiments, the Ecoflex may have an elasticity modulus of 0.05-0.125 MPa. The various material properties, such as the elasticity of modulus, can be varied in order to provide a particular targeted treatment.

    [0066] The use of elastomeric materials provides tunable mechanical strength and surface properties to each of the cells 6. The properties of the elastomer (e.g., elastomeric material), such as elastic modulus, may be adjusted to change fluidic resistance and the pressure distribution across different cells 6.

    [0067] In some embodiments, the clastic modulus of an elastomer material, such as Sylgard 184 or Ecoflex, is controlled by a ratio between a monomer and a curing agent. In some embodiments, the composition of the working material, such as a hydrogel, may be selected to further adjust the properties of an elastomer with respect to the geometry of the functional cell pack 100 to affect pressure redistribution within the cell pack 100 when stimulated by force or head movement.

    [0068] In each cell 6, the upper layer 10a, the lower layer 10b, and the perimeter wall 12 shown in FIG. 1 are for illustration only. The shape of cell 6 can be of an irregular shape or of a smooth shape. The upper layer 10a, the lower layer 10b, and the perimeter wall 12 may be in one unitary structure. Or they may be molded in two parts as described herein. One side may be softer than the other side in some embodiments. Both sides may be based on the same polymer chemistry. The harder side may be reinforced with fibers or fillers so that it can have enough rigidity and can be fixed onto an interior surface of the protective headwear.

    [0069] The fluid used may be flowable while also building up a resistance inside the channels. The fluid may have a viscosity in a suitable range, for example, in the range of from 1.810.sup.5 Pa-s to 2 Pa-s.

    [0070] In some embodiments, a Newtonian fluid is used. Examples of a suitable Newtonian fluid include, but are not limited to air, water, glycerin, any combination thereof. For example, a mixture of water and glycerin may be used. The viscosity of air at 20 Celsius is 1.8110-5 Pa-s. The viscosity of water at 20 Celsius being 1.001610-3 Pa-s. The viscosity of glycerin at 20 Celsius is 1.414 Pa-s. A mixture of water and glycerin may have a viscosity between pure water and pure glycerin.

    [0071] Alternatively, a non-Newtonian fluid may be used and its viscosity not only depends on temperature, but also depends on the shear rate of the fluid. Such non-Newtonian fluid can be used for energy-absorbing materials. A suitable non-Newtonian fluid may be a shear-thicknessing fluid. Examples of a suitable non-Newtonian fluid include, but are not limited to, a cornstarch water mixture, a polymer solution, or a combination thereof. The polymer solution may include particles such as silica particles.

    [0072] A cornstarch-water mixture is also called Oobleck, which is a classic shear-thickening fluid that demonstrates remarkable energy absorption properties. For example, 1.6 L of Oobleck can absorb 250 joules of impact energy, protecting delicate materials from fracture. Shear thickening fluids may also be fumed silica particles suspended in polyethylene glycol or ethylene glycol. Shear thickened liquids have some unique energy-absorbing capabilities. These fluids change viscosity under critical shear rates and transition from liquid-like to solid-like properties during violent impacts.

    [0073] D3O fluid, available from D3O lab, is a shear-thickening fluid and is composed of a polymer substance suspended in an oily, liquid lubricant. It is a specialized non-Newtonian fluid designed specifically for energy absorption. It can protect objects from sudden impacts by changing its material properties under stress.

    [0074] For the cell pack structure comprising a plurality of cells as described herein, the pressure drop and flow rate may be calculated or estimated as follows: for laminar flow of an incompressible, Newtonian fluid through a cylindrical pipe, the relationship between the flow rate (Q) and the pressure drop (P) is given by the Hagen-Poiseuille equation:

    [00001] Q = R ? P 8 L ? indicates text missing or illegible when filed [0075] Where: [0076] Q: Volumetric flow rate (m.sup.3/s).Math. [0077] R: Radius of the pipe (m) [0078] P: Pressure drop across the pipe (Pa) [0079] : Dynamic viscosity of the fluid (Pa.Math.s) [0080] L: Length of the pipe (m)

    [0081] As shown in this equation, the change in the length or diameter of the channels connecting different cells, or viscosity of the fluid, will result in differences in the pressure drop. The principle may be used to design a cell pack structure and a resulting protective headwear to meet the needs for pressurization. The fluid used is flowable, but also provides resistance and pressure in the cell pack structure.

    [0082] In the present disclosure, the protective headwear (or headgear) has a unique design.

    [0083] The protective element in existing helmet designs includes inner foam liners for their shock-absorbing properties. Though typical helmets have foam linings that dissipate energy during impacts to the head, hence protecting against internal brain injury, the structural integrity of the foam liners eventually degrades due to fatigue. As those repeatedly endure impact loading cycles, the performance of these foam liners degrades.

    [0084] In the present disclosure, the proposed design, which leverages the dissipative properties of fluids, circumvents this issue. Instead of using foam liners, the design features a set of interconnected, fluid-filled, flexible cells that are strategically placed on the inner surface of a helmet. When a cell happens to be in the way of an incoming blow, the impact powers the discharge of its fluid to the surrounding cells, hence diverting its energy through viscous dissipation. This type of dissipation is called modulated dissipation. While foam linings depend on their deformabilitywhich is diminished by fatigueto retain their protective properties, fluids will always remain viscous and therefore hold onto their ability to dissipate energy by simply flowing. This underlying energy absorption and dissipation mechanism does not hinge on straining a solid structure. The cells may be filled with any fluid out of the examples listed above, depending on the desired viscosity behavior. With several tunable parameters such as fluid choice, connecting channels size and configuration, cell shape, size, and configuration, etc., the design space would be much richer, and therefore likelier to offer a more protective and durable product.

    [0085] The new helmet design provided in the present disclosure incorporates the cell-network technology. A fluid-filled cell pack with tunable design parameters, including fluid choice, connecting channels size and configuration, cell shape, size, and configuration, etc., is embedded into a shell of a helmet. Upon impact, the fluid in the cell network is forced to redistribute to accommodate the sudden imposed relative motion between a wearer's head and the shell. This redistribution process then dissipates the impact energy by virtue of the fluid's viscosity. The design parameters of embedded designs would then be optimized towards tolerable and safe sustained acceleration levels, which constitute the main determinant of the impact aftermath.

    [0086] The fatigue issues associated with the foam liners would be much less of a concern with the new proposed design with cell-pack structures, as the underlying energy absorption and dissipation mechanism does not rely on straining a solid structure. With a larger number of tunable parameters, our design space would be much richer and therefore likelier to offer a more reliable and durable product.

    [0087] In some embodiments, one or more cushioning members may be disposed at different locations inside the shell, depending on the areas for protection needed.

    [0088] In some embodiments, more than one cell of the second type are disposed around each cell of the first type, which is referred as a central cell having a larger size compared to the surrounding cells. For example, each of the plurality of cells has a circular or oval sectional shape, and more than one cell of the second type are disposed concentrically around each central cell of the first type.

    [0089] Referring to FIGS. 2A-2B, an exemplary cell pack structure and a resulting helmet are illustrated. FIG. 2A is a plan view illustrating an exemplary cell pack structure comprising a central cell, a plurality of surrounding cells, and a plurality of connecting channels in accordance with some embodiments. FIG. 2A shows the design of a cell unit 100a comprising one large central cell 6a connected to smaller cells 6b surrounding it. The numbers of the large cell 6a and 6b are shown for illustration only. Each cell structure 100 may include a plurality of large cell 6a and corresponding small cells 6b.

    [0090] FIG. 2B is a sectional view illustrating an exemplary headwear 200 such as a helmet comprising any exemplary cell pack structure 100 as described herein. The helmet 200 includes a shell 210, which includes an exterior layer 202, a middle layer 204, and an interior layer 206. The helmet 200 may include other components such as fixtures 208. The helmet 200 has its inner surface featuring cell pack structures 100 (or called cell units) placed at select spots. Each cell unit can be placed in any part of the helmet that needs protection.

    [0091] The cell pack structures are disposed to protect the weak points of a head or neck. When a concussion occurs, the weak point is typically at the stem (closer to the neck of a human subject), where there is a higher concentration of neurons. The cell pack can be placed in this part closer to the neck. The head is very sensitive to rotational impact, the cell pack can handle shear impact and dissipate energy due to rotational impact, which traditional rigid helmet cannot do. Referring to FIG. 2B, the cell pack structures 100 are placed in a back bottom portion and a back lower bottom portion corresponding to protect the stem closer to a neck and a back of a head of a human subject, respectively. An additional cell pack structure 100 may be disposed on the upper front portion to protect the forehead of a human subject.

    [0092] The cells have any suitable shapes and sizes. In some embodiments, each of the first dimension and the second dimension is a diameter in a range of from about 0.2 cm to about 8 cm. Each of the plurality of channels has a length in a range of from 0.2 cm to 5 cm and a diameter in a range of from 0.2 mm to 8 mm, for example, from 0.3 mm to 0.5 mm or from 0.5 to 3 mm. The cell unit/string dimensions listed below are tentative and subject to adjustments pending further testing.

    [0093] In some embodiments, the central cell is a hemisphere with a diameter of 4 cm. The surrounding cells are hemispheres with a diameter of 1 cm. The connecting channels are of a size of 1.5 cm long and 3 mm in diameter.

    [0094] The cell units can be placed around the front and back of the head, and the temples.

    [0095] FIG. 3A is a plan view illustrating an exemplary cell pack structure 100b comprising a plurality of surrounding cells 6a, 6b in a cell string and connected via a plurality of connecting channels 16 in accordance with some embodiments. FIG. 3B is a sectional view illustrating an exemplary headwear 220 such as a helmet comprising the exemplary cell pack structure of FIG. 3A.

    [0096] Referring to FIGS. 3A-3B, in some embodiments, the first type of cells and the second type of cells are connected in series in a string pattern. The first type of cells and the second type of cells may be in an alternating pattern. FIG. 3A illustrates an alternating arrangement of large cells 6a and small cells 6b. This cell string can be placed in any direction around the inside of the headwear such as a helmet, as illustrated in FIG. 3B. Such a cell string conforms to the inner surface of a shell 210 of the headwear 220 such as a helmet. The exemplary headwear 220 is one example of headwear 200 and may include other components 205.

    [0097] The cells have any suitable shapes and sizes. In some embodiments, each of the first dimension and the second dimension is a diameter in a range of from about 0.2 cm to about 8 cm. Each of the plurality of channels has a length in a range of from 0.2 cm to 5 cm and a diameter in a range of from 0.2 mm to 8 mm, for example, from 0.3 mm to 0.5 mm or from 0.5 to 3 mm. The cell unit/string dimensions listed below are tentative and subject to adjustments pending further testing.

    [0098] In some embodiments, in a cell pack structure with a cell string, the larger cells may be hemisphere with a diameter of 2 cm. The smaller cells may be hemispherical with a diameter of 1 cm. The connecting channels may be of a size of 1.5 cm long and 3 mm in diameter.

    [0099] Depending on the head circumference, which is about 56 cm on average, the total string length could range from 20 cm to 26 cm. Two strings may be placed on the inside of the helmet. One extending between the two temples, and running around the lower back of the head, and another extending from the front to the upper back.

    [0100] An ice pad may not provide the same protection because the flow in it is not sufficiently confined. The proposed design can be fine-tuned to restrict the flow enough to prevent excessive relative motion between the head and the helmet during impact, but not so restricted that adequate energy transfer and dissipation is stymied.

    [0101] FIG. 4 illustrates a side sectional view of an exemplary protective headwear 230 in accordance with some embodiments. The cell structures 100 may be placed to cover the interior surface of the shell 210, and may include a repeated pattern in shape. The protective headwear 230 may also include other components such as face guard 207.

    [0102] FIGS. 5A-5C are schematic views showing exemplary cell pack structures 100c, 100d, and 100e in accordance with some embodiments. In FIGS. 5A-5C, only a portion of a respective cell pack is illustrated, and only a limited number of the cells 6 (or called a basic configuration unit of cells) is illustrated. Additional cells 6 exist in such a portion and throughout the respective cell pack 100. The dimensions are also shown for demonstration only. The cells 6, the channels 16, and the cell structures or the cushion members can be of any suitable size. In FIGS. 5A-5C, the channels 16 are shown in a single line for illustration only. However, each line may represent one or more channels 16.

    [0103] In some embodiments, the plurality of cells 6 including the first type of cells 6a and the second type 6b of cells are disposed and connected with each other in an array, and each cell has a circular or oval sectional shape. Each cell may have a suitable shape such as a flat circle, a sphere, or an ovoid or ellipsoid, or a combination thereof. In FIGS. 5A-5B, each cell has a flat circle shape. For example, as shown in FIG. 5A, each circle has a diameter of 16 mm and a height of 3 mm. The channels 16 have a diameter of 1.5 mm. In FIGS. 5A-5B, the plurality of the cells 6 are illustrated as the same for illustration purpose. In some embodiments, the plurality of cells 6 may include the first type of cells 6a and the second type 6b of cells, which are different. The structures of the cell packs 100c and 100d shown in FIGS. 5A-5B are the same, except that the size of the cells 6 in FIG. 5B is larger than that of the cell pack shown in FIG. 5A. In addition, in some embodiments, all the adjacent cells 6 may be connected with one another. For example, the cells 6 in the second row as illustrated in FIGS. 5A-5B may be connected together through channels 16.

    [0104] Referring to FIG. 5C, in some embodiments, two or more cells 6b the second type are disposed around each cell 6a the first type. For example, each of the plurality of cells 6 is a circular or oval sectional shape. Each cell may have a suitable shape such as a sphere, or an ovoid or ellipsoid, or a combination thereof. As illustrated in FIG. 5C, the cell 6a may have an oval sectional shape, and the cells 6b may have a circular sectional shape.

    [0105] In some embodiments, the first material also has two types including the first type on the first side of the cushion member contacting the interior surface of the shell and the second type on the second side of the cushion member configured to contact a head of a subject or user. The second type of the first material is softer and has lower hardness than that of the first type of the first material. The two types of the first material have the same chemistry but different hardness. In some other embodiments, the cushion member is made of the same first material, while a fiber layer or another reinforcement layer is added on the first side of the cushion member to make the first side harder than the second side of the cushion member. The increased hardness on the first side makes the cushion member comprising cell pack structures to be attached easily onto the helmet and be held in more stably.

    [0106] Further tests on prototypes of different materials, dimensions, and working fluids are needed to pinpoint the combination that best mitigates the risk of leakage.

    [0107] In various embodiments, cell pack 100 may comprise the required shape (round, square, rectangular, etc.), number, distribution, size, and configuration of different cells including larger cells and smaller cells.

    Manufacturing and Materials

    [0108] The cell unit and cell string will be made from stretchy materials such as rubber, latex, plastic, polychloroprene, or silicone elastomers. In some embodiments, the material used is a silicone elastomer, which may be platinum cured silicone.

    [0109] To create a chamber, the upper and lower halves (of the cell unit/string) will be made first and then combined. To manufacture a cell string/unit, the design along with the corresponding inverted molds for upper and lower layers will be specified first. Next, flexible materials (e.g., Ecoflex monomer with curing agent added) will be poured into the molds to form the cured rubber pieces. Two pieces will then be glued together with Ecoflex to form a cell unit/string shell. After the required fluid volume is injected into the cell unit/string shell, Ecoflex fluid will be used again to seal and complete them. Finally, the fabricated product will be attached to the inside surface of the helmet, wherever protection is needed, using Ecoflex as adhesive.

    [0110] In some embodiments, after connecting the cells using channels, the same or different material as the cells may be used to glue the cells and the channels such as silicone tubes. Subsequently, the working fluid will be inserted to complete the fabrication of the cell unit/string.

    [0111] In another aspect, the present disclosure provides a method of making the protective headwear such as a helmet as described herein. Referring to FIGS. 6 and 8, such an exemplary method 600 comprises steps in the method 500 of making the cushioning member.

    [0112] Referring to FIG. 6, an exemplary method of making an exemplary cell pack structure in accordance with some embodiments is illustrated. The method 500 for making the cushioning member may include steps of 502-510.

    [0113] At step 502, upper and lower halves of the plurality of cells are formed.

    [0114] At step 504, upper and lower halves of the plurality of channels are formed.

    [0115] At step 506, the upper and lower halves of the plurality of cells are bonded. The plurality of cells are formed and sealed to define the internal cavities.

    [0116] At step 508, the upper and lower halves of the plurality of channels are bonded. The channels are formed and sealed with internal openings.

    [0117] At step 510, the plurality of the cells and the plurality of channels are attached and sealed to provide the at least one cushioning member.

    [0118] In some embodiments, the plurality of cells and the plurality of channels are made of the same materials and have a unitary structure. The steps 502, 504, and 510 of forming upper and lower halves of the plurality of cells, forming upper and lower halves of the plurality of channels, and attaching the plurality of the cells and the plurality of channels to provide the at least one cushioning member are preformed concurrently in one step such as a molding or 3D printing process.

    [0119] The exemplary method 500 may also include step of introducing the fluid into the cell-pack structure.

    [0120] FIGS. 7A-7C are sectional views of the apparatus and materials illustrating the exemplary method of making an exemplary cell pack structure 100 in accordance with some embodiments. The structures during and after steps 502-510 are illustrated in FIGS. 6A-6C.

    [0121] Referring to FIG. 7A, the molding may begin with a mold 802 that has been appropriately shaped to create the cell pack 100 required. In other words, the size of the internal cavity 8, shape of the cells 6, number and shape of the channels 16 are determined by the mold. Next, the appropriate compounds/materials are put into the mold and cured, as is known in the art, to form one half, i.e., a first half 101 or a second half 102, of the cell pack 100, as shown in FIG. 7B. Once the two halves 101 and 102 of the cell-pack 100 are formed and removed from the mold 802, as shown in FIG. 7C, they may be joined together as described herein.

    [0122] The shapes of the cells 6 in FIG. 7C are for illustration only. The shape of the cells or its halves can be of any suitable shapes as described herein.

    [0123] In some embodiments, the size of each of the cells 6 and/or the connecting channels 16 can be varied. In some embodiments, the diameter of each of the connecting channels 16 may be sized from about 0.3 mm to about 3 mm. The size of the connecting channels 16 may be selected to control flow resistance across the connecting network. In some embodiments, a surface of an elastomer can be modified using an oxygen plasma process to tailor adhesion with the supporting fabrics.

    [0124] In some embodiments, the molding/forming of the cell pack 100 may be an iterative process. For example, portions of the cell pack 100 having common composition may formed at the same time. Once that portion has cured, other portions of the cell pack 100 having different properties or made of different materials may be formed and allowed to cure. Other processes may be used to form the cell pack 100 such that it is made of different materials and/or has varying processes, for example, using 3D printing.

    [0125] In some embodiments, each of the cells 6 and/or the connecting channels 16 may be formed by a 3D printing process. For example, the cells 6 and/or the connecting channels 16 may be formed directly by 3D printing. As another example, a 3D printing mold may be generated using any suitable additive manufacturing process, such as, a QIDI Technology Dual head 3D printer available from QIDI Technology of China.

    [0126] In some embodiments, the cell pack structures are made through 3D printing and is made of silicone.

    [0127] In various embodiments, the dimensions of the cell pack 100 are selected to provide predetermined fluidity, viscosity, and/or applied pressures. The viscosity may be selected to provide a Newtonian or non-Newtonian response. In some embodiments, a non-Newtonian response and resistance to temperature change are provided by a bio-safe hydrogel, or slime. For example, in some embodiments, a working material may include a material having water, polyvinyl alcohol, borax, e.g., Na.sub.2B.sub.4O.sub.7.Math.10H.sub.2O, or any other fluid of suitable viscosity for the desired resistance to flow, e.g., glycerin, lubricating oil, etc. A non-exhaustive range of viscosities includes 0.85-954 mPa-s. The various material properties can be varied to provide a particular targeted treatment through designed fluid flow and distribution of pressures across a cell pack 100. For example, water may have a viscosity of between 0.85-0.95 mPa-s and, e.g., Glycerin 954 mPa-s.

    [0128] In some embodiments, the disclosed material may be formed using a hybrid manufacturing process, including, but not limited to, cast molding, 3D printing and plasma treatment, configured to generate a network of flexible cells filled with a viscous Newtonian or non-Newtonian fluid. The network of flexible cells provides tunable fluid dynamics and responsive material designed to provide a good impact resistance to protect the head of a subject.

    [0129] Referring to FIG. 8, an exemplary method for making the protective headwear further comprises steps of providing the shell (step 604) and attaching the at least one cushioning member onto the interior surface of the shell (step 608). The steps 604 and 608 are additional to the process of making the at least one cushioning member.

    [0130] In some embodiments, the upper halves and the lower halves are made of a same first material while having different hardness. As described herein, in the at least one cushioning member has a first side and a second side. The first side is disposed on the interior surface of the shell. The second side is configured to contact a head of a subject, and the second side has a hardness lower than that of the first side. In some other embodiments, the cushion member is made of the same first material, while a fiber layer or another reinforcement layer is added on the first side of the cushion member to make the first side harder than the second side of the cushion member.

    [0131] To evaluate the effectiveness of each helmet design, the inventors designed a drop test. FIG. 9A is a perspective view illustrating an exemplary model 310 comprising an exemplary protective headwear 200 such as a helmet and a 3D-printed head 300 (or called head model) for testing protective capability in accordance with some embodiments. FIG. 9B is a perspective view illustrating an exemplary testing set-up, in which the exemplary model of FIG. 9A is freely dropped sideway from a certain height. The testing set-up was established in the Cellular Biomechanics and Sports Science Laboratory of Villanova University.

    [0132] The exemplary headwear 200 such as a helmet includes fixture components 205. A head of a live human was 3D scanned then printed to create an exact replica, i.e., the 3D-printed head 300, with capability of rotation. The mounting plate was constructed to be compatible with both the drop tester and the head model. The head 300 was fixed onto a mounting plate 306 though a neck mimics 302. This configuration was used to mimic a head connected with the neck. The size and the weight of the helmet were about 5558 cm and 440 g15 g, respectively. The mounting support plate had a weight of about 2650 g. An accelerator (not shown) was disposed at the interface between a top of the head model 300 and an interior surface of the shell of the helmet. The accelerator is connected with wires connected to an instrument for testing the impact indicated by acceleration during the drop test. The accelerator was used to measure the rotational acceleration of the head model dropped to and hit a floor.

    [0133] Referring to the FIG. 9B, the head model was set up on the drop tester with its front faces in a side way so that its nose is protected during the drop test. The head model was lifted to a height such as 15 cm and then freely dropped. The acceleration due to the impact was tested using the accelerator.

    [0134] FIGS. 10A-10B show exemplary impact results represented by the acceleration experienced by the 3D-printed head inside the exemplary protective headwear without and with the cell pack structures, respectively. The cell pack structures included silicone cells containing pressurized fluid. As shown in FIG. 10A, the peak acceleration for the standard helmet was 903.9 G. As shown in FIG. 10B, the peak acceleration for the helmet provided in the present disclosure was 536.8 G. With the cell pack structures, the peak acceleration was reduced by 40.6%. The result shows that the cell pack structures remarkably increase impact resistance of the headwear. The cell pack structures have the capacity to absorb force of impact.

    [0135] In another aspect, the present disclosure provides a method of using the protective headwear such as a helmet as described herein. Such a method comprises a step of applying the protective headwear onto the head of a subject. The subject is a human subject.

    [0136] The product and the method provided in the present disclosure have many advantages. For example, in addition to comfortability, the product provides superior impact resistance and fatigue resistance and provides good protection to the head of a wearer. In some embodiments, the product provided in the present disclosure is a helmet with enhanced protection, and the helmet is similar in outer appearance to its traditional counterparts. Primarily, the product can be used as protective headgear for professional athletes, including but not limited to, players for football, field hockey, and equestrian events. In addition, the product can also be used as headwear for amateur athletes, including but not limited to, cyclists, motorbike owners/racers, sports car racers, and bike riders such as children. The product is also a helmet for military personnel such as war fighters and factory or construction workers. The product will provide better protection from strong impacts or other forces to avoid accident, and also provide better protection in the event of an accident, hence alleviating the health and economic burdens.

    [0137] Although the subject matter has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments, which may be made by those skilled in the art.