Helmet Integrated with Modulated Dissipation for Enhanced Impact Protection, Method of Making and Method of Using the Same

This application claims the priority of U.S. Provisional Application No. 63/659,157, filed Jun. 12, 2024, which is incorporated herein by reference in its entirety.

The invention was made with government support under 2322067 awarded by the National Science Foundation (NSF). The government has certain rights in the invention.

The disclosure relates to protective headwear generally. More particularly, the disclosed subject matter relates to protective headwear such as a helmet having enhanced impact protection, a method of making and a method of using the same.

Concussive injuries in professional sports are a major concern. It is reported that an estimated 2.8 million people in the U.S. sustain a traumatic brain injury (TBI) annually, among whom 56,000 die, 282,000 are hospitalized, and 2.5 million are treated and released from an emergency department. TBI contributes 30.5% of all injury-related deaths in the US. Other studies estimated that anywhere from 1.6 to 2.8 million TBIs worldwide are caused annually by sports alone. These injuries come at a hefty price. In the US alone, the costs incurred by TBI, including medical expenses and lost productivity, total an estimated $60 billion annually. These figures underscore the need for better performing protective headgear, which is what this invention attempts to meet.

Chronic traumatic encephalopathy (CTE) is a progressive degenerative disease resulting from head trauma and particularly a history of recurrent head trauma. Military personnel may be exposed to blasts and other head impacts, which may lead to the development of CTE. Other environments where people may be subjected to head trauma include the health care industry, and industrial environments such as in a factory or construction site. Athletes participating in contact sports such as football, soccer, rugby and boxing suffer repetitive head trauma that has been shown to lead to the development of CTE in some individuals. CTE may result from symptomatic concussions as well as sub-concussive head trauma. Many athletes may experience frequent sub-concussive head trauma during participation in a contact sport and never have a symptomatic concussion. These athletes may still develop CTE. The effect of these impacts is a growing concern.

CTE may result from repetitive damage to axons in the brain, such as shearing caused by high acceleration of the brain tissue. High acceleration is caused by rapid head velocity change, such as that caused by an impact to the head. Axons connect neurons in the brain. Damage to the axons can result in immediate and/or delayed effects, such as CTE. Brain injury, such as axonal shearing, may create neurochemical and neurometabolic cascade effects. Even mild trauma to the brain can result in neuronal depolarization, which leads to neuronal discharge and the release of neurotransmitters and increased extra cellular potassium (K). This may be followed by an increased glucose demand and metabolism (hyperglycolysis) and a resultant relative ischemia from reduced cerebral blood flow. Axonal injury may also result from an influx of extra cellular calcium that reduces cerebral blood flow through vasoconstriction, and the release of oxygen free radicals. These neurochemical, and neurometabolic effects from even mild head trauma may result in the development of CTE.

Protective headwear such as helmets are used to protect a wearer's head from accidental trauma caused by external forces such as high impact collisions. In addition to military personnel, athletes, and construction workers, recreational and amateur sports players such as bicycle riders also need to wear protective headwear. These helmets are typically made of a hard, durable material designed to deflect and disperse the effects of external forces imparted thereto.

The present disclosure provides protective headwear such as a helmet having enhanced impact protection, a method of making and a method of using the same.

In accordance with some embodiments, the protective headwear comprises a shell and at least one cushioning member. The shell has an exterior surface and an interior surface and is configured to circumferentially accept the head of a subject in need thereof and cover it from the interior surface. The cushioning member(s) is/are disposed on and at least partially cover(s) the interior surface of the shell.

The cushioning member(s) comprise(s) a cell pack structure, which comprises a plurality of cells defining a plurality of internal cavities, a plurality of channels fluidly connecting the cells to form a network, and a fluid disposed within the plurality of internal cavities and the plurality of channels.

In some embodiments, the 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.

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.

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

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

In some embodiments, two or more cells of the second type are disposed around each cell of the first type. For example, each of the plurality of cells has a circular or oval sectional shape, and two or more cells of the second type of cells are disposed concentrically around each of the first type of cells.

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.

In some embodiments, 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.

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 mm to 3 mm.

In some embodiments, the fluid is a Newtonian fluid. In some embodiments, the fluid is a non-Newtonian fluid. For example, the fluid may be a shear-thickening fluid.

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.

In some embodiments, the protective headwear is a helmet.

In another aspect, the present disclosure provides a method of making the protective headwear such as a helmet as described herein. Such a method comprises steps of making the cushioning member. These steps include 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 cells and the plurality of channels to provide the at least one cushioning member. Alternatively, the upper half comprises cell pack structures, and the lower half may not comprise cell pack structures and include a solid substrate only, for example a film.

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 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 cells and the plurality of channels to provide the cushioning member(s) are preformed concurrently in one single process.

The method for making the protective headwear further comprises providing the shell and attaching the at least one cushioning member onto the interior surface of the shell.

In some embodiments, the upper halves and the lower halves are made of a same first material while having different hardness. As described herein, 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.

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.

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.

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.

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.

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.

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.

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.

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.

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 inare described with reference to the exemplary structure described in.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Referring to, an exploded view of a cell in an exemplary cell pack structurein accordance with some embodiments is illustrated.

A cell pack structureincludes a plurality of cells (collectively “cells”) that each defines an internal cavity. The cells may be made of a first material. The cellsinclude an upper layer, a lower layer, and a perimeter wallthat collectively define the internal cavity. In some embodiments, the upper layerand/or the lower layerincludes a material having a first (e.g., higher) elasticity and the perimeter wallincludes a material having a lower (e.g., lower/more rigid) elasticity. In some embodiments, the upper layerand/or the lower layermay be defined by a portion of the material, such as a fabric material, suitable for a material contained therein. In some embodiments, the internal cavityis filled with a working fluid and/or gel. The fluid may be viscous in some embodiments.

In some embodiments, the perimeter wallmay 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.

Each of the cellsis interconnected by one or more connecting channels(collectively “connecting channels” or “channels”). The cells and the connecting channels are fluidly connected. The channels may be fibrous in some embodiments. The connecting channelsmay be formed of the same material (described below) as that of the perimeter wallof each of the cells. In some embodiments, the connecting channels interlink, or knit together, the plurality of cells. When one or more of the cellsare compressed (e.g., squeezed). A pressure build-up may displace the fluid into adjacent cellsthrough the connecting channels. The force displacement/build-up of the working material provides compression and conformity.

Due to the elastic nature of each cell, e.g., the elastic nature of the upper layerand/or the lower layer, the extra working material that is received in each of the cellswill 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 cellspushes the extra working fluid back into a central, depressurized cell(or a larger cell), restoring initial equilibrium.

In some embodiments, the flow throughout the entire material, e.g., throughout the entire network of cell packs, may be simulated using computational fluid dynamics and/or as a first order approximation treating the network of cell packsas a hemodynamic circuit where cellsact as capacitors, and the connecting channelsas resistors.

In some embodiments, each cell packmay 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.