Patent Description:
Bacteria that exist in health care settings differ significantly from bacteria found in a general community setting, primarily in their resistance to antibiotic therapy. In many ways, the hospital environment contributes to the problem by harboring virulent strains of bacteria, fungi, and viruses. This is at least partly a result of the fact that many conventional disinfection methods are ineffective and may actually spread contaminants. Additionally, when subjected to the methods of disinfection on a regular basis, bacteria develop resistance to the methods over time. These contaminants are present on objects, and in particular, medical devices in the hospital setting. For medical devices that cannot be disposed of after a single use, the devices must be disinfected between uses. Additionally, some medical devices which are placed partially inside the body and partially outside the body for an extended period of time are at an increased risk of infection.

Examples of such medical devices are flexible and rigid endoscopes. Some systems for cleaning such endoscopes are configured to allow the endoscope to be housed in a processing tank to be cleaned and disinfected with the use of liquid detergent and disinfectant solution. However, endoscopes may have a plurality of interior channels or lumens that are difficult to reach and disinfect. Such channels are used to inject liquid irrigants, suction, and to pass flexible surgical instruments such as biopsy forceps.

Some mechanical aids have been developed for use in cleaning the interior channels or lumens of an endoscope. For example, brush devices that fit into interior channels or lumens are equipped with bristles that project from a central shaft to provide mechanical abrasion to the surfaces of the interior channels or lumens of an endoscope. Also, sponge devices that fit into interior channels or lumens spread contamination into a substantially uniform film on the surfaces of the interior channels or lumens of an endoscope so that enzymatic cleaners can more efficiently and uniformly digest the contaminating material. However, the bristles of the brush devices do not provide uniform contact with the surfaces of the interior channels or lumens of an endoscope, and the sponge devices merely spread contaminants and are not configured to provide the mechanical force needed to remove contaminants adhering to surfaces of the interior channels or lumens of an endoscope. <CIT> is directed to UV radiation systems for medical device infection control. <CIT> is directed to UV sterilization of instruments lumens. <CIT> relates to optical fiber illumination systems and methods.

The present invention relates to a medical device. The medical device includes at least one interior channel and at least one cylindrical optical diffuser disposed in optical communication with the least one interior channel, the at least one cylindrical optical diffuser having an outer surface and an end optically coupled to a light source that generates light having at least one wavelength between <NUM> and <NUM>. The at least one cylindrical optical diffuser is configured to scatter guided light through the outer surface to form a light diffuser portion having a length that emits substantially uniform radiation over its length, and has a scattering-induced attenuation greater than <NUM> dB/km. The at least one cylindrical optical diffuser comprises a light diffusing optical fiber having a core, a primary cladding, and a plurality of nano-sized structures. The guided light is scattered through the outer surface via the nano-sized structures away from the core, and said nano-sized structures situated in the core are gas filled voids containing at least one of: SO<NUM>, Kr, Ar, CO<NUM>, N<NUM>, O<NUM>, or mixture thereof.

The present invention further relates to a disinfection method. The method includes inserting at least a portion of at least one cylindrical optical diffuser into an interior channel of a medical device and introducing light having at least one wavelength between <NUM> and <NUM> from a light source into an end of the at least one cylindrical optical diffuser optically coupled to the light source and emitting the light through the outer surface of the diffuser to illuminate a portion of the diffuser and to expose the interior channel to the emitted light. The at least one cylindrical optical diffuser is configured to scatter guided light through the outer surface to form a light diffuser portion having a length that emits substantially uniform radiation over its length, and to disinfect at least one surface of the interior channel. The at least one cylindrical optical diffuser comprises a light diffusing optical fiber having a core, a primary cladding, and a plurality of nano-sized structures. The guided light is scattered through the outer surface via the nano-sized structures away from the core, and said nano-sized structures situated in the core are gas filled voids containing at least one of: SO<NUM>, Kr, Ar, CO<NUM>, N<NUM>, O<NUM>, or mixture thereof. The light diffusing optical fiber has a scattering-induced attenuation greater than <NUM> dB/km.

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments.

The disclosure will be understood more clearly from the following description and from the accompanying figures, given purely by way of non-limiting example, in which:.

Reference will now be made in detail to the present embodiment(s), an example(s) of which is/are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

The singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. The endpoints of all ranges reciting the same characteristic are independently combinable and inclusive of the recited endpoint.

Embodiments of the present disclosure relate to medical devices, and disinfection methods. Embodiments of the present disclosure include at least one cylindrical optical diffuser that may transmit ultraviolet irradiation, or short wavelength visible light. As used herein, a cylindrical optical diffuser refers to a diffuser that emits light through its outer surface when light is introduced into the diffuser as guided light. While some of the embodiments included herein describe "at least one cylindrical optical diffuser", it should be understood that embodiments including a plurality of cylindrical optical diffusers are also comprehended. As used herein, the term "ultraviolet" (UV) light is used for a wavelength of light being less than about <NUM>, and the term "short wavelength visible light" is used for a wavelength of light being between about <NUM> and about <NUM>. Ultraviolet light, particularly in the C bandwidth, when given in adequate doses is lethal to all known pathogens. As used herein, the term "ultraviolet light in the C bandwidth" (UV-C) is used for a wavelength of light being utilized for its germicidal properties, the wavelength being between about <NUM> and about <NUM>. Additionally, recent studies have shown that short wavelength visible light, such as violet and blue light, is also lethal to bacteria, fungi, and viruses at certain doses. Such short wavelength visible light may be, for example, between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>.

The cylindrical optical diffuser may be, for example, a side-emitting fiber, or a bundle of two or more side-emitting fibers. Side-emitting fibers can be, for example, a single plastic or glass core without any cladding or coating in which light sent into the core is lost through the side surfaces of the fiber because the light is not trapped or internally guided. Side-emitting fiber may include scattering defects introduced into the fiber at various locations, such as by doping the core of the fiber with small refractive and/or reflective light-scattering particles, or by modifying a surface of the core to have surface features that scatter light out of the core. Examples of light-emitting surface defects include serrations, notches, scratches, texture, roughness, corrugations, etching, abrasion, etc. Alternatively, the cylindrical optical diffuser may be a light diffusing optical fiber. As used herein, the term "light diffusing optical fiber" refers to a flexible optical waveguide configured to diffuse light out of the sides of the fiber, such that light is guided away from the core of the waveguide and through the outer surfaces of the waveguide to provide illumination.

Concepts relevant to the underlying principles of the claimed subject matter are disclosed in U. Patent Application Publication No. <CIT>. As described in greater detail below, exemplary light diffusing optical fiber includes a core, a primary cladding, and a plurality of nano-sized structures situated within the core or at a core-cladding boundary. The optical fiber further includes an outer surface, and an end configured to optically couple to a light source. The light diffusing optical fiber is configured to scatter guided light via the nano-sized structures away from the core and through the outer surface, to form a light-source fiber portion having a length that emits substantially uniform radiation over its length.

The term "light source" refers to a laser, light emitting diode or other component capable of emitting electromagnetic radiation that is either in the UV light range of wavelengths or is of a wavelength that can interact with a luminophore to emit light in the UV light range of wavelengths.

The term "luminophore" refers to an atom or chemical compound that manifests luminescence, and includes a variety of fluorophores and phosphors.

The following terms and phrases are used in connection with light diffusing fibers having nano-sized structures.

The "refractive index profile" is the relationship between the refractive index or the relative refractive index and the waveguide (fiber) radius.

The "relative refractive index percent" is defined as <MAT> where n(r) is the refractive index at radius r, unless otherwise specified. The relative refractive index percent is defined at <NUM> unless otherwise specified. In one aspect, the reference index nREF is silica glass with a refractive index of <NUM> at <NUM>, in another aspect it is the maximum refractive index of the cladding glass at <NUM>. As used herein, the relative refractive index is represented by Δ and its values are given in units of"%", unless otherwise specified. In cases where the refractive index of a region is less than the reference index nREF, the relative index percent is negative and is referred to as having a depressed region or depressed-index, and the minimum relative refractive index is calculated at the point at which the relative index is most negative unless otherwise specified. In cases where the refractive index of a region is greater than the reference index nREF, the relative index percent is positive and the region can be said to be raised or to have a positive index.

An "updopant" is herein considered to be a dopant which has a propensity to raise the refractive index relative to pure undoped SiO<NUM>. A "downdopant" is herein considered to be a dopant which has a propensity to lower the refractive index relative to pure undoped SiO<NUM>. An updopant may be present in a region of an optical fiber having a negative relative refractive index when accompanied by one or more other dopants which are not updopants. Likewise, one or more other dopants which are not updopants may be present in a region of an optical fiber having a positive relative refractive index. A downdopant may be present in a region of an optical fiber having a positive relative refractive index when accompanied by one or more other dopants which are not downdopants.

Likewise, one or more other dopants which are not downdopants may be present in a region of an optical fiber having a negative relative refractive index.

The term "a-profile" or "alpha profile" refers to a relative refractive index profile, expressed in terms of Δ(r) which is in units of "%", where r is radius, which follows the equation, <MAT> where ro is the point at which Δ(r) is maximum, r<NUM> is the point at which Δ(r)% is zero, and r is in the range r<NUM> ≤ r ≤ rf, where Δ is defined above, r<NUM> is the initial point of the a-profile, rf is the is final point of the a-profile, and α is an exponent which is a real number.

As used herein, the term "parabolic" therefore includes substantially parabolically shaped refractive index profiles which may vary slightly from an α value of <NUM> at one or more points in the core, as well as profiles with minor variations and/or a centerline dip. In some exemplary embodiments, α is greater than <NUM> and less than <NUM>, more preferably greater than <NUM> and less than <NUM> and even more preferably between <NUM> and <NUM> as measured at <NUM>. In other embodiments, one or more segments of the refractive index profile have a substantially step index shape with an α value greater than <NUM>, more preferably greater than <NUM> even more preferably greater than <NUM> as measured at <NUM>.

The term "nano-structured fiber region" describes a fiber having a region or area with a large number of gas filled voids, or other nano-sized structures. The region or area may have, for example, more than <NUM> voids, or more than <NUM> voids, or even more than <NUM> voids in the cross-section of the fiber. The gas filled voids contain at least one of SO<NUM>, Kr, Ar, CO<NUM>, N<NUM>, O<NUM>, or mixture thereof. The cross-sectional size (e.g., diameter) of nano-sized structures (e.g., voids) as described herein may vary from about <NUM> to about <NUM> (for example, from about <NUM> to about <NUM>), and the length may vary from about <NUM> millimeter to about <NUM> meters (for example, from about <NUM> to about <NUM> meters, or from about <NUM> to about <NUM> meters).

In standard single mode or multimode optical fibers, the losses at wavelengths less than <NUM> are dominated by Rayleigh scattering. These Rayleigh scattering losses Ls are determined by the properties of the material and are typically about <NUM> dB/km for visible wavelengths (<NUM>-<NUM>). Rayleigh scattering losses also have a strong wavelength dependence (i.e., LS oc <NUM>/λ,<NUM>,see <FIG>, comparative fiber A), which means that at least about <NUM> to about <NUM> of the fiber is needed to dissipate more than <NUM>% of the input light. Shorter lengths of such fiber would result in lower illumination efficiency, while using long lengths (about <NUM> to about <NUM>, or more) can be more costly and can be difficult to manage.

In certain configurations of lighting applications it is desirable to use shorter lengths of fiber, for example, having a length of about <NUM> meters to about <NUM> meters. This requires an increase of scattering loss from the fiber, while being able to maintain good angular scattering properties (uniform dissipation of light away from the axis of the fiber) and good bending performance to avoid bright spots at fiber bends. A desirable attribute of at least some of the embodiments described herein is uniform and high illumination along the length of the fiber illuminator. Because the optical fiber is flexible, it allows a wide variety of the illumination shapes to be deployed. It is preferable to have no bright spots (due to elevated bend losses) at the bending points of the fiber, such that the illumination provided by the fiber does not vary by more than about <NUM>%, preferably by less than about <NUM>% and more preferably by less than about <NUM>%. The average scattering loss of the fiber is greater than about <NUM> dB/km, and the scattering loss does not vary more than about <NUM>% (i.e., the scattering loss is within ±<NUM>% of the average scattering loss) over any given fiber segment having a length of about <NUM> meters. The average scattering loss of the fiber is greater than about <NUM> dB/km with the scattering loss varying by less than about <NUM>% over fiber segments of having a length of less than about <NUM> meters. The average scattering loss of the fiber is greater than about <NUM> dB/km with the scattering loss varying by less than about <NUM>% over fiber segments having a length of about <NUM> meters. The average scattering loss of the fiber is greater than about <NUM> dB/km with the scattering loss varying by less than about <NUM>%, and preferably by less than about <NUM>% over fiber segments having a length of about <NUM> meters.

According to embodiments of the present disclosure, the intensity variation of the integrated light intensity diffused through sides of the fiber at the illumination wavelength is less than about <NUM>% for the target length of the fiber, which can be, for example, between about <NUM> meters to about <NUM> meters. The integrated light intensity diffused through sides of the fiber at a specified illumination wavelength can be varied by incorporating fluorescent material in the cladding or coating. The wavelength of the light scattering by the fluorescent material is different from the wavelength of the light propagating in the fiber.

Fiber designs described herein include a nano-structured fiber region (region with nano-sized structures) placed in the core area of the fiber, or very close to the core. The fiber have scattering losses in excess of about <NUM> dB/km, for example, greater than about <NUM> dB/km, greater than about <NUM> dB/km, greater than about <NUM> dB/km, greater than about <NUM> dB/km, greater than about <NUM> dB/km, or even greater than about <NUM> dB/km. The scattering loss, and thus illumination, or light radiated by the fiber, is uniform in angular space.

In order to reduce or to eliminate bright spots as bends in the fiber, it is desirable that the increase in attenuation at a <NUM>° bend in the fiber is less than about <NUM> dB/turn, for example, less than about <NUM> dB/turn, less than about <NUM> dB/turn, or even less than about <NUM> dB/turn when the bend diameter is less than about <NUM>. In exemplary embodiments, these low bend losses are achieved at even smaller bend diameters, for example, less than about <NUM>, less than about <NUM>, or even less than about <NUM>. The total increase in attenuation may be less than about <NUM> dB per <NUM> degree turn at a bend radius of about <NUM>.

The bending loss is equal to or is less than the intrinsic scattering loss from the core of the straight fiber. The intrinsic scattering is predominantly due to scattering from the nano-sized structures. Thus, according to at least the bend insensitive embodiments of optical fiber, the bend loss does not exceed the intrinsic scattering of the fiber. However, because scattering level is a function of bending diameter, the bending deployment of the fiber depends on its scattering level. For example, the fiber may have a bend loss of less than about <NUM> dB/turn, or even less than about <NUM> dB/turn, and the fiber can be bent in an arc with a radius as small as about <NUM> without forming bright spots.

According to the invention, the light diffusing fiber <NUM> includes a core at least partially filled with nanostructures for scattering light, a cladding surrounding the core, and may optionally include at least one coating surrounding the cladding. For example, the core and cladding may be surrounded by primary and secondary coating layers, and/or by an ink layer. In some embodiments, the ink layer contains pigments to provide additional absorption and modify the spectrum of the light scattered by the fiber (e.g., to provide additional color(s) to the diffused light). In other embodiments, one or more of the coating layers comprises molecules which convert the wavelength of the light propagating through the fiber core such that the light emanating from the fiber coating (light diffused by the fiber) is at a different wavelength. In some embodiments, the ink layer and/or the coating layer may comprise phosphor in order to convert the scattered light from the core into light of differing wavelength(s). In some embodiments, the phosphor and/or pigments are dispersed in the primary coating. In some embodiments the pigments are dispersed in the secondary coating, in some embodiments the pigments are dispersed in the primary and secondary coatings. In some embodiments, the phosphor and/or pigments are dispersed in the polymeric cladding. Preferably, the nanostructures are SO<NUM> filled voids.

According to some embodiments, the optical fiber <NUM> includes a primary coating, an optional secondary coating surrounding the primary coating and/or an ink layer (for example located directly on the cladding, or on one of the coatings. The primary and/or the secondary coating may include at least one of: pigment, phosphors, fluorescent material, hydrophilic material, light modifying material, or a combination thereof.

According to some embodiments, a light diffusing optical fiber includes: (<NUM>) a glass core, a cladding, and a plurality of nano-sized structures situated within said core or at a core-cladding boundary, the optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized structures away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than <NUM> dB/km at illumination wavelength; and (<NUM>) one or more coatings, such that either the cladding or at least one coating includes phosphor or pigments. According to some embodiments, these pigments may be capable of altering the wavelength of the light such that the illumination (diffused light) provided by the outer surface of the fiber is of a different wavelength from that of the light propagating through fiber core. Preferably, the nanostructures are SO<NUM> filled with voids.

According to some embodiments, a light diffusing optical fiber includes: a glass core, a cladding, and a plurality of nano-sized structures situated within said core or at a core-cladding boundary. The optical fiber further includes an outer surface and is configured to (i) scatter guided light via said nano-sized structures away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than <NUM> dB/km at illumination wavelength; wherein the entire core includes nano-sized structures. Such fiber may optionally include at least one coating, such that either the cladding or at least one coating includes phosphor or pigments. According to some embodiments the nanostructures are SO<NUM> filled voids.

According to some embodiments, a light diffusing optical fiber includes: a glass core, and a plurality of nano-sized structures situated within said core such that the entire core includes nano-structures, the optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized structures away from the core and through the outer surface, (ii) have a scattering-induced attenuation greater than <NUM> dB/km at illumination wavelength, wherein the fiber does not include cladding. According to some embodiments, the nanostructures are SO<NUM> filled voids. The SO<NUM> filled voids in the nano-structured area greatly contribute to scattering (improve scattering).

According to some embodiments, a light diffusing optical fiber includes: a glass core, and a plurality of nano-sized structures situated within said core such that the entire core includes nano-structures, said optical fiber further including an outer surface and is configured to (i) scatter guided light via said nano-sized structures away from the core andthrough the outer surface, (ii) have a scattering-induced attenuation greater than <NUM> dB/km at illumination wavelength wherein said fiber does not include cladding. According to some embodiments, the fiber optionally includes at least one coating such that either the cladding or the coating includes phosphor or pigments. According to some embodiments, the nanostructures are SO<NUM> filled voids. As stated above, the SO<NUM> filled voids in the nano-structured area greatly contribute to scattering (improve scattering).

<FIG> is a schematic side view of a section of a light diffusing fiber with a plurality of voids in the core of the light diffusing optical fiber <NUM> having a central axis, or centerline <NUM>. <FIG> is a schematic cross-section of light diffusing optical fiber <NUM> as viewed along the direction <NUM>-<NUM> in <FIG>. Light diffusing optical fiber <NUM> can be, for example, any one of the various types of optical fiber with a nano-structured fiber region having periodic or non-periodic nano-sized structures <NUM>. As an example, fiber <NUM> includes a core <NUM> divided into three sections or regions. The sections or regions include a solid central region <NUM>, a nano-structured ring portion <NUM>, and an outer, solid portion <NUM> surrounding the nano-structured ring portion <NUM>. A cladding <NUM> surrounds the core <NUM> and has an outer surface. The cladding <NUM> can be, for example, a low index polymer such as UV or thermally curable fluoroacrylate or silicone. The cladding <NUM> may include pure low index polymer. Additionally, the cladding <NUM> may also include pure or F-doped silica. The cladding <NUM> may have low refractive index to provide a high numerical aperture (NA). The NA of fiber <NUM> may be equal to, or greater than, the NA of a light source directing light into the fiber <NUM>. According to embodiments of the present disclosure, the NA of fiber <NUM> may be greater than about <NUM>, greater than about <NUM>, or even greater than about <NUM>.

According to exemplary embodiments, the nano-structured ring portion <NUM> of light diffusing fiber <NUM> comprises a glass matrix <NUM> with a plurality of non-periodically disposed nano-sized structures <NUM> situated therein, such as the example voids shown in detail in the magnified inset of <FIG>. The voids may be periodically disposed, such as in a photonic crystal optical fiber, wherein the voids typically have diameters between about <NUM> × <NUM>-<NUM> m and about <NUM> × <NUM>-<NUM> m. The diameters of the voids may be at least about <NUM>. The voids may also be non-periodically or randomly disposed. The glass matrix <NUM> in nano-structured ring portion <NUM> may be for example, but without limitation, a fluorine-doped silica or an undoped pure silica.

The nano-sized structures <NUM> scatter the light away from the core <NUM> and toward the outer surface of the fiber. The scattered light is then diffused through the outer surface of the fiber <NUM> to provide illumination. That is, most of the light is diffused via scattering through the sides of the fiber <NUM> along the fiber length. According to embodiments of the present disclosure, the fiber emits substantially uniform radiation over its length, and the fiber has a scattering-induced attenuation of greater than about <NUM> dB/km in the illumination wavelength. The scattering-induced attenuation may be greater than about <NUM> dB/km, greater than about <NUM> dB/km, greater than about <NUM> dB/km, greater than about <NUM> dB/km, or even greater than about <NUM> dB/km in the illumination wavelength. Such scattering losses are about <NUM> to about <NUM> times greater than the Rayleigh scattering losses in standard single mode and multimode optical fibers. The amount of the loss via scattering can be increased by changing the properties of the fiber <NUM>, the width of the nano-structured region <NUM>, and the size and the density of the nano-sized structures <NUM>.

In some embodiments, nano-structured region <NUM> includes pure silica including a plurality of nano-sized structures <NUM>. The minimum relative refractive index and the average effective relative refractive index of nano-structured region <NUM>, taking into account the presence of any voids, may both be less than about -<NUM>%. The nano-sized structures <NUM>, or voids, may contain one or more gases, such as argon, nitrogen, oxygen, krypton, or SO<NUM> or can contain a vacuum with substantially no gas. However, regardless of the presence or absence of any gas, the average refractive index in nano-structured region <NUM> is lowered due to the presence of nano-sized structures <NUM>. Nano-sized structures <NUM> can be randomly or non-periodically disposed in the nano-structured region <NUM>. Alternatively, nano-sized structures <NUM> may be disposed periodically in the nano-structured region <NUM>.

According to exemplary embodiments, solid central region <NUM> may include germania doped silica, core inner annular region <NUM> may include pure silica, and the cladding <NUM> may include a glass or a low index polymer. The nano-structured region <NUM> may include a plurality of nano-sized structures <NUM> in pure silica, or, alternatively, nano-structured region <NUM> may include a plurality of nano-sized structures <NUM> in fluorine-doped silica. According to other exemplary embodiments, the entire core <NUM> may be nano-structured (filled with voids, for example), with the core <NUM> being surrounded by the cladding <NUM>. The core <NUM> may have a "step" refractive index delta, or may have a graded core profile, with a-profile having, for example, α -value between about <NUM> and about <NUM>.

Glass in solid central region <NUM> and core inner annular region <NUM> may include updopants, such as Ge, Al, Ti, P and combinations thereof. By "non-periodically disposed" or "non-periodic distribution," it is meant that when one takes a cross-section of the optical fiber, such as shown in <FIG>, the nano-sized structures <NUM> are randomly or non-periodically distributed across a portion of the fiber. As an example, where the nano-sized structures <NUM> include voids, similar cross-sections taken at different points along the length of the fiber will reveal different cross-sectional void patterns, i.e., various cross-sections will have different voids patterns, wherein the distributions of voids and sizes of voids do not match. That is, the voids are non-periodic, i.e., they are not periodically disposed within the fiber structure. These voids are stretched (elongated) along the length (i.e. parallel to the longitudinal axis) of the optical fiber, but do not extend the entire length of the entire fiber for typical lengths of transmission fiber. The voids may extend less than about <NUM> meters, and in many cases less than about <NUM> meter along the length of the fiber <NUM>.

As described above, solid central region <NUM> and core inner annular region <NUM> may include silica doped with germanium, i.e., germania-doped silica. Dopants other than germanium, singly or in combination, may be employed within the core, and particularly at or near the centerline <NUM>, of the optical fiber <NUM> to obtain the desired refractive index and density. The relative refractive index profile of the optical fiber <NUM> disclosed herein is non-negative in core sections solid central region <NUM> and core inner annular region <NUM>. The optical fiber may contain no index-decreasing dopants in the core. Additionally, the relative refractive index profile of the optical fiber <NUM> may be non-negative in solid central region <NUM>, nano-structured ring portion <NUM> and/or core inner annular region <NUM>.

The fiber <NUM> optionally includes a coating <NUM> surrounding the cladding <NUM>. Coating <NUM> may include a low modulus primary coating layer and a high modulus secondary coating layer. The coating <NUM> may be a polymer coating such as an acrylate-based or silicone based polymer. The coating may have a constant diameter along the length of the fiber. The coating <NUM> may be designed to enhance the distribution and/or the nature of light that passes from core <NUM> through cladding <NUM>. The outer surface of the cladding <NUM> or the outer surface or the optional coating <NUM> represents the sides <NUM> of fiber <NUM> through which light traveling in the fiber exits via scattering, as described herein. The coating <NUM> may be a resin that transmits UV light. For example, the resin that transmits UV light may be, but is not limited to, resins having structutes of: tripropylene glycol diacrylate (TPGDA), polyester tetraacrylate, polyester hexaacrylate, aliphatic urethane diacrylate + hexanediol diacrylate, polyether tetraacrylate, silicone diacrylate, silicone hexaacrylate, epoxydiacrylate based on bisphenol A, and epoxydiacrylate based on bisphenol A + <NUM>% TPGDA.

According to embodiments of the present disclosure, core <NUM> may be a graded-index core, and may have a refractive index profile having a parabolic (or substantially parabolic) shape. For example, the refractive index profile of core <NUM> may have an α-shape with an α value of about <NUM> as measured at <NUM>. The α value may be between about <NUM> and about <NUM>. According to other exemplary embodiments, one or more segments of the refractive index profile may have a substantially step index shape with an α value greater than about <NUM>, or greater than about <NUM>, or even greater than about <NUM>, as measured at <NUM>. The refractive index of the core may have a centerline dip, wherein the maximum refractive index of the core <NUM>, and the maximum refractive index of the entire optical fiber <NUM>, is located a small distance away from centerline <NUM>. Alternatively, the refractive index of the core <NUM> has no centerline dip, and the maximum refractive index of the core <NUM>, and the maximum refractive index of the entire optical fiber <NUM>, is located at the centerline. According to exemplary embodiments, the refractive index of fiber <NUM> may have radial symmetry.

According to embodiments of the present disclosure, fiber <NUM> has a silica-based core <NUM> and depressed index (relative to silica) polymer cladding <NUM>. The low index polymer cladding <NUM> may have a relative refractive index that is negative. For example, the relative refractive index of the low index polymer cladding <NUM> may be less than about -<NUM>%, or even less than about -<NUM>%. The cladding <NUM> may have a thickness of greater than about <NUM>, and the outer diameter of the cladding <NUM> may have a constant diameter along the length of fiber <NUM>. The cladding <NUM> may have a lower refractive index than the core <NUM>, and a thickness of greater than about <NUM>. The cladding <NUM> may have an outer diameter of <NUM>×Rmax. For example, the cladding <NUM> may have an outer diameter of about <NUM>, such as between about <NUM> and <NUM>, or between about <NUM> and about <NUM>. Alternatively, the cladding <NUM> may have a diameter that is less than about <NUM>, such as between about <NUM> and about <NUM>.

The outer diameter 2R3 of core <NUM> may be constant along the length of the fiber <NUM>. Additionally, the outer diameters of solid central region <NUM>, nano-structured ring portion <NUM> and core inner annular region <NUM> may also be constant along the length of the fiber <NUM>. By constant, it is meant that the variations in the diameter with respect to the mean value are, for example, less than about <NUM>%, or less than about <NUM>%, or even less than about <NUM>%.

The outer radius Rc of core <NUM> may be greater than about <NUM> and less than about <NUM>, for example, between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>. The outer radius Rc of core <NUM> may be between about <NUM> and about <NUM>. As shown in <FIG>, the outer radius Rc of core <NUM> is equal to the outer radius R<NUM> of core inner annular region <NUM>.

The solid central region <NUM> may have a radius R<NUM> such that <NUM>. 1Rc<R<NUM><<NUM> Rc, or such that <NUM>. 5Rc≤ R<NUM>≤<NUM>. R<NUM> may be between about <NUM> and about <NUM> such that the diameter of the solid central region <NUM> is between about <NUM> and <NUM>. For example, R<NUM> may be greater than about <NUM>, greater than about <NUM>, or even greater than about <NUM>. The nano-structured ring region <NUM> may have a width W<NUM> such that <NUM>. 05Rc<W<NUM><<NUM>. 9Rc, or such that <NUM>. 1Rc≤W<NUM>≤<NUM>. Additionally, width W<NUM> may be <NUM>. 5Rc≤W<NUM>≤<NUM>. According to embodiments of the present disclosure, a wider nano-structured region <NUM> provides a higher scattering-induced attenuation for the same density of nano-sized structures <NUM>. The radial width W<NUM> of nano-structured region <NUM> may be greater than about <NUM>. For example, W<NUM> may be between about <NUM> and about <NUM>, such as less than about <NUM>. W<NUM> may also be, for example, between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, between at least <NUM> and about <NUM>, or even between about <NUM> and about <NUM>. W<NUM> may be, for example, at least about <NUM>. The core inner annular region <NUM> may have a width W<NUM> such that W<NUM>=R<NUM>-R<NUM> and has a midpoint R3MID=(R<NUM>+R<NUM>)/<NUM>. The core inner annular region <NUM> may have a width W<NUM> such that <NUM>. 1Rc>W<NUM>><NUM>. For example, W<NUM> may be between about <NUM> and about <NUM>. Additionally, the cladding <NUM> has a radius R<NUM>, which is also the outermost periphery of the optical fiber <NUM>. The width of the cladding <NUM>, which is equal to R<NUM>-R<NUM>, may be, for example, greater than about <NUM>, or greater than about <NUM>, or even greater than about <NUM>.

<FIG> is a plot of the exemplary relative refractive index Δ versus fiber radius for an example fiber <NUM> shown in <FIG> (solid line). The core <NUM> may also have a graded core profile, with a-profile having, for example, α-value between about <NUM> and about <NUM> (e.g., about <NUM> to about <NUM>). Solid central region <NUM> extends radially outwardly from the centerline to its outer radius, R<NUM>, and has a relative refractive index profile Δ<NUM>(r) corresponding to a maximum refractive index n<NUM> (and relative refractive index percent Δ1MAX). According to the embodiment of <FIG>, the reference index nREF is the refractive index at the cladding. The nano-structured region <NUM> has minimum refractive index n<NUM>, a relative refractive index profile Δ<NUM>(r), a maximum relative refractive index Δ2MAX, and a minimum relative refractive index Δ<NUM>, wherein some embodiments Δ2MAX = Δ<NUM>. The core inner annular region <NUM> has a maximum refractive index n<NUM>, a relative refractive index profile Δ<NUM>(r) with a maximum relative refractive index Δ3MAX and a minimum relative refractive index Δ<NUM>, wherein some embodiments Δ3MAX = Δ<NUM>. As further shown in <FIG>, the cladding <NUM> has a refractive index n<NUM>, a relative refractive index profile Δ<NUM>(r) with a maximum relative refractive index Δ4MAX and a minimum relative refractive index Δ<NUM>. In some embodiments, Δ4MAX = Δ<NUM>. In some embodiments, Δ1MAX > Δ4MAX and Δ3MAX > Δ4MAX. In some embodiments Δ<NUM> > Δ4MAX. In the embodiment shown in <FIG>, Δ1MAX > Δ3MAX > Δ2MAX > Δ4MAX, and the refractive indices of the regions have the following relationship n<NUM>>n<NUM>>n<NUM>>n<NUM>.

Solid central region <NUM> and core inner annular region <NUM> may have a substantially constant refractive index profile, as shown in <FIG> with a constant Δ<NUM>(r) and Δ<NUM>(r). In addition, Δ<NUM>(r) may be either slightly positive (<NUM>< Δ<NUM>(r) <<NUM>%), negative (-<NUM>% < Δ<NUM>(r) <<NUM>), or substantially constant. The absolute magnitude of Δ<NUM>(r) may be less than about <NUM>%, for example, less than about <NUM>%. According to embodiments of the present disclosure, absolute magnitude of Δ<NUM>(r) may be less than about <NUM>%, or even less than about <NUM>%, for more than about <NUM>% of the radial width of the nano-structured ring portion <NUM>. The cladding <NUM> may have a substantially constant refractive index profile, as shown in <FIG> with a constant Δ<NUM>(r), where Δ4(r) = <NUM>%. In some embodiments the cladding <NUM> may have a refractive index-<NUM>%<Δ<NUM>(r) <<NUM>%. The solid central region <NUM> may have a refractive index where Δ<NUM>(r) ><NUM>%. Additionally, nano-structured ring portion <NUM> may have a relative refractive index profile Δ2(r) having a negative refractive index with absolute magnitude less than about <NUM>%, and Δ<NUM>(r) of core inner annular region <NUM> may be, for example, positive or zero. In at least some embodiments, n<NUM>>n<NUM> and n<NUM>>n<NUM>.

<FIG> schematically illustrates an exemplary light diffusing fiber <NUM>. As shown, the fiber <NUM> includes a core <NUM> with a relative refractive index Δ<NUM> and a nano-structured region <NUM>' situated over and surrounding the core <NUM>. The core <NUM> may have a step index profile, or a graded core profile, with a-profile having, for example, α-value between about <NUM> and about <NUM>. The nano-structured region <NUM>' is an annular ring with a plurality of voids. The width of nano-structured region <NUM>' may be as small as about <NUM> to about <NUM>, and may have a negative average relative refractive index Δ<NUM>. The cladding <NUM> surrounds the nano-structured region <NUM>', the cladding <NUM> having a width that may be as small as about <NUM>. The cladding <NUM> may have a negative, a positive or a substantially constant relative refractive index. The main difference between the examples shown in <FIG> is that nano-structured region <NUM> shown in <FIG> is located in the core <NUM> of the light diffusing fiber <NUM>, and nano-structured region <NUM>' shown in <FIG> is located at the interface of the core <NUM> and the cladding <NUM>. In the direction moving radially outwardly from the centerline, the nano-structured region <NUM>' begins where the relative refractive index of the core first reaches a value of less than about -<NUM>%. In the embodiment shown in <FIG>, the cladding <NUM> has a relative refractive index profile Δ<NUM>(r) having a maximum absolute magnitude less than about <NUM>%, where Δ3MAX < <NUM>% and Δ<NUM> > -<NUM>%, and the nano-structured region <NUM>' ends where the outmost void occurs in the void-filled region. Additionally, as shown in <FIG>, the index of refraction of the core <NUM> is greater than the index of refraction n<NUM> of the nano-structured region <NUM>', and the index of refraction n<NUM> of the cladding <NUM> is also greater than the index of refraction n<NUM> of nano-structured region.

<FIG> illustrates an examplary optical fiber <NUM>. The fiber <NUM>, which was made, has a core region <NUM>, a nano-structured region <NUM>, a third core region <NUM> and a polymer cladding <NUM>. The fiber <NUM> had a first core region <NUM> with an outer radius R<NUM> of about <NUM>, a nano-structured region <NUM> with an outer radius R<NUM> of about <NUM>, a third core region <NUM> with an outer radius R<NUM> of about <NUM>, and a polymer cladding <NUM> (not shown) with an outer radius R<NUM> of about <NUM>. The material of the core was pure silica, the material of the cladding <NUM> was a low index polymer (e.g., UV curable silicone having a refractive index of <NUM> commercially available from Dow-Corning of Midland, Michigan under product name Q3-<NUM>). The fiber <NUM> had an NA of <NUM>. The fiber <NUM> included nano-sized structures containing SO<NUM> gas. Applicants found that filled SO<NUM> voids in the nano-structured ring <NUM> greatly contribute to scattering. Furthermore, when SO<NUM> gas was used to form the nano-structures, it has been discovered that this gas allows a thermally reversible loss to be obtained, i.e., below <NUM> the nano-structured fiber scatters light, but above <NUM> the same fiber will guide light. This unique behavior that SO<NUM> imparts is also reversible, in that upon cooling the same fiber below <NUM>, the fiber <NUM> will act as light diffusing fiber and will again generate an observable scattering effect.

The light diffusing fiber <NUM> according to embodiments of the present disclosure can be made by methods which utilize preform consolidation conditions which result in a significant amount of gases being trapped in the consolidated glass blank, thereby causing the formation of voids in the consolidated glass optical fiber preform. Rather than taking steps to remove these voids, the resultant preform is used to form an optical fiber with voids, or nano-sized structures, therein. The resultant fiber's nano-sized structures or voids are utilized to scatter or guide the light out of the fiber, via its sides, along the fiber length. That is, the light is guided away from the core <NUM>, through the outer surface of the fiber, to provide desired illumination.

As used herein, the diameter of a nano-sized structure such as a void is the longest line segment contained within the nano-sized structure whose endpoints are at the boundary of the nano-sized structure when the optical fiber is viewed in perpendicular cross-section transverse to the longitudinal axis of the fiber. A method of making optical fibers with nano-sized voids is described, for example, in <CIT> Al.

According to embodiments of the present disclosure, light diffusing fiber <NUM> provides uniform illumination along the length of the fiber <NUM>. The light scattering axially from the surface of the fiber has a variation relative to the mean scattering intensity that is less than about <NUM>%, less than about <NUM>%, less than about <NUM>%, or even less than about <NUM>%. The dominant scattering mechanism in conventional silica-based optical fibers without nano-sized structures is Rayleigh scattering, which has a broad angular distribution. The uniformity of illumination along the fiber length may be controlled such that the minimum scattering illumination intensity is not less than about <NUM> of the maximum scattering illumination intensity. As described below, such minimum scattering illumination intensity may be achieved by controlling fiber tension during the draw process, or by selecting the appropriate draw tension. Appropriate draw tensions may be, for example, between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>.

<FIG> is a plot of attenuation versus wavelength for a fiber such as shown in <FIG> which included SO<NUM> gas filled voids. The figure depicts attenuation as a function of wavelength for a light diffusing fiber <NUM> drawn at a tension of <NUM> and a light diffusing fiber <NUM> drawn at a tension of <NUM>. <FIG> illustrates that light diffusing fibers <NUM> can achieve very large scattering losses, and thus can provide high illumination intensity, in the visible wavelength range. More specifically, <FIG> illustrates that higher fiber draw tensions result in lower scattering losses and that lower fiber draw tensions result in a fiber section with higher scattering loss, and thus, stronger illumination.

<FIG> is a plot of attenuation versus wavelength for a light diffusing fiber <NUM> drawn at a tension of <NUM>, a light diffusing fiber <NUM> drawn at a tension of <NUM>, a comparative multiple mode fiber (labeled fiber A) with normalized loss, and a theoretical fiber having a loss dependence of <NUM>/λ. The light diffusing fibers <NUM> shown in <FIG> included nano-sized structures containing SO<NUM> gas. (The graph of <FIG> depicts wavelength dependence of the loss. In this example, in order to compare the slope of the scattering for the light fiber <NUM> and fiber A, the loss of low loss fiber (fiber A) was multiplied by a factor of <NUM>, so that the two plots can be easily shown in the same Figure). As shown, the average spectral attenuation from <NUM> to <NUM> was about <NUM> dB/m for the fiber drawn with a tension of about <NUM>, and was about <NUM> dB/m for the fiber drawn with a tension of about <NUM>. <FIG> illustrates that optical fiber <NUM> has a relatively flat (weak) dependence on wavelength as compared to standard single-mode transmission fiber, such as for example, SMF-28eR fiber. In standard single mode or multimode optical fibers, the losses at wavelengths less than about <NUM> are dominated by Rayleigh scattering. These Rayleigh scattering losses are determined by the properties of the material and are typically about <NUM> dB/km for visible wavelengths between about <NUM> and about <NUM> where Rayleigh scattering losses are proportional to <IMG>-p, where p is about <NUM>. In contrast, light diffusing fiber <NUM> according to the present disclosure, have scattering losses proportional to <NUM>/<IMG>-p, where p is less than <NUM>, less than <NUM>, or even more less than <NUM>. According to embodiments of the present disclosure, p may be less than <NUM>, less than <NUM>, or even more less than <NUM> over at least about <NUM>% of the wavelength range of <NUM>-<NUM>.

Without being bound to any particular theory, it is believed that the increase in the scattering losses when the draw tension decreases, for example from about <NUM> to about <NUM>, is due to an increase in the average diameter of the nanostructures. Therefore, this effect of fiber tension could be used to produce constant attenuation along the length of the fiber by varying the fiber tension during the draw process. For example, a first fiber segment drawn at high tension, T<NUM>, with a loss of α<NUM> and length, L<NUM>, will attenuate the optical power from an input level P0 to P0 exp(-α<NUM>*L<NUM>/<NUM>). A second fiber segment optically coupled to the first fiber segment and drawn at lower tension T<NUM> with a loss of α<NUM> and length L<NUM> will further attenuate the optical power from P0 exp(-α<NUM>*L<NUM>/<NUM>) to P0 exp(-α<NUM>*L<NUM>/<NUM>) exp(-α<NUM>*L<NUM>/<NUM>). The lengths and attenuations of the first and second fiber segments can be adjusted to provide uniform intensity along the length of the concatenated fiber.

Embodiments of the present disclosure further relate to medical devices having interior channels, and to systems for disinfecting medical devices having interior channels. For ease of discussion, a flexible endoscope is used to illustrate such medical devices. However, it should be understood that embodiments of the present disclosure may include any medical device having at least one interior channel, and particularly to medical devices which are conventionally used to perform more than one procedure such that it is recommended that they be disinfected between uses. For example, such medical devices may also be, but are not limited to, laparoscopic devices, indwelling catheters, non-indwelling catheters, IV and other medical tubing (i.e. feeding or ventilation tubes), luminal surgical equipment, dental devices, arthroscopic shavers, and inflow/outflow cannulas. Additionally, it should be understood that an interior channel is not limited to those of the illustrated flexible endoscope. As used herein, an interior channel may be, but is not limited to, any passage fluidly connecting one opening of a medical device to another opening of a medical device.

<FIG> is a schematic illustration of an endoscopic surgical system according to an embodiment of the present disclosure. The endoscopic surgical system includes an endoscope <NUM> and an operation section <NUM>. The endoscope <NUM> includes an elongated insertion portion <NUM> having a proximal end portion configured to be coupled to the operation section <NUM>. The insertion portion <NUM> is configured to be inserted into the body of a patient. The insertion portion <NUM> includes an elongated flexible tube portion <NUM>, a bending portion <NUM> coupled to a distal end of the flexible tube portion <NUM>, and a distal end hard portion <NUM> coupled to a distal end of the bending portion <NUM>. The operation section <NUM> includes features, such as knobs, that control the bending portion <NUM> to bend in different directions, such as, but not limited to, upward, downward, leftward and rightward directions. The operation section <NUM> also includes channel port <NUM> which communicates with a use channel <NUM> (shown in <FIG>) for the insertion of surgical instruments.

<FIG> is a front view of a face of the distal end hard portion of an endoscope in accordance with embodiments of the present disclosure. The distal end hard portion <NUM> includes an observation window <NUM>, illumination windows 119a and 119b, a use opening <NUM>, and a gas-feeding/water-feeding nozzle <NUM>. The configuration of the distal end hard portion <NUM> shown in <FIG> is merely exemplary and is not intended to limit embodiments of the present disclosure to any particular configuration. It should be understood that the different features may be positioned on the face of the distal end hard portion <NUM> in any manner. It should further be understood that some embodiments of the present disclosure may not include all the features shown in <FIG> and that various different combinations of the observation window <NUM>, the illumination windows 119a and 119b, the use opening <NUM>, and the gas-feeding/water-feeding nozzle <NUM> are comprehended.

<FIG> is a schematic sectional view of the distal end hard portion of an endoscope according to an embodiment of the present disclosure. As shown, the observation window <NUM> may be fitted with an imaging section provided with an optical system such as an objective lens <NUM> and an imaging element such as CCD (not shown). The illumination windows 119a and 119b may be fitted with illumination lenses. The endoscopic surgical system further includes light guides <NUM> having respective fore end portions disposed in confronting relation with the illumination lenses of windows 119a and 119b. The light guides <NUM> are detachably connectable to a light source and transmit illumination light from the light source to the respective illumination windows 119a and 119b. The light guides <NUM> may be, for example, fiber optic cables, or bundles of fiber optic cables. As further shown in <FIG>, the endoscope includes a use channel <NUM> which provides a passage for insertion of surgical instruments through use opening <NUM> and into the body of a patient. The use channel <NUM> communicates with channel port <NUM> and surgical instruments may be inserted into channel port <NUM>, through use channel <NUM> and out of use opening <NUM> during performance of a surgical procedure. Additionally, the gas-feeding/water-feeding nozzle <NUM> is fluidly connected to a source of water through water channel <NUM> and to a source of gas through gas channel <NUM>.

<FIG> also illustrates the insertion of cylindrical optical diffuser <NUM> into an interior channel of the endoscope <NUM>. As shown, the cylindrical optical diffuser <NUM> is connected to a light source <NUM> which is capable of emitting electromagnetic radiation that is in the UV and/or the short wavelength visible light range of wavelengths. The cylindrical optical diffuser <NUM> may be inserted through the channel port <NUM> and into at least one interior channel of the endoscope <NUM> where the cylindrical optical diffuser <NUM> emits UV or short wavelength visible light to disinfect the at least one interior channel. For example, where channel port <NUM> communicates with the use channel <NUM> for insertion of surgical instruments as described above, the cylindrical optical diffuser <NUM> may be inserted through the channel port <NUM> and into the use channel <NUM>. Light from the light source <NUM> may then be introduced into the cylindrical optical diffuser <NUM> such that the fiber emits UV or short wavelength visible light to disinfect the use channel <NUM>. According to embodiments of the present disclosure, the endoscope <NUM> may further include ports in communication with water channel <NUM> and gas channel <NUM>, and at least one cylindrical optical diffuser <NUM> may be inserted through the ports and into water channel <NUM> and gas channel <NUM> where UV or short wavelength visible light may be emitted from the cylindrical optical diffuser <NUM> to disinfect the channels. Alternatively, the endoscopic surgical system may be disassembled in order to provide access to use channel <NUM>, water channel <NUM> and/or gas channel <NUM>, and at least one cylindrical optical diffuser <NUM> may be inserted directly into use channel <NUM>, water channel <NUM> and/or gas channel <NUM> where UV or short wavelength visible light may be emitted from the cylindrical optical diffuser <NUM> to disinfect the channels.

<FIG> is a front view of a face of the distal end hard portion of an endoscope in accordance with another embodiment of the present disclosure. The distal end hard portion <NUM> includes an observation window <NUM>, illumination windows 119a and 119b, a use opening <NUM>, and a gas-feeding/water-feeding nozzle <NUM>. As shown, the endoscope also includes cylindrical optical diffuser <NUM> physically integrated into the endoscope. The configuration of the integrated cylindrical optical diffusers <NUM> shown in <FIG> is merely exemplary and is not intended to limit embodiments of the present disclosure to any particular configuration. It should also be understood that endoscopes according to the present disclosure could include any number of integrated cylindrical optical diffusers.

<FIG> illustrates one exemplary configuration of the cylindrical optical diffusers physically integrated into a medical device. As shown, the endoscope includes cylindrical optical diffusers disposed in optical communication with the use channel <NUM>, the water channel <NUM> and the gas channel <NUM>. In the embodiment shown in <FIG>, at least a portion of the wall of the interior channels are formed from a material that is transmissive to UV and/or short wavelength visible light. As such, light for disinfecting the interior channels can be transmitted into the interior channels from the cylindrical optical diffusers which are disposed outside of the channels. According to another embodiment, the cylindrical optical diffusers may be entirely disposed in the interior channels. Alternatively, the cylindrical optical diffusers may be partially disposed in the interior channels such that the volume of the channel which is occupied by the fibers is limited. For example, a portion of the cylindrical optical diffusers may be recessed into the wall of the interior channels. It should be understood that endoscopes according to the present disclosure may include cylindrical optical diffusers integrated into any number of the channels shown in <FIG>.

According to embodiments of the present disclosure, the cylindrical optical diffuser may include a coating disposed on an end of the cylindrical optical diffuser opposite an end where light from the light source is input into the cylindrical optical diffuser. The coating may cover at least a portion of the end of the cylindrical optical diffuser such that guided light in the cylindrical optical diffuser is prevented from being transmitted out of the end of the cylindrical optical diffuser. Where the cylindrical optical diffuser is a side-emitting fiber, the coating may cover an end of at least the core and may cover a portion of the surrounding cladding. The coating may be, for example, a reflective coating or an absorptive coating. In certain applications of embodiments of the present disclosure, it may be advantageous to limit the transmission of light from the end of the cylindrical optical diffuser such that substantially all light emitted from the diffuser is emitted through the outer surface of the diffuser.

Embodiments of the present disclosure also relate to disinfection methods. A method according to the present disclosure includes inserting at least a portion of at least one cylindrical optical diffuser into an interior channel of a medical device. For purposes of the present disclosure, inserting at least a portion of at least one cylindrical optical diffuser into an interior channel of a medical device may include any manual or automated process for introducing the cylindrical optical diffuser into the interior channel. Additionally, inserting at least a portion of at least one cylindrical optical diffuser into an interior channel of a medical device may include providing a medical device with an integrated cylindrical optical diffuser, wherein the integrated optical diffuser is configured to emit light into the interior channel. Alternatively, the method may include positioning the cylindrical optical diffuser outside of an interior channel formed from a material that is transmissive to UV and/or short wavelength visible light.

The method further includes introducing light from the light source into the end of the at least one cylindrical optical diffuser optically coupled to the light source and emitting the light through the outer surface of the cylindrical optical diffuser to disinfect at least one surface of the interior channel of the medical device. Light emitted through the outer surface of the cylindrical optical diffuser may also disinfect human body substances such as tissue and fluids which may contain bacteria.

The method of the present disclosure includes exposing the interior channel of the medical device to a dose of light sufficient to disinfect the interior channel of the medical device. The dose of light may be sufficient to reduce greater than <NUM>% of bacteria, fungi, and/or viruses in the interior channel of the medical device. Alternatively, the dose of light may be sufficient to reduce greater than <NUM>% of bacteria, fungi, and/or viruses in the interior channel of the medical device. Where the light is UV light, the dose of light may be, for example, greater than about <NUM> mJ/cm<NUM>, such as between about <NUM> mJ/cm<NUM> and about <NUM> mJ/cm<NUM>. The dose of light may be between about <NUM> mJ/cm<NUM> and about <NUM> mJ/cm<NUM>, or even between about <NUM> mJ/cm<NUM> and about <NUM> mJ/cm<NUM>. Where the light is short wavelength visible light the dose of light may be, for example, greater than about <NUM> J/cm<NUM>, such as between about <NUM> J/cm<NUM> and about <NUM> J/cm<NUM>. The dose of light may be between about <NUM> J/cm<NUM> and about <NUM> J/cm<NUM>, or even between about <NUM> J/cm<NUM> and about <NUM> J/cm<NUM>.

Claim 1:
A medical device (<NUM>) comprising:
at least one interior channel; and
at least one cylindrical optical diffuser (<NUM>) disposed in optical communication with the least one interior channel, the at least one cylindrical optical diffuser having an outer surface and an end optically coupled to a light source (<NUM>) that generates light having at least one wavelength between <NUM> and <NUM>, and having a scattering-induced attenuation greater than <NUM> dB/km,
wherein the at least one cylindrical optical diffuser is configured to scatter guided light through the outer surface to form a light diffuser portion having a length that emits substantially uniform radiation over its length; and
wherein the at least one cylindrical optical diffuser comprises a light diffusing optical fiber (<NUM>) having a core (<NUM>), a primary cladding (<NUM>), and a plurality of nano-sized structures (<NUM>),
and wherein the guided light is scattered through the outer surface via the nano-sized structures away from the core, and wherein said nano-sized structures situated in the core are gas filled voids containing at least one of: SO<NUM>, Kr, Ar, CO<NUM>, N<NUM>, O<NUM>, or mixture thereof.