Patent Publication Number: US-10786585-B2

Title: Anti-bacterial light delivery system and method for disinfecting a surface

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of and claims priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 15/001,641 filed Jan. 20, 2016, which is a divisional application of and claims priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 14/540,265 filed Nov. 13, 2014, which in turn claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No. 61/908,915 filed on Nov. 26, 2013, which are all hereby incorporated by reference in their entireties for all purposes, as if fully set forth herein. 
    
    
     BACKGROUND 
     This disclosure pertains to a light delivery system to promote photochemical reaction for disinfecting a surface to provide a sterile environment. 
     Anti-bacterial applications or disinfectants are commonly applied to surfaces, such as surgery tables or other surfaces in clean rooms and other environments to provide sterile surfaces. Known anti-bacterial treatments typically involve applying an anti-bacterial lotion or liquid to the surface to kill bacteria to thereby decontaminate and clean the surface. It is desirable to provide a means for disinfecting a surface that does not require the time and expense of applying an anti-bacterial lotion or liquid to the surface. 
     SUMMARY 
     In accordance with one embodiment, a light delivery system to promote a photochemical reaction for disinfecting a surface is provided. The system includes a light source and a light diffusing element operatively coupled to the light source and further embedded within a surface to be disinfected. The light diffusing element outputs light to the surface to promote a photochemical reaction to disinfect the surface. 
     In accordance with another embodiment, a method of disinfecting a surface by promoting a photochemical reaction is provided. The method includes the steps of coupling a light diffusing element to a surface to be disinfected, supplying light having a wavelength to promote a photochemical reaction to the light diffusing element, and applying the light output from the light diffusing element to the surface to promote a photochemical reaction to disinfect the surface. 
     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 embodiments, and together with the description serve to explain principles and operation of the various embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic cross-sectional view of one embodiment of a light diffusing fiber useful as a light diffusing element in a light delivery system; 
         FIG. 2  is a top schematic diagram illustrating a light delivery system for promoting photochemical reaction for disinfecting a surface with the use of the light diffusing element, according to one embodiment; 
         FIG. 3  is a perspective view illustrating the light diffusing element embedded in a channel in the surface of a table, according to one embodiment; 
         FIG. 4  is a cross-sectional view taken through line IV-IV of  FIG. 3  further illustrating the table; 
         FIG. 5  is an exploded view of the table and the embedded light diffusing element of  FIG. 3 ; 
         FIG. 6  is a perspective view of a light delivery system employing the light diffusing element embedded in a table around a perimeter of the table surface, according to a second embodiment; 
         FIG. 7  is a cross-sectional view taken through line VI-VI of  FIG. 5  further illustrating the table; and 
         FIG. 8  is an exploded view of the table and work surface further illustrating the arrangement of the light diffusing element embedded around the perimeter of the table and work surface shown in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present preferred embodiments, examples of which 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 following detailed description represents embodiments that are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanied drawings are included to provide a further understanding of the claims and constitute a part of the specification. The drawings illustrate various embodiments, and together with the descriptions serve to explain the principles and operations of these embodiments as claimed. 
     Referring to  FIGS. 1-4 , a light delivery system  10  is illustrated for promoting a photochemical reaction for disinfecting a surface  12  of an object, such as the work surface of a table  15 . The light delivery system  10  employs an active light and an optional photocatalyst to promote a photochemical reaction in the volume on the surface  12  of the table  15  to disinfect the table surface. The light applied to illuminate the surface  12  may include light having a wavelength that serves to kill germs or inhibit the growth of microorganisms such as bacteria. The light may be used alone or may be used in combination with a photocatalyst such as rutile TiO 2 . The light wavelength may be in the range of 200 nm to 2000 nm, according to one embodiment. According to a specific embodiment, an ultraviolet (UV) light having a wavelength in the range of 200 to 400 nm may be used. The light may include a combination of wavelengths and may include a red laser light that is known to help increase sterility. Further, combinations of infrared (IR) light can also be used as an additional heat source for accelerating the photochemical processes. 
     The light delivery system  10  includes at least one electrically powered light source  16  for generating and supplying an active light with select wavelength(s) to promote the photochemical reaction. The light source  16  may be a collimated or Lambertian light source. The light source  16  may include one or more lasers, light emitting diodes (LEDs), incandescent bulbs, ultraviolet lamps or a combination of light sources. The light source(s)  16  may generate light having a unique color or may combine various colors, such as red, green and blue light sources to generate custom colors. In one embodiment, one or more ultraviolet light sources are employed. 
     The light delivery system  10  also includes at least one light diffusing element  30  operatively coupled to the light source  16  to receive the light supplied by the light source  16  and disperses the light. The light diffusing element  30  is embedded within surface  12  of the table  15  to be disinfected. The light diffusing element  30  is a high scatter light transmission fiber that receives the light generated by light source  16  and scatters and outputs the light to the surface  12  to promote a photochemical reaction to disinfect the surface  12 . The high scatter light transmission achieved with the light diffusing element  30  has a light attenuation of 0.5 dB/meter or greater. The light diffusing element  30  may include one or more light diffusing fibers, according to one embodiment, disposed within a channel  24  or within a plurality of channels  24  formed in the table  15  such as are shown in  FIGS. 3 and 4 . According to another embodiment, the light diffusing element  30  may include one or more light diffusing rods. 
     The surface  12  may be the top work surface of a table  15  such as a surgical or operating table, a laboratory table, a countertop table in the home or office, or any other table surface. The surface  12  may be associated with other objects such as toilet seats, handles, and other objects, according to other embodiments. In one exemplary embodiment, the surface  12  may be the work surface of a table  15  used in a clean room  14  (e.g., operating room) for hospitals. The table  15  includes a panel  22  having a top surface, a bottom surface, an edge around the periphery and channels  24  shown formed in the top surface for receiving the light diffusing element  30 . A light transmissive cover  26  may be disposed on top of panel  22  to allow light generated by the light diffusing element  30  to illuminate the top surface  12 . The cover  26  may be translucent such that the light is transmitted through the cover  26  and diffused. A reflective surface  28  may be provided on the inner side walls and bottom wall of channels  24  to reflect the light upwards towards the top surface  12 . In one embodiment, the panel  22  may include a metal material and the cover  26  may include a glass overlay and the metal panel  22  may include light reflective proportions to eliminate the need for an additional reflective surface. The channel(s)  24  and light diffusing element  30  may be arranged in various shapes and sizes to properly illuminate select areas or the entire surface to be disinfected. While the table  15  shown is rectangular, it should be appreciated that other shapes and sizes may be used. 
     The light delivery system  10  may further include a low scatter light transmission medium  18  coupled between the light source  16  and the light diffusing element  30 . According to one embodiment, the low scatter light transmission medium  18  may include an optical fiber designed to transmit light with low signal loss. The low scatter light transmission achieved with the transmission medium  18  has a light attenuation of less than 0.5 dB/meter. The low scatter light transmission medium  18  is shown in one embodiment coupled to the light diffusing element  30  by way of an optical coupler  20 . It should be appreciated that the low scatter light transmission medium  18  may otherwise be operatively coupled to the light diffusing element  30  using various optical connections including splices, butt couplings and other light transmission couplings. 
     In the embodiment shown in  FIG. 2 , the surface  12 , such as the work surface of an operating table  15 , is shown located within a clean room  14 , whereas the electrically powered light source  16  is located outside of the clean room  14 . The low scatter light transmission medium  18  advantageously allows light generated by the light source  16  to be transmitted a substantial distance with low light signal loss into the clean room  14  to the light diffusing element  30  where the light is diffused and transmitted to the surface  12  of table  15  for disinfecting the surface  12 . As such, the light diffusing element  30  may be employed as a flexible remote light illuminator that allows continuous sterilization in wet, explosive, or other sterile environments, while positioning the light source  16  outside of the clean room  14 . As such, the light source  16  does not need to be sterilized and may be electrically powered from outside the clean room  14 . 
     The low scatter light transmission medium  18  may include a transmission fiber that may be a single fiber, a bundled (or ribbonized) collection of fibers, a plastic optical fiber (POF), or other light transmission medium. The low scatter light transmission medium  18  may employ a fused silica rod, according to another embodiment, that can also be used as efficient delivery of light from the light source  16  to the light diffusing element  30 . The low scatter transmission medium  18  may be connected to the light diffusing element  30  by the optical coupler  20  or by butt coupling to the light diffusing element  30 . 
     The light diffusing element  30  may be configured as a single light diffusing fiber or may be bundled (or ribbonized) collections of light diffusing fibers. The light diffusing fiber  30  may be flexible, thus allowing ease in installation within the channel  24 . In one embodiment, the light diffusing fiber  30  has a diameter of 1,000 microns or less, and more particularly of about 250 microns. In other embodiments, the light diffusing fiber  30  may be more rigid such as in the form of a light diffusing rod having a diameter greater than 1,000 microns. 
     One embodiment of a light diffusing fiber  30  is illustrated having a typical cross-sectional structure shown in  FIG. 1 . The light diffusing fiber  30  may include the formation of random air lines or voids in one of the core and cladding of a silica fiber. Examples of techniques for designing and forming such light diffusing fibers may be found, for example, in U.S. Pat. Nos. 7,450,806; 7,930,904; and 7,505,660, and U.S. Patent Application Publication No. 2011/0305035, which are hereby incorporated by reference. The light diffusing fiber  30  has a glass core  32  which may include an F-doped core. An SiO 2  cladding layer  34  having air lines for scattering light is shown surrounding the core  32 . The cladding layer  34  may be formed to include air lines or voids to scatter the light and direct the light through the side walls. It should be appreciated that the random air lines may be disposed in the core  32  or in the cladding  34  or in both, according to various embodiments. It should be appreciated that high scattering losses are generally preferred in the light diffusing fiber  30 . A low index polymer primary protective layer  36  generally surrounds the cladding layer  34 . Additionally, an outer secondary layer  38  may be disposed on the primary protective layer  36 . Primary protective layer  36  may be soft and liquidy, while secondary layer  38  may be harder. 
     The secondary layer  38  may include a photoreactive agent according to one embodiment. The photoreactive agent may be provided as the secondary coating having a hardness greater than the first cladding coating. The photoreactive agent may include materials such as TiO 2 , W 2 O 3 , and other catalytic elements that photo-oxidizes when the light activates the material. 
     Scattering loss of the light diffusing fiber  30  may be controlled throughout steps of fiber manufacture and processing. During the air line formation process, the formation of a greater number of bubbles will generally create a larger amount of light scatter, and during the draw process the scattering can be controlled by using high or low tension to create higher or lower loss, respectively. To maximize loss of light, a polymeric cladding may be desirably removed as well, over at least a portion of the light diffusing fiber  30  length if not all. Uniform angular loss in both the direction of light propagation, as well as in the reverse direction can be made to occur by coating the light diffusing fiber  30  with inks that contain scattering pigments or molecules, such as TiO 2 . An ultraviolet light source may be used as well, with a fluorescent dye or phosphor materials applied to the fiber cladding (effectively down converting the ultraviolet wavelength of light with approximately 100 percent efficiency to a desired wavelength). Use of such fluorescence down-conversion creates very uniform angular light distribution. The high scattering light diffusing fiber  30  may have a modified cladding to promote scattering and uniformity. Intentionally introduced surface defects on the light diffusing fiber  30  or core or cladding may also be added to increase light output, if desired. 
     The light diffusing fiber  30  may have a region or area with a large number (greater than 50) of gas filled voids or other nano-sized structures, e.g., more than 50, more than 100, or more than 200 voids in the cross section of the fiber. The gas filled voids may contain, for example, SO 2 , Kr, Ar, CO 2 , N 2 ,  0   2,  or mixture thereof. The cross-sectional size (e.g., diameter) of the nano-size structures (e.g., voids) may vary from 10 nanometers to 1 micrometer (for example, 15 nanometers to 500 nanometers), and the length may vary depending on the area of the surface to be disinfected. 
     While the light diffusing fiber  30  is shown and described herein having air lines, it should be appreciated that other light scattering features may be employed. For example, high index materials such as GeO 2 , TiO 2 , ZrO 2 , ZnO, and others may be employed to provide high scatter light transmission. It should further be appreciated the light diffusing element  30  may be a light diffusing rod that is less flexible, has a larger diameter and may have no coating. 
     Referring to  FIGS. 5-7 , a light delivery system  10 , according to another embodiment is illustrated employing a light diffusing element  30  extending within the surface  12  and around the periphery of a table  15  having a surface  12  to be disinfected. The light diffusing element  30  may be a light diffusing fiber or light diffusing rod and is shown extending along all four side edges of a light transmissive medium  40 , such as a glass panel. As such, the light diffusing element  30  edge lights the glass panel so that light passing through the light diffusing element  30  is effectively illuminated into the glass medium. The glass medium  40  may be made of a translucent material so that the light further diffuses and illuminates the top surface. Additionally, the bottom surface of the glass medium  40  has a reflective surface  42  for reflecting light upward towards surface  12  to be disinfected. Additionally, edge coverings  44  are disposed along the peripheral edges of the table outside of the light diffusing element  30  and may include an internal reflective surface  46  to reflect light back into the glass medium  40 . As such, light passing through the light diffusing element  30  is reflected upwards by the bottom surface and inwards by the edge coverings  44  into the glass medium  40  from where it propagates up to surface  12  to be disinfected. 
     A method of disinfecting a surface by promoting a photochemical reaction with the use of the light delivery system  10  will now be described. The method includes the step of coupling a light diffusing element  30  to a surface  12  to be disinfected. The surface  12  may be a table  15 , such as an operating table used within a clean room. The method also includes the step of supplying light having a wavelength to promote a photochemical reaction to the light diffusing element  30 . The method further includes the step of applying the light output from the light diffusing element  30  to the surface  12  to promote a photochemical reaction to disinfect the surface  12 . 
     The method may further include the step of supplying the light from a light source  16  to a low scatter light transmission medium  18 , and further coupling the low scatter light transmission medium  18  to the light diffusing element  30 . The light diffusing element  30  may be disposed within a channel  24  formed in the surface  12 . The surface  12  may be disposed within a clean room  14  and the light source  16  may be disposed outside of the clean room  14 . The light diffusing element  30  may be a light diffusing fiber having a glass core, a cladding, and a plurality of air lines disposed in one of the core and the cladding. The cladding may include a coating comprising a photoreactive agent. 
     Accordingly, the light delivery system  10  and method advantageously delivers light from a light source  16  to a light diffusing element  30  embedded within a surface  12  such as a table  15  to disinfect the surface  12  with light generated by the light source  16 . As such, the surface  12  may be disinfected with light that is generated remotely and transmitted to the surface by way of the light diffusing element  30  in a manner that is safe, easy to use and clean. 
     Various modifications and alterations may be made to the examples within the scope of the claims, and aspects of the different examples may be combined in different ways to achieve further examples. Accordingly, the true scope of the claims is to be understood from the entirety of the present disclosure in view of, but not limited to, the embodiments described herein. 
     It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claims.