Patent Publication Number: US-9834456-B2

Title: Ultraviolet disinfection system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is continuation-in-part of U.S. application Ser. No. 14/733,494, filed Jun. 8, 2015, assigned to the present assignee and incorporated herein by reference. 
    
    
     DESCRIPTION OF RELATED ART 
     BACKGROUND 
     The bandgap of III-nitride materials, including (Al, Ga, In)—N and their alloys, extends from the very narrow gap of InN (0.7 eV) to the very wide gap of AN (6.2 eV), making III-nitride materials highly suitable for optoelectronic applications such as light emitting diodes (LEDs), laser diodes, optical modulators, and detectors over a wide spectral range extending from the near infrared to the deep ultraviolet. Visible light LEDs and lasers can be obtained using InGaN in the active layers, while ultraviolet (UV) LEDs and lasers require the larger bandgap of AlGaN. 
     UV LEDs with emission wavelengths in the range of 230-350 nm are expected to find a wide range of applications, most of which are based on the interaction between UV radiation and biological material. Typical applications include surface sterilization, water purification, medical devices and biochemistry, light sources for ultra-high density optical recording, white lighting, fluorescence analysis, sensing, and zero-emission automobiles. 
     UV radiation has disinfection properties that inactivate bacteria, viruses, and other microorganisms. A low-pressure mercury lamp may produce UV radiation in the range of 254 nm. Since most microorganisms are affected by radiation around 260 nm, UV radiation is in the appropriate range for germicidal activity.  FIG. 1  illustrates a known UV treatment device. A cylindrical chamber  110  houses a UV bulb  112  along a central axis of the chamber  110 . The bulb may be encased in a quartz sleeve. UV radiation  114  is emitted from the bulb  112 . Untreated water enters the chamber at inlet  116 , and flows toward outlet  118 , where treated water may be removed from the chamber. A flow control device  120  may prevent the water from passing too quickly past the bulb, assuring appropriate radiation contact time with the flowing water. The chamber is stainless steel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view of a prior art UV disinfection system. 
         FIG. 2  is a plan view of multiple pixels in a flip chip UV-emitting device (UVLED). 
         FIG. 3  is a cross sectional view of one pixel in the UVLED of  FIG. 2 . 
         FIG. 4  illustrates a package including a UVLED and a transparent plate. 
         FIG. 5  illustrates a package including a UVLED and a sealing material. 
         FIG. 6  illustrates a package including a UVLED and an optic. 
         FIG. 7  is a cross sectional view of a batch-process UV disinfection system. 
         FIG. 8  is a cross sectional view of a continuous-flow UV disinfection system. 
         FIG. 9  is a cross sectional view of a continuous-flow UV disinfection system including a fluid permeable structure. 
         FIG. 10  illustrates multiple continuous-flow UV disinfection chambers in a close-packaged arrangement. 
         FIG. 11  is a block diagram of a circuit for controlling a UV disinfection system. 
         FIG. 12  is a bisected view of a water container with an integral UVC LED source at the bottom, where the light is reflected off the inner walls by TIR to disinfect the liquid. 
         FIG. 13  is a bisected view of a water container with an integral UVC LED source at the bottom, where the light is reflected off an air/gap interface by TIR to disinfect the liquid. 
         FIG. 14  is a bisected view of a water container with an integral UVC LED source, similar to  FIG. 12  but where the UVC LED(s) are located around the side walls of the vessel. 
         FIG. 15  is a bisected view of a water container with an integral UVC LED source, similar to  FIG. 13  but where the UVC LED(s) are located around the side walls of the vessel. 
       Elements that are the same or similar in the various figures are labeled with the same numerals. 
     
    
    
     DETAILED DESCRIPTION 
     Though the devices described herein are III-nitride devices, devices formed from other materials such as other III-V materials, II-VI materials, Si are within the scope of embodiments of the invention. The devices described herein may be configured to emit UV A (peak wavelength between 340 and 400 nm), UV B (peak wavelength between 290 and 340 nm), or UV C (peak wavelength between 210 and 290 nm) radiation. 
     In embodiments of the invention, one or more UVLEDs are used in a disinfection device, suitable for disinfecting a fluid, such as water, air, or any other suitable material. 
     Commercially available UVA, UVB, and UVC LEDs may be used in the various embodiments.  FIGS. 2 and 3  are examples of the assignee&#39;s own UVB and UVC LEDs that may be used.  FIG. 2  is a top down view of a portion of an array of UVLED pixels  12 , and  FIG. 3  is a bisected cross-section of a single UVLED pixel  12 . Any suitable UVLED may be used and embodiments of the invention are not limited to the device of  FIGS. 2 and 3 . 
     The UVLEDs are typically III-nitride, and commonly GaN, AlGaN, and InGaN. The array of UV emitting pixels  12  is formed on a single substrate  14 , such as a transparent sapphire substrate. Other substrates are possible. Although the example shows the pixels  12  being round, they may have any shape, such as square. The light escapes through the transparent substrate, as shown in  FIG. 3 . The pixels  12  may each be flip-chips, where the anode and cathode electrodes face the mount (described below). 
     All semiconductor layers are epitaxially grown over the substrate  14 . An AlN or other suitable buffer layer (not shown) is grown, followed by an n-type region  16 . The n-type region  16  may include multiple layers of different compositions, dopant concentrations, and thicknesses. The n-type region  16  may include at least one Al a Ga 1-a N film doped n-type with Si, Ge and/or other suitable n-type dopants. The n-type region  16  may have a thickness from about 100 nm to about 10 microns and is grown directly on the buffer layer(s). The doping level of Si in the n-type region  16  may range from 1×10 16  cm −3  to 1×10 21  cm −3 . Depending on the intended emission wavelength, the AlN mole fraction “a” in the formula may vary from 0% for devices emitting at 360 nm to 100% for devices designed to emit at 200 nm. 
     An active region  18  is grown over the n-type region  16 . The active region  18  may include either a single quantum well or multiple quantum wells (MQWs) separated by barrier layers. The quantum well and barrier layers contain Al x Ga 1-x N/Al y Ga 1-y N, wherein 0 &lt;x &lt;y &lt;1, x represents the AlN mole fraction of a quantum well layer, and y represents the AlN mole fraction of a barrier layer. The peak wavelength emitted by a UV LED is generally dependent upon the relative content of Al in the AlGaN quantum well active layer. 
     A p-type region  22  is grown over the active region  18 . Like the n-type region  16 , the p-type region  22  may include multiple layers of different compositions, dopant concentrations, and thicknesses. The p-type region  22  includes one or more p-type doped (e.g. Mg-doped) AlGaN layers. The AlN mole fraction can range from 0 to 100%, and the thickness of this layer or multilayer can range from about 2 nm to about 100 nm (single layer) or to about 500 nm (multilayer). A multilayer used in this region can improve lateral conductivity. The Mg doping level may vary from 1×10 16  cm −3  to 1×10 21  cm −3 . A Mg-doped GaN contact layer may be grown last in the p-type region  22 . 
     All or some of the semiconductor layers described above may be grown under excess Ga conditions, as described in more detail in US 2014/0103289, which is incorporated herein by reference. 
     The semiconductor structure  15  is etched to form trenches between the pixels  12  that reveal a surface of the n-type region  16 . The sidewalls  12   a  of the pixels  12  may be vertical or sloped with an acute angle  12   b  relative to a normal to a major surface of the growth substrate. The height  138  of each pixel  12  may be between 0.1-5 microns. The widths  131  and  139  at the bottom and top of each pixel  12  may be at least 5 microns. Other dimensions may also be used. 
     Before or after etching the semiconductor structure  15  to form the trenches, a metal p-contact  24  is deposited and patterned on the top of each pixel  12 . The p-contact  24  may include one or more metal layers that form an ohmic contact, and one or more metal layers that form a reflector. One example of a suitable p-contact  24  includes a Ni/Ag/Ti multi-layer contact. 
     An n-contact  28  is deposited and patterned, such that n-contact  28  is disposed on the substantially flat surface of the n-type region  16  between the pixels  12 . The n-contact  28  may include a single or multiple metal layers. The n-contact  28  may include, for example, an ohmic n-contact  130  in direct contact with the n-type region  16 , and an n-trace metal layer  132  formed over the ohmic n-contact  130 . The ohmic n-contact  130  may be, for example, a V/Al/Ti multi-layer contact. The n-trace metal  132  may be, for example, a Ti/Au/Ti multi-layer contact. 
     The n-contact  28  and the p-contact  24  are electrically isolated by a dielectric layer  134 . Dielectric layer  134  may be any suitable material such as, for example, one or more oxides of silicon, and/or one or more nitrides of silicon, formed by any suitable method. Dielectric layer  134  covers n-contact  28 . Openings formed in dielectric layer  134  expose p-contact  24 . 
     A p-trace metal  136  is formed over the top surface of the device, and substantially conformally covers the entire top surface. The p-trace metal  136  electrically connects to the p-contact  24  in the openings formed in dielectric layer  134 . The p-trace metal  136  is electrically isolated from n-contact  28  by dielectric layer  134 . 
     Robust metal pads electrically connected to the p-trace metal  136  and n-contact  28  are provided outside of the drawing for connection to power supply terminals. Multiple pixels  12  are included in a single UVLED. The pixels are electrically connected by large area p-trace metal  136  and the large area n-trace metal  132 . The number of pixels may be selected based on the application and/or desired radiation output. A single UVLED, which includes multiple pixels, is illustrated in the following figures as UVLED  1 . 
     In some embodiments, substrate  14  is sapphire. Substrate  14  may be, for example, on the order of hundreds of microns thick. In a 1 mm square UVLED  1  with a 200 μm thick sapphire substrate, assuming radiation is extracted from the top and sides of the substrate, the top surface accounts for about 55% of the extraction surface, and the sides account for about 45% of the extraction surface of the substrate. Substrate  14  may remain part of the device in some embodiments, and may be removed from the semiconductor structure in some embodiments. 
     The UVLED may be square, rectangular, or any other suitable shape when viewed from the top surface of substrate  14 , when the device is flipped relative to the orientation illustrated in  FIG. 3 . 
     The UVLED illustrated in  FIGS. 2 and 3  may be disposed in a package. Three packages are illustrated in  FIGS. 4, 5, and 6 . In each package, UVLED  1  is attached to a mount  70 . The mount  70  may be, for example, a ceramic mount, a circuit board, a metal-core printed circuit board, a silicon mount, or any other suitable structure. Circuit elements such as driver circuitry for UVLED  1  or any other suitable circuitry may be disposed on or within mount  70 . In each of the packages illustrated in  FIGS. 4, 5, and 6 , more than one UVLED may be attached to mount  70 . In each of the disinfection chambers described below, a single UVLED may be used, multiple UVLEDs disposed in a single package may be used, or multiple packages including one or more UVLEDs each may be used, in order to provide UV radiation sufficient for disinfection in the disinfection chamber. 
     In the package of  FIG. 4 , UVLED  1  is attached to mount  70 . A transparent plate  72  is disposed over UVLED  1 . Transparent plate  72  may be quartz or any suitable material. UVLED  1  may be in direct physical contact with transparent plate  72  as illustrated in  FIG. 4 , in optical contact with transparent plate  72  by, for example, filling the space  74  between mount  70  and transparent plate  72  with an index matching material such as oil or any other suitable material, or spaced apart from transparent plate  72 . 
     In the package of  FIG. 5 , UVLED  1  is attached to mount  70 . UVLED  1  and empty space on mount  70  adjacent to UVLED  1  are covered with a material  76  that seals UVLED  1 . Suitable sealing materials are UV-hard, transparent, and protect UVLED  1 . Any suitable material, such as glass, may be applied by any suitable technique, such as a sol gel process. Sealing material over the top surface of UVLED  1  may be etched back to reveal the top surface of UVLED  1  (often the top surface of the grown substrate). 
     In the packages of  FIGS. 4 and 5 , in some embodiments, sidewalls  78  form a sealed chamber, such that UVLED  1  is isolated and protected from the fluid to be disinfected. For example, if the fluid is a liquid, the mount  70 , sidewalls  78 , and transparent plate  72  or sealing material  76  form a water-tight compartment in which UVLED  1  is placed. The sidewalls  78  may be walls of the disinfecting chamber, a metal or plastic container, or any other suitable structure. 
     In the package of  FIG. 6 , a UVLED  1  is attached to a mount  70 , and an optic  60  is attached to the UVLED  1 . The optic  60  may be any suitable optic, including for example, a dome lens, a Fresnel lens, the compound parabolic collimator illustrated, or any other suitable lens or optic. The optic  60  illustrated in  FIG. 6  may create a radiation pattern that is more collimated than the radiation pattern emitted by the UVLED  1  without the optic  60 . In some embodiments, the optic  60  is a compound parabolic collimator. UV radiation encountering curved sidewall  64  is reflected toward outlet surface  62 . The optic  60  may be a solid, transparent material, that reflects UV radiation off sidewalls  64  by total internal reflection (TIR), or an open, hollow structure filled with air, with sidewalls that are formed from or coated with reflective material. In the case of an open structure, the outlet surface  62  may be simply an opening. A compound parabolic collimator may be more suited to an application where the UV radiation source is disposed on an end wall of an elongate disinfection chamber. A dome lens may be more suited to an application where the UV radiation source is disposed on a side wall of an elongate disinfection chamber. 
     Optic  60  may be a truncated inverted pyramid or cone. The outlet surface  62  of optic  60  may be, for example, rotationally symmetric, oval, round, square, rectangular, or any other suitable shape. The shape of the outlet surface  62  of optic  60  may be matched to the shape of the disinfection vessel. The surface of the optic  60  that is optically coupled to the top surface of the UVLED may be only slightly larger than the top surface of the UVLED; no more than 10% larger in some embodiments, no more than 20% larger in some embodiments, and no more than 30% larger in some embodiments. In some embodiments, a lens or other optic is disposed over UVLED  1 , between the UVLED  1  and optic  60 . 
     A solid optic  60  is formed from a material that is transparent to UV radiation at wavelengths emitted by UVLED  1 , and able to withstand the UV radiation without degrading. For example, in some embodiments, the optic may be formed from a material that transmits at least 85% of UV radiation at 280 nm. The material may degrade no more than 1% after 1000 hrs of exposure to UV radiation at 280 nm. In some embodiments, optic  60  is formed from a material that is moldable, such as, for example, glass, IHU UV transmissive glass available from Isuzu Glass, Inc., and UV-resistant silicone. In some embodiments, optic  60  is formed from a material that may be shaped by, for example, grinding and polishing, such as quartz or sapphire. An optic formed by molding may be less expensive; an optic formed by grinding and polishing may be of better optical quality. 
     In some embodiments, optic  60  is optically coupled to only the top surface of the UVLED  1 , typically a surface of the growth substrate, or a major surface of the semiconductor structure of UVLED  1 . In some embodiments, optic  60  may extend over and be optically coupled to the sides of UVLED  1  as well. Optic  60  may extend over the sides of just the growth substrate, or over the sides of both the growth substrate and the semiconductor structure. 
     As illustrated in  FIG. 6 , in some embodiments, only the top surface of UVLED  1  is optically coupled to the optic  60 . The side surfaces of UVLED  1  are not optically coupled to the optic, such that radiation emitted from the side surfaces is lost. Capturing the radiation from just the top surface increases the etendue of the UVLED/optic system. Increasing the etendue may increase the irradiance of the system and reduce the source size, which may be useful for some applications. The radiation emitted to the side is discarded in these embodiments, though in UV-emitting systems, radiation may preferentially be emitted toward the side surfaces of a UVLED, rather than the top surface of the UVLED, due to polarization within the AlGaN active layer(s). 
     In embodiments where the optic is a solid material that directs radiation by total internal reflection such as, for example, the optic illustrated in  FIG. 6 , the optic may have a TIR surface combined with other surfaces that may or may not direct radiation by TIR. For example, the TIR surfaces  64  of the optic illustrated in  FIG. 6  may be combined with a domed surface spaced apart from UVLED  1 , for example in place of flat output surface  62 . 
     A UVLED  1  with an optic  60  may be used in a disinfection chamber as illustrated in  FIG. 6 , in either of the packages illustrated in  FIG. 4 or 5 , or in any other suitable package. 
       FIG. 7  is a cross sectional view of one embodiment of a disinfection device. The device of  FIG. 7  includes a disinfection chamber  40 . The disinfection chamber  40  is elongate; length  42  may be, for example, at least five times greater than width  44  in some embodiments, and no more than a hundred times greater than width  44  in some embodiments. The cross section at plane  45  may be circular, square, rectangular, hexagonal, or any other suitable shape. 
     UV radiation source  50  is disposed along at least one wall of the disinfection chamber. In the embodiment illustrated in  FIG. 7 , one UV radiation source  50  is disposed at one end of the elongate disinfection chamber  40 , on one of the short walls of the disinfection chamber. In each of the disinfection chambers described herein, a single UV radiation source may be positioned on any wall of the disinfection chamber, or in any part of the disinfection chamber, or multiple UV radiation sources may be positioned on the same or multiple walls of the disinfection chamber. In some embodiments, a UV radiation source is positioned on a longer sidewall of the elongate chamber, rather than or in addition to on a shorter end wall of the elongate chamber. In some embodiments, UV radiation sources are positioned on both end walls of the disinfection chamber. In order to achieve a predetermined amount of UV radiation for disinfection at every point in the chamber, the use of two UV radiation sources at either end of the chamber may allow lower power UV devices to be used, as compared with a single UV radiation source positioned at one end, which must produce sufficient UV radiation at the opposite end of the chamber. 
     In the embodiment illustrated in  FIG. 7 , UV radiation source  50  may be disposed on what may be considered the top of the disinfection chamber. The surface  54  of the top  52  of the disinfection chamber that faces into the disinfection chamber may be formed from or coated with a UV-reflective material. The surface  48  of the bottom of the disinfection chamber (i.e., the short wall opposite the top) that faces into the disinfection chamber may be formed from or coated with a UV-reflective material. Surfaces  48  and  54  may have the same reflective coating, though this is not required. Examples of suitable reflective coatings for surfaces  48  and  54  include metals, silver, aluminum, Teflon, polytetrafluoroethylene (PTFE), barium sulfate, oxides, oxides of silicon including SiO 2 , oxides of yttrium, oxides of hafnium, a multilayer stack, a distributed Bragg reflector, and combinations thereof. 
     The side surface(s)  46  of the elongate disinfection chamber  40  (i.e. the surface(s) perpendicular to the top and bottom surfaces described above) may be formed from or coated with a material that causes total internal reflection (TIR), or attenuated total internal reflection (ATR), where the material is reflective but somewhat absorbing, such that some power is lost when radiation is incident on the ATR material. A TIR material may be preferred in some embodiments for better reflection, but an ATR material may be used for other reasons such as cost, durability, etc. In some embodiments, the elongate disinfection chamber is formed from a durable, inexpensive material such as plastic or polycarbonate, with the interior surface coated with a material that causes TIR or ATR. Examples of suitable coatings and/or materials for forming the disinfection chamber include materials that cause TIR of UV radiation and are not absorbing or substantially not absorbing such as Teflon, Fluorilon 99-U, and any of the materials listed above for coatings for surfaces  48  and  54 . The disinfection chamber may be made from, for example, the examples of suitable coatings for the disinfection chamber and/or surfaces  48  and  54  listed above, plastic, metal, glass, or any suitable material. 
     In some embodiments, one or more surfaces of the disinfection chamber  40  that encounter water, such as the side surfaces or top and bottom surfaces described above may be coated with or otherwise treated with a photocatalytic material such as TiO 2 . TiO 2  may photocatalyze water into OH radicals, which may purify water by breaking down organic material. 
     In some embodiments, the water disinfection device illustrated in  FIG. 7  is used to disinfect fluid in a batch process. For example, the disinfection device may be a water bottle. The top  52  may be removable; for example the top  52  may be a screw-on lid, a clamp-on lid, or a structure secured to the disinfection chamber by any other suitable means. The top  52  may be removed, the disinfection chamber  40  filled with water, and the UV radiation source  50  activated, for example by pressing a button or flipping a switch (not shown in  FIG. 7 ). The UV radiation source  50  may irradiate the water in the disinfection chamber  40  until, for example, automatically switched off or deactivated by a user. The top  52  may then be removed, and the disinfected water removed. In some embodiments, a single UV radiation source  50  may be disposed at the bottom of the water bottle, rather than the top, such that the water to be disinfected is in close enough proximity to the UV radiation source to act as a heat sink to the UV radiation source. In addition, placing UV radiation source  50  at the bottom of a water bottle, rather than the top, may reduce or eliminate losses associated with TIR at an air gap between the UV radiation source and the fluid, which may be caused by incomplete filling of the water bottle. 
       FIG. 8  is a cross sectional view of one embodiment of a water disinfection device, which may disinfect water in a continuous-flow process, rather in than a batch process like the device illustrated in  FIG. 7 . In the device of  FIG. 8 , the UV radiation source  50  is disposed at one end of the elongate disinfection chamber  140 , as in  FIG. 7 , and irradiates the disinfection chamber  140  when activated. The top and bottom  48  ends of the elongate disinfection chamber  140  may be coated or formed from a UV reflective material, as in  FIG. 7 . The interior surface(s)  46  of the disinfection chamber  140  may be coated with a TIR or ATR material, as in  FIG. 7 . 
     In the device illustrated in  FIG. 8 , water to be disinfected flows into the disinfection chamber  140  through inlet  56 . Water flows through the disinfection chamber  140  toward outlet  58 , where the disinfected water flows out of the disinfection chamber  140 . The device illustrated in  FIG. 8  is not to scale; the disinfection chamber  140  may be much longer and the inlet  56  and outlet  58  spaced much further apart than illustrated in  FIG. 8 . For example, the disinfection chamber  140  may be at least 10 times longer than it is wide in some embodiments, at least 100 times longer than it is wide in some embodiments, and at least 500 times longer than it is wide in some embodiments. The disinfection chamber  140  is sufficiently long that the water spends enough time in the disinfection chamber to be exposed to sufficient UV radiation to disinfect the water. 
     Disinfection chamber  140  may be, for example a flexible plastic hose, or any other suitable material. In some embodiments, the inlet  56  (and the UV radiation source  50  in some embodiments) is submersible in a water body, such that a user may suck or pump water toward the outlet  58 . 
     Unlike in the device of  FIG. 1 , where the UV source is disposed within the chamber such that UV radiation is emitted radially, in the device illustrated in  FIGS. 7 and 8 , the UV source  50  is disposed at one end of the chamber, such that radiation is emitted longitudinally, down the length of the elongate chamber. 
       FIG. 9  is a cross sectional view of a continuous-flow disinfection chamber including a fluid-permeable structure such as a filter. In the device of  FIG. 9 , a disinfection chamber  84  is defined by elongate sidewalls  80 , and filters  82  disposed on either end of chamber  84 . Fluid enters at  86 , flows through filter  82  into the chamber  84 , then through a second filter  82 , where it exits the chamber at  88 . A UV radiation source  50  is disposed on sidewall  80 , or at any other appropriate location. As in  FIG. 8 , the disinfection chamber may be flexible (such as, for example, a plastic tube), or rigid. The disinfection chamber is typically elongate, though it may be any suitable shape. 
     Filters  82  may be any suitable structure through which fluid may pass. Filters  82  may filter out some or all particulate matter in the fluid, though this is not required. Filters  82  may also be reflective of UV radiation, such that light emitted by UV radiation source  50  is trapped in chamber  84 . Filters  82  may be any suitable material including, for example, porous aluminum, aluminum screens, or Teflon particles sintered into porous Teflon made by Porex, Inc. The length and diameter of chamber  84 , the porosity of filters  82 , the radiative power emitted by UV radiation source  50 , and other characteristics may be selected such that at a predetermined flow rate, the fluid (e.g. air, water, or any other appropriate fluid) spends sufficient time in chamber  84  to disinfect the fluid. 
     In some embodiments, some or all of the walls of the chamber  84  may be coated with a photocatalytic material, as described above. Since photocatalytic disinfection requires close proximity between the fluid and the photocatalytic material, other structures coated with or formed from a photocatalytic material may be disposed in the chamber  84 . In an embodiment including a photocatalytic material, the fluid may be disinfected three ways: mechanical filtering by filters  82 , disinfection by UV radiation from UV radiation source  50 , and disinfection by OH radicals created by the interaction of the photocatalytic material with UV radiation. 
       FIG. 10  illustrates multiple disinfection chambers  84 , such as the one illustrated in  FIG. 9 , in a close-packed arrangement. Disinfection chambers may be added as necessary to reach a desired throughput of fluid. Though the individual disinfection chambers are hexagonal, to maximize the area of the disinfection chambers in cross section, the individual disinfection chambers may be any suitable cross section. 
       FIG. 11  is a block diagram of a circuit, which may control a UV radiation source in any of the disinfection chambers described above. Any suitable circuit may be used. Not all of the components illustrated in  FIG. 11  are necessary in all embodiments. The components may be disposed on or in a mount, described above, and electrically connected to each other as illustrated via the mount, a circuit board, or any other suitable structure. UV radiation source  50  may be connected to a microprocessor  90 , which may turn the UV radiation source  50  on and off, and may adjust the power to UV radiation source  50 . A switch  91 , which may be user-activated or automatic, and may be any suitable switch, may activate the UV radiation source directly (not shown in  FIG. 11 ), or may activate the microprocessor, which turns on the UV radiation source. 
     The amount of time that the fluid is exposed to radiation from UV radiation source may be dictated by a timer  94 , which may count a predetermined amount of time, after which the microprocessor  90  may turn off UV radiation source  50 . An indicator  92 , such as a light or any other suitable indicator, may indicate whether UV radiation source  50  is emitting UV radiation. 
     A detector  96  may detect an amount of UV radiation at a given point in the disinfection chamber. The amount of UV radiation emitted by source  50  may be adjusted accordingly by microprocessor  90 . A second detector  98  may be used to detect whether the UV radiation source  50  is functioning properly. For example, first detector  96  may be positioned near UV radiation source  50 , and second detector  98  may be positioned far from UV radiation source  50 . When UV radiation source  50  is on, the amount of UV radiation detected by each of detectors  96  and  98  may be compared. If detector  96  indicates a higher amount of UV radiation and detector  98  indicates a lower amount of UV radiation, the fluid may be contaminated with particulate matter. If detectors  96  and  98  both indicate a low amount of UV radiation, the UV radiation source  50  may not be functioning properly. Indicator  92  may be used to indicate to a user that UV radiation source  50  is not functioning properly. 
     In one operation, a user activates switch  91 . In response, microprocessor  90  turns on UV radiation source  50 . Microprocessor  90  may also switch indicator  92  to a status indicating the UV radiation source is disinfecting. The amount of UV radiation is measured by detector  96 . In response, microprocessor  90  may adjust the amount of time that the UV radiation source  50  stays on, and/or the power to UV radiation source  50 , in order to deliver a sufficient dose of UV radiation to disinfect the fluid. Once the dose is reached, microprocessor  92  may switch off UV radiation source  50 , and switch off indicator  92  or change indicator  92  to a status indicating the UV radiation source is finished disinfecting. 
       FIG. 12  is a bisected view of a portable cylindrical water vessel  150  with one or more integral UVC LEDs  152  at the bottom, where the light is reflected off the inner walls  153  of the liner  155  by TIR to disinfect the liquid. TIR occurs when the incident light is at less than the critical angle of the interface. Between the outer wall  156 , such as aluminum, and the next wall  158  there may be insulation  160  to keep the water cool. The light ray  162  emitted from the LEDs  152  assumes the vessel  150  is full of water  164 . The LEDs  152  emit light in the UVC range 260-280 nm, which is the most effective range for killing microorganisms to disinfect the water. The UVC disrupts the cell walls and DNA of the microorganisms to essentially render them harmless. 
     Water has an index of refraction of about 1.35. The liner  155  is preferably a molded polymer that has a smooth inner surface and an index of below about 1.33 (somewhat below that of water) to enable TIR to occur. A suitable polymer is MY-133-V2000, available from MY Polymers Ltd, or Topas&#39; 8007 polymer available from Topas Advanced Polymers, GmbH. Other polymers with other suitable indices are also available. With TIR, there is essentially no reflective loss (reflectivity &gt;99.5%), as compared to a reflective material such as a polished metal (reflectivity about 90-95%). The liner  155  is not considered a reflector and may be transparent. The UVC light continually reflects off the water/liner  155  interface until absorbed by the microorganisms or becomes attenuated by particles in the water  164 . 
     Locating the LEDs  152  in the bottom, such as molded into the bottom of the polymer liner  155  for protection, enables the UVC light to always be reflected within any amount of water and at the top air/water interface. In another embodiment, the UVC LED  152  is encapsulated within a lens and affixed to an inner wall of the liner  155  to minimize waveguiding within the liner  155 . If the UVC LED  152  is affixed to the inner wall of the liner  155 , any electrical connection to a power source may be made by running conductors through a sealed hole in the liner  155 . 
     The outer wall  158  of the liner  155  may be a deposited reflective metal film  158  over the polymer, such as aluminum, chrome, or silver, to reflect back any light that was above the critical angle and passed through the transparent polymer liner  155 . To mitigate the effects of waveguiding within the transparent polymer liner  155 , the outer surface may include molded prisms or roughening to cause the reflected light to be at a wide variety of angles to increase the percentage of UVC light that is reflected back into the water  164 . 
     A dose of 2000-8000 μW·s/cm −2  is known to kill the target microorganisms. 
     A small controller circuit  166  includes a replaceable battery, a switch, and a timer. A solar cell may also be included for recharging the battery. Once the user fills the vessel with water, such as from a stream, the user presses the switch, and power is applied to the LEDs  152  for a predetermined time deemed needed to kill the microorganisms. The timer may be settable, depending on the source of the water. Alternatively, the LEDs  152  are automatically energized whenever the controller circuit  166  senses that the cap  167  has been opened then closed. A dosage detector may also be incorporated in the vessel to measure the cumulative amount of UVC energy supplied to the water. After a threshold is reached, the dosage detector controls the UVC LEDs to turn off.  FIG. 11  illustrates a possible embodiment of the controller circuit  166 . 
       FIG. 13  is a bisected view of another portable cylindrical water vessel  170  with an integral UVC LED source  152  at the bottom, where the light is reflected off an air/gap interface by TIR to disinfect the liquid. An outer wall  156  may be aluminum. Between the outer wall  156  and the transparent polymer liner  174  is an air gap  175  (index of refraction about 1). The liner  174  may be the same polymer described with respect to  FIG. 12  except that the outer wall of the liner  174  is not covered by a reflective material, since the reflection off the outer wall of the liner  174  is by the more efficient TIR. A light ray  176  from the LEDs  152  is shown reflecting off the air/liner  174  interface by TIR. Light is also reflected off the inner wall of the liner  174  by TIR, as shown in  FIG. 12 . The aluminum outer wall  156  may have a polished inner surface to reflect light that passed through the liner  174  back into the water  164 . 
       FIG. 14  is a bisected view of a water vessel  188  similar to that of  FIG. 12  but where the LEDs  152 A and  152 B are located within the side walls of the transparent liner  155 . LEDs  152  may also be at the bottom. Adding LEDs in different locations allows more UVC coverage within the vessel, which reduces the required time for disinfection. A UVC light ray  190  is shown. 
     This technique of mounting the LEDs  152 A and  152 B on the side walls and using TIR may be also used when the vessel is a pipe that transports water between an input and an output, such as shown in  FIGS. 8-10 . The embodiments of  FIGS. 14 and 15  may easily be converted to pipe portions that are used to disinfect water running through the pipe. 
       FIG. 15  is a bisected view of a portable water vessel  200  similar to that of  FIG. 13  but where the LEDs  152 A and  152 B are located within the side walls of the transparent liner  174 . The TIR and other reflection features are the same as in  FIG. 13 . 
     Having described the invention in detail, those skilled in the art will appreciate that, given the present disclosure, modifications may be made to the invention without departing from the spirit of the inventive concept described herein. In particular, different features and components of the different devices described herein may be used in any of the other devices, or features and components may be omitted from any of the devices. A characteristic of, for example, the optic, described in the context of one embodiment, may be applicable to any embodiment. Suitable materials described for a particular component in a particular embodiment may be used for other components, and/or in other embodiments. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.