GB2602293A - UVGI Unit - Google Patents

Abstract

A decontamination device 100, comprising one or more enclosures, wherein the enclosures are configured to receive one or more objects, one or more LEDs 105 configured to emit UV radiation into the enclosures, a timer configured to control the duration of operation of each of the LEDs, one or more UV detectors 112, wherein each of the one or more UV detectors is configured to measure the level of UV irradiation, and a processor in communication with the timer and the one or more UV detectors, wherein the processor is configured to calculate a duration for which the LEDs are operational using a measured UV irradiation and a predetermined UV dosage, wherein the predetermined UV dosage delivers a known log reduction of contamination. A decontamination device comprising one or more enclosures, a plurality of LEDs arranged to emit UVC radiation into the enclosures, a sensor configured to sense whether the closure is closed, a switchlock configured for selective engagement of a power switch and a controller configured to supply power to the LEDs when the closure is closed.

Description

UVGI Unit

Technical Field of the Invention

The present invention relates to a decontamination device for decontaminating objects. More specifically, the invention relates to a cabinet or other receptacle within which objects undergo surface purification/disinfection by ultraviolet radiation.

Background of the Invention

It is well known that UVC radiation can be used for disinfection and sterilisation. Related methods are often referred to as UV germicidal irradiation (UVGI). UVC radiation (i.e. UV radiation in the C band, having a wavelength between approximately 100nm and 280nm) kills or inactivates microorganisms and pathogens by destroying the nucleic acids and disrupting their DNA, thus rendering them unable to perform vital cellular function.

Log reduction is a measure of the relative extent of disinfection. It is generally defined as the common logarithm of the ratio of the level of contamination before a decontamination process and after the decontamination process. A log reduction factor denotes the percentage reduction of decontamination, as exemplified below: Log reduction Relative number of colony forming units (CFUs) % reduction Times smaller 0 log (Log0) 1 00000 0% N/A 2 log (Log2) 10 000 99% x 100 4 log (Log4) 100 99.99% x 10 000 6 log (Log6) 1 99.9999% x 1000000 The higher the log reduction factor, the greater the extent of disinfection.

In UVGI disinfection methods, the effectiveness of disinfection is dependent upon UVC dosage (in Joules per unit area). UV dosage is the product of UV irradiance (in Watts per unit area, and sometimes also known as intensity) and exposure time (in seconds or milliseconds). UV irradiance is the power received on a surface per unit area. Therefore the output power of the UVC source and the distance between the object or entity to be sterilised and the UVC source will determine UV irradiation for any given application. Additionally, to achieve a specified log reduction factor (e.g. 1, 2, 3, 4, 5 or 6), the UV dosage required will differ for different microbes. For example, to achieve a 90% (log 1) reduction, it has been determined that the Murine Coronavirus requires a dosage of 7 J/m2 but that the SARS Coronavirus Hanoi requires a dosage of 134 J/m2. For E.coli, a 54 J/cm2 dose achieves log 1 reduction (90%), but a 216 J/cm2 achieves a log 4 reduction (99.99%). Accordingly, for a known UV irradiation value, the duration of exposure determines the UV dosage delivered. The UV dosage can therefore be specified in order to achieve a specified log reduction factor to kill or render inactive different CFUs or classifications on CFUs. The exposure time can be adjusted to achieve a different log reduction factor.

Many UVGI systems often use mercury-based lamps to generate UVC radiation. Mercury is a highly toxic metal which can have adverse effects on living organisms and the environment. An EU regulation came into effect in May 2017 to attempt to eliminate mercury-added products (Mercury regulation 2017/852/EU). As well as being dangerous, mercury-based UVC lamps are also susceptible to damage and generally have a useful life of just a few hundred hours. Furthermore, since most UVC lamps emit radiation in all directions, attempting to focus the direction of radiation usually results in energy wastage. Moreover, mercury-based UVC lamps are generally bulky and consume considerable power, making them difficult and expensive to use. They also require time to 'warm up'; i.e. to reach maximum UV irradiation output. This can mean that calculations for UV dosage are often inaccurate, which may ultimately jeopardise the efficacy of any disinfection operation they are used for.

US2013335027A1 discloses a mobile electronic device kiosk which provides UV sterilisation. Each compartment in the kiosk includes a UV source, such as one or more low wattage UV LEDs, located on the inner side of the compartment. Many such low wattage LEDS would be required to achieve an adequate level of disinfection, and for a kiosk containing many compartments, the component and servicing costs of such a large number of LEDs will be significant.

It is an aim of the present invention to overcome, or at least mitigate, drawbacks of the prior art.

Summary of the Invention

According to a first aspect of the invention, there is provided a decontamination device, comprising one or more enclosures, wherein each of the one or more enclosures are configured to receive one or more objects to be disinfected, one or more LEDs configured to emit UVC radiation into the one or more enclosures, a timer configured to control the duration of operation of each of the one or more LEDs, one or more UV detectors, wherein each of the one or more UV detectors is configured to measure UV irradiation in the one or more enclosures, a processor in communication with the timer and the one or more UV detectors, wherein the processor is configured to calculate a duration of operation of each of the one or more LEDs based on a measured UV irradiance and a predetermined UV dosage. Accordingly, the timer duration is set per disinfection cycle and compensates for UVC absorption by objects within the enclosure to ensure a predetermined UV dosage is delivered. Preferably, the calculation is the predetermined UV dosage divided by the measured level of UV irradiation.

Optionally, each of the one or more enclosures are defined by a plurality of surfaces, wherein at least one of the surfaces is configured to reflect at least 70% of at least one wavelength of the incident UVC radiation, wherein the at least one wavelength is between 100nm and 280nm. This increases the efficacy of the LEDs, since less radiation is absorbed by interior surfaces of the enclosure. Preferably, the at least one surface is configured to diffusely reflect at least 85% of incident UVC radiation having a wavelength between substantially 100nm and 280nm. The at least one surface may be comprised of porous polytetrafluoroethylene.

The device may further facilitate the selection of a log reduction of contamination from a plurality of log reduction factors. This may be by depression of a DIP switch on a PCB, wherein one of a plurality of DIP switches is operable to select a predetermined UV dosage delivered by a predetermined duration of operation of each of the LEDs.

Preferably, the device comprises at least one door reed switch between the closure and a wall of the housing and a switch lock, wherein the device is preferably configured to supply power to the LEDs only when the switch lock is engaged and the one or more door reed switches are closed. Engagement of the switch lock to 'on' may complete a power circuit which supplies power to the LEDs. The switch of the switch lock is preferably therefore a power switch.

Optionally, at least one of the one or more enclosures comprise a shelf, wherein the shelf allows UVC radiation having a wavelength between substantially 100nm and 280nm to pass through it. The shelf may be comprised of fused quartz or cyclic olefin copolymer (COC).

The processor may be configured to calculate the duration based on the lowest UV irradiance value measured by an individual UV detector.

According to a second aspect of the invention, there is provided a method, comprising measuring the UV irradiance in an enclosure, wherein the enclosure is illuminated by UVC radiation emitted by one or more LEDs, calculating an LED operating duration based on the measured UV irradiance and a predetermined UV dosage, wherein the predetermined UV dosage delivers a known log reduction of contamination, and operating the LEDs for the calculated duration, wherein operating the one or more LEDs for the calculated duration delivers the predetermined UV dosage.

According to a further aspect of the invention, there is provided a decontamination device, comprising one or more enclosures, wherein each enclosure is defined by a housing and a closure, and wherein each enclosure is arranged to receive one or more items to be disinfected, a plurality of LEDs arranged to emit UVC radiation into at least one of the plurality of enclosures, at least one sensor between the closure and a wall of the housing of at least one or the one or more enclosures, wherein the sensor is configured to sense whether the closure is closed, a lock configured to lock the closure of an enclosure, and a controller in communication with the at least one sensor and the lock, wherein the controller is configured to supply power to the LEDs when it is determined that the lock is locked and the at least one closure is closed. This ensures safe operation of the device by preventing operation of the LEDs unless the closure is secure.

Preferably, the device further comprises a timer configured to control operation of one or more of the LEDs of the plurality of LEDs to deliver a first predetermined UV dosage to items housed in one or more of the one or more enclosures, wherein the predetermined UV dosage delivers a first known log reduction of contamination.

Optionally, each enclosure comprises a plurality of interior surfaces, wherein at least one of the plurality of interior surfaces is configured to reflect at least 70% of incident UVC radiation, wherein the at least one wavelength is between 100nm and 280nm. Reflective surfaces 'recycle' the radiation output by the LEDs and ensure surfaces of items in the enclosures receive omnidirectional UVC radiation.

Preferably, one or more UVC detectors are in communication with the controller, wherein the one or more UVC detectors are configured to detect UVC radiation in the one or more enclosures. The controller and/or one or more UVC sensors may be configured to measure the UV irradiance in an enclosure, wherein the controller is configured to a duration of operation of the LEDs based on the measured UV irradiation and a predetermined UV dosage.

The device may further comprise means for selecting a log reduction factor for disinfection, wherein each selectable log reduction factor specifies a different predetermined UV dosage. The device may further comprise means for securing keys, and may be a key cabinet.

According to a further aspect of the invention, there is provided a disinfection device, comprising an enclosure defined by one or more surfaces, wherein the enclosure is configured to house one or more objects to be disinfected; a plurality of LEDs arranged to emit UVC radiation into the enclosure; wherein at least a portion of at least one of the one or more surfaces is configured to reflect at least 70% of incident radiation having a wavelength between 100nm and 280nm. Preferably, at least 80% of at least one of the one or more surfaces is configured to diffusely reflect at least 70% of incident radiation.

According to a yet further aspect of the invention, there is provided a decontamination device, comprising a housing comprising a plurality of walls and a closure, wherein the plurality of walls and closure comprise surfaces defining an enclosure, wherein the enclosure is configured to house objects to be decontaminated; a plurality of LEDs arranged to emit UVC radiation into the enclosure, wherein at least one of the surfaces is configured to reflect at least 70% of at least one wavelength of the incident UVC radiation, wherein the at least one wavelength is between 100nm and 280nm, and a timer, wherein the timer specifies a duration of operation of the LEDs to deliver a first predetermined UV dosage to objects housed in the enclosure, wherein the predetermined UV dosage delivers a first known log reduction of contamination.

Preferably, the device further comprises one or more UVC sensors configured to detect UVC radiation and a processor in communication with the one or more UVC sensors, wherein the processor and/or one or more UVC sensors is configured to determine a UV irradiance value, wherein the processor is configured to calculate a duration of operation of the LEDs based on the predetermined UV dosage and a measured UV irradiance. The sensors may also detect visible light.

Optionally, a printed circuit board of the device comprises one or more DIP switches, wherein one of the one or more DIP switches is operable to select a second predetermined UV dosage to objects housed in the enclosure, wherein the second predetermined UV dosage delivers a second known log reduction factor for decontamination.

At least one surface may be configured to diffusely reflect at least 85% of incident UVC radiation having a wavelength between substantially 100nm and 280nm. The at least one surface may be comprised of porous polytetrafluoroethylene. At least 4 of the surfaces may be configured to reflect at least 70% of incident UVC radiation.

Optionally, the LEDs are arranged on at least one LED surface, wherein the at least one LED surface is comprised in a heatsink.

The device may further comprise at least one door reed switch between the closure and a wall of the housing and a power switchlock, wherein the device is configured to supply power to the LEDs only when the switch of the switchlock is 'on' and the one or more door reed switches are closed.

Preferably, the enclosure comprises a shelf, wherein the shelf allows UVC radiation having a wavelength between substantially 100nm and 280nm to pass through it. The shelf may be comprised of fused quartz or cyclic olefin copolymer (COC).

The device may further comprise means for securing keys.

According to a further aspect of the invention, there is provided a device for disinfecting objects, comprising a housing comprising a plurality of walls and a closure, wherein the plurality of walls and closure comprise surfaces which define an enclosure, wherein the enclosure is configured to house objects to be disinfected; a plurality of LEDs arranged to emit UVC radiation into the enclosure, wherein the at least one of the surfaces is configured to reflect at least 70% of incident radiation having a wavelength within the UV-C range, and a controller, wherein the controller comprises means for selecting a log reduction factor for disinfection, wherein a selectable log reduction factor specifies a UV dosage, and wherein controller is further configured to calculate a duration of operation of the LEDs based on the UV dosage and a measured UV irradiance.

Preferably, the controller comprises an asset register, wherein the controller is configured to selectively control operation of one or more LEDs and /or duration of operation of the one or more LEDs based on asset register information.

According to a further aspect of the invention, there is provided a device for disinfecting items comprising a plurality of compartments, wherein each compartment is arranged to receive one or more assets to be disinfected, wherein each compartment comprises a plurality of interior surfaces, wherein at least one of the plurality of interior surfaces is configured to reflect at least 70% of incident UVC radiation; a plurality of LEDs arranged to emit UVC radiation into at least one of the plurality of compartments; and a controller, wherein the controller is configured to record compartment use information relating to use of each compartment, wherein the controller is configured to selectively control operation of one or more of the LEDs of the plurality of LEDs according to the use information to deliver a predetermined UV dosage to one or more items in one or more compartments.

According to a further aspect of the invention, there is provided a method of designing a UVGI device, comprising modelling a UVC irradiance distribution in an enclosure defined by one or more interior surfaces, wherein the model is based on a set of variables comprising: dimensions of the enclosure; the number, arrangement and UVC power output of UVC LEDs which direct UVC radiation into the enclosure, a reflectivity value for one or more of the one or more interior surfaces, wherein the reflectivity value is a percentage of incident UVC radiation within a wavelength range that is reflected; for a set of variables, calculating a duration of operation of the LEDs required to deliver a defined UV dosage; and generating a design in accordance with the set of variables and the calculated duration. Optionally, the method further comprises manufacturing a UVGI device according to the design.

Preferable features of the invention are defined in the appended dependent claims.

Brief description of the drawings

The invention will be described with reference to the drawings in which: Figure 1 is a front view of a UVGI disinfection unit; Figure 2 is an isometric view of the disinfection unit of figure 1; Figure 3 is a side view of the disinfection unit of figure 1; Figure 4 is a sectional view along section A-A of figure 1; Figure 5 is a further sectional view along section A-A of figure 1; Figure 6 is a further sectional view of a disinfection unit; Figure 7 is a diagram showing LED fixture positions on a heat sink interior surface of a disinfection unit; Figure 8 is a diagram of irradiance distribution on an interior surface of a disinfection unit caused by radiation output by LEDs according to the LED arrangement of Figure 7; Figure 9 is a schematic of an interlock wiring design; Figure 10 is a schematic representation of data and power transfer for operation of a disinfection unit; Figure 11 is a schematic representation of data and power transfer for operation of a disinfection unit with controller; Figure 12 is a schematic representation of data and power transfer for operation of a controller for a disinfection unit; Figure 13a is a front view of a UVGI disinfection unit having multiple enclosures; and Figure 13b is a side view of the disinfection unit of figure 13a.

Detailed description

The present invention utilises light emitting diodes (LEDs) to generate UVC radiation having a wavelength less than 280nm. Beneficially, LEDs do not require a 'warm-up', but rather achieve maximum power output near-instantaneously and have a long usable life (over 20,000 hours).

Because of their immediacy, the duration of operation of the LEDs can be easily and accurately controlled. Most UVC LEDs are manufactured such that the direction of emittance is generally hemispherical, thereby providing a degree of control over the direction of irradiation. By employing specific silicon based optics, the beam pattern of the LED output can be changed to allow the irradiation to be concentrated in a specific location or area.

A front view of a UVGI disinfection unit 100 is shown in Figure 1 and a side view is shown in Figure 3. Cabinet 100 comprises two main structural parts -enclosure 101 and plinth 102. Enclosure 101 comprises a door 103 and handle 104 to provide access to the interior of enclosure 101. Instead of or in additional to handle 104, a switch lock and/or manual lever latch (not shown) may also be affixed to or integral with door 103. Enclosure 101 defines a sealed cavity when door 103 is closed. In Figures 1 to 5, door 103 may be opaque. In an alternative embodiment of the invention, door 103 is transparent to allow the contents of the enclosure to be visible. Ninth 102 may house a power supply unit (PSU), relay timer, door interlock control and LED drivers, as will be described in further detail below.

Enclosure 101 is shown in more detail in Figures 2 and 4. Heatsink 106 is affixed to door 103 and lies adjacent to the interior surface of door 103. Heatsink 106 and door 103 are separated by airgap 113. Surface 108 of heatsink 106 comprises a plurality of LED strips 105 on which one or more LEDs are attached. The LEDs are preferably WICOP (Wafer level Integrated Chip On PCB) LEDs which allow for direct connection of the LED chip to a PCB. As such, no packaging (such as die or wire bonding) is required, making them very small. The LEDs face the interior of enclosure 101. Heatsink 106 draws away and dissipates heat generated by the LEDs to prevent the LEDs from overheating, which reduces their output intensity and lifespan. An increase of 20 degrees centigrade can halve the lifespan of an LED. Heatsink 106 thus maintains the LEDs below a predetermined operational temperature. The number and positioning of LEDs will be determined according to the size and shape of the cabinet, the output intensity of the LEDs chosen, the number of surfaces which reflect radiation emitted by the LEDs and the reflectance of those interior surfaces, along with other possible variables.

Also disposed on surface 108 of heatsink 106 are spectral detectors 112. Spectral detectors 112 are photodiodes which are configured to detect UVC radiation and measure UV irradiance, based on the amplitude of current generated. One or more of the spectral detectors may also be configured to measure the temperature of, for example, the heat sink, to ensure that the LEDs do not exceed their maximum operating temperature. Using knowledge of the irradiation distribution for a specific enclosure (as discussed below) and the location of the spectral detector, the measured UV irradiance can indicate that an LED has failed or is malfunctioning if the measured UV irradiance is below a known value. This allows for the adjustment of the duration for which the LEDs are operational in order to achieve a required log reduction factor, and may also indicate the need for replacement of one or more LEDs. Spectral detectors 112 therefore enable the determination of whether a disinfection cycle is in process (i.e. whether the LEDs are on) and also whether there is degradation or malfunction of individual LEDs. Additionally, spectral detectors 112 may also detect visible light, and their output can therefore indicate whether door 103 is open. Over time, regular UV irradiation measurements from spectral detectors 112 could be used to monitor variations in UV irradiance to ensure that the measured UV irradiance and 'on' duration of the LEDs achieve the required log reduction factor. For example, if, over time, the UV irradiation measured by spectral detectors 112 gradually decreases, a timer which controls the on' duration of the LEDs can be adjusted accordingly to ensure a specified log reduction factor is actually being achieved. The precise positioning and number of spectral detectors 112 will be chosen according to the size and shape of enclosure 101, the number of LEDs and the measurement range and sensitivity required.

Interior rear surface 109 of enclosure 101 (which directly faces surface 108 of heatsink 106 and LED strips 105) may comprise one or more peg holes within which a peg can be positioned. Alternatively, the peg holes may be comprised on a peg board which is separate from surface 109, and may be spaced from rear surface 109. The peg board may be at least partially constructed from a material that is transparent to UVC radiation, an example of which is discussed below. The peg may hold an object to be disinfected, for example a key. Alternatively, rear surface 109 may comprise an array of receptacles within which a key or fob (which may be attached to a key or other asset) can be inserted.

With reference to Figures 2 and 5, interior rear surfaces 109, interior top surface 116 and bottom surface 111, interior side surface 110, opposing interior side surface 117 (not shown) and surface 108 of heatsink 106 comprise a UVC reflective material which reflects between approximately 70% and 85% incident UVC radiation. The arrows within enclosure 101 in Figure 5 schematically show how the UVC radiation emitted by the LEDs traverses the depth of enclosure 101 and is reflected by surface 109 (and, to a lesser extent, surfaces 111, 116, 110 and 117). This reflected radiation is then incident on surfaces 111, 116, 110, 117 as well as heatsink interior surface 106.

Reflectance is generally defined as the fraction of incident radiation that is reflected at a boundary (in this case, the material of the interior surfaces of the cabinet) and is in general a function of the wavelength of the incident radiation. It is therefore possible to define a reflectance value (usually the percentage of incident radiation that is reflected) for a specific wavelength or wavelength range of incident radiation. Diffuse reflectance occurs when the reflected radiation is scattered at many angles The UVC reflective material is preferably porous PTFE (polytetrafluoroethylene). Beneficially, porous PTFE has diffuse reflectivity characteristics (and can provide Lambertain reflection in the UVC range).

It is well-suited for use LEDs as in the present invention because its highly diffuse reflective properties scatter the narrow, directional light from the LEDs. This results in more uniform illuminance with the enclosure. The UVC reflective material may also be polished aluminium or stainless steel, although these provide less diffuse reflection (and more specular reflection) than porous PTFR. The diffuse reflectivity of porous PTFE can be several times greater than the diffuse reflectivity of aluminium or stainless steel. Porous PTFE is also resistance to degradation.

The porous PTFE may be a sintered PTFE which can provide greater than 90% diffuse reflection in the UVC wavelength range (generally between 100nm to 280nm). Sintered PTFE it omnidirectional. As such, and as long as rear interior surface 109 receives incident UVC radiation, the surface of objects in enclosure 101 facing rear interior surface 109 will be disinfected. This may not necessarily be the case with a mirror-polished rear interior surface 109 which may simply reflect the UVC back to heatsink 106. Accordingly, in an embodiment where all interior surfaces of enclosure 101 are covered with a sintered PTFE, UVC radiation will be scattered within enclosure 101 until it hits a non-reflecting object or other non-reflecting item or part in enclosure 101. It will therefore be appreciated that the greater the interior surface area covered by a highly reflective material, the fewer LEDs required.

The internal reflectance of UVC radiation emitted from the LEDs has a number of advantages. It 'recycles' the radiation within enclosure 101 to create a uniform distribution of irradiation, which results in the need for fewer LEDs to achieve effective UV irradiation, thus reducing manufacturing costs and power consumption. Additionally, the reflectance of the UVC radiation in all directions means that UVC radiation is incident on an object in enclosure 101 from all directions. Crucially, this improves the disinfection of the object because it is uniformly exposed to UVC radiation. In some embodiments, only a portion of one or more interior surfaces of enclosure 101 comprises a material which reflects UVC radiation. In other embodiments, the entire area of some interior surfaces may comprise a reflective material, but other interior surfaces do not. However, having the greatest internal surface area comprised of a reflective material is advantageous to maximise efficacy of the UVC radiation output by the LEDs.

Another embodiment of the invention is shown in Figure 6. The structure of unit 100 is the same as that described with reference to Figure 5. In the embodiment of Figure 6, shelf 115 is positioned horizontally within enclosure 101. It may be affixed to rear wall and/or the side walls of cabinet 101. LED strips 105 are positioned on upper heatsink 106a which lies adjacent to the top interior surface 116 and lower heatsink 106b which lies adjacent to lower interior surface 111. Interior surfaces 108, 109, 110, 117 as well as the surfaces of heatsinks 106a and 106b are comprised of a material which reflects preferably at least 70% of UVC radiation.

Shelf 115 provides a surface on which objects to be disinfected can be placed, and may be a shelf, moulded container or other structure on which objects to be disinfected can be hung or otherwise supported within enclosure 101. Shelf 115 is preferably comprised of fused quartz/silica glass. Fused silica is close to 100% UV transparency, so that radiation directed towards an object on shelf 115 is not impeded by shelf 115. Shelf 115 may also be comprised of a cyclic olefin copolymer (COC) material, such as TOPASu 8007S-04 which is transparent, medical-grade and can be processed by injection molding. A Teflon" AF (amorphous fluoropolymer) resin may also be used for shelf 115 or any other container or structure in enclosure 101. Shelf 115 may alternatively comprise a chrome plated open mesh.

Spectral detectors 112 are positioned on rear interior surface 109 and are generally vertically equidistant from shelf 115. As shown by the arrows within enclosure 101 in Figure 6, radiation emitted by the LEDs is generally directed upwards towards shelf 115 and downwards toward shelf 115. The emitted UVC radiation is reflected by surfaces 108, 109 and the surfaces of heatsinks 106a and 106b.

The results of a simulation of the irradiance distribution achieved by an exemplary LED arrangement in an enclosure having maximum reflective interior surface area is shown in Figure 8. Figure 7 depicts three LEDs positioned on an interior surface of enclosure 101, such as on surface 108 as shown in Figure 5. The three LEDs are horizontally aligned and equally spaced across the width of the interior surface, each having an equal vertical position. As can be seen from Figure 8, the highest irradiance (in mW/cm2) is shown by a dipole-shaped region surrounding the central LED. The intensity decreases generally uniformly with distance from the LEDs. Measurements from two spectral detectors confirm the reduction in irradiance with distance.

Since the UV dosage required to 'kill' or otherwise render inactive various pathogens is known, it is possible to calculate the duration of time of activation of the LEDs to achieve a particular log reduction factor for a specific arrangement of LEDs and size/shape of enclosure. Simulation software (such as that used to generate the data in Figure 8) can calculate an irradiance distribution using enclosure dimensions, reflectivity percentage, the number of LEDs, the location of the LEDs and their output power. In the present invention, such simulations were run to determine numbers and arrangements of LEDs in an enclosure having a known shape and size (and with reflective interior surfaces) that would deliver a UV dosage of 200 J/m2 in a known time (i.e. a specific log reduction factor). Since the UV dosage required to achieve different log reduction factors for an array of pathogens is known, the duration of operation of the LEDs to achieve those different log reduction factors can be determined.

For example, the simulations were based on delivering a target minimum UV dosage of 200 J/m2 (log 2). Input parameters were then adjusted to determine a practical combination of LED quantity and positions, LED 'on' duration and enclosure dimensions that would deliver a minimum dosage of 200 J/m2. For a particular combination (i.e. for known cabinet dimensions, reflectivity surface area and number, position and output power of LEDs), a maximum UV dosage of 200J/m2 was delivered in approximately 7 seconds. For many pathogens, this UV dosage results in a log reduction factor of 2 (log 2). For the same model, a 400J/m2 dosage would take about 14 seconds (the level recommended for surface sterilisation, and which results in a log 3 reduction). To achieve log 4 reduction, the time/duration would increase to approximately 28 seconds.

Exemplary system components enabling UVGI unit operation are shown in Figure 9. The interlock system of Figure 9 comprises 3 LED strips 123, each comprising 24 LEDs. It will be appreciated from the discussion above that the number of LED strips and the number of LEDs per strip will be dependent upon the dimension of the cabinet and the reflectivity of the internal surfaces of enclosure 101, amongst other factors. Each strip has a corresponding driver 124.

Switch 121 is preferably a switch lock. Switch locks require a key in order to engage or disengage a switch (i.e. turn the switch on or off). Engagement of switch 121 completes a circuit to allow mains power to be supplied to driver 123. Door reed switches 120 between door 103 and enclosure 101 detect secure closure of door 103. As is known in the art, a closed door reed switch closes a circuit.

Monitoring the status of the circuit (i.e. closed/activated or open/deactivated) enables determination of whether or not the door is properly closed. Timer PCB 135 monitors the status of power switch 121 and door reed switches 120. When switches 120 and 121 are on (and thus power is supplied to driver 124), timer PCB 135 outputs a light as a visual indication that the LEDs are on and door 103 is closed.

Moreover, disengagement of switch 121 breaks the LED power safety circuit. When the disinfection cycle is finished, switch 121 can be disengaged and the key can be removed.

Figure 10 shows wiring to connect components in a UVGI disinfection unit which comprises enclosure 101, plinth 102 and heatsink 106. It will be appreciated from the discussion above that the physical location of heatsink 106 is in enclosure 101. Power supply unit 131 in plinth 102 receives 110-240V AC mains power and supplies 12V DC to reed switches 120 in enclosure 101 and timer PCB 135. DIN rail relay 137 receives110-240V AC mains power and controls power to LED drivers 123 according to timer PCB 135. Timer PCB 135 comprises an onboard seven-segment display. DIN rail relay 137 is switched on by timer PCB 135 only once switch 121 is engaged to provide 240V to the LED drivers 123, which in turn provides a pre-determined constant current supply to LED strip 105 in heatsink 106. The timer on timer PCB 135 is therefore activated once the LED power safety circuit has been completed by engagement of one or more switch locks (such as switch 121) and engagement of an array of two or more magnetic proximity sensors (such as door reed switches 120) and specifies the duration for which LEDs are 'on' per disinfection cycle. The duration of the timer is set according to the log reduction factor selected by DIP switch on the timer PCB 135 and its progress is output to the seven-segment display. Once the timer reaches 0, a LED will light up on the timer PCB to indicate that the disinfection cycle is complete and that the operator can open door 103 and retrieve the objects in enclosure 101. In certain environments, multiple units 100 may be connected to each other. In this case, only the LEDs of units whose doors are shut (and therefore the LED driver circuit is complete) will operate.

To disinfect objects using unit 100, a user opens door 103 by pulling handle 104 or by operating a manual lever latch and places items to be disinfected inside enclosure 101. The user then shuts door 103 (and turns the handle to a closed position if a manual latch is present). Shutting door 103 closes magnetic proximity sensors 120. The user then inserts a key into the switch lock and turns the key to turn a power switch to an 'on' position. This completes the power circuit, such that power is delivered to timer PCB 135 via a second reed switch 120. Timer PCB 135 sends power to LED drivers 123 to turn on LED strip 105. Switch 121 can stay in the 'on' position and if the circuit is completed again, the system will power up. If the power switch is turned to off or the door opened at any point, the circuit will be broken and the system immediately powered off.

In view of the discussion above with regard to Figure 8, and because UV dosage = irradiance*time, it will be understood that timer duration and irradiance can be varied to result in a specific UV dosage.

Experiments using LEDs in a reflective chamber have shown that 2.8mW/cm2 is an irradiance value which delivers a UV dosage of 20 m.1/cm2 (log 2) in 7.12 seconds, and a UV dosage of 320m1/cm2 (log 6) in 113.92 seconds. A higher or lower irradiance value will obviously require more or less time to achieve the required UV dosage but is achievable for the UV application described herein; i.e. disinfection cabinets.

Once the LEDs are switched on, readings from the one or more spectral detectors inside the cabinet take a near-instantaneous measurement of UV irradiance inside the cabinet. In a preferred embodiment, each cabinet comprises four spectral detectors. The output from the spectral detectors is sent to timer PCB 135. Timer PCB 135 bases the following calculation on the lowest reading from the spectral detectors; the lowest UV irradiance detected (in W/cm2, the equivalent of which is J/s/cm2). The firmware of the timer PCB stores the UV dosage corresponding to each log reduction factor. Timer PCB 135 calculates a timer duration for each cycle, based on the lowest spectral detector measurement, by dividing the required UV dosage for the target/specified log reduction factor by the lowest measured irradiation. For example, if the target log reduction factor is 2 (20mJ/cm2) and the measured average irradiation is 2.2mW/cm2, then the timer duration required for achieving the target dosage is 20/2.2 = 9.9 seconds (i.e. higher than 7.14s which would deliver the required UV dosage at the preset irradiation value). If the target log reduction factor is 2 (20mJ/cm2) and the measured average irradiation is 3 mW/cm2, then the timer duration required for achieving the target dosage is 20/3 = 6.6 seconds. In an alternative embodiment, the maximum irradiance value is taken to be the preset irradiation value -if the lowest measured irradiance is greater than 2.8 mW/cm2, timer PCB will use 2.8 mW/cm2 in its calculation of the timer duration.

Timer PCB 135 therefore calculates a timer duration for every disinfection cycle. The LEDS are operational for the calculated duration to deliver a specific log reduction of contamination, regardless of whether the items inside the cabinet have absorbed any UV radiation, or indeed whether one or more of the LEDs are faulty. Indeed, the timer calculated has accounted for any absorption of UV radiation by items inside the cabinet by using the irradiance measured by the spectral detectors. Different items will have different effects on the measured UV irradiance in a cabinet/enclosure. For example, an item of personal protective equipment (PPE) may absorb more UVC radiation than a medical instrument.

The calculated timer duration will be displayed on the seven segment display. The timer counts down and a red light on timer PCB 135 lights up to indicate that a disinfection cycle is in progress and the display counts down in the remaining timer duration in red. When the timer countdown reaches 0, the timer PCB 135 will no longer deliver power to LED drivers 123 and a green LED will be illuminated on timer PCB 135 to indicate that the disinfection cycle is complete. Door 103 can then be opened.

If the calculated timer duration is above a threshold value, the seven segment display will output ERR to notify the user of the error and the timer will end immediately. A red LED on timer PCB 135 will flash until the unit is opened and the power circuit to LED driver 123 is broken.

Timer PCB 135 controls operation of cabinet 100 as described above and does not require an additional controller. The LEDs are operational for the calculated time, and a disinfection cycle (i.e. the duration for which the LEDs are on continuously) only begins when door reed switches 120 and switch 121 are closed/engaged. A unit comprising an enclosure and plinth can therefore be used 'offthe-shelf' to disinfect objects to a specified log reduction factor. Different log reduction factors can be selected via a DIP switch on timer PCB 135. To ensure unit 100 continues, over time, to decontaminate effectively (and thus provide user assurance and quality), the UVC irradiance measurement derived from sensors 112 may be analysed to identify a trend in measured UV irradiance, which may indicate degradation of materials.

Routine 'clean' cycles may also be specified in firmware. A 'clean' disinfection cycle is one which runs for a predetermined time period to disinfect an empty enclosure. Such a 'clean' cycle may be run after a set number of disinfection cycles (which may be log factor reduction-specific or otherwise) or after a cumulative duration for which the LEDs are on (which may approximate a specific number of cycles).

Figure 11 is a schematic showing power and data transfer for a UVGI unit according to an embodiment of the invention. Figure 11 shows a disinfection unit comprising an enclosure 101, plinth 102, controller 128 and heatsink 106. It will be appreciated from the discussion above that the physical location of heatsink 106 is in enclosure 101. Controller 128 comprises a single board computer (SBC) 141 which receives 12V DC power from power distribution PCB 133 in enclosure 101. As will be discussed further below, SBC 141 receives user control data. PSU 131 in plinth 102 receives 240V AC input power and supplies 12V DC to both battery 136 and power distribution PCB 133 in enclosure 101. Power distribution PCB 133 also supplies 12V DC power to SBC 141, interface PCB 134, key track PCBs 151, 152 and door reed switches 120 (which in turn supply power to timer PCB 135 and relay 137). Interface PCB 134 receives and sends 12V DC power to door latch sensor 144.

Interface PCB 134 receives data from SBC 141 of controller 128 and sends data to key track PCBs 151 and 152. Key track PCBs 151 and 152 each control access to one or more keys or other objects which may be stored in unit 100. There may be any number of key tracks. A key track controls access to one or more keys in conjunction with an asset register. For example, each key track controls a locking mechanism which locks a fob (associated with a key or other asset) in a receptacle. Unlocking of the fob may only occur if specific criteria are met. In one embodiment, operation of one or more LEDs in enclosure 101 may be based on the operation of a key track, such that only the LED strips which are physically located closest to one or more keys/assets associated with a key track are operated if it is determined that assets have been returned to that particular key track with a predefined period of time, or which otherwise meet other criteria. Accordingly, LED strips or individual LEDs can be selectively operated according to information such as the relative distance between each LED and the location of the object/asset/key housed in enclosure 101 and information from an asset register. Selective control of individual LEDs and or LED strips may be achieved by using separate relays for each LED or LED strip.

In plinth 102, DIN rail relay 137 receives 240V main power and controls the supply of mains power to LED drivers 123 which supply a predetermined constant current to LED strips 105 in heatsink 106. Relay 137 is controlled by timer PCB 135. Timer PCB 135 receives instruction from interface PCB 134. Preferably, timer 135 has an associated seven-segment display which displays the countdown of timer 135 during operation of the LEDs. Timer countdown progress may also be output to a touchscreen of controller 128, as mentioned below.

Figure 12 shows wiring to connect components in controller 128. Controller 128 can be used with enclosures having different dimensions and specifications. Controller 128 comprises SBC 141 which receives 12V DC from power distribution PCB 133 in enclosure 101 and sends data to interface PCB 134 in enclosure 101. SCB 141 sends power to and exchanges data with any one or more user controls and interfaces such as touchscreen 136, fingerprint reader 137, card reader 138, keypad 139 and camera 140.

To disinfect items using a disinfection unit as exemplified by figure 11, a user first requires authorisation to access the cabinet, for example by identification checks using a personal identification number, fingerprint scan, etc. Via screen 138, the user may be prompted to select the door to be opened (in an embodiment where there are multiple enclosures). The user's selection is sent from SBC 141 to interface PCB 134 which in turn sends a command to unlock the selected door, and the user can then remove or deposit items and shuts the door. Once interface PCB 134 receives confirmation of completion of the lock circuit and SBC 141 has received an instruction to begin a disinfection cycle, interface PCB 134 sends power to timer PCB 135. A disinfection cycle may not necessarily be run every time the door is closed -one option available to the user may be 'no cycle'.

Once the LEDs are switched on, readings from spectral detectors 112 inside the cabinet or a compartment can be used to determine the UV irradiance inside the cabinet/compartment. The output from the spectral detectors is sent to timer PCB 135, which averages the value measured by each detector. As described above, timer PCB 135 calculates a timer duration for each cycle, based on the measurements from the spectral detectors, by dividing the required UV dosage for the target/specified log reduction factor by the measured irradiation.

If the calculated duration is above a preset value, the seven segment display will output ERR to notify the user of the error and the timer will end immediately. A red LED on timer PCB 135 will flash until the unit is opened and the power circuit to LED driver 123 is broken. Otherwise, the timer duration will be displayed on the seven segment display of timer PCB 135 before the timer countdown starts from the calculated duration. A red light on timer PCB 135 lights up to indicate that a disinfection cycle is in progress and the seven segment display counts down the remaining timer duration in red. When the timer countdown reaches 0, the timer PCB will no longer deliver power to LED drivers and a green LED will be illuminated on timer PCB 135 to indicate that the disinfection cycle is complete. The cabinet or compartment door can then be opened via the controller by a user with access.

Controller 128 can be used to enable selection of log reduction factors and control access to objects in the UVGI unit with use of a database and a user software application which permits user entry only at specific times and to specific doors/closures (in embodiments in which there are multiple lockers/compartments, as discussed below). Controller 128 may also allow for the specification of various criteria and timings, and/or the adjustment of the duration of operation of the LEDs per disinfection cycle, thus allowing for the adjustment of default log reduction factor, or for the choice of log reduction cycle per cycle, as may be required in different environments and for different objects or types of objects. For example, in a hospital, it may be that some types of equipment require disinfection to log factor 4 (e.g. face shields), but other types of equipment require only disinfection to log factor 2 (e.g. stationary).

Depending on the environment in which the disinfection unit is installed and the type of objects that it will disinfect, such criteria may specify a log 2 reduction factor for all cycles occurring between certain fixed hours in the day, and a log 6 ('super clean') cycle to occur at a different fixed hour (or at regularly fixed intervals), provided the door is properly closed, as per the safety protocols discussed above. Depending on the environment in which the disinfection unit is installed and the type of objects that it will disinfect, the controller may record the times at which a disinfection cycle is run, and the duration/log reduction factor, the person instructing the disinfection cycle, and, in conjunction with an asset register, which objects (from an array of objects in the enclosure) are removed, when and by whom. In conjunction with an asset monitoring system or asset register, controller 128 may also or alternatively monitor the number of door opening, door closing, door lock and door unlock events. As an example of this latter case, the rear wall of the enclosure may comprise an array of receptacles for receiving fobs (where each fob may be associated with a specific key). An asset register for such a case is described in the applicant's co-pending patent application GB 1919132.9.

Figures 13a and 13b show a further embodiment of the invention. Unit 200 comprises plinth 202 and cabinet 201 which comprises multiple enclosures 201a, 201b, 20k, 201d, having respective doors/closures 203a, 203b, 203c, 203d and lever locks 204a, 204b, 204c, 204d. Each enclosure can be opened, closed, locked and unlocked independently of other enclosures. A timer is associated with each enclosure, and the LEDs for enclosures whose doors are closed and locked will receive power. Each enclosure may have one or more associated spectral detectors, and the timer adjustment process as described above can also be implemented for individual enclosures.

The enclosures may be created by virtue of a quartz matrix structure, or a cyclic olefin copolymer (COC) material, which has similar UVC transmission properties to quartz (fused silica). The quartz allows UVC to traverse the matrix structure unhindered and thus disinfect objects in the enclosures in a manner described above. Alternatively, each enclosure has one or more reflective interior surfaces and is independently irradiated by one or more LEDs. When used in conjunction with an asset monitoring system, the controller can control operation of the LEDs such that only LEDs in recently-used sub-enclosures (e.g. where an asset has been registered as being returned to an enclosure) are turned on when a disinfection cycle is instructed. Similarly, the controller may instruct operation of a subset of the LEDs (and determine the log reduction factor of a cycle) according to who has recently accessed a particular sub-enclosure, what specific object or type of object was returned to the sub-enclosure, and how long the object or asset was absent from the sub-enclosure.

Claims (21)

1. Claims 1. A decontamination device, comprising one or more enclosures, wherein each of the one or more enclosures are configured to receive one or more objects to be disinfected, one or more LEDs configured to emit UV radiation into the one or more enclosures, a timer configured to control the duration of operation of each of the one or more LEDs, one or more UV detectors, wherein each of the one or more UV detectors is configured to measure the level of UV irradiation in the one or more enclosures, and a processor in communication with the timer and the one or more UV detectors, wherein the processor is configured to calculate a duration for which the LEDs are operational using a measured UV irradiation and a predetermined UV dosage, wherein the predetermined UV dosage delivers a known log reduction of contamination.
2. 2. The device of claim 1, wherein the calculation is the predetermined UV dosage divided by the measured level of UV irradiation.
3. 3. The device of claim 1 or claim 2, wherein each of the one or more enclosures are defined by a plurality of surfaces, wherein at least one of the surfaces is configured to reflect at least 70% of at least one wavelength of the incident UVC radiation, wherein the at least one wavelength is between 100nm and 280nm.
4. 4. The device of any preceding claim, wherein the at least one surface is configured to diffusely reflect at least 85% of incident UVC radiation having a wavelength between substantially 100nm and 280nm.
5. 5. The device of claim 4, wherein the at least one surface is comprised of porous polytetrafluoroethylene.
6. 6. The device of claim 2, further comprising a printed circuit board, wherein the printed circuit board comprises one or more DIP switches, and wherein one of the one or more DIP switches is operable to select a predetermined UV dosage.
7. 7. The device of any preceding claim, further comprising at least one door reed switch between the closure and a wall of the housing and a switchlock configured to allow selective engagement or disengagement of a power switch, wherein the device is configured to supply power to the LEDs only when the power switch is engaged and the one or more door reed switches are closed.
8. 8. The device of any preceding claim, wherein at least one of the one or more enclosures comprise a shelf, wherein the shelf allows UVC radiation having a wavelength between substantially 100nm and 280nm to pass through it.
9. 9. The device of claim 8, wherein the shelf is comprised of fused quartz.
10. 10. The device of claim 8, wherein the shelf is comprised of cyclic olefin copolymer (COC).
11. 11. The device of any preceding claim, wherein the calculation is based on the lowest UV irradiance measured by the one or more UV detectors.
12. 12. A method, comprising measuring the UV irradiance in an enclosure, wherein the enclosure is illuminated by UVC radiation emitted by one or more LEDs, calculating an LED operating duration based on the measured UV irradiance and a predetermined UV dosage, wherein the predetermined UV dosage delivers a known log reduction of contamination, and operating the LEDs for the calculated duration, wherein operating the one or more LEDs for the calculated duration delivers the predetermined UV dosage.
13. 13. A computer readable medium comprising executable instructions which, when executed by a processor, perform the method according to claim 12.
14. 14. A decontamination device, comprising one or more enclosures, wherein each enclosure is defined by a housing and a closure, and wherein each enclosure is arranged to receive one or more items to be disinfected, a plurality of LEDs arranged to emit UVC radiation into at least one of the plurality of enclosures, at least one sensor between the closure and a wall of the housing of at least one of the one or more enclosures, wherein the sensor is configured to sense whether the closure is closed, a switchlock, wherein the switchlock is configured for selective engagement or disengagement of a power switch, and a controller in communication with the at least one sensor and the power switch, wherein the controller is configured to supply power to the LEDs when it is determined that the power switch is engaged and the at least one closure is closed.
15. 15. The device of claim 14, further comprising a timer, wherein the timer is configured to control operation of one or more of the LEDs of the plurality of LEDs to deliver a first predetermined UV dosage to items housed in one or more of the one or more enclosures, wherein the predetermined UV dosage delivers a first known log reduction of contamination.
16. 16. The device of claim 14 or 15, wherein each enclosure comprises a plurality of interior surfaces, wherein at least one of the plurality of interior surfaces is configured to reflect at least 70% of incident UVC radiation, wherein the at least one wavelength is between 100nm and 280nm.
17. 17. The device of any of claims 14 to 16, further comprising one or more UVC detectors in communication with the controller, wherein the one or more UVC detectors are configured to detect UVC radiation in the one or more enclosures.
18. 18. The device of claim 17, wherein the controller and/or one or more UVC sensors is configured to measure the UV irradiance in an enclosure, wherein the controller is configured to calculate an operating duration of the one or more LEDs by dividing a predetermined UV dosage the lowest UV irradiance value measured by an individual UVC detector.
19. 19. The device of any of claims 14 to 18, further comprising means for selecting a log reduction factor for disinfection from a plurality of log reduction factors, wherein each log reduction factor corresponds to a predetermined UV dosage.
20. 20. The device of any of claims 14 to 18, wherein the controller is configured to disconnect power to the LEDs if it is determined that the at least one door closure is open.
21. 21. The device of any preceding claim, comprising means for securing keys, and preferably wherein the device is a key cabinet.