# Patent

## Title
Method for eliminating airborne microorganisms

## Abstract

A method for eliminating airborne microorganisms in an air duct comprises placing a device containing at least one light emitting diode (LED) in the air duct so that the air flow passes through the beam emitted by the LED.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part of U.S. patent application Ser. No. 10/241,620, filed on Sep. 11, 2002, now U.S. Pat. No. 7,084,389 the disclosure of which is herein incorporated by reference.


BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for the elimination or destruction of a wide variety of microorganisms, particularly harmful bacteria in the air.
2. The Prior Art
In the early years prior to the present invention, light emitting diodes (LED) did not produce light of sufficient intensity for many applications since they required a lot of power and in some instances extra cooling. Moreover, the typical life estimates of high output ultraviolet LED's was so short as to render them unsatisfactory for many uses. More recently, however, due in part to the advances made by the NASA Marshall Space flight Center and others, the technology relating to LED's has advanced dramatically. The present day LED's have become extremely powerful, cold to the touch and require very little energy.
Accordingly, light emitting diodes are now finding a wide variety of applications in both industrial and medical fields. For instance the newer LEDs are now capable of destroying a wide variety of microorganisms, particularly bacteria which cause skin infections including staph, strep and the like. LEDs have also been found to be useful in the destruction of the small pox virus, anthrax and the like.
Much of the published experimental work done by NASA with LEDs relates to the affects of LEDs on cells, muscle and bone since it had been observed that normal wound healing and cell growth are negatively affected by diminished gravity as is encountered in space. It has been observed that the applications of light therapy with the use of LEDs significantly improved wound healing and cell and bone growth of astronauts on long term space missions.
Another area of technology in the medical field is the use of LEDs in photodynamic therapy where an injected photosensitizer such as in cancer therapy, concentrates in a tumor, and when activated by a light source, can destroy the tumor.
Prior to the advance in LED technology, low level laser therapy had been used for performing therapy on patients particularly for the management and symptomatic relief of pain. The low level laser therapy could reach deep into tissues and yet without harm to the tissues. However, the combined wavelengths of light which are optional for wound healing cannot be efficiently produced and the size of wounds that can be treated by lasers is severely limited. Hence, LEDs offer an effective alternate to lasers for many applications, including pain therapy. LEDs are safe, non-invasive, drug free and therapeutic. It is believed that LED treatment stimulates natural physiological changes in the cells of a patients' body and helps to relieve pain naturally.
Although the use of ultra violet light for the sterilization of microorganisms was not practical up to the present due to the estimated limited life span of high output ultraviolet light emitting diodes, more recently technology has been developed high power ultra violet emitting diodes which have much longer spans. For example, it is now possible to have systems of 500 milliamps as opposed to the lower earlier systems of 30 milliamps.
Accordingly, the interest in developing method for sterilization of air and surfaces, including the treatment of human tissue, with LED's has increased markedly.
However, prior to the present invention, the devices presently used were somewhat cumbersome and tied to a fixed energy source which limited their portability. The present invention, therefore, has provided a small device which can be obtained in the form of a kit and useful for a variety of applications.
It is therefore an object of the present invention to provide a small, compact ultra-violet LED device which is useful in the destruction of microorganisms, and in particular, harmful bacteria. The device is also useful in a wide variety of therapeutic treatments. Another object of this invention is to provide a device which is compact and has its own independent energy source or can be connected to an existing energy source. A still further object is to provide a hand held device which can be used to destroy bacteria that can cause pimples, boils, infections, and the like. Another aspect of this invention is to provide an LED device which emits a strong ultra-violet light source capable of penetrating through several layers of skin to destroy infectious bacteria or to be strategically placed to kill airborne bacteria. A still further object is to provide a hand held device which contains restraints to avoid accidental activation of the LED or unnecessary exposure to emitted light. Another object of this invention is to provide a device which contains a timer to limit the interval that the device is on. A still further object is to provide methods for utilizing the device of the present invention for the destructions of microorganisms and the treatment of various patient conditions. Another object is to provide a kit comprised of the device, preferably in the shape of a pen, battery, battery recharger and goggles for eye protection. Another object is to provide a device for placement in an air duct to decontaminate air flowing through the air duct.
These and other objects will readily become apparent to those skilled in the art in light of the teachings herein set forth.
SUMMARY OF THE INVENTION
In its broad aspects, the present invention is directed to a device containing at least one light emitting diode (LED) which is useful both for the destructions of microorganisms and for therapeutic purposes. The device being comprised of an enclosure having:
(a) at least one unidirectional light emitting diode (LED); disposed so as to emit light from the device and having a child proof protective means to prevent unintentional exposure to light emission;
(b) a rechargeable or direct power source to activate the diode.
In addition to the hand held device, the present invention is also directed to a method for using the device for elimination of microorganisms in the air. A kit is also provided which contains the device and a power source.



BRIEF DESCRIPTION OF THE DRAWINGS
The device of the present invention will be better understood by reference to the drawings wherein:
FIG. 1 is a perspective view of a hand-held, light emitting diode device in the shape of a pen useful for the destruction of microorganisms;
FIG. 2 illustrates the hand-held device of FIG. 1 and depicts it being held by a medical technician or physician for the treatment of microorganisms on a surface; and
FIG. 3 shows the device installed in an air duct for use in decontaminating air flowing through the duct.



DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, and more particularly to FIG. 1, the device 10 of the present invention is shown in the shape and approximate size of a pen having a barrel containing zone 12 which contains one or more light emitting diodes, zone 14, which contains the rechargeable power source, switch assembly 16 which has child proof restraints to prevent inadvertent activation of the device; timing means 18 to control and deactivate the device after a set time interval; and zone 20 from which the light is emitted in a unidirectional manner and which also contains child proof restraint means to prevent accidental light emission.
FIG. 2 depicts a physician or technician holding the device of this invention and directing the light to a surface 22 which could contain bacteria or could be the skin of a patient in need of treatment, for example, of an infection. Under the skillful hands of a physician or surgeon, the device can be employed for treating infections in the oral cavity, or other areas of a patients' body.
As indicated above, low level laser technology has in the past been employed for the therapeutic management a relief of pain in humans. For example, in U.S. Pat. No. 5,464,436, which issued Nov. 7, 1995, there is described a method of treating the external skin layer of a patient with a laser source which emits a laser light having a wave-length between 800 nm and 870 nm and at a level of 1 joule/cm2 for each treatment cycle. It is indicated in this patent that while laser light of conventional systems can penetrate skin layers and cause injury to a patient, the use of a low level laser light therapy (LLLT) can reach into deep tissues to provide beneficial effects without doing harm to the tissue. In contract, the device of the present invention does not employ a laser source and due to the advances in LED technology is believed to be much safer and as efficient.
In practice it has been found that the device of the present invention provides wavelengths in the ultra violet range of about from 200 to 450 nanometers and higher, and energy levels of up to 35,000 microwatt seconds/cm2, which are necessary to eliminate or destroy most microorganisms such as bacteria, spores, algae and viruses. Most bacteria can be destroyed at ultra violet energies of from about 3,000 to about 5,000 microwatt-seconds/cm2 while mold spores may require energies in the 20,000 to 35,000 mW-seconds/cm2.
In contrast to the commercial systems for ultra violet light sterilizations which are costly and difficult to maintain, LED technology has become of particular interest since systems which use this technology are at least as efficient and can operate for much longer periods of time than in the past.
In addition to its use in the destruction of microorganisms and for therapeutic applications, the device of the present invention is also useful in photodynamic therapy for activating photosensitizers. Improvements in semiconductor technology has greatly increased the light output of LED chips and has rendered them particularly attractive for various applications. For example, aluminum-gallium-arsenide is an excellent semiconductor and LEDs which have been manufactured from such composition are particularly attractive for use the absorption spectrum of certain photosensitizes such as lutetium texaphyrin and benzophorphyrin derivatives which are currently finding use in the treatment of brain tumors.
The enclosure for the power source and LED can be pen-like in shape for ease of handling as depicted in FIG. 2, or it can be fabricated in other configurations as well. As shown in FIG. 1 the power source is preferably located in the rear section which can be threadably attached to the other section and easily removed when the batter power source needs recharging. Alternatively, the section containing the battery can have a lid opening allowing for a recharger to be temporarily connected to the battery without its removal from the enclosure.
FIG. 3 shows the device 24 installed in a typical air duct (e.g., heating and air-conditioning, etc.), so that air 27 flowing through duct 25 along the arrows passes through beam 26 and is decontaminated before entering the room through register 30 on wall 31. In this embodiment, device 24 is not pen-shaped but is configured more box-like as a hollow tube with the LEDs 28 inside cleaning the air that passes through it for simpler installation in air duct 25. Device 24 could be installed in ducts that enter rooms through walls 31, floors and ceilings, and can be mounted in a variety of ways. It is preferable if device 24 is mounted so that beam 26 is positioned perpendicular to the air flow 27. An exhaust fan 32 is added to the inside of the hollow enclosures forcing air through the chamber in the duct system. Device 24 can be mounted via any conventional means 34 such as by a bracket, screw, adhesive or any other suitable mounting means. Device 24 could also be installed in air ducts of automobiles, air planes, cruise ships, or any other structure. Of particular importance is its use in hospitals. A fan 32 could be placed in the duct to further direct air past beam 26 of the wind tunnel device 24. A rechargeable power source 33 can be employed to provide power to the device.
The battery and the recharger are commercially available items. The battery will, of course, have sufficient power to provide the necessary energy levels indicated above for activation of the LED, and for the destruction of microorganisms as well as for therapeutic treatment. Direct power sources may be included in the duct variation since the life span of LED's are now up to 15 years under continuous operation.
The particular diodes employed in the device of the present invention can be selected from a variety of crystals or chips depending upon the particular wave length desired
A wide variety of inorganic electroluminescent compounds can be used as the light emitting diode. These compounds, or phosphors, are commercially available in crystal form. When exposed to an electrical current they fluoresce at different wavelengths depending upon the particular chemical composition of the phosphor and in many instances the kind of impurities present in, or added to, the phosphors.
Typical phosphors include but are not limited to, crystal compounds such as cadmium selenide, zinc sulfide, cadmium sulfide, mercury sulfide, zinc sulfide doped with copper, complexes of chromium, lithium and germanium oxides, complexes of zinc, cadmium, and selenium, yttrium oxysulfide and the like.
Of more recent interest are some of the organometallic compounds which are electroluminescent and in some instances may be competitive with the inorganic compounds presently in use as LED's.
Although the device of the present invention is deemed to be safer and at least as efficient as devices which employ lasers, it is not entirely without danger and reasonable cautions must be followed in its use. The device should only be used by technicians or medical personnel who have been trained in its use and who wear proper eye protection.
Accordingly, to maximize safety the device of the present hand held invention has restraints on both the switch assembly and the point where light is emitted. Several known child proof features or a combination of features can be employed to prevent accidental or unauthorized activation of the device. For example, it may be necessary to twist one section of the pen-shaped device while simultaneously pressing down on the switch assembly to allow the device to be activated or a shutter mechanism to be opened to permit light emission.
Additionally, the hand held device includes a built-in timer which will allow the device when activated to emit light for a predetermined interval and then automatically turn off. Such timing devices are known in the art and are commercially available.
While the invention is directed to a hand held device which is free of a connection to an external power source, in some instances it may be desirable to be able to plug in the device to an external source via an appropriate extension cord.
Although the invention has been illustrated by the preceding disclosure, it is not to be construed as being limited to the materials employed herein, but rather, the inventions pertains to the generic area as hereinbefore disclosed. Various modifications and embodiments thereof can be made without departing from the spirit and scope thereof.

## Claims

1. A method for the destruction of airborne microorganisms, comprising:
installing in an air duct a flow-through device comprising at least one ultraviolet light emitting diode (LED) disposed so as to emit light substantially perpendicularly to a flow of air in the air duct; and
destroying airborne microorganisms by direct interaction of the microorganisms with the ultraviolet light.

2. The method of claim 1, wherein the light is emitted from the LED comprising an aluminum gallium arsenide crystal.

3. The method of claim 1, wherein the device has a rechargeable power source.

4. The method of claim 1, wherein the device is installed in a heating duct.

5. The method of claim 1, wherein the device is installed in an air-conditioning duct.

6. The method of claim 1, further comprising the step of placing a fan inside the enclosure to force air past the light emitted by the LED.

7. The method of claim 1, wherein the LED power is 20,000 to 35,000 microWatt-seconds per square centimeter (μW-s/cm2).