Application prospects of LED light sources in the medical lighting market

　　In recent years, LED lighting technology has developed rapidly and has been widely used in various fields. The overall level of lighting products (except functional lighting) and production and technology used in the medical field in China is relatively low, and the brand concentration is not high. Most medical lighting products used in hospitals are purchased from foreign countries, such as Martin and Chuanghu in Germany. The market is almost monopolized by foreign companies. Although the number of medical lighting products is not as large as that of common lighting, they are expensive and have a high market value, which deserves attention.

　　In my country, the medical lighting industry belongs to the medical device industry. According to statistics in 2008, there are more than 7,300 companies engaged in the production of medical devices, but less than 3% of them can produce medical lighting products, and most companies only produce low-end products such as viewing lamps. It was not until recent years that medical lighting products using LED as light source appeared and were used.

　　With the society's emphasis on medical health, medical rehabilitation, green environmental protection and energy conservation, my country's LED medical lighting started to take off in 2007. However, due to the high entry threshold of the product, the great technical risk, and the fact that most medical device companies are not familiar with the performance and application technology of LEDs, and the fact that medical lighting products involve medical mechanisms, light, machinery, electricity, heat and other complex technologies, only a small number of large companies cooperate with medical institutions to produce such products. In addition, the certification procedures for medical lighting products are complicated, so the progress of LED medical lighting is not ideal and does not meet the needs.

　　At present, there are nearly 3,000 LED companies in China, many of which have strong research, development and production capabilities in LED landscape lighting and functional lighting products. However, they lack entry channels because they do not belong to the medical device industry.

　　According to the Ministry of Health's "Statistical Bulletin on Health Development", in 2008, there were 278,000 medical and health institutions in my country, including more than 20,000 hospitals, more than 60,000 health centers, and more than 170,000 street and community clinics. These institutions currently use traditional light source lighting devices, and the market scale is very large. Considering energy saving alone, the upgrading of medical lighting based on semiconductor lighting technology has become inevitable.

　　However, it must be known that medical lighting is a medical device, which has strict regulations and certification requirements, and extremely strict requirements in terms of technology and safety rules. Compared with ordinary functional lighting, the technical risks are greater. For this reason, the access license review of production enterprises should be more stringent, but non-medical device companies should not be excluded, such as permitting LED lighting companies to enter this field.

　　LED lighting is currently extending from landscape lighting to functional lighting, from outdoor lighting to indoor lighting, and from general lighting to special lighting. This is an inevitable result of technological and social progress.

　　LED light sources suitable for medical lighting meet the requirements of adjustable and controllable, high reliability and long life, and are the best solid light sources to replace current halogen lamps, mercury lamps and xenon lamps.

　　Since 2010, domestically produced LED shadowless surgical lamps have been used in some tertiary hospitals and exported to Japan, Australia, the Philippines and other countries.

　　LED light source: energy saving, environmental protection and lowest cost

　　LED is the most energy-efficient artificial light source. Replacing incandescent lamps, fluorescent lamps, sodium lamps (HID), halogen lamps, mercury vapor lamps, and xenon lamps with LED light sources can save energy by 30% to 80%. At present, LED is the light source with the lowest cost during its life cycle.

　　Technical characteristics of LED light sources

　　Energy saving: So far, among artificial light sources other than LED, the one with the highest electro-optical conversion efficiency is low-pressure sodium lamp (LPS), which is about 140lm/W. In 2011, the laboratory level of power LED light efficiency has reached 203lm/W. LED is the most energy-saving artificial light source. Using LED light source to "replace" incandescent lamps, fluorescent lamps, sodium lamps (HID), halogen lamps, mercury vapor lamps, and xenon lamps can save energy by 30% to 80%.

　　Environmental protection: LED light source is a semiconductor solid light source (SSL), which is electroluminescent, not thermoluminescent, but cold light. The light source does not contain toxic and harmful substances; while traditional light sources such as fluorescent lamps, sodium lamps (HID), mercury vapor lamps, xenon lamps, etc. contain harmful substances such as mercury, sodium, cadmium, etc., and their waste will pollute the environment. An energy-saving (fluorescent) lamp contains 5mg to 10mg of mercury. Once broken, it will cause serious pollution to water and land. 1mg of mercury can pollute 5 tons of water. In addition, the cost of recycling and processing waste from traditional light sources is also extremely high, while LED light sources do not have problems such as pollution to the environment.

　　Pure spectrum, no harmful spectrum: III-V semiconductor electroluminescence makes the LED radiation spectrum pure, with a half-wave width of only 20nm to 30nm. Monochromatic light such as red (R), blue (B), yellow (Y), and green (G) does not contain ultraviolet light (UV) and infrared light (IR) (except UVLED and IRLED). Even multi-color mixed light, such as white light (R or other wide-spectrum light colors, does not contain UV and IR and other light radiation that is harmful to human eyes and skin. Compared with other artificial light sources, such as incandescent lamps and halogen lamps, the spectrum contains 45% to 70% IR light; the spectrum of fluorescent lamps and sodium lamps contains 15% to 25% UV light. If such products are used without protection, they will cause light pollution to users. LED lamps are called the healthy light of the 21st century.

　　Easy to realize intelligent control: LED has fast response and is easy to adjust color (color temperature), dimming (optical power) and the projection direction of light, which is easy to realize intelligence and form a smart light source.

　　Because it is a semiconductor light-emitting device, the transient response of LED is only at the nanosecond level, and it can be driven at a frequency of tens to hundreds of kilohertz, without flickering that causes visual fatigue. For this reason, it is easy to achieve digital and intelligent control. For example, continuous adjustment of the color temperature (CCT) of the light source, which is difficult to achieve with other artificial light sources, can be easily implemented with LED. This is very important for observing the clarity of different lesions, different tissues, and blood colors in surgical lighting and surgical debridement lighting.

　　LED is a low-voltage driven light source, safe and reliable: LED light sources are driven by low voltage and can be instantly switched to battery operation during emergency lighting. The switching time is only a few tenths of a second, and there will be no accidents caused by power outages. In addition, LED light sources switch quickly, and there is no noise from emergency generators during the switching process.

　　The LED driver power supply device can meet the international and domestic standards for medical devices, such as EN60601-1-2, UL60950, IEC68-2-29 and 3C, as well as the certification requirements for electrical safety and electromagnetic interference of medical equipment.

　　LED is a light source with high reliability and long life cycle: LED is a solid light source with high reliability and long life. Its 30% light decay time (i.e. life judgment value time) can work in an ambient temperature of -30℃～+55℃, and its life span can reach 30,000 hours～50,000 hours, which is the longest life span of artificial light sources at present. (The life span of incandescent lamp filament is about 2,000 hours, fluorescent lamp is 8,000 hours, sodium lamp and mercury vapor lamp are only about 10,000 hours).

　　LED is currently the light source with the lowest cost of use (the sum of the cost of purchasing energy, repair and maintenance, and replacement during the life cycle) within the life cycle of the light source.

　　Disadvantages of traditional light sources

　　At present, the artificial light sources and LED light sources commonly used in the medical field have the following shortcomings in addition to the basic characteristics mentioned above, such as energy efficiency, spectral purity, color temperature control, response time, reliability, life span and life cycle cost.

　　Mercury vapor discharge light source - vapor blue lamp, etc.:

　　It requires high voltage power supply, has slow response, contains UV and IR light radiation; it is a heat source, which will cause the illuminated surface to heat up, and protection is required when using it; it contains mercury, which is not conducive to waste disposal.

　　Solid laser light source - He-Ne laser, etc.:

　　The cost is high, the power supply system is complex, protection is required when in use, and the safety is poor; when the power is high, water cooling technology is required to dissipate heat, which has poor safety.

　　Halogen lamp, xenon lamp, etc.:

　　It contains IR radiation and is a heat source. When necessary, it is necessary to set up a lens to filter out IR, or apply an IR absorbing film on the reflector, etc., and the life cycle cost is high.

　　LED light source medical applications: wide range and obvious advantages

　　Medical lighting classification

　　Functional lighting inside and outside hospital buildings: refers to functional lighting other than the display of medical resources, medical guides and other information. Most of them use fluorescent lamps, grille lamps, ceiling lamps, spotlights, downlights and HID street lamps.

　　These traditional light sources, such as fluorescent energy-saving lamps, fluorescent lamps, sodium lamps and halogen lamps, can be replaced by LED lighting.

　　Peeping lighting: used for lesion detection and observation. It mainly uses projection-type, small-angle, directional lighting lamps, which are divided into internal and external types. Currently, existing products use laser (LD) and LED as light sources.

　　Surgical lighting: There are two types: fixed and mobile. They are used to provide high-quality lighting for doctors when they are operating on patients. Currently, the mainstream is xenon lamps, which are very expensive.

　　Disinfection and sterilization radiation light source: using ultraviolet light to disinfect and sterilize medical devices, medical equipment and medical utensils has the advantages of fast speed and high efficiency. Currently, mercury vapor lamps are mostly used.

　　UV irradiation disinfection and sterilization uses ultraviolet light to penetrate the cell membrane and nucleus of microorganisms, destroying their DNA or RNA molecular chains, making them lose their replication ability and activity functions, and achieving the purpose of sterilization and disinfection. With UV disinfection, there is no problem of handling waste liquid and containers after boiling disinfection, which is environmentally friendly and reliable.

　　Phototherapy - Light irradiation therapy light source: It uses the photobiological effect to promote or inhibit the growth of human skin or certain tissue cells with light of a specific wavelength to achieve the purpose of treatment. The efficacy of LED light source for phototherapy is becoming more and more prominent.

　　Compared with traditional light sources, LEDs are more in line with the special requirements of light therapy. They mainly have the characteristics of wide range of light wavelength selection, controllable and adjustable radiation light quantity and irradiation spot, pure light color, no harmful spectral components, and electrical safety. Therefore, LEDs will inevitably become the preferred healthy light source to replace traditional light therapy light sources and become an effective clinical treatment method.

　　Pathology detection light source

　　Detection of ESR: 570nm green light can be used to measure ESR; 640nm blue light and 900nm IR light can be used to detect the chloride content in the blood.

　　Bladder cancer diagnosis: Irradiate the urine sample with 488nm blue light and observe whether there is a peak in the 550nm-570nm green light spectrum region in the fluorescence spectrum to diagnose whether bladder cancer has occurred.

　　Application scope of LED light source

　　Ultraviolet light: The wavelength range of ultraviolet LED is 311nm~400nm, the wavelength width is 20nm~30nm, and the optical power is a few milliwatts to several hundred milliwatts. UVA can treat skin diseases such as psoriasis, and can also be used for beauty and sterilization.

　　Infrared light: LED infrared chips are suitable for manufacturing near-infrared light devices. IR LEDs in the range of 780nm to 1200nm can be selected for anti-inflammatory, analgesic, and metabolism promotion.

　　Blue light: LED light sources in the range of 425nm to 475nm can be used to treat neonatal jaundice, etc. LED light sources in the range of 446nm to 477nm can promote the secretion of melatonin, a pinealamine hormone that regulates the human biological cycle, and are beneficial to enhancing human brain activity.

　　Red light: Red light LED can be used as a light source in the range of 615nm to 700nm. The light color is pure and red light can promote cell synthesis, promote wound healing, and treat various diseases through photochemical effects.

　　Mixed light and white light: LED white light or several different wavelength LEDs mixed in the same package to form yellow-green light, purple light and blue-green mixed light, etc., can meet different treatment needs. White light irradiation with different color temperatures can be used for insomnia regulation treatment.

　　Advantages of LED light sources

　　LED light sources can form point, line, and surface light sources of any geometric shape and any size, and can also be miniaturized. LED light sources can be used to form soft light sources and blanket-type light sources, and can even be combined with clothes to form wearable light sources. For example, encapsulating blue light LEDs in blanket-shaped baby quilts can be used to protect the eyes when treating neonatal jaundice without eye masks.

　　LEDs can operate with a DC voltage lower than 6V, and do not have electrical safety issues caused by high voltage like mercury vapor lamps.

　　Medical literature reports that using LED as a light source for phototherapy with blue light, red light, near-infrared light, ultraviolet light, and multi-color mixed light has achieved significant clinical results. Major companies in the United States, Japan, and Europe have launched various phototherapy devices using LED light sources, and domestic related companies, schools, and medical institutions have also achieved a lot of results.

　　Surgical shadowless lamp: LED light source is widely recognized

　　When doctors perform surgery on patients, the heads, hands, and surgical instruments of medical staff will cast shadows on the surgical site, interfering with the doctor's visual identification of the surgical site. Therefore, surgical lighting must meet the requirements of shadowlessness. Shadowless lamps are a large-area light source that can illuminate light at any angle without creating shadows.

　　Cold light and color temperature are adjustable, and color rendering requirements are high

　　Surgical lighting source: The radiated light does not contain IR spectrum, does not generate heat, does not cause fatigue to medical staff, and can reduce the risk of infection at the patient's wound site due to excessive temperature.

　　Since different parts of human tissue have different visual clarity under different light color temperatures, the color temperature of surgical lighting is required to reach 2700K~6500K and be adjustable. At the same time, the color rendering index must be higher than 90 to improve the medical staff's ability to identify and judge the color changes of lesions, blood, etc.

　　The light source can be adjusted remotely as needed

　　The lamp arm, lamp head, etc. of the lamp can be moved up and down, left and right in a circular motion as needed, and can be remotely controlled, and the size of the light field can also be adjusted.

　　Lamps and lanterns will affect the air conditioning, clean laminar flow, temperature and cleanliness of the operating room, which requires solving the problem from the aspects of lamp design and material selection.

　　Emergency treatment

　　Surgical lighting fixtures must have a power outage emergency function. Once a power outage occurs, they will instantly switch to battery or backup power supply. The conversion time is less than 1 minute, there is no noise, and the emergency time is 4 to 6 hours, ensuring that no medical accidents are caused by power outages.

　　No glare

　　Surgical lighting must not cause flashes or reflected light by shining on surgical instruments, bed sheets, gauze, medical utensils and other items, which may interfere with the medical staff's vision and cause glare hazards.

　　The requirements for surgical shadowless lamps are very strict, involving the composite application of optics, electronics, micro-electromechanical, modeling structure, laminar flow analysis, and colorimetry, etc., with high technical content. With the popularity of cardiac surgery and ankle surgery, the demand for surgical shadowless lamps is gradually increasing. LED light sources are being widely recognized for their outstanding advantages and have a promising future.