I have already briefly introduced the application of LED in medical applications, which can be classified from two angles: use and light source (such as ultraviolet light, infrared light, etc.). Firstly, the characteristics of LED and traditional light source are compared and analyzed. Then, the application of LED in medical and health field is summarized and analyzed. It is mainly discussed from three aspects: medical special lighting, disease diagnosis and medical treatment. Of course, the following examples are just a small part of LED medical applications.
1, LED and traditional light source comparison
LED has the advantages unmatched by traditional light sources. The light source is small in size, high in luminous efficiency, low in energy consumption, low in power, long in life and environmentally friendly. The comparison of various performances is shown in Table 1.
From the above comparison, it can be seen that:
(1) led luminous efficiency and environmental protection, so it can be used for general lighting in medicine;
(2) LED is a point light source, small in size, and the color temperature range can be adjusted within a certain range, so it can replace medical special lighting equipment, such as shadowless lamps and dental headlights;
(3) The LED is small in size and has many optional light-emitting bands. It can be used as a light source for diagnostic equipment, so it can be used for medical diagnosis;
(4) The LED has good directivity and many illuminating bands, so it can be used for targeted therapy.
2, medical special lighting
Under normal circumstances, the illuminance value of the visual function examination room (mainly refers to ophthalmology) needs to reach 7500 Ix, and dimming to 50 lx range is required; for the operating room, the general illumination requirement is not less than 1000 lx, and the shadowless lamp is used as local illumination. The operating table reaches more than 20,000 Ix within 30cm, and requires an adjustable auxiliary light source; the illumination of the endoscope inspection room, X-ray fluoroscopy room, ophthalmic dark room, etc. is in the range of 50-100 lx, and dimmable to 0 lx. In the past, the thermal radiation source or gas discharge source mainly used in the medical environment, due to many reasons such as low luminous efficiency and short service life, it is difficult to meet the requirements of the rapidly developing medical and health science. For the requirements of such illumination, visible light LEDs can be used instead of conventional light sources.
At present, the shadowless lamps used in clinical practice are mostly halogen lamps, and the heat generated in the illumination is high, and it is easy to cause turbulent flow of gas in the operating room, which causes the aseptic conditions to change and affects the aseptic level. LED is a cold light source. In the process of illuminating, there is only a very small amount of ultraviolet and infrared radiation, which avoids long-time illuminating and generates high heat. It has little effect on the ambient temperature and does not produce turbulent flow, which can create a stable surgical environment and eliminate The bacteria level is greatly improved, and the LED has a long service life, the driving voltage and current are small, and the power supply stability is stronger throughout the operation.
Chongqing has combined LED technology with mechanical technology, and successfully developed a high-power LED chip surgical shadowless lamp with continuously adjustable color temperature . By using the good illuminating characteristics of LED and the new mechanical process - universal joint cantilever technology, the new surgical shadowless lamp Compared with traditional equipment, it has great advantages, no stroboscopic, strong mechanical, and low energy consumption. The key is to achieve the color temperature characteristics of different human tissues under different color temperature conditions by adjusting the color temperature. Inspired by a new generation of medical devices, but also need to be validated and continuously improved in clinical applications.
Due to the small size of the semiconductor illuminator and the concentration of the light beam, the plasticity in the design process is stronger. Therefore, in the illumination process, the control of the light can be more fine, covering a wider area, reaching a corner that the conventional light source cannot reach, and realizing The concept of "shadowless light". In addition, the plasticity of the LED is not only makes the lighting effect in the lighting process more perfect and accurate, but also greatly reduces the size of the lighting device. It can be designed as a small, light and sensitive illuminator that is easy for doctors to carry, and is convenient for doctors to work.
With the development of optical fiber technology, a new generation of optical fibers with good characteristics is widely used in various medical instruments, especially in endoscopes, surgical hooks, deep illuminators in the mouth, and headlights. The key to this technology is also how to introduce light into the fiber. In this respect, traditional light sources such as halogen lamps, arc lamps, illuminating, low illumination, it is difficult to meet the demand, and most of the lasers have high heat production, and it is easy to damage the instrument after working for a long time.
The light source widely used in endoscopes is a xenon lamp, but because of its basic technical principle, high-voltage breakdown is still adopted, so that a higher driving voltage is inevitably required, and the operating temperature is also high; while the LED light source does not exist. In this regard, the LED package unit, all the light is concentrated within 15° angle, the light beam is narrow, so that the light and the fiber are more easily coupled, and the luminous efficiency and the luminous intensity are guaranteed, which can be simplified or omitted in theory. Complex drive circuits and cooling systems increase the efficiency of the instrument.
In July 2008, Xu Jia and others proposed the LED lighting system design based on Etendue and color rendering characteristics . The W-LED was used as the main light source to develop the endoscope lighting system test prototype, which provided high brightness and uniform illumination, and added another A complementary color path improves color rendering. It is also mainly used to apply the wide spectrum that W-LED can provide, so that the object can reflect the light of the corresponding wavelength according to its spectral reflectance, thus showing the correct color of the object. The development of fiber optic technology will inevitably require higher performance light sources. The current semiconductor illuminators have considerable prospects in terms of existing optical properties and development space.
In order to meet the needs of medical lighting, high-power LEDs are needed as a light source, and the price of high-power white light-emitting diodes on the market is higher than that of conventional light sources, which increases equipment costs. In addition, a fatal disadvantage of LEDs is the low color rendering index. Although basic requirements have been met, in order to make semiconductor illuminators truly popular in medical lighting and imaging, these problems must be solved technically and technologically. At present, studies have shown that mixing orange, yellow, blue, and green phosphors at a certain ratio can improve color rendering.
3, medical treatment
Compared with the laser, the LED emission spectrum can cover the wavelength range of 365 to 880 nm, and has more options than the laser, and the price is relatively low. Compared with ordinary wide-spectrum light sources, the emission spectrum of LEDs can be controlled within a range of about 10 nm, and the best therapeutic effect band can be used without worrying about the effects of stray light.
Compared with medical treatment and surgical treatment, the new technology photodynamic therapy (PDT) is no side effect, but the laser used in photodynamic therapy has low luminous efficiency, high price and complicated operation. In recent years, more research institutions have shown that it is completely feasible to replace the laser with LED as the light source, and the method is simple and safe. The new LED light source makes it easy to produce portable therapeutic devices, and can be used for large-area treatment through LED dot matrix. It also uses its narrow beam and high efficiency to make directional treatment instruments and concentrate treatment on target targets.
Disinfecting and sterilizing the irradiation source, currently using more mercury vapor lamps. If ultraviolet light LEDs are used to sterilize medical devices, medical equipment and medical utensils, they have the advantages of high speed and high efficiency. UV irradiation disinfection and sterilization use ultraviolet light to penetrate the microbial cell membrane and nucleus, destroying the molecular chain of its DNA or RNA, so that it loses its replication ability and activity function, and achieves the purpose of sterilization and disinfection. With UV disinfection, there are no problems such as disposal of waste liquids and containers after retort sterilization, and it is environmentally friendly and reliable.
Semiconductor illuminators are also widely used in beauty, and have great development prospects. Due to the wide variation of the wavelength range of the LED, the large illumination range, and no scarring, it has been widely favored by users, and is currently used for wrinkle removal, skin rejuvenation, and removal of hemorrhoids.
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