Application Analysis of LED Light Source in Biomedicine

At present, LED PDT, LED skin beauty, LED fluorescence spectrum detection technology, etc. have achieved innovative and practical results. However, there are still a lot of practical work to be done in the field of biomedical research, including the continued development of medical high-power LEDs with better light efficiency, the development of professional LED medical devices for biomedical applications, and the study of LEDs. The physiological mechanism of various types of cells in the human body, research and restoration of astronauts with LED light sources in space, etc., also requires sufficient attention from the LED biomedical industry.

This paper first analyzes the characteristics of biomedical LED light source, then introduces and discusses the application and existing problems of LED light source in biomedicine, and prospects the application of LED light source in biomedicine.

1 characteristics of biomedical LED light source

With the development of LED light source technology, LED has greatly improved the performance of parameters such as luminous efficiency, color stability and chromaticity. This laid the foundation for the application of LED light sources in the field of biomedicine. Compared with traditional biomedical light sources, LED light sources have the following characteristics and advantages:

1) Safe and reliable. LED is a non-thermal effect solid-state cold light source, which will not cause thermal damage to skin, eyes, muscles, etc., and has low voltage driving. It has higher safety than high-voltage driven laser light source system. In addition, LED light source has long service life. The advantages, applications in medical equipment can guarantee its high reliability.

2) Energy saving and environmental protection. LED lighting efficiency is high, and it can be used in places where medical space requires functional lighting, which can achieve energy saving in lighting.

At the same time, it has the advantages of no mercury and no ultraviolet radiation.

3) A wide range of wavelengths. The wavelength of the light emitted by the LED has been covered by ultraviolet, infrared, and visible light, and there are many optional wavelength bands.

4) The spectrum is pure, the spectral half-wave bandwidth is narrow, and can be controlled within 10 nm, avoiding the interference of stray light, and at the same time facilitating dimming and color grading.

5) Small size. The small size of the LED provides unlimited possibilities for the design and manufacture of medical devices while being easy to carry and operate.

6) The beam is narrow, the directivity is good, and the light can be precisely controlled, which is convenient for targeted therapy and accurate detection.

In addition, the overall cost of LED light source medical devices is relatively low compared to biomedical laser source systems.

2 application analysis

The experimental basis and theoretical basis for the application of LED light sources in the field of biomedicine are laid by KARU TI, YOUNG S and others. Through experimental research, they proposed that the light stimulating effect and phototherapy are mainly related to the wavelength of light, the dose of irradiation and the way of irradiation, and the coherence and polarization of light are not necessary. This opens up the application of non-coherent, non-polarized LED light sources in the biomedical field.

In recent years, with the continuous improvement of the cost performance of LED light sources, the application of LED light sources in biomedicine is increasing. The application of LED light sources in biomedicine mainly includes medical lighting, phototherapy, biomedical diagnosis and the like.

2.1 LED light source in biomedical therapy

As a new treatment method, research on alternative treatment of antibiotics has become a hot topic in the field of biomedicine. With the continuous improvement of LED luminous efficiency, the continuous expansion of wavelength range, and the deepening of research on the physiological mechanism of living cells in LED, the application of LED light source in biomedical therapy is becoming more and more extensive.

2.1.1 Application in dermatology

Different wavelengths of LED light can be absorbed by different chromophores in the skin tissue. In general, red, near-infrared (630 nm ~ 830 nm) wavelength LED light sources are used to treat deep skin tissue structures, where light from a 660 nm wavelength LED source can reach the reticular layer of the skin tissue dermis, thus Skin fiber cells in the dermis function; blue light (400nm ~ 470nm) wavelength LED light source is used to treat skin damage in the epidermis; ultraviolet light (200nm ~ 380nm) wavelength LED light source can promote the skin stratum corneum to form cells, release the endothelium Prime. As a non-thermal effect light source, LED light source has been used for the treatment of skin inflammation, acne, pigmentation, wound healing, scar prevention, etc., and has achieved many clinical application results.

1) LED is used for wound healing. Difficulties in wound healing are common complications in various clinical departments. Small-volume LED light sources can be arranged in arrays for large-area wound illumination, making them an advantage for low-energy illumination applications in wound healing. The near-infrared wavelength LED light source is used to illuminate the body tissues, and the heat shock protein (HSP 70) with a molecular weight of 72-kDa is induced in the body to counteract the increase of body temperature of cells, tissues and organs, increase the survival rate of cells, and promote oxindole. Synthetic synthesis, which promotes the formation of scars and the healing of wounds.

2) LED is used for skin beauty. The water molecules and hemoglobin in the human body absorb different light of different wavelengths and different intensities, resulting in different biological effects. LED light can stimulate the metabolism of mitochondria in skin cells, stimulate the activity of fibroblasts, and promote the production of collagen cells and elastic cells to achieve skin regeneration and enhance skin repair ability. In addition, the use of a specific wavelength of LED light source to illuminate the skin, can kill abnormal cells on the surface of the skin or subcutaneous, so that it loses vitality and is absorbed by normal cells and tissues around it, thereby achieving skin diseases such as acne and eczema, and achieving cosmetic effects. .

3) LED is used for skin anti-inflammatory and anti-inflammatory. The blue LED light source is used to illuminate the skin, which has the effect of rapidly inhibiting inflammation, can effectively destroy the formation of skin bacteria, promote the metabolism of skin cells, and produce anti-inflammatory and anti-inflammatory effects during skin inflammation.

In addition, the LED light source is also used to reduce skin damage after ultraviolet irradiation, prevent or treat post-inflammatory hyperpigmentation, and improve pain, itching, and the like in patients with skin diseases. With the continuous innovation of LED light source technology, the research on the mechanism of LED skin biological effects is deepening, and the application of LED in dermatology has unlimited prospects. 2.1.2 applied to the circadian rhythm

David Berson discovered that there is a new photoreceptor cell (ipRGC) on the retina of the human eye. It is independent of the rod-shaped cells and cone-shaped cells of the human eye. It directly senses the light signal and transmits the received signal to the non-visual pathway. The hypothalamic suprachiasmatic nucleus (SCN) of the brain acts directly on the pineal gland and participates in mediating many physiological effects of the human body, including changes in vital signs such as alertness, heart rate and body temperature, and melatonin secretion. Wait. LED light source color temperature, wavelength, brightness and other performance parameters can be adjusted to provide advantages for its application in regulating human circadian rhythm.

1) LED light source for the treatment of seasonal affective disorder (SAD). SAD is a kind of depression reported in recent years. Its symptoms mainly include sleep disorders, eating disorders, and emotional disorders, which seriously affect the physical and mental health of patients. Kripke et al first found that light can alleviate the depressive symptoms of SAD patients. Clinical trials have shown that the duration of light and the intensity of light are related to the incidence of SAD. The brightness of the LED light source is adjustable, the light is controllable, and the sunlight can be simulated. The effect of relieving and treating depressive symptoms can be achieved according to the individualized needs of SAD patients.

2) LED light source is used to promote sleep. Irregular working hours, irregular work schedules, excessive use and contact of various illuminating devices, etc., have affected people's normal circadian rhythms, causing adverse symptoms such as neurasthenia and insomnia. Sleep is related to melatonin secreted by the pineal gland of the brain. The secretion of melatonin increases at night, and the body temperature and pulse gradually decrease, which helps to sleep at night; the secretion of melatonin decreases in the morning, and the body temperature and pulse rise gradually. Help people wake up. Experiments show that the blue light band of LED is closely related to the secretion of melatonin. It can effectively regulate the secretion of melatonin by artificially adjusting the blue light band LED, thereby achieving the effects of improving sleep quality and treating sleep disorders such as insomnia.

In addition, the warm-light LED lighting makes people excited and active, and the cool-colored LED lighting makes people quiet, so the mental and emotional effects can be adjusted by adjusting the color temperature of the LED light source. Moreover, according to the wide coverage of the LED light source and the adjustable color temperature and brightness, we can design and develop an LED light source or LED array that conforms to the human circadian rhythm to meet the illumination requirements for different wavelengths and intensities during psychotherapy.

2.1.3 Application in Stomatology

1) For dental medical devices. 1 dental LED light curing machine, that is, LED dental photosensitive resin curing machine, used to cure photosensitive resin materials when the dentist repairs the teeth. LED is a non-thermal effect cold light source, used for curing photosensitive resin materials, has the advantages of fast curing speed, less pollution, energy saving, excellent curing product performance, and the curing effect is no less than the curing effect of the halogen curing machine. 2 oral LED cold light whitening instrument. The low-temperature cold-light LED light source performs cold-light whitening on the externally-induced discolored teeth (such as coffee, tea stains, smoke stains, etc.), drug-induced discolored teeth, hereditary yellow teeth, and dental fluorosis, and the whitening process does not contact the gums. It avoids the stimulation of the teeth in the operation and does not cause any damage to the teeth.

2) For the treatment of oral cancer lesions. LED red light treatment of oral leukoplakia lesions and other oral precancerous lesions, the effect is good. In addition, patients with chemotherapy often cause acute oral ulcers, which cause difficulty in swallowing. The patient is treated with an LED light source with a wavelength of 688 nm, and the oral pain is relieved, and the oral ulcer is well cured.

3) For the treatment of periodontitis. Periodontitis is a chronic inflammatory disease that invades the gums and periodontal tissues. It can cause periodontal swelling and pain, bleeding, overflowing pus, etc., and eventually cause tooth loss. LED light source is used for the treatment of periodontitis, has a good bactericidal effect, and has a simple structure, a small volume, a strong portability, and a good monochromaticity.

In biomedical therapy, other applications of LED light sources include: 1 LED photodynamic therapy (PDT) for the treatment of brain tumors in children and adults, especially LED^PDT is suitable for aviation environment, and is expected to become the first choice in aerospace medicine. . 2LED light angle is small, strong directionality, wavelength can be concentrated in the visible light band, can be used to treat amblyopia. 3 blue LED cold light source is used to treat neonatal jaundice, with good curative effect and light adverse reaction. 4 Using the on/off of the LED light source can increase the speed of heating or cooling the gene sample and accelerate the replication of the DNA. In addition, based on the biological effects of human tissue on different wavelengths of light, LED light sources in suitable bands can also be used to treat breast cancer, mastitis, optical acupuncture treatment, optical extension, optical therapy, etc., treatment for non-invasive, painless, convenient, cost Low, side effects, and combined with LED control, dimming and other features can also provide patients with personalized optimization treatment options.

2.2 Application of LED light source in biomedical diagnosis

LED light source can be used not only to treat diseases, but also to diagnose diseases, such as for diagnosis of prostate diseases, lumbar disc herniation, fundus diseases, early gastric cancer, early colorectal cancer, skin cancer, etc., and can be used for preliminary diagnosis of hereditary And infectious diseases, etc. LED light source has a wide wavelength range, pure spectrum and controllable beam. It can be used for biological cell detection and diagnosis, which can reduce the interference of stray light and improve the accuracy of detection and diagnosis. In addition, the small size of the LED light source reduces the size of the diagnostic instrument and enables detection and diagnosis of dead angles.

1) LEDs are used for fluorescence spectroscopy. Due to its long life, small size, low voltage power supply, pure spectrum and high luminous efficiency, the LED light source is not only safe, stable and reliable, but also easy to operate. It can realize miniaturization and portable LED fluorescence spectrum detection equipment. The design also facilitates data collection and analysis. In the diagnosis of clinical diseases, LED fluorescence spectrum detection technology has the advantages of no damage, good specificity and high sensitivity, which has been paid attention to by medical personnel. LED fluorescence spectrometry has been used for early diagnosis of microscopic carcinogenesis and atypical tissue proliferation that are difficult to detect by the naked eye. It is used to induce fluorescence spectra in human blood to detect and analyze blood for early indoor and outdoor environments. Diagnosis of dermatology, used to diagnose dental calculus, etc. In addition, LED fluorescence spectrum detection technology is also used to detect medical drugs, detect flavomycin, detect pesticide residues, and detect algae on the spot. The application range is very broad.

2) LED medical endoscope. LED light source has small volume, good color performance and adjustable light color, which makes LED medical endoscopes have the advantages of miniaturization, simple operation, safety and reliability, and can improve the ability of doctors to distinguish different tissues, and it is easy to reach more narrow. Parts, such as blood vessels, lymph, etc., are mainly used to detect and diagnose diseases of the digestive tract, intestinal diseases, early-stage pharyngeal cancer, esophageal intraepithelial cancer, early gastric cancer, early colorectal cancer and other diseases.

3) LED medical image viewing light. The medical image viewing light is a device for directly obtaining diagnostic information of digital image photos, and the performance of the film directly affects the quality of the diagnosis. The LED light source has the advantages of high luminous efficiency, adjustable brightness color temperature, small beam angle, narrow spectrum and small volume. It can be applied to medical image viewing lamps, which can expand the brightness range, eliminate the negative effect light, and improve the image information reading rate. It reduces the user's visual fatigue and has the advantages of energy saving, convenient maintenance, easy operation and long service life. LED medical image viewing light, also has the characteristics of movable operation and low-voltage power supply. It is suitable for reading and watching movies at the bedside of medical staff in clinical departments. It can be used for emergency reading of medical institutions in the absence of power supply or power failure. The film diagnosis not only improves the accuracy and quality of digital image photo diagnosis, but also improves the efficiency of medical image diagnosis, and can also improve the visual comfort of medical workers in film diagnosis.

In addition, other applications of LED light source in biomedical diagnosis include: 1 LED eye chart light box made of LED light source, suitable for clinical diagnosis of ophthalmology and optics, visual measurement of academic research, etc., which can easily replace the visual target. Eliminate the possibility of memorizing the visual target and ensure the accuracy of the visual diagnosis result. 2 LED fluorescent microscope made of LED light source, showing excellent image quality and intelligent automatic characteristics, used for diagnosis of Mycobacterium tuberculosis in tuberculosis laboratory, its diagnostic effect is better than traditional Ziehl-Neelsen smear Microscopic examination method. 3 LED living body detection device made of LED is used for diagnosis and identification of finger veins, which can accurately detect whether the vein characteristics of the user trying to enter the system are living, and to some extent, avoid the influence of forgery features on the subsequent recognition system, and increase The reliability of the reflective finger vein recognition system. In addition, the LED light source can also be used to make an animal living body imaging system, detecting weak fluorescence in a living body, and the like.

2.3 LED light source in biomedical lighting applications

LED light source has developed into a mainstream light source for lighting due to its energy saving and environmental protection advantages. It is widely used in road/tunnel lighting, urban landscape lighting, building architectural lighting, etc. Biomedical sites, including medical spaces, biomedical diagnostic rooms, biomedical workbench, patient lounges, etc., must not only meet the physiological needs of medical staff during treatment and diagnosis, but also meet medical staff and patients. The psychological needs of their families have certain specialities. With the development of LED light source technology and its integration with intelligent control technology, the application of LED light source in biomedical lighting is more and more E9-22.

1) For operating room lighting. The LED light source has the characteristics of adjustable color temperature, controllable light, small volume and stable performance. It is used for operating room lighting (including operating table lighting, general lighting, indicating lighting, etc.), breaking through the color temperature of traditional operating room lighting. Limitations, poor surgical vision, poor visual perception, etc., can provide a wider illumination area, more modern visual experience, more precise focus area lighting, and solve the visual fatigue problem of medical staff during long hours of work. Improve the efficiency and precision of surgery. LED surgical shadowless lamp is an important equipment for operating room lighting. It has good chromaticity performance, can increase the color difference between blood and other tissues and organs of the human body, making the doctor's vision clearer during operation, and it is easier to distinguish between drooling and infiltration. The various tissues and organs of the human body in the blood are convenient for observing objects with different depths, sizes and contrasts in the incisions and body cavities, ensuring safer and smoother operation and improving the quality of the operation. In addition, the LED light source is also applied to a head-mounted surgical light (ie, a medical headlight) worn by a surgeon during an operation such as otolaryngology, stomatology, or brain surgery. LED medical headlights have the characteristics of directional precision illumination, convenient carrying, excellent color reproduction performance, etc. If the technology of integrating the Internet, big data, intelligent control, etc., in addition to functional lighting, it also has the functions of camera and data transmission. The images and voices during the operation can be transmitted to the electronic terminal in real time through the high-definition digital transmission system for other doctors to observe and video teaching, and remote consultation can also be carried out.

2) Used for ward lighting. The ward is the home of the patient in the hospital, and is also the place where the family members of the patient visit. The lighting includes general lighting, reading lighting, observation lighting, nurse station lighting, etc., and needs to meet the physiological and psychological needs of patients, family members and nurses. The warm color tone LED light source is used for ward lighting, which can create a comfortable and pleasant light environment, and the brightness of the LED light source is flexible and controllable, and the color temperature is adjustable, which can meet the individual needs of the patient's light environment, and can not only relieve the patient's physiology. The pain can also alleviate the psychological pressure of the patient, making him feel the kindness and warmth in the spirit, which is conducive to the stability of the patient's mood and the recovery of the body.

3) For large space lighting in hospitals. The hospital's large space includes hospital entrance halls, registration halls, toll halls, and drug collection halls. It has the characteristics of deep, large, and spacious, and is generally the first place where patients enter the hospital. In addition to meeting the requirements of functional lighting, the lighting of this space should also provide patients and their families with a comfortable and intimate light environment, so that they can put down the feelings of depression, fear, anxiety and nervousness, and enhance the confidence to overcome the disease. LED light source has the advantages of no glare, controllable brightness, color temperature, good color characteristics, etc. It can create a visual and comfortable light environment for hospital large space lighting, giving patients and their families a good light environment experience, making them Establishing a friendly and friendly first impression of the hospital is conducive to the establishment of a good doctor-patient relationship between patients and their families and medical and medical staff. At the same time, the use of LED light sources in large-scale lighting in hospitals will fully realize the energy conservation of medical buildings and contribute to the comprehensive project of energy conservation and emission reduction in China.

In addition, the LED light source can also be used for medical identification lighting, providing patients and their families with convenient medical treatment flow lines, ensuring the normal operation of the medical treatment, and the personal safety of doctors and patients in an emergency state. As an auxiliary measure for medical treatment, the LED media interface has also been introduced into the biomedical field to transform and enhance the light environment of the medical space, creating a relaxed, friendly and harmonious environment for patients and medical staff. With the development of green medical buildings and the concept of 'biological-psychological-social medical care', the application of LED light sources in the field of biomedicine will be more and more.

3 problems

With the improvement of the cost performance of LED light sources and the deep research of LED biomedical basic theory, LED light sources are more and more used in the field of biomedicine, but there are still many problems to be solved.

1) The application of LED light sources in the field of biomedicine has developed into a subfield of semiconductor lighting applications. More and more LED lighting business companies are beginning to get involved in in vitro diagnostic equipment, medical imaging imaging systems, biomedical lighting, intelligent care products, home medical examination systems, etc., various LED therapeutic devices, LED diagnostic instruments, LED beauty instruments The quality of the products is uneven. However, modern biomedicine is a cross-cutting discipline that integrates medical imaging technology, biomedical information, image processing, nanoscience, and biological materials. With the introduction of the social-psychological-biomedical model, modern systems biomedicine continues to develop, The professional requirements of LED light sources in the field of biomedicine are getting higher and higher, that is, the entry barrier is constantly improving. At present, many LED biomedical devices and equipment lack innovation in R&D and design. There is still a considerable gap between the professional and specialized requirements of the integrated biomedical field and the actual needs of the relevant practitioners. It is simply to replace the LED light source with the traditional one. The light source is used in biomedicine, and it does not fully exert the advantages of good color quality, controllability, dimming, etc. of the LED light source, and does not provide better service and technical support for the practical application of biomedicine.

2) LED light therapy has been developed for many years, and its basic research and applied research have achieved practical results. There are many successful cases of LED light therapy for treating neonatal jaundice, and other clinical application cases are numerous. We know that after receiving light from LED light, biological tissues convert the absorbed light energy into heat energy and chemical energy, which leads to a series of physiological reactions such as photodecomposition, photopolymerization, photooxidation and photosensitization inside the body. For tissue light of different wavelengths and different intensities, biological tissue cells will produce different mechanism responses, which provides a theoretical basis for the treatment of different diseases by LED light therapy. However, what kind of wavelength band, what spectral distribution, and how many light intensity LED light sources can achieve the best effect of treating patients through how long and how much dose of radiation, how to better and better cure The physiological pain of the patient can well alleviate the psychological and mental negative emotions of the patient. This is a key scientific issue in the research and application of LED light therapy. The true scientific and effective LED phototherapy mechanism is still in the Exploring and exploring. According to the photobiological and photochemical stimulating effects of different biological organisms, according to the individualized and special needs of different biological organisms, the actual requirements of biomedical clinical and the parameter performance of LED light source, R&D and innovative design specialization and individuality The LED phototherapy system has a lot of practical work that we need to do.

3) LED light source is a new type of solid-state light source. Its application to the human eye retina, skin, circadian rhythm, etc., and its photobiosafety, photochemical hazard, etc. have attracted wide attention, and everyone is building and perfecting LED light source. The voice of related products and application standards has become increasingly high. The standards related to the application of LED light sources in the biomedical field are: 1 IEC/EN 62471 "Photobiosafety of Lamps and Lamp Systems" series, which regulates the thermal hazard, blue light hazard and ultraviolet hazard of the lamp and lamp system on the human retina. Evaluation of the photochemical UV hazard and thermal hazard of the skin, and the corresponding test requirements are given, but the standard series does not have a photobiosafety test and evaluation for the field, and the scope of application does not include medical instruments, but medical LED devices need Refer to the standard requirements of this series to evaluate and test the risk level of photobiosafety of the equipment. 2 IEC 60601 "Medical Electrical Equipment" series, which specifies the performance requirements and safety requirements of non-laser light source equipment for treatment, diagnosis, monitoring and cosmetic/aesthetic use, and limits the prevention of dangerous output and the hazard of light radiation. 3GB 50034 "Architectural Lighting Design Standards" JGJ 312 "Electrical Building Electrical Design Code", regulates the lighting indicators of operating rooms, medical intensive care rooms, diagnostic rooms, treatment rooms and other places in medical buildings. In addition, ISO 15004-2 "Ophthalmic Instruments - Basic Requirements and Test Methods Part 2: Light Hazard Protection" classifies the categories of ophthalmic instruments and proposes appropriate measures based on the risk level; YY 0055. 2 "Dental Light Curing Machines 2 Part: LED light bulbs stipulate the light radiation value and test requirements in the specific wavelength range of the LED light curing machine; YY/T 061 "General technical conditions for medical image observation devices" gives the light source used in the medical image observation device. Performance requirements and safety requirements. Other relevant standards include photobiosafety thresholds, guidelines, and statements for non-related sources issued by ICNIRP. However, with the continuous improvement of the luminous intensity of LED light sources, the wide use of blue light band, ultraviolet band and infrared band LED light source, the research on the physiological mechanism of LED light acting on biological organisms is deepening, about the radiation dose of LED light source, the duration of irradiation, radiation The requirements for limits, etc., need to be continuously updated in relevant standards. The classification system for radiation risk levels of LED biomedical devices in the standard needs to be more refined to better guide and standardize equipment manufacturers and equipment users according to standard science. Use it effectively and safely.

The application of LED light source in biomedical field is an interdisciplinary integrated cross-application field. There are also many other problems, such as how to change the color temperature and color rendering of LED light source to improve the ability to distinguish body tissue during medical anatomy, how to integrate LED Light source and traditional detection and diagnosis technology to improve the accuracy of the diagnosis of pathological tissue, LED light source effect on the physiological mechanism of biological organism tissue research results are applicable to astronauts flying in space and so on.

4 Conclusion

With the continuous development of LED light source technology, the application of LED light source in skin beauty and body, psychotherapy, mood regulation, biomedical diagnosis and treatment has been expanding, and its application in biomedicine has not only opened up a new market for semiconductor lighting applications. It also contributed an important force to the development of biomedicine and life sciences. Although there are still many problems in the application of LED light sources in biomedicine, there are still many practical work to be done, but we believe that these problems can be solved in the semiconductor lighting industry and the biomedical field. With effective solutions, its development and application prospects are very broad.

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