Current situation and development trend of electromagnetic compatibility of medical electrical equipment and construction of professional medical electromagnetic compatibility laboratory_Century Wisdom (Suzhou) Testing Technology Co., Ltd

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Current situation and development trend of electromagnetic compatibility of medical electrical equipment and construction of professional medical electromagnetic compatibility laboratory

Release time:

2013-04-01 00:00

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introduction

Electromagnetic compatibility technology is a multi-disciplinary and multi-disciplinary fringe science gradually developed at the beginning of this century. Its core is electromagnetic waves, and its theoretical basis covers electromagnetic fields, microwaves, antennas, radio wave transmission, communications, circuit electronics and even biomedicine. The main core of its research is the electromagnetic compatibility of electrical equipment, which we often call EMC ( ElectroMagnetic Compatibility ). The purpose of electromagnetic compatibility technology is to control the " accidental " energy within a " controllable " range, so that all equipment or devices in the entire electromagnetic environment can " coexist peacefully " , and will not even be affected by the background electromagnetic environment of nature itself (eg surge).

Status quo of EMC standardization and certification for medical electrical equipment

Internationally, in 1993 , IEC published the electromagnetic compatibility standard IEC 60601-1-2 for medical electrical equipment to regulate its electromagnetic compatibility requirements, and European countries have fully implemented this standard since 1996 . EMC standards for medical electrical equipment and systems are discussed in Electromagnetic Compatibility Experiments for Medical Electrical Equipment. In China, from the perspective of protecting the lives and health of patients and medical staff, the country has carried out mandatory product certification for medical electrical equipment - the first mentioned is the electrical safety certification of medical electrical equipment, and the corresponding form test The testing standard is the GB9706 series of medical electrical equipment standards published successively in the 1990s . As an important part of safety testing, the electromagnetic compatibility testing standard has been blank for a long time. Until 2005 , the national The Food and Drug Administration promulgated for the first time the equivalent transformation version of the IEC60601-1-2 standard YY0505-2005 "Electromagnetic Compatibility Requirements and Tests for Medical Electrical Equipment", which is a parallel standard about the GB9706.1 standard and is about the first The extension of the requirements of Chapter 36 " Electromagnetic Compatibility " is also the first national mandatory standard on the requirements for electromagnetic compatibility of medical electrical equipment.

The requirements for electromagnetic emission in the YY0505-2005 standard mainly include the limitation of electromagnetic radiation disturbance and conduction disturbance level at the power supply terminal. For example: simple electrical devices (dental drills, ventilators and operating tables, etc.) are in accordance with GB4343-2003 standards; lighting fixtures ( X -ray film lamps, operating room shadowless lamps, etc.) are in accordance with GB17743-1999 standards; medical ITE equipment is in accordance with GB9254-1998 standard requirements; In addition, the electromagnetic emission requirements of all medical equipment are in accordance with GB4824-2003 standard requirements. Among them, GB4824-2003 is the most cited standard in YY 0505-2005 on radio protection services.

In addition, the YY0505-2005 standard also puts forward requirements for electromagnetic immunity, mainly including two aspects: radiation immunity and conduction immunity, and a large number of references to GB17626 series standards. A lot of requirements have been made in many aspects such as value. In fact, in industries such as home appliances and automobiles, at the national regulatory level, more attention is paid to the requirements for electromagnetic disturbance, and there are not too many requirements for immunity, mainly because this type of civilian equipment, manufacturers Pay more attention to other aspects of performance. After all, ensuring the normal use of equipment is a necessary factor for manufacturers to be able to sell products. However, medical equipment is completely different. This is due to the particularity of its product category. We will analyze it below. Therefore, the YY0505-2005 standard puts forward very detailed requirements for equipment immunity. We must consider these aspects when designing the electromagnetic compatibility laboratory.

2. The particularity of electromagnetic compatibility of medical electrical equipment

( 1 ) Functional safety

According to the definition of IEC61508 standard, functional safety ( function safety ): the ability of a safety related system to carry out the actions necessary to achieve a safe state for the EUC or to maintain a safe state for the EUC . In fact, the function of medical electrical equipment is often related to its safety. After all, most medical electrical equipment is used on patients. If the normal use of the function cannot be guaranteed at this time, the patient may not receive timely treatment. And cause safety problems, which is determined by the use of medical electrical equipment.

( 2 ) The structure of medical electrical equipment and the particularity of the use environment

In order to complete the purpose of diagnosis and treatment, today's medical electrical equipment tends to be automated and miniaturized, and electronic components and microprocessors are ubiquitous. The large number of applications of these components, on the one hand, improves the working speed and accuracy of medical electrical equipment, and greatly reduces its external size, on the other hand, it also increases the difficulty of improving electromagnetic compatibility performance. The application of high-speed microprocessors, on the one hand, increases the complexity of the electromagnetic energy radiated by medical electrical equipment and expands the spectrum range of its electromagnetic spectrum. On the other hand, due to the improvement of accuracy, the immunity of the equipment decreases. The reduced size adds difficulties to the rectification of the EMC test.

Information technology equipment and new concept equipment are widely used in medical electrical equipment. The application of PACS has increased the application of information technology equipment in the medical environment; more and more medical electrical equipment has begun to be controlled by computers; Bluetooth, microwave, industrial computer, and robotics are playing an increasingly important role in medical electrical equipment ; Air conditioners, lamps and other traditional civilian electrical equipment are also widely used in the medical environment.

( 3 ) Particularity of places where medical electrical equipment is used

First, the healthcare environment is also becoming increasingly complex. Today's hospital can be said to be a systematic project. All medical electrical equipment, household equipment, information technology equipment, communication equipment, and natural background noise are coupled to medical electrical equipment through various coupling methods. Radiation sources and susceptible equipment tend to complicate. Secondly, due to the limited grounding conditions in the medical environment, in order to realize the functions of the equipment, the use conditions tend to be diversified. Thirdly, most of the operators of medical electrical equipment are medical staff, and they have limited knowledge of electrical knowledge. All these factors increase the difficulty of realizing electromagnetic compatibility.

3. The current development of electromagnetic compatibility of medical electrical equipment in China

At present, the electromagnetic compatibility of medical electrical equipment in my country is not optimistic, which is mainly reflected in:

( 1 ) The electromagnetic compatibility design capability is low

In the process of exchanging and training the engineers of medical electrical equipment manufacturers, we found that many engineers have little understanding of the electromagnetic compatibility performance of the equipment. This situation is more common among domestic enterprises that do not export. In fact, if the requirements of electromagnetic compatibility are considered in the product design and development stage and applied to the product, it will greatly reduce the cost of rectification in the later stage of the product. At the same time, manufacturers of medical electrical equipment do not pay attention to the training of design and development engineers and quality management personnel in electromagnetic compatibility technology.

( 2 ) The electromagnetic compatibility test environment is poor

There are relatively few electromagnetic compatibility laboratories in my country, and they are mainly distributed in developed areas such as the southeast coast, and the distribution of electromagnetic compatibility testing resources is uneven. In addition, due to the huge construction and maintenance costs of the electromagnetic compatibility laboratory, generally speaking, the construction cost of the 10- meter method electromagnetic compatibility laboratory is about 10 million, and only those manufacturers with strong strength can build it. According to our research on domestic EMC laboratories, so far, only GE in Beijing has its own EMC laboratory among manufacturers of medical electrical equipment. This situation has led to the fact that even in the product design stage, we have considered the requirements of electromagnetic compatibility, and there is no channel to test the effectiveness of the design in the finished product stage.

( 3 ) The subjective initiative of enterprises to improve the electromagnetic compatibility capability of products is not high

Since my country does not make mandatory requirements for the electromagnetic compatibility of medical electrical equipment, manufacturers of medical electrical equipment in my country are not enthusiastic about improving the electromagnetic compatibility of their products.

( 4 ) Imported equipment is seriously simplified

During the safety type test of medical electrical equipment, we found that a lot of imported equipment had their EMC components removed after localization to reduce costs. This situation has been found in the detection process in recent years. The main reason is also due to the insufficient supervision of electromagnetic compatibility of medical electrical equipment in my country.

4. The effective way to solve the problems at this stage is to establish a professional medical electrical equipment electromagnetic compatibility testing laboratory

( 1 ) Electromagnetic compatibility testing of medical electrical equipment is an integral part of safety testing of medical electrical equipment

Chapter 36 of the national standard GB9706.1-2007 is the requirement of " electromagnetic compatibility " . In fact, many chapters of safety testing include the idea of electromagnetic compatibility testing. Items such as 6.8 random documents, 15 voltage and energy limits, 42 overtemperature, 44.4 leakage, 52 abnormal operation and fault status, 56.4 connection of capacitors, etc., some of them consider the safety characteristics of electromagnetic compatible components, and some combine the equipment's developed for electromagnetic compatibility. When we conduct electromagnetic compatibility testing, we cannot look at electromagnetic compatibility issues in isolation, it is often related to safety testing.

In addition, for the consideration of " functional safety " , the electromagnetic compatibility of the equipment and its safety testing have to be considered as a whole. In fact, the concept of " basic performance " in EMC immunity testing is another interpretation of " functional safety " . When we conduct EMC testing, we must first define the basic performance of the equipment. The special standards of some product categories define the basic performance, but the basic performance of more product categories needs to be defined by the manufacturer according to the characteristics of its products. The testing engineer must It is necessary to have a certain understanding of the working principle of medical electrical equipment, the use environment, and even what problems may arise during use to determine whether the basic performance defined by the manufacturer is sufficient. In addition, whether the judgment of basic performance will affect the " functional safety " of the equipment in the safety test, only engineers who are very familiar with the safety test standards can flexibly handle these " safety " issues during the electromagnetic compatibility test .

( 2 ) The electromagnetic compatibility test of medical electrical equipment has a high degree of specialization

The specialization degree of electromagnetic compatibility testing of medical electrical equipment is often relatively high. To give the simplest example: when testing X-ray equipment for diagnosis, the equipment is required to simulate the normal working state, which requires electromagnetic compatibility testing . The room has a certain X -ray shielding ability. According to our tests on the ferrite tiles of several EMC laboratory suppliers on the market, in the case of 100kV , the lead content of the ferrite tiles is even less than 0.3mm , if only the material of the laboratory itself There is no doubt that X -ray shielding is not enough. In this case, we need professional planning and design of the laboratory. Another example is that when we test nuclear magnetic resonance products, there is no doubt that there is no way to test all the components. We must have special auxiliary equipment to simulate some components in the nuclear magnetic resonance equipment to complete the test.

( 3 ) The rectification needs to be coordinated with the safety test

When we conduct tests, the following situation often occurs: when we complete the EMC test and rectify a certain part, the result is that the safety test cannot pass at all, and then we rectify the safety part, the result may lead to EMC performance. decline. In this case, we need good communication between electromagnetic compatibility test engineers and safety test engineers, that is to say, EMC test engineers can not only understand the knowledge of EMC testing, he must have certain characteristics and testing standards of medical electrical equipment. Only by understanding can you be competent for this job.

Through the above discussion, it is not difficult to find that the electromagnetic compatibility standards of medical electrical equipment in China lag behind seriously, and at the same time, the corresponding EMC testing capabilities of manufacturers are relatively low, and medical electrical equipment has one or another particularity in terms of electromagnetic compatibility. As a result, it cannot fully learn from the existing mature experience of other industries, and can only find a way to improve the electromagnetic compatibility level that suits the characteristics of this industry. Establishing a specialized medical electrical equipment electromagnetic compatibility laboratory and carrying out electromagnetic compatibility testing is undoubtedly a solution to the current problems. As an indispensable part of the type test of medical electrical equipment, a professional medical electrical equipment electromagnetic compatibility laboratory can not only provide technical support for the testing of medical electrical equipment in my country, improve supervision, and promote supervision effects, but also be more effective. Improve the quality and ability of medical electrical equipment practitioners in my country, and provide guarantee for the safety and effectiveness of medical electrical equipment.

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