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Metrology and its characteristics - focus on microfluidic control technology

Metrology, used to be called “measures and measures” in China, its original meaning is the measurement of length, volume and quality. The main instruments are rulers, buckets and scales. Although with the advancement of the times, the concept and content of "measures and measures" are constantly changing and enriching, it is still difficult to get rid of the limitations of history and cannot meet the needs of science and technology, economy and social development. Therefore, since the 1950s, China has gradually replaced “measures and measures” with “measurement”. It can be said that “metering” is the development of weights and measures; others are called “modern weights and measures”.
In order to understand the measurement, first understand the "quantity". Quantity is an attribute that can be qualitatively and quantitatively determined by phenomena, objects or substances. This is currently an internationally accepted statement. In other words, everything in nature is made up of certain "quantities" and is embodied by "quantity." Therefore, in order to understand nature, use nature, and transform nature for the benefit of mankind, it is necessary to analyze and confirm various quantities, both to distinguish the nature of the quantity and to determine its specific quantity; Important means. Therefore, it can be said that measurement is a process of qualitative analysis and quantitative determination of “quantity”.

The characteristics of measurement can include the following:
1, accuracy (accuracy)
Accuracy is a fundamental feature of measurement. It characterizes how close the measurement results are to the true value being measured. Strictly speaking, only the magnitude, and the result of no accuracy, is not the measurement result. That is to say, the measurement should not only clearly give the measured value, but also the uncertainty (or error range) of the quantity, ie the accuracy. More strictly speaking, the value or range of the amount of influence of the measurement results should also be indicated. Otherwise, the measurement results will not have sufficient social practical value. The so-called unity of quantity also refers to the unity within a certain degree of accuracy.

2, consistency
The unity of measurement units is an important prerequisite for consistent values. Measurements should be made at any given time, anywhere, using any method, using any appliance, and any person, as long as the requirements of the relevant measurement are met, and the measurement results should be consistent within a given uncertainty (or margin of error). Otherwise, the measurement will lose its social significance. The consistency of measurement is not limited to domestic, but also applies to the international.

3, traceability
In actual work, the requirements for calculation results vary depending on the purpose and conditions. However, in order to make the measurement results accurate and consistent, all the same magnitude must be transmitted from the same measurement basis (or original standard). In other words, any measurement can be traced back to the measurement baseline through a continuous comparison chain. This is traceability. It can be said that "traceability" is the technical return of "accuracy" and "consistency". Because any accuracy and consistency are relative and are closely related to contemporary technological level and people's cognitive ability. That is to say, "trace source" can make the measurement technology and people's understanding relatively unified, so that the "accuracy" and "consistency" of measurement are guaranteed by technology. As far as a country is concerned, all magnitudes should be traced back to national measurement benchmarks; internationally, they should be traced back to international measurement benchmarks or agreed measurement standards. Otherwise, the magnitude is multi-source, not only is it not accurate and consistent, but it is bound to cause technical and application confusion, which leads to serious consequences.

4. Legality
The social nature of measurement itself requires a certain legal guarantee. In other words, accurate and consistent quantity, not only must have certain technical means, but also have the corresponding administrative management of laws and regulations, especially those that have a significant impact on the national economy and people's livelihood, such as social security, health care, and the environment. The protection and the measurement in trade settlement must have legal protection. Otherwise, the exact consistency of the magnitude cannot be achieved, and the role of measurement cannot be achieved.
It can be seen that the measurement is different in general measurement. Measurements are all operations performed to determine the magnitude, and are usually not available or required to have the above-described metrology features. Therefore, the measurement belongs to the measurement, but is stricter than the general measurement; it can also be said that the measurement is a measurement of the exact value of the quantity. Of course, in actual work or literature, there is generally no need to strictly distinguish between “measurement” and “measurement”. This is the case at home and internationally. Incidentally, when translating foreign materials, such as English measurement, it can be translated as "measurement" or "measurement", depending on the specific circumstances and practices.

As for the "test", the test has a certain experimental (exploratory) measurement. In recent years, measurements that are not strictly in accordance with agreed procedures or mature schemes are often referred to as tests, and sometimes tests can be understood as a combination of measurements and tests.

From the perspective of disciplinary development, measurement is originally part of physics, or a branch of physics. With the development of science and technology, economy and society, the concept and content of measurement are constantly expanding and enriching, which has gradually formed a comprehensive discipline of measurement theory and practice - metrology. In other words, metrology is a field of knowledge about measurement theory and practice.
As far as the discipline is concerned, metrology can be further divided into:

(1) General metrology – involves all common problems of measurement and not specific to the measured metrology part. For example, general knowledge of the unit of measurement (structure of the unit system, conversion of the unit of measurement, etc.), measurement error and data processing, basic characteristics of the measuring instrument, and the like.
(2) Applied metrology – the metrology part of a specific measurement. General metrology is generic and not specific to measurement; applied metrology is a measure of a specific specific quantity, such as length measurement, frequency measurement, and so on.
(3) Technical metrology – a metrology part involving metrology techniques, including process measurement problems. For example, automatic measurement, online measurement, and the like.
(4) Theoretical metrology – the metrology part of measurement theory. For example, theory on quantity and unit of measurement, theory of measurement error, etc.
(5) Quality metrology – the metrology part of quality management. For example, regarding raw materials, materials, equipment, and measuring instruments, measuring methods, measurement results, etc. used to inspect and ensure relevant quality requirements in production.
(6) Legal metrology – the metrology part of legal management. For example, in order to ensure public safety, national economic and social development, measurement units, measuring instruments, measurement methods and measurement accuracy (or uncertainty) and professional skills are required according to legal, technical and administrative needs. Mandatory management.
(7) Econometrics – the metrology part of the economic benefits of measurement. This is a marginal subject that people have paid close attention to in recent years. For example, measuring the economic role and status in social production systems, measuring the role of technological development, productivity growth, product quality improvement, material resource conservation, national economic management, health care, and environmental protection.
Of course, the above division of metrology is not absolute, but highlights the measurement of a certain aspect.

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