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Metrology and Its Features - Focus on Microfluidic Control Technology

Metrology, formerly known as “metrics” in our country, has its original meaning in terms of length, volume, and quality. The main instruments are rulers, buckets, and scales. Although the concept and content of "metrics" have constantly changed and enriched as the times progressed, it is still difficult to get rid of the limitations left by history and cannot adapt to the needs of science and technology, economy and social development. Thus, starting in the 1950s, China gradually replaced "metrics" with "measurement." It can be said that "measurement" is the development of weights and measures; others also call it "modern weights and measures."
In order to understand the measurement, first understand the "quantity." Quantity is an attribute that qualitatively distinguishes between a phenomenon, an object, or a substance and determines it quantitatively. This is the current internationally accepted statement. In other words, everything in the natural world is made up of a certain amount of "quantity," and it is expressed through "quantity." Therefore, to understand nature, use nature, and transform nature for the benefit of mankind, it is necessary to analyze and confirm various quantities. It is necessary to distinguish the nature of quantities and determine their specific quantities; and measurement is just for this purpose. Important means. Therefore, it can be said that measurement is the qualitative analysis and quantitative determination of "quantity".

The characteristics of measurement may include the following:
1, accuracy (accuracy)
Accuracy is the basic characteristic of measurement. It represents the closeness of the measurement result to the measured true value. Strictly speaking, only the magnitude, but not the degree of accuracy, is not a measurement result. In other words, measurement should not only clearly give the measured value, but also should give the value of the uncertainty (or error range), that is, accuracy. More strictly speaking, the value or range of influence of the measurement result should also be stated. Otherwise, the measurement results will not have sufficient social and practical value. The so-called unified value refers to the unity within a certain degree of accuracy.

2. Consistency
The unity of the unit of measurement is an important prerequisite for consistent values. The metering results shall be consistent within a given uncertainty (or margin of error) as long as the metering requirements are complied with by any method, instrument, or person at any time, any place. Otherwise, measurement will lose its social significance. The consistency of measurement is not limited to domestic but also applicable to international.

3, traceability
In actual work, due to different goals and conditions, the requirements for calculation results are also different. However, in order for the measurement results to be exactly the same, all the same kind of values must be passed from the same measurement standard (or original standard). In other words, any measurement result can be traced back to the measurement benchmark through a continuous comparison chain. This is traceability. It can be said that "trackability" is the technical return of "accuracy" and "consistency". Because any accurate and consistent is relative, it is closely related to the current level of science and technology and people's ability to understand. In other words, "retrospection" can make measurement science and technology and people's understanding relatively uniform, so that the "accuracy" and "consistency" of measurement are guaranteed by technology. As far as a country is concerned, all quantities should be traced back to national measurement benchmarks; for international use, they should be traced back to international metrology benchmarks or agreed measurement standards. Otherwise, because the quantity is derived from multiple sources, it is not only inaccurate and unanimous, but it is bound to cause confusion in technology and application, resulting in serious consequences.

4, legality
The social nature of measurement requires a certain amount of legal protection. In other words, the accuracy and consistency of the values requires not only certain technical means, but also the corresponding administration of laws and regulations, especially those measures that have a significant impact on the national economy and people’s livelihood, such as social security, health care, and the environment. Measures for protection and trade settlement must also have legal protection. Otherwise, the accuracy and consistency of the value cannot be achieved, and the effect of measurement will not be realized.
It can be seen that the measurement is different from the general measurement. Measurements are all operations that are performed to determine the magnitude, and usually do not have and do not need to have the above-mentioned measurement characteristics. Therefore, the measurement belongs to the measurement, and it is stricter than the general measurement. It can also be said that the measurement is the exact and uniform measurement of the value. Of course, in actual work or literature, it is generally not necessary to strictly distinguish between "measurement" and "measurement." This is the case in China and internationally. By the way, when translating foreign materials, for example, English measurement can be translated as "measurement" or "measurement", depending on the specific circumstances and customs.

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

From the point of view of discipline development, measurement is originally a part of physics, or a branch of physics. With the development of science and technology, economy, and society, the concept and content of measurement have also been continuously expanded and enriched, resulting in the gradual formation of a comprehensive discipline—metrics that studies the theory and practice of measurement. Or, metrology is a field of knowledge about measurement theory and practice.
In terms of disciplines, metrology can be further divided into:

(1) Universal metrology - All common problems related to measurement are not targeted at specific measurable parts of measurement. For example, the general knowledge of the measurement unit (structure of the unit system, conversion of the unit of measurement, etc.), measurement error and data processing, basic characteristics of the measurement instrument, and the like.
(2) Applied metrology - a metrology component that involves specific measures. General-purpose metrology is general and does not aim at specific measurement. Applied metrology is about the measurement of a specific amount, 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, etc.
(4) Theoretical econometrics – involves the metrology part of econometric theory. For example, the theory of the amount and unit of measurement, the measurement error theory, and the like.
(5) Quality metrology - the metrology part involving quality management. For example, with respect to raw materials, materials, equipment, and measuring instruments used in production to check and guarantee relevant quality requirements, measurement methods, and measurement results.
(6) Legal metrology - The metrology part involving legal management. For example, in order to ensure public safety, national economic and social development, according to the needs of law, technology and administrative management, measurement units, measuring instruments, measurement methods and measurement accuracy (or uncertainty), and professional skills, etc. Enforced management.
(7) Econometrics - The metrological part of the economic benefits involved in measurement. This is a fringe discipline that has attracted considerable attention in recent years and involves a wide range of issues. For example, measuring the economic role and status in the social production system, 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 it highlights some aspects of measurement problems.

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