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The development phase of metrology - focus on microfluidic control technology

The development of measurement can be roughly divided into three stages.

1. Classical stage
The classical stage is an initial stage dominated by power and experience, with no or no sufficient scientific basis. As the highest basis for measurement, use a certain part of the human body, animal hair or some ability, plant fruits, musical instruments and articles.
For example, in ancient China, "the hand of the cloth", "the hand is the ascending", "the ten is the process", the "ten process is the minute"; the British "code" is the king Henry I will flatten his arm forward Stretching, the distance from the tip of his nose to the tip of his finger; feet are the length of the feet of Charlemagne; the acre is the area of the land that the two cattle ploughed on the same day, and so on.

2. Classical stage
From a global perspective, the signing of the 1 meter "Metrical Convention" can be considered the beginning of the classic stage. With the advancement of science and technology and the development of social productivity, the measurement benchmarks have begun to shake off the original state of using human bodies, natural objects, etc., and entered a stage of science-based development. Due to the limitation of technology level, the measurement benchmarks of this period are macroscopic instruments or phenomena under the guidance of classical theory. For example, a length reference base made of platinum-rhodium alloy according to 1/4 of the length of the earth meridian, 1/10 000 000; a platinum-rhodium alloy based on the mass of 1 cubic centimeter of water at the temperature at which the density is maximum The manufactured mass unit is the reference kilogram original; the current unit amperage defined according to the force generated between the two energized wires; the time unit second determined according to the rotation period of the earth around the sun;
Such macroscopic physical benchmarks, over time, are inevitably subject to minor changes due to physical, chemical, and wear in use. In addition, due to the limitations of principles and techniques, the accuracy of such benchmarks is difficult to increase so much that they cannot meet the needs of an increasingly social society. Therefore, the topic of establishing a more stable and accurate new measurement standard was proposed.

3. Modern stage
The basic sign of the modern stage is based on the theory of classical theory and is based on quantum theory, from a macroscopic physical reference to a microscopic quantum reference.
Microscopic natural benchmarks, or quantum benchmarks, based on quantum theory, are superior to macroscopic physical benchmarks, more accurate, more stable and reliable. Because, according to quantum theory, the quantity of the microcosm can only be a leap-forward change, and no arbitrary small changes can occur; at the same time, the atoms and molecules of the same kind of matter are strictly consistent and do not change with time and place. This is the so-called stability and homogeneity of the microcosm. Quantum benchmarks are built using the stability and homogeneity inherent in the microscopic world.
To date, quantum benchmarks that have been officially established internationally have a length unit meter reference, a time unit second reference, a voltage unit volt reference, and a resistance unit ohm reference.

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