Development of the hottest microfluidic system

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Overview of the development of microflow systems

review on microflow the volatile organic pollutants (VOCs) emitted in the production process are also increasingly restricted devices and systemsyin Zhizhong et al a review on the development in microflow devices and systems is introduced

Ke should be replaced words: MEMS, microfluidics, microsensor, micropump, microvalve, microchannel 1 preface micro electro mechanical systems (MEMS) generally refers to devices that are mass produced by integrated circuits and other processes, and integrate micro mechanisms, micro sensors, micro actuators, signal processing and control circuits. In 1959, the famous physicist Richard Feynman proposed the idea of micro machinery. In 1962, the first silicon micro pressure sensor came out, and then some micro mechanisms were successfully developed, such as micro gears, pneumatic turbines, etc. However, until the 1980s, with the development and maturity of microelectronic industry, materials and control technology, MEMS did not have the technical basis for development [1]. In 1987, the University of California at Berkeley developed a rotor with a diameter of 60 ~ 120 μ M silicon micro electrostatic motor has attracted great attention. Over the past decade, MEMS has developed rapidly and is considered to have a bright future [2, 3]

mems has the characteristics of small size, light weight, fast response, high precision, good performance and low cost, which makes it have potential huge application prospects in the fields of industry, information processing and communication, national defense, aerospace, navigation, medicine and Bioengineering, agriculture and family services. Some people in Japan even call it "mechanical Renaissance" [4]

As an important branch of MEMS, microfluidic system has made great progress in recent years. Micro flow system is a micro electro mechanical system composed of micro flow components such as micro pump, micro valve and micro sensor, which can control the pressure, flow and direction of micro fluid and analyze its composition. As a larger branch of MEMS, microfluidic system also has the characteristics of integration and mass production. At the same time, due to its small size, it can reduce the invalid volume in the flow system, reduce energy consumption and sample consumption, and have fast response, so it has a wide application prospect; For example, the maximum energy measurement range of the liquid drop hammer impact experimental machine is 300j, which can carry out three kinds of experimental bodies: a method, B method and C method, gas flow distribution, chemical analysis, micro injection and drug delivery, micro cooling of integrated circuits, propulsion of micro satellites, etc. The following is an overview of each part of the microfluidic system. The micro flow sensor has designed a glass fiber fabric structure and multilayer composite felt that meet the requirements. In theory, any physical quantity related to flow that can be obtained by theoretical or experimental methods can be used for flow measurement. Micro flow sensor has the advantages of small volume, small interference of flow field, easy integration and mass production. 2.1 piezoresistive micro flow sensor Figure 1 shows a micro flow sensor developed by SS and others based on hydrodynamic measurement [5]. The force acting on the cantilever end has a nearly linear relationship with the flow. Figure 1 cantilever micro flow sensor Figure 2 micro flow sensor based on temperature change piezoresistive micro flow sensor is characterized by relatively simple manufacturing process and fast response, but it is generally greatly affected by temperature. 2.2 micro flow sensor based on temperature change figure 2 is a schematic diagram of a typical micro flow sensor based on temperature change [6]. After heating resistance h, due to the flow of fluid, its upstream temperature (T1) is lower than its downstream temperature (T2), and the temperature difference between the two contains flow information [7]

literature [8] gives a systematic introduction to micro flow sensors. Micropump micropump, as an important micro flow actuator, is an important symbol of the development level of micro flow system. The micropumps published so far can be divided into valved micropumps and valveless micropumps according to whether they have movable valve plates. 3.1 valved micropump valved micropump is mainly a reciprocating membrane pump based on different actuation principles. The basic structure of the reciprocating membrane pump is shown in Figure 3 [9]. The difference between various pumps lies in the different driving methods for the film [10], including electrostatic, piezoelectric, electromagnetic, thermal, pneumatic and shape memory alloy. Figure 4 and figure 5 are electrostatic and piezoelectric driven micropumps, respectively. Fig. 3 basic structure of reciprocating membrane pump Fig. 4 electrostatic driven micropump Fig. 5 piezoelectric driven micropump 3.2 Valveless Micropump valved micropump with movable valve plate is generally complex in structure and has certain difficulties in process realization and integration. Valveless Micropump is characterized by simple structure and manufacturing process, and novel pumping principle. Figure 6 is a Valveless Diffuser micropump, which uses the different resistance of fluid flowing through the contraction tube and the diffuser to transport fluid, but this

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