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Gas micro-flow measurement and control have always been one of the key core technologies in high-end manufacturing, and the core sensors and control components in this field are precisely the gas mass flow meters and gas mass flow controllers that we will be discussing today. 1. What are gas mass flow meters and gas mass flow controllers used for? Examples of flow meters in traditional industries; examples of flow meters/controls in high-end industries. As the name implies, they are used to measure and control gas flow. The gas referred to here is not the natural gas used at home, nor the gas utilized by traditional energy and chemical industries, power plants, etc. In such scenarios, the gas flow rates that need to be measured and controlled, along with the corresponding pipe diameters, are generally quite large; the gas flow rates are usually above 15 m3/hour, while the pipe diameters range from 15 mm to 3000 mm (or even larger). The gas mass flow meters and gas mass flow controllers discussed here refer to sensors and devices suitable for measuring and controlling gas flows at low to very low rates (ranging from 0.000001 m3/hour to 300 m3/hour, corresponding to pipe diameters from 3 mm to 65 mm). Such devices require a very compact size (usually about the size of a palm), offer high precision in measurement and control (with a repeatability accuracy better than two per thousand), and must be able to withstand the effects of ambient temperature and pressure as well as different gas media. Currently, there are mainly two types of products that meet these requirements: 1) gas mass flow meters and controllers based on the laminar flow principle, and 2) gas mass flow meters and controllers based on the thermal principle. 2. In which fields are laminar flow principle and thermal principle gas mass flow meters and gas mass flow controllers applied? I would like to focus on this issue. They are present in almost every high-tech industry or advanced manufacturing sector where precise gas measurement and control are required. Due to space constraints, I will give a brief overview first and then provide a few examples. These products that we use frequently in our lives all feature them, such as smartphones, computers, wristbands, AR/VR devices, TVs, cars, medicines, beer, air conditioners, watches, gas stoves, batteries, jewelry, and so on. There are also areas of high-end, cutting-edge technology that are not commonly encountered in daily life, but which have their uses. Examples include satellite manufacturing, graphene production, synthetic diamonds (ring-grade), nuclear power plants, fusion reactors, optical fibers, quantum computers, chip manufacturing, cancer-fighting drugs and gene-based medications, ventilators and **machines, online environmental monitoring systems, equipment for air pollution control, electric vehicles, fuel cells, solar panel production, and so on. Since they are present in so many fields and products, could we learn more specifically about where exactly they are used? Brother Shouyi spent a great deal of time doing research and consulting many professionals; let’s take a look at two examples to get an idea of it. Let’s take the most common phone, jokingly referred to as a “human organ”. Let’s first look at the phone’s casing. Phone casings are generally smooth, delicate, and have high wear resistance and hardness. How is this surface created? The specific manufacturing process is quite complex, so it will not be detailed here. However, the most critical step takes place in a device known as a vacuum coating machine; in this vacuum environment, ionized gases and process gases are introduced. The plasma resulting from ionization collides with the target material, thereby applying a special thin film to the surface of our phone cases on a microscopic scale. It is this protective film that gives our phones a smooth texture and wear-resistant properties. This vacuum coating machine is equipped with a large number of gas mass flow controllers, which are used to precisely control the amount of ionized gas and process gas entering the machine; the flow rate is approximately 500 SCCM. The second important function of a phone case is water resistance; since there are numerous electronic components inside the phone, water resistance is particularly important. Early mobile phones did not have very good water resistance; they could easily get water inside them and get damaged if not handled carefully. With ongoing advancements, modern smartphones now possess excellent water resistance. But how can we determine whether the waterproof performance meets the standards? More powerful air leakage detectors are needed; Apple’s iPhone and other devices make extensive use of CTS’s air leakage detectors for waterproofness testing, as these detectors offer high sensitivity and fast testing speeds. The flow-type airtightness tester used by CTS is a more advanced detection method compared to pressure and differential pressure leak detectors; its key component is a micro-flow gas mass flow meter (as shown in the schematic diagram above), with a flow rate range of 0.001 ml/min (or SCCM) to 2 ml/min (or SCCM). In China, there are no reliable suppliers for such advanced airtightness testers; the market is almost monopolized by two American companies. One of the main reasons for this is that only a few companies around the world are capable of producing these high-performance micro-flow gas mass flow meters. Before the release of the iPhone 8, Apple CEO Tim Cook personally went to the CTS headquarters in Cincinnati, Ohio, to thank them for their leak detection devices, which played a crucial role in ensuring the quality of Apple’s products – highlighting thus their importance!