MEMS Basics: System Features and Classifications

Catalog

Ⅰ Introduction

The MEMS is Micro Electromechanical System. It is mainly composed of three parts: sensors, actuators, and micro-energy. Micro electromechanical systems involve physics, semiconductors, optics, electronic engineering, chemistry, materials engineering, mechanical engineering, medicine, information engineering and biological engineering, and other disciplines and engineering technologies. It has opened up a wide range of applications such as intelligent systems, consumer electronics, wearable devices, and smart homes. Common products include MEMS accelerometers, MEMS microphones, micro motors, micro pumps, micro vibrators, MEMS pressure sensors, MEMS gyroscopes, MEMS humidity sensors, etc., and their integrated products. 

MEMS circuit

MEMS will have broad application prospects in the national economy and military systems. The main civilian fields are electronics, medicine, industry, automotive, and aerospace systems. In summary, MEMS has the following basic characteristics: miniaturization, intelligence, multi-function, high integration, and suitable for mass production.

Ⅱ MEMS system Features

MEMS (Micro-Electro-Mechanical System) was first used in automotive airbags, and then widely used in various fields of automobiles in the form of MEMS sensors. With the further development of MEMS technology. The demand for small-volume, high-performance MEMS products is increasing rapidly. MEMS products have also appeared in large numbers in consumer electronics, medical and other fields.

MEMS

1) Miniaturization: MEMS devices are small in size, light in weight, low in energy consumption, low inertia, high in resonance frequency, and short in response time.

2) With silicon as the main material, the mechanical and electrical properties are excellent: the strength, hardness, and Young's modulus of silicon are equivalent to iron. The density is similar to aluminum, and the thermal conductivity is close to molybdenum and tungsten.

3) Mass production: With silicon micromachining technology, hundreds of micro-electromechanical devices or complete MEMS can be manufactured on a single silicon wafer at the same time. Mass production can greatly reduce production costs.

4) Integration: It can integrate multiple sensors or actuators with different functions, different sensitive directions or actuation directions, or form a microsensor array, a microactuator array, or even integrate devices with multiple functions. Form a complex microsystem. The integration of micro-sensors, micro-actuators, and microelectronic devices can produce highly reliable and stable MEMS.

5) Multidisciplinary: MEMS involves multiple disciplines such as electronics, machinery, materials, manufacturing, information and automatic control, physics, chemistry, and biology, and integrates many cutting-edge achievements in the development of science and technology today.

Ⅲ MEMS classifications

1.Sensing MEMS technology

Sensing MEMS technology refers to devices and systems that are processed by microelectronics and micromachines, and use sensitive components such as capacitors, piezoelectrics, piezoresistance, thermocouples, resonance, and tunnel current to sense and convert electrical signals. It includes various sensors such as speed, pressure, humidity, acceleration, gas, magnetism, light, sound, biology, chemistry, etc. According to the types, there are mainly: area array touch sensor, resonance force sensitive sensor, miniature acceleration sensor, vacuum microelectronic sensor, etc... 

MEMS sensor

The development of sensors is array, integration, and intelligence. Since the sensor is the tentacle for humans to explore the natural world and the neuron of various automated devices, it will be valued by countries all over the world in the future.

2.Biological MEMS technology

Biological MEMS technology is a chemical/biological micro-analysis and detection chip or instrument manufactured with MEMS technology. There is a micro-drive pump, micro-control valve, channel network, sample processor, mixing cell, metering, and augmentation manufactured on a substrate. Expanders, reactors, separators, detectors, and other components are integrated into a multifunctional chip. It can realize the whole analysis process of sample injection, dilution, reagent addition, mixing, amplification, reaction, separation, detection, and post-processing. It shrinks the traditional analytical laboratory functions on a chip. 

MEMES components

Biological MEMS system has the characteristics of miniaturization, integration, intelligence, and low cost. In terms of functions, it has the characteristics of a large amount of information, high analysis efficiency, few connections between the system and the outside, real-time communication, and continuous detection. Internationally, the research of biological MEMS has become a hot spot, and it will soon bring about a major innovation in biological and chemical analysis systems.

3.Optics MEMS technology

With the rapid development of information technology and optical communication technology, another field of MEMS development called micro-opto-electromechanical systems (MOEMS), that is, the integration of basic technologies such as microelectronics, micromechanics, and optoelectronics has appeared. It can completely integrate various MEMS structural parts with micro-optical devices, optical waveguide devices, semiconductor laser devices, photoelectric detection devices, etc. MOEMS has the characteristics of small size, low cost, mass production, precise driving, and control, etc. More successful applied scientific research mainly focuses on two aspects:

The first is a new display and projection equipment based on MOEMS, which mainly studies how to spatially modulate light through the physical movement of the reflecting surface. Typical representatives are digital micromirror array chips and grating light valves. The second is communication systems, which mainly research through micromirrors. The physical movement of the optical path is used to control the expected change of the optical path. The more successful optical communication devices such as optical switch modulators, optical filters, and multiplexers. MOEMS is a highly comprehensive and highly interdisciplinary high-tech. Carrying out scientific and technological research in this field can drive the development of a large number of new concept functional devices.

4.Radio frequency

Radio frequency MEMS technology is traditionally divided into two types, fixed and movable. Fixed MEMS devices include body micro-machined transmission lines, filters, and couplers, and movable MEMS devices include switches, tuners, and variable capacitors. According to the technical level, it is divided into: 1. The basic device-level composed of micromechanical switches, variable capacitors, and inductive resonators; 2. The component level composed of phase shifters, filters, and VCOs; 3. The application system-level composed of variable beam radar phased array radar antennas, etc. With the passage of time and the gradual development of technology, the content of MEMS is constantly increasing and becoming more abundant.

The world-famous information technology journal "IEEE Proceedings" summarized the content of MEMS in the 1998 MEMS album as integrated sensors, microactuators, and microsystems. People also classify micromachines, microstructures, and smart sensors into the category of MEMS. The technology of making MEMS includes two parts: microelectronics technology and micromachining technology. The main contents of microelectronics technology are: oxide layer growth, photolithography mask production, photolithography selective doping (shielding diffusion, ion implantation), thin-film (layer) growth, connection production, etc. The main content of micro-processing technology includes silicon surface micro-processing and silicon body micro-processing (anisotropic corrosion, sacrificial layer) technology, wafer bonding technology, and LIGA technology for making high-aspect-ratio structures. The use of microelectronics technology can manufacture integrated circuits and many sensors. Micromachining technology is very suitable for making certain pressure sensors, acceleration sensors, micro pumps, microvalves, micro grooves, micro reaction chambers, microactuators, micro machines, etc. This can give full play to the advantages of microelectronics technology and use MEMS Technology manufactures high-reliability micro-satellites in large quantities and at low cost.

MEMS technology is an emerging technology field, mainly belonging to the category of micron technology. The development of MEMS technology has gone through more than 10 years. Most of them are based on the existing technology and are manufactured with technological approaches from large to small. A number of new integrated devices have been developed, which greatly improved the function and efficiency of the devices. The development of MEMS technology may, like microelectronics, have a revolutionary impact on science and technology and human life, especially for the development of micro-satellites, which will open the door to mass production of low-cost, high-reliability micro-satellites.