“Micro-Electro-Mechanical Systems (MEMS) are compact devices that combine various functions, such as mechanics, optics, fluids, and electronics, on a single silicon chip, and are a major enabling technology for developments in medical, transportation, and telecommunications. MEMS accelerometers, MEMS gyroscopes, MEMS pressure sensors, MEMS switches, MEMS vibration energy harvesters, MEMS biosensors, MEMS oscillators, these are all familiar products.

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Micro-Electro-Mechanical Systems (MEMS) are compact devices that combine various functions, such as mechanics, optics, fluids, and electronics, on a single silicon chip, and are a major enabling technology for developments in medical, transportation, and telecommunications. MEMS accelerometers, MEMS gyroscopes, MEMS pressure sensors, MEMS switches, MEMS vibration energy harvesters, MEMS biosensors, MEMS oscillators, these are all familiar products.

MEMS devices have the advantages of light weight, small size, low cost, and low power consumption, which are very beneficial to the application of MEMS devices in industries such as telecommunications and consumer electronics. In recent years, MEMS technology has become increasingly popular in the automotive industry, especially in vehicle safety systems including airbag systems.

Technological Advances in MEMS

The first laboratory demonstrations of MEMS devices took place in the 1960s, in the form of MEMS pressure sensors. The real commercial development and manufacturing began in the 1990s. The smartphones, smartwatches and fitness trackers we use today are basically equipped with MEMS devices.

Whereas aviation gyroscope systems used to determine roll, pitch and yaw in aircraft cockpits weighed several kilograms, MEMS gyroscopes used in smartphones now weigh less than a milligram, the size of a grain of sand. As the size shrinks, the manufacturing cost of MEMS is significantly reduced and the economies of scale are improved. Compared with traditional mechanical devices, MEMS devices have lower power consumption and higher sensitivity. For example, MEMS resonant strain gauges consume only microwatts of power and can provide extremely high sensitivity in the nanostrain range.

MEMS are used not only for sensors, but also for communication modules, actuators and data processing equipment, and perception sensors, with components ranging from one micron to one millimeter in size. The resulting machines range from simple machines without any moving parts to complex electromechanical systems with multiple moving parts. There are many different types of these systems: magnetic, electrical, thermal, chemical, optical and mechanical.

Market potential of MEMS

According to Yole, the value of the global MEMS and sensors market will nearly double from $48 billion in 2018 to $93 billion in 2024. In 2018, the MEMS and sensing market accounted for more than 10% of the overall IC market as more MEMS devices and sensors, such as MEMS, image sensors, and RF filters, were integrated into end products such as consumer products and automobiles.

From 2019 to 2024, the MEMS market will grow by 8.3% annually, driven by applications such as pressure, radio frequency, inertial, and biomedical. Affected by the new crown epidemic, in 2020, the MEMS market value is about 12.1 billion US dollars, an increase of about 2% over the previous year.

After a weak 2019 and 2020, analysts at Yole expect the MEMS market to grow 11% to $13.4 billion in 2021. After that, MEMS’ annual revenue will increase to $18.2 billion by 2026, a compound annual growth rate of about 7%. Among them, traditional MEMS devices will continue to grow, but at a slower rate, and related products include microphones and optical MEMS. MEMS revenue is mainly driven by the consumer market, with consumer applications accounting for approximately 62% of the total market and the automotive industry accounting for 16% of the total market.

Figure 1: Development of MEMS industry applications (Source: Yole)

Market analysis from Mordor intelligence shows that in 2020, the global MEMS market is valued at approximately $10.92 billion and is expected to reach $18.88 billion by 2026, growing at a CAGR of 8.71% during the forecast period from 2021 to 2026, These figures are slightly higher than Yole’s forecast.

Mordor intelligence pays more attention to the development of the consumer market and believes that wearable devices are an important step in the development of the Internet of Things and a new application field of MEMS sensors. With MEMS, the final product will have a better product appearance and increased functionality. Likewise, MEMS also play a key role in the automation industry. For example, MEMS accelerometers and gyroscopes are ideal for industrial automation applications.

The relevant market data in the “Global MEMS Industry Report” published by the Report linker was lower than Yole’s forecast. Report linker data shows that the global MEMS market is estimated at $11.5 billion in 2020 and is expected to reach a size of $16.9 billion by 2026, growing at a compound annual growth rate of 6.7% during the period.

Consumer electronics accounted for the largest share in the past few years due to the increasing use of MEMS technology in smartphones, tablets, laptops, wearables, digital cameras, game consoles, media players and portable navigation devices . Consumer electronics, one of the segments, is expected to grow at a CAGR of 7.3% to reach $10.3 billion by 2026. Report linker is also bullish on the potential of the automotive market and says that increasing demand for automotive automation, growing trends in driverless cars, increasing number of electric vehicles and intense competition within the automotive industry are some of the major factors driving the demand for sensors in the automotive industry. Growth in the automotive industry will grow at a CAGR of 5.9% over the next seven years, and the segment currently accounts for 15.1% of the global MEMS market. Among them, the US market is expected to reach US$2.1 billion in 2021, and the Chinese market is expected to reach US$3.9 billion in 2026.

With the continuous expansion of the MEMS market, the market competition is becoming more and more intense, and the entire market is currently dominated by several companies in the Asia-Pacific region, followed by companies in the Americas and Europe. Broadcom (Broadcom), Bosch (Bosch), STMicroelectronics (STMicroelectronics), TI (Texas Instruments), Qorvo, Infineon (Infineon), NXP (NXP), etc. are some of the major players in the market today.

MEMS sensor applications in automobiles

Over the years, sensors have been integrated into the overall design and manufacture of vehicles. A car can now have 100 or more sensors that monitor and control certain driving parameters. The public acceptance of electric vehicles and the future development of autonomous vehicles will largely depend on the ultra-reliability of these sensors. Among these sensors, MEMS sensors account for about one-third.

Verified market research estimates that the automotive MEMS sensor market size is valued at $1.89 billion in 2020, growing at a compound annual growth rate (CAGR) of 14.5% from 2021 to 2028, and is expected to reach $5.03 billion by 2028. Energy-saving and environmentally friendly technologies are a key factor for the revenue growth of the automotive MEMS sensor market, and government regulations on safety, efficiency, and driver assistance will boost the market growth. Europe and North America are currently the two largest markets for automotive MEMS sensors. However, the growth of the Asia-Pacific market represented by China and India is extremely significant.

Automotive MEMS sensors have the advantages of high efficiency, small size, and low cost. The most common MEMS sensors in vehicles today are: inertial sensors, magnetometers, pressure sensors, thermal sensors, gas sensors, micro-optics. Inertial sensors include accelerometers and gyroscopes, which can be used individually or in combination. Among them, the accelerometer is used to measure static (gravity) and dynamic (motion or vibration) acceleration, and the gyroscope is responsible for identifying changes in angle. These sensors are the dominant type in the automotive industry and are used in many critical applications.

Electrification and intelligence are two important trends in the automotive industry. As this trend accelerates, it is affecting the design and application of automotive semiconductor devices, including MEMS sensors. High-value sensing modules are also gaining traction in automotive systems. Quick integration. For example, MEMS sensors are gaining popularity in vehicle safety systems including airbags.

Bosch SMA7xy series MEMS sensors have extremely fast signal processing capability and can be integrated directly into the airbag ECU or located on the A-, B- or C-pillars or the front bumper to detect a crash or car side in seconds Overturn event, and send this information to the airbag ECU. Next, the airbag ECU will quickly trigger the vehicle’s passive safety system. The SMA760, one of the SMA7xy series products, can accurately detect frontal and side impacts. Another sensor in the same series, the SMA720, contains an x ​​and a z channel and can be used to measure acceleration along a vertical axis, making it an ideal companion for vehicle rollover detection. All sensors of the SMA7xy series meet the ASIL D safety level of ISO 26262 and comply with the VDA AK-LV27 specification.

Figure 2: Bosch SMA7xy family of MEMS sensors (Image credit: Bosch)

A gyroscope in a car can measure or maintain the vehicle’s orientation and angular velocity. MEMS-based gyroscopes in ESP (Electronic Stability Control Program) are widely accepted and powerful safety systems in the automotive industry. To this end, MEMS sensor suppliers are stepping up the development of inertial measurement units (IMUs) for autonomous driving and battery pressure monitoring sensors for lithium-ion electric vehicle batteries to address the new opportunities presented by electrified and automated vehicles.

The automotive industry is an emerging market for high-end IMUs. As high-end automakers move closer to L5 autonomous driving in the next few years, this move will bring huge development opportunities for IMU-driven MEMS sensors. Automotive MEMS IMUs are probably the most complex MEMS devices used in cars. This type of IMU consists of multiple gyroscope and accelerometer sensing elements and signal processing modules integrated in a single package to build an inertial sensor capable of measuring up to six degrees of freedom (6DoF), including: rotational motion yaw, roll, and pitch, and lateral, longitudinal, and vertical accelerations for linear motion.

STMicroelectronics’ automotive-grade 6-axis inertial module ASM330LHH with 3D digital accelerometer and 3D digital gyroscope is an automotive-qualified sensor that is AEC-Q100 qualified and has an extended temperature range up to +105°C, designed to address automotive non-safety applications question. The full-scale acceleration range of the ASM330LHH is ±2/±4/±8/±16g, and the angular rate range is ±125/±250/±500/±1000/±2000/±4000dps. All design aspects of the ASM330LHH have been optimized for excellent output stability, extremely low noise and complete data synchronization, which is beneficial for sensor-assisted applications such as dead reckoning and sensor fusion for use in a wide range of automotive applications .

Figure 3: STMicroelectronics automotive-grade 6-axis inertial module ASM330LHH (Image credit: Mouser)

TDK’s IAM-20680HT is also a 6-axis motion tracking product for automotive non-safety applications. It combines a 3-axis gyroscope and a 3-axis accelerometer in a small 3×3×0.75mm (16-pin LGA) in package. It also features a 4096-byte FIFO by allowing the system processor to burst read sensor data and then enter a low-power mode.

Figure 4: TDK’s 6-axis motion tracking product IAM-20680HT (Source: TDK)

The use of large lithium-ion batteries in electric vehicles (EVs) has created new applications for MEMS sensors. We know that cell thermal runaway is one of the known risks of lithium-ion batteries, and monitoring every second counts at this point. Studies have shown that it is a good solution to measure the pressure in the battery pack in advance and predict whether the thermal runaway of the battery has begun. In order to be able to detect such pressure pulses in time, it is required that the MEMS pressure sensor must be in working condition all the time. The sensor cannot stop working even when the vehicle is completely turned off.

NXP has developed a new MEMS pressure sensor specifically to address this new safety application in electric vehicles. NBP8x/NBP9x is a fully integrated battery pressure monitoring sensor series (BPMS) in NXP’s pressure sensor product family, in a small 4x4mm package size, providing low power consumption, PWM, SPI, ready/interrupt and power enable functions. This battery pressure monitoring sensor has a built-in MCU capable of sensing pressure changes, making configuration-based decisions, and taking action based on this decision, while providing this information to the host system.

Figure 5: NXP’s new MEMS pressure sensor NBP8x/NBP9x (Image source: NXP)

Summary of this article

MEMS sensors are widely used in today’s vehicles and their range of applications is expanding. While separate sensor, control, and actuator modules were common a few years ago, these functions are now consolidated into microintegrated packages.

At present, inertial applications for safety are the largest role of MEMS sensors in the automotive field. Accelerometers or inertial sensors and their associated electronics identify any sudden deceleration caused by a frontal collision. With MEMS technology, a tiny chip containing an accelerometer and a microprocessor can be installed near or inside an airbag or seatbelt pretensioner assembly. For side impacts, MEMS sensors evaluate rapid increases in air pressure in the doors to decide whether side airbags should be deployed. Due to its small size, high reliability, low power consumption, high speed and low cost, MEMS sensors have broad application prospects in terms of performance and convenience.

In future self-driving cars, dozens of sensors will be required to interact with their surroundings as human drivers increasingly hand over control to electronic systems. The sensors also have to be as small as possible so they don’t take up the space required by other devices, such as people and batteries. As a result, the automotive industry is also one of the fastest growing areas in the production and use of MEMS sensors. The development of autonomous vehicles will drive greater demand for MEMS, especially those related to optics and radio frequency. Companies that overcome these challenges will usher in a transformative period for MEMS and development dividends.