Four Major Application Areas of MEMS Technology

Low Cost MEMS Gyro

1. Medical

MEMS sensors are used in non-invasive fetal heart rate detection. Detecting fetal heart rate is a highly technical task. Because the fetal heart rate is very fast, between 120 and 160 beats per minute, using traditional stethoscopes or even only amplifying ultrasound doppler It is difficult to measure accurately with manual counting.

Ultrasound doppler fetal heart rate monitor with digital display function is expensive, only used in a few large hospitals, and cannot be popularized in medium and small hospitals and vast rural areas. In addition, the ultrasonic vibration wave acts on the fetus, which will have a great adverse effect on the fetus. Although the detection dose is very low, it also belongs to the category of destructive detection, which is not suitable for frequent and repetitive inspections and home use.

The fetal heart rate is converted into an analog voltage signal by the acceleration sensor, and the difference is amplified by the instrument amplifier used for pre-amplification. Then a series of intermediate signal processing such as filtering is performed, and the analog voltage signal is converted into a digital signal with an A/D converter. The optical isolation device is input to the single-chip microcomputer for analysis and processing, and finally the processing result is output. The fetal heart rate detector designed based on the MEMS acceleration sensor can be used as a terminal to make a remote fetal heart rate monitoring system after proper improvement. The central signal acquisition, analysis and monitoring host on the hospital side provides automatic analysis results, and the doctor diagnoses the results. If there is any problem, the pregnant woman will be notified to the hospital in time. The technology is beneficial for pregnant women to check the condition of the fetus at any time, and is beneficial to the health of the fetus and pregnant women.

2. Cars

MEMS pressure sensors are mainly used to measure air bag pressure, fuel pressure, engine oil pressure, intake pipe pressure and tire pressure.

This sensor uses single-crystal silicon as the material, and uses MEMS technology to make a force-sensitive diaphragm in the middle of the material, and then diffuses impurities on the diaphragm to form four strain resistors, and then connects the strain resistors by a Wheatstone bridge. circuit to obtain high sensitivity.

There are several common forms of automotive MEMS pressure sensors, such as capacitive, piezoresistive, differential transformer, and surface acoustic wave.

The principle of MEMS accelerometer is based on Newton’s classical laws of mechanics, which is usually composed of a suspension system and a detection mass. The acceleration detection is realized by the offset of the micro-silicon mass block. It is mainly used in automotive airbag systems, anti-skid systems, and automotive navigation. In addition to capacitive and piezoresistive types, MEMS accelerometers also include piezoelectric, tunnel current, resonant, and thermocouple types for systems and anti-theft systems.

Among them, capacitive MEMS accelerometers have the characteristics of high sensitivity and little influence by temperature, and are the mainstream products in MEMS micro-accelerometers.

Micro gyroscope is an angular rate sensor, which is mainly used for GPS signal compensation of car navigation and car chassis control system, mainly including vibration type and rotor type.

The most widely used is vibrating gyroscope, which uses the Coriolis effect generated when the vibrating mass of single crystal silicon or polycrystalline silicon is rotated by the base to sense the angular velocity.

For example, when the car is turning, the system uses the gyroscope to measure the angular velocity to indicate whether the steering wheel is turned in place, and actively applies appropriate braking to the inner or outer wheels to prevent the car from leaving the lane. Usually, it forms an active control together with a low accelerometer. system.

At present, there are about 600 units around the world engaged in the development and production of MEMS, and hundreds of products including micro pressure sensors, acceleration sensors, micro inkjet print heads, and digital micro mirror displays have been developed, among which MEMS sensors a considerable proportion. ERICCO is a leading high-precision MEMS sensor manufacturer in China, and its MEMS gyroscopes have broken through technical barriers, and many of them can even achieve the same accuracy as FOG.

3. Motion Tracking

In the daily training of athletes, MEMS sensors can be used to measure 3D human motion, record each action, and coaches analyze the results and compare them repeatedly in order to improve the performance of the athletes.

With the further development of MEMS technology, the price of MEMS sensors will also decrease, which can also be widely used in mass gyms.

In terms of skiing, the pressure sensors, acceleration sensors, gyroscopes and GPS in 3D sports tracking allow users to obtain extremely accurate observation capabilities. In addition to providing the movement data of the skis, they can also record the user’s position and distance. The same is true in surfing, where 3D motion tracking installed on the surfboard can record information such as wave height, speed, surfing time, paddle distance, water temperature and calories burned.

4. Consumer Electronics

Before the emergence of MEMS Drive, the camera of mobile phone mainly achieved anti-shake by moving the lens group by voice coil motor (referred to as lens anti-shake technology), which was greatly limited. Another high-end anti-shake technology on the market: multi-axis anti-shake, which uses a moving image sensor (Image Sensor) to compensate for jitter, but because this technology is bulky and consumes more power than the mobile phone load, it has not been able to be used on mobile phones. application.

With the breakthrough of MEMS in volume and power consumption, the latest technology, MEMS Drive, is similar to a planar motor posted on the back of the image sensor, which drives the image sensor to move in three rotation axes.

The anti-shake technology of MEMS Drive is to sense the instantaneous jitter in the process of taking pictures through a gyroscope, and rely on a precise algorithm to calculate the movement range of the motor and make quick compensation. This series of actions must be completed within one hundredth of a second, and the image you get will not be blurred by jitter.

MEMS sensor is a new type of sensor manufactured using microelectronics and micromachining technology. Compared with traditional sensors, it has the characteristics of small size, light weight, low cost, low power consumption, high reliability, suitable for mass production, easy integration and realization of intelligence. At the same time, the feature size on the micrometer scale makes it possible to perform some functions that traditional mechanical sensors cannot.

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