The differences between Quartz Accelerometer and MEMS Accelerometer

  In the field of modern industry and science and technology, accelerometers, as an important sensor, are widely used in aerospace, navigation systems, vehicle control and industrial automation and other fields. With the development of technology, there are many types of accelerometers on the market, of which quartz accelerometers and MEMS accelerometers are the most common. So, what's the difference between these two accelerometers?

1、Quartz accelerometers are based on the piezoelectric properties of quartz crystals. When acceleration is applied to a quartz crystal, piezoelectric charges are generated inside the crystal that are proportional to the acceleration, and the magnitude of the acceleration is determined by measuring these charges.

Quartz accelerometers are known for their superior accuracy, stability and reliability and are preferred for high-precision applications such as aerospace, defense, seismic monitoring and inertial navigation systems. Unlike MEMS accelerometers, quartz accelerometers have extremely low noise, extremely high resolution, and can accurately measure accelerations down to tiny levels.

2、MEMS accelerometers are manufactured using MEMS technology. It usually consists of a tiny movable mass block and fixed electrodes, and the acceleration causes the mass block to shift, which causes a change in the capacitance or resistance, and then measures the acceleration.

One of the main advantages of MEMS accelerometers is their small size, which makes them ideal for applications where size and weight require them, such as consumer electronics, mobile devices, and Internet of Things (loT) applications. In addition, MEMS accelerometers have high sensitivity and wide dynamic range, enabling accurate detection of both small and large accelerations.

3、Main aplication

①Quartz accelerometers

• Satellite navigation and attitude control

   Communications satellites in space require precise attitude control to ensure that the antenna is always pointed at the Earth to achieve stable communication. Quartz accelerometers can provide high-precision acceleration measurements to help satellites adjust their attitude and maintain a stable orbit and orientation.

• Dynamic monitoring of oil drilling platform

 In the operation of offshore oil drilling platforms, real-time monitoring of platform vibration and tilt is required to ensure the structural safety of the platform. Quartz accelerometers can be installed at key parts of the platform to accurately measure small changes in acceleration, detect possible structural problems in time, and prevent accidents.

• Submarine navigation

 When submarines are sailing underwater, they need to rely on inertial navigation systems for accurate navigation without revealing their position. Quartz accelerometers can provide accurate acceleration data, combined with sensors such as gyroscopes, to help the submarine calculate the current position and heading, ensuring that the submarine can safely and accurately complete the task.

②MEMS accelerometers

•  Smartphone attitude sensing

   Smart phones need to automatically adjust the screen orientation according to the user's posture. For example, when the user switches the phone from portrait to landscape, the MEMS accelerometer is able to detect the change in real time and instruct the system to adjust the orientation of the screen display. In addition, in gaming applications, MEMS accelerometers are also used to detect the tilt and shake of the phone, providing a more immersive gaming experience.

• Automotive Electronic Stability Control (ESC)

In the process of vehicle driving, if there is an emergency steering or wet road causes the wheel to slip, the car's ESC system will rely on MEMS accelerometer to sense the acceleration and attitude changes of the vehicle, timely adjust the braking force and engine output, and maintain the stability of the vehicle.

• Health monitoring

MEMS accelerometers are used to detect health data such as the user's movement status, step count and sleep quality. Its compact size, low power consumption and high precision make it the core sensor to achieve a variety of health monitoring functions .

4、Merits and demerits

①Quartz accelerometers —Merits

• High precision: It is usually able to provide very accurate and reliable acceleration measurement with minimal error, which is suitable for applications requiring extremely strict measurement accuracy, such as high-precision navigation, scientific research, etc.

         For example, in satellite navigation systems, the high accuracy of quartz accelerometers helps to determine the position and attitude                  of satellites more precisely.

• Excellent stability: It has good long-term stability and is not easily affected by environmental changes (such as temperature, humidity, pressure, etc.), and the consistency of measurement results is high.This makes it reliable in geological monitoring projects that require stable measurements over long periods of time, with small data deviations.

• High dynamic range: The ability to measure a wide range of acceleration changes, from very small acceleration to large impact acceleration can be accurately measured.In the testing of aircraft in the aerospace field, acceleration changes can be accurately captured whether it is a routine flight or a violent maneuver.

Quartz accelerometers —Demerits

• High cost: Due to its complex manufacturing process and the special materials used, it leads to high production costs, which limits its widespread use in some cost-sensitive applications.

           For example, in large-scale consumer electronics, quartz accelerometers are often not preferred due to cost factors.

• Larger size and heavier weight: Compared to MEMS accelerometers, their larger size and weight make them less suitable for applications with space and weight limitations, such as small drones or wearable devices.

        For devices such as smartphones that pursue thin and light designs, the size and weight of quartz accelerometers can be an obstacle.

• Relatively high power consumption: In some battery-powered applications, it may have a certain impact on the battery life of the device.

         For example, in some portable measuring devices that need to work for a long time, higher power consumption may require a larger capacity battery or more frequent charging.

②MEMS accelerometers—Merits

• Small size, light weight: Due to the MEMS manufacturing process, its volume can be very small, light weight, easy to integrate into a variety of compact equipment.

       As in modern smartphones, MEMS accelerometers can achieve a variety of functions without adding too much volume and weight.

• Low cost: Suitable for mass production, it can reduce the cost of individual devices, giving it a cost advantage in consumer electronics and large-scale industrial applications.

       Widely used in a variety of low-cost iot devices and mass consumer electronics.

• Low power consumption: For battery-powered devices, it can effectively extend battery life, making it more attractive in portable and wireless applications.

          For example, in wireless sensor networks, low-power MEMS accelerometers help to extend the operating time of nodes.

MEMS accelerometers—Demerits

• Relatively low accuracy: Although it can meet the needs of most general applications, it may not be able to meet the requirements in some cases where the accuracy is very high, such as high-end scientific instruments or precision industrial measurements.

     In high-precision inertial navigation systems, more accurate quartz accelerometers may be needed to ensure the accuracy of navigation.

• Temperature sensitivity: Its performance may be greatly affected by temperature changes, resulting in deviations in measurement results, and temperature compensation is required to improve measurement accuracy.

          In devices that operate outdoors in extreme temperature environments, the temperature characteristics of MEMS accelerometers may affect the measurement results.

• Limited impact resistance: Performance degradation or damage may occur when subjected to large shocks or vibrations.

          In the strong impact monitoring of some industrial machinery, it may not be as durable as quartz accelerometers.