What is a quartz accelerometer? How do they work?

A quartz accelerometer is a high-precision sensor that uses the piezoelectric properties of quartz crystals to measure acceleration, known for its exceptional stability and reliability in demanding applications. 

How They Work

Quartz accelerometers are typically force-balance sensors (also called servo accelerometers). 

• Sensing Mechanism: A proof mass, connected by a quartz flexure (a highly stable, all-elastic structure), experiences displacement when subjected to acceleration along its sensitive axis.

•  Closed-Loop System: A position detector (often a differential capacitor) senses this minute displacement. The resulting signal is amplified and sent to a force generator (an electromagnetic coil).

• Force Rebalance: The force generator produces an equal and opposite force to push the proof mass back to its original "balanced" position. The current required to generate this balancing force is directly proportional to the input acceleration.

• Output: This current is then measured and converted into a highly accurate digital or analog signal representing the acceleration. 

Key Features and Applications

Quartz accelerometers are prized for their performance in applications where precision is paramount, due to specific characteristics. 

Features

• High Accuracy and Stability: The inherent stability of quartz crystal results in very low noise levels, excellent long-term stability, and high resolution.

• Environmental Resilience: They are well-suited for harsh operating conditions due to superior temperature stability and high resistance to shock and vibration.

• Reliability: The all-elastic, non-friction design (no jewel eyes or shaft tips) eliminates mechanical wear and static friction, improving reliability over time. 

Applications

• Aerospace and Aviation: Used in high-precision navigation systems, flight control, and satellite microgravity measurement.

• Oil and Gas Drilling: Integrated into measurement-while-drilling (MWD) tools and inclinometer systems to guide drilling direction in high-temperature, high-shock environments.

• Geological and Seismic Monitoring: Utilized for studying earthquakes, crustal movements, and general geological exploration due to their ability to measure minute acceleration changes.

• Defense: Employed in guidance systems for missiles and other defense applications where accuracy is critical.