An accelerometer sensor measures acceleration, the rate of change of velocity, along one or more axes, usually expressed in units of g (where 1g equals Earth's gravitational acceleration, about 9.81 m/s²). In practice that makes it a vibration sensor: any shaking, impact, or dynamic movement shows up as a changing acceleration signal that can be captured, logged and analysed.
How Accelerometers Work
Most modern accelerometers used in monitoring applications are MEMS (micro-electromechanical systems) devices: a microscopic proof mass suspended by tiny springs on a silicon chip. When the sensor accelerates, the proof mass lags behind due to inertia, deflecting slightly relative to the chip frame. That deflection changes a capacitance (in capacitive MEMS designs) or generates a charge (in piezoelectric designs), and the resulting signal is proportional to the acceleration experienced.
A single-axis accelerometer measures movement along one direction only. A tri-axial accelerometer measures acceleration along all three spatial axes simultaneously, which is what's needed to fully characterise real-world vibration and dynamic structural response, since a building, bridge or machine rarely moves in a single clean direction.
Types of Accelerometers
Piezoelectric accelerometers
Use a piezoelectric crystal that generates a voltage proportional to applied force. Rugged, self-powered in terms of signal generation, and well suited to high-frequency vibration measurement on machinery.
Capacitive MEMS accelerometers
Measure the change in capacitance as the proof mass deflects. These are compact, low-power, and can measure down to DC (constant acceleration, including gravity itself), which is what makes them useful for both vibration and static tilt-style measurements.
Piezoresistive accelerometers
Use a strain-sensitive resistive element attached to the proof mass. Well suited to shock and impact measurement across a wide dynamic range.
Accelerometers in Structural & Infrastructure Monitoring
- Seismic monitoring: capturing how buildings and critical infrastructure actually respond during an earthquake, in real time, rather than inferring damage afterward from a visual inspection.
- Bridge dynamics: detecting resonance, impact damage from vehicle strikes, or fatigue-inducing vibration under traffic loading.
- Machinery & predictive maintenance: tracking bearing wear, imbalance and misalignment in rotating equipment long before failure, a core input for vibration-based predictive maintenance programmes.
- Construction monitoring: measuring vibration transmitted to adjacent structures from piling, demolition or blasting works.
Key Specifications to Evaluate
When comparing accelerometer sensors for a monitoring deployment, four specifications matter most: the measurement range (in g, how large a vibration event it can capture without clipping), sensitivity (how much output changes per unit of acceleration, which drives resolution), sampling rate (how many readings per second, needed to resolve higher-frequency vibration), and frequency response (the band of vibration frequencies the sensor can accurately capture). Sentra's accelerometer sensors are tri-axial by default, so a single unit captures the full vibration picture rather than requiring multiple single-axis sensors per monitoring point.
Takeaway
An accelerometer sensor is what turns dynamic movement, an earthquake, a resonating deck, a failing bearing, into a measurable signal. Tri-axial MEMS accelerometers give the most complete picture for structural and machinery monitoring alike.
Explore Sentra AccelerometersFrequently Asked Questions
Accelerometer sensors measure vibration and dynamic movement, used across seismic monitoring of buildings, bridge dynamic response, machinery vibration for predictive maintenance, and construction vibration monitoring near sensitive structures.
A MEMS (micro-electromechanical systems) accelerometer is a microscopic sensor built on a silicon chip, containing a tiny suspended proof mass that deflects under acceleration. That deflection is converted into an electrical signal proportional to the acceleration experienced, making MEMS accelerometers compact, low-power and highly reliable for continuous monitoring.
Rotating machinery develops characteristic vibration signatures as bearings wear or components fall out of balance, well before an audible or visible failure. Continuous accelerometer monitoring captures those signatures early, giving maintenance teams a data-driven trigger to intervene before a breakdown, rather than relying on a fixed inspection schedule.
A single-axis accelerometer only measures acceleration along one direction, so it can miss vibration or movement occurring in other planes. A tri-axial accelerometer measures all three spatial axes at once, giving a complete picture of real-world movement from a single sensor, which is why it's the standard choice for structural and machinery monitoring.
