Ultra-low-noise sensors for seismic measurements

The ASC EQ-series detects even the smallest acceleration amplitudes

ASC has expanded its product portfolio with high-precision capacitive accelerometers: The ASC EQ-series measures even the smallest vibration amplitudes and is therefore ideal for seismic measurements, structural health monitoring of safety-relevant structures or noise reference measurements.

The inertial sensors are available as uniaxial, biaxial and triaxial designs, each with measuring ranges of ±3 g and ±5 g. They detect both static (DC) and dynamic accelerations up to a bandwidth of 700 Hz and are characterized by a ultra-low noise level. They achieving a resolution of less than 1 µg and therefore fulfill the requirements of the motion class B category. With a noise density of 0.7 µg/√Hz to 1.2 µg/√Hz, the new sensors are significantly more sensitive than ASC’s capacitive low-noise accelerometers, which already have a very low noise density of 7 µg/√Hz to 400 µg/√Hz, depending on the measuring range.

ASC's new seismic sensors also feature a self-test option to continuously verify their functionality. The self-test is an important feature for the use of the sensors in safety-relevant monitoring applications, such as the monitoring of dams, bridges and power plants or of buildings in areas prone to earthquakes. In such cases, the sensors must function correctly at all times. The self-test option also makes it possible to validate the measurement data collected by the sensors. All the sensitive axes of the ASC EQ sensors have a temperature sensor, which significantly increases the accuracy of measurement achievable in applications involving fluctuating ambient temperatures.

ASC manufactures the new capacitive accelerometers of the EQ-series with both aluminum (IP67) and stainless steel (IP68) housings. The sensors are based on high-quality MEMS technology and offer excellent long-term stability. Their differential analog voltage output (±2.7 V FSO), flexible power supply from 5 VDC to 40 VDC and customizable cable lengths up to 25 m offer test and measurement engineers considerable design freedom.

Keywords: Seismic sensors, capacitive accelerometers, structural health monitoring, noise reference measurements, structural monitoring, ASC GmbH, sensor technology