Only a couple of decades ago we saw the first use of micro-electro-mechanical systems (MEMS) technology in the fabrication of inertial sensors, and particularly accelerometers. Yet MEMS accelerometers have now conquered diverse markets including inertial sensing, industrial and even health care. The reason for this success is low price, small size, high reliability, and low power consumption of MEMS-based sensors.
Open-Loop MEMS accelerometers are mainly used for industrial application, however the use of In-Plane bulk micromachining technology extend applications to tactical grade performance. Implementation of Closed-Loop MEMS accelerometers enabled MEMS sensors technology to compete with expensive traditional technologies of mechanical quartz pendulum sensors. Application of ΔΣ (sigma-delta) MEMS technology, enables extremely low linearity, stability and repeatability errors with extremely low Vibration Rectification Error (VRE).
Physical Logic MEMS Technology
Physical Logic is developing and manufacturing Open-Loop and Closed-Loop MEMS accelerometer for tactical and inertial navigation applications which are based on fully differential capacitive sensing architecture, enabling noise and parasitic rejection. Our technology applies to a broad range of mechanical, chemical, optical, and biotech products such as sensors, microstructures, and actuators.
Our technology has the following benefits
Superior Scale Factor Linearity
Scale factor linearity is crucial for any accelerometer. It indicates the sensor’s accuracy during exposure to high accelerations. By offering a topology which is a combination of comb and parallel plate sensing capacitors, we successfully managed to reduce deviation to less than 0.5% (for Open-Loop sensors) and 0.03% (for Closed-Loop sensors) of the accelerometer’s dynamic range. That’s a remarkable improvement in scale factor linearity over competing MEMS accelerometers.
Ultra-Low Noise
Low sensor output noise is a key parameter for applications such as seismic and tilt sensing. It allows detection of the slightest changes in external acceleration. Our design reduces output noise to <0.25ppm of dynamic range/√Hz — an unprecedented value in MEMS technology. In-plane design allows us to reduce the thermomechanical noise that is coming from MEMS element whilst implementation of the chopping concept in our AFE (analog front end) ASIC reduces the electronic noise
Excellent long-term stability
Our MEMS, ASIC and package are especially designed to neutralize variations in environmental conditions such as vibrations, mechanical shocks and temperature. Special care was taken in the design of the packaging, and in the development of the assembly process for our Open-Loop and Closed-Loop series. Preservation of mechanical equilibrium in the Closed-Loop capacitor structure in various of environmental conditions, enables an order of magnitude improvement of long term stability compared with Open-Loop architecture.