Introduction to MEMS Technology
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, industry and even health care. The reason for this success is low price, small size, high reliability, and low power consumption of MEMS-based sensors. Recently, MEMS accelerometers started competing with traditional electro-mechanical accelerometers in applications that require tactical grade performance.
Physical Logic provides advanced tactical-grade open-loop accelerometers, with linearity and stability that can compete with that of mechanical accelerometers in quite a few applications. Our technology is superior to other providers in terms of bias and scale factor stability, noise, and linearity.
Physical Logic MEMS Technology
Physical Logic is developing and manufacturing open loop and closed loop MEMS accelerometer. Our open-loop MEMS accelerometers for tactical navigation applications 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% of the accelerometer’s dynamic range. That’s a remarkable improvement in scale factor linearity over competing open-loop MEMS devices. Further improvement of scale factor linearity to less than 0.1% is observed in our newly designed sigma delta closed loop accelerometer.
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 is especially designed to be able to neutralize changes in environmental conditions such as vibrations and temperature. Special care was taken in the design of the packaging, and in the development of the assembly process for our open loop series, enabling excellent results of <100ppm of dynamic range stability.