Ultra-low pressure sensors from 0 ... 25 Pa

The thermal mass flow measurement was miniaturized and integrated into a silicon chip measuring only 2 x 2 mm² by microstructuring.
Their high sensitivity combined with good overpressure behavior predestines the LDE/LME/LMI sensors from AMSYS for measuring volume flows. These sensors are used primarily in medical technology and in ventilation and air-conditioning technology. For reasons of efficiency, the obstruction required for volume flow measurement should be as low as possible, which places increased demands on the differential pressure sensors due to the low pressure drop - ideal requirements for the new Micro-Flow ultra-low pressure sensors from AMSYS.
The operating principle of thermal mass flow measurement is based on a heating element that heats the gas in a small opening between the two pressure ports. Pressure differences cause an asymmetric temperature gradient to form in the connecting channel due to the gas flow. This is detected with temperature sensors on both sides of the heating element and converted into a linearized differential pressure signal.

The advantage of mass flow measurement is its enormously high sensitivity for the smallest pressure differences. This allows measuring ranges from 0 ... 25 Pa or +/-25 Pa with simultaneous high overpressure resistance of up to 2 bar possible. The solution via a tiny, microstructured connection channel in a silicon die minimizes the unwanted flow in which the pneumatic impedance increases to about 200 kPa/(ml/s). This means a factor of 1000 compared to similar sensors and makes the low pressure sensors from AMSYS robust against dust and interference from long hoses.
The very small SMD package of the LME / LMI sensors is optimized for direct mounting in valve assemblies (manifold mounting). Alternatively, with the LDE series, a version with hose connections for SMD or DIP mounting is also available.
As output signal a 16bit I²C- (LMI series) or SPI- and 0,5 ... 4.5V analog signal (LME/LDE series) available. The value of the integrated temperature sensor can also be queried via the digital outputs. During manufacturing, the low pressure sensors are individually linearized, calibrated and temperature compensated. Thus, no additional circuitry, such as a compensation network, is required.
AMSYS offers the LDE/LME/LMI micro-flow pressure sensors in the range of 0... 25 Pa to 0 ... 50 mbar, alternatively as bidirectional version with ±25 Pa to ±50 mbar.