Silicon Microstructures Launches Ultra-Low Differential Pressure Sensor with CPAP Applications

SMI (Silicon Microstructures Inc) introduces the SM933X Series of ultra low MEMS pressure sensor systems. The temperature-compensated and pressure-calibrated sensor with pressure ranges as low as 125 Pa (0.50 inH2O) enables precise pressure sensing in medical, HVAC, and industrial applications. Output accuracy (1% FS) and long-term stability is achieved by combining SMI’s proprietary MEMS pressure transducer with a signal-conditioning IC in one package.

The SM933X is a solution for flow sensing applications, delivering high performance regardless of the tubing length and is not affected by particles in the airflow. In the medical market, ultra low pressure sensors are used for CPAP flow sensing. The integration and use in CPAP devices is eased by the insensitivity of the sensor to the mounting orientation, its high resolution, and low noise performance.

The differential pressure sensor system is available in two configurations: SM9333, with a pressure range of +/- 125 Pa (0.50 inH₂O), and SM9336, with a pressure range of +/- 250 Pa (1 inH₂O). The total accuracy after board mount and system level Autozero is less than 1%FS over the full compensated temperature range of -20 to 85ºC. The 16 bit resolution provides the ability to resolve signals as small as 0.0038 Pa. The excellent warm-up behavior and long term stability further assures its expected performance over the life of the part.

The system supply ranges from 3.0 to 5.5V and it is well suited for low power applications with its low current consumption and available sleep mode. The ASIC architecture and higher order noise filtering provides low noise and extremely low EMI susceptibility.

The small SO16 package with dual vertical port allows for easy system integration and pressure connection, while the MEMS sensor itself is robust with high burst pressure and virtually no mounting or vibration sensitivity.

“SMI has had a tradition of being on the cutting edge of MEMS low pressure sensors dating back to the mid 90’s. With the launch of the SM933X series, the company looks to extend that leadership into its 3rd decade,” says Omar Abed, president and CEO of SMI. “We have received overwhelmingly positive feedback from our lead customers. We are convinced that the launch of this new product line will set the benchmark for ultra-low pressure sensors below 2 inH₂O and usher in a new wave of innovation in medical and industrial flow and ultra-low pressure applications.”