Fully calibrated MEMS Pirani vacuum transducer

Fully calibrated MEMS Pirani vacuum transducer

New Products |
By Jean-Pierre Joosting

Posifa Technologies has introduced its new PVC4100 series fully calibrated MEMS Pirani vacuum transducer. Designed for cost-effective OEM integration, the device consists of a surface-mount MEMS Pirani sensor and microcontroller-based measuring electronics — all packaged in an ultra-compact PCB assembly featuring a connector-terminated wire harness.

The Psensor element is based on Posifa’s second-generation MEMS thermal conduction chip, which operates under the principle that the thermal conductivity of gas is proportional to its vacuum pressure. The transducer’s microcontroller-based measuring electronics amplify and digitize the senor’s signal, providing output via an I²C interface. To compensate for variations in thermal conductivity due to changes in ambient temperature, the device features a temperature-compensation algorithm, which takes its input from a built-in temperature sensor.

The transducer released today is ideal for digital vacuum gauges and leak detection in closed systems maintained under primary vacuum pumps, such as vacuum-insulated panels. For these applications, the device combines low power consumption with extremely fast response times of 250 ms and a wide effective range from 0.1 millitorr (0.013 Pa) to 1 atm (760 torr, or 101 kPa), with accuracy of 15 percent from 1 millitorr to 200,000 millitorr.

Samples and production quantities of the PVC4100 are available now.

Recently, Posifa Technologies introduced its PGS1000 series of MEMS thermal conductivity hydrogen sensors. Designed for stable, cost-effective safety monitoring in environments where hydrogen is used and stored, the devices consist of two thermal conductivity dies in a differential configuration — all packaged in a compact surface-mount form factor.

PGS1000 series hydrogen sensors detect hydrogen concentrations in the air by measuring the change in thermal conductivity of the gas mixture. This measurement approach provides better long-term stability, and enables a smaller form factor, than hydrogen sensors that are triggered by chemical reactions that eventually cause the sensor to degrade. Posifa’s technology also allows the hydrogen detection capability to be realized at a much lower cost thanks to the company’s highly repeatable, high-volume CMOS MEMS technology.

The PGS1000 series is based on Posifa’s second-generation thermal conductivity die. The devices feature one die sealed in dry air and acting as a reference, while the other is exposed to the gas mixture. This design enables an excellent signal-to-noise ratio due to common-mode noise rejection and a maximization of the signal amplification. For safe operation, the sensor is excited with a pulsed waveform (400 ms on and 1,000 ms off) to minimize the heater temperature.
The sensors released today are ideal for hydrogen leak detection and monitoring in industrial processes, medical facilities, and automotive fuel cells.


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