Posifa Technologies has introduced its new PVC4000 series microelectromechanical system (MEMS) Pirani vacuum transducer. Designed for cost-effective original equipment manufacturer (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 PVC4000's sensor 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 sensor's signal, providing output via an inter-integrated circuit interface. The interface also allows users to store calibration data in the microcontroller, which is utilized by a built-in piecewise linearization algorithm to provide calibrated output.
To compensate for variations in thermal conductivity due to changes in ambient temperature, the PVC4000 features a temperature compensation algorithm, which takes its input from a built-in temperature sensor. In addition, a pulsed excitation scheme, in which the sensor chip is heated for about 100 ms and then turned off for one second, prevents signal drift due to self-heating, and also reduces the power consumption of the transducer.
The transducer released today is ideal for digital vacuum gauges. For these applications, the device combines low power consumption with extremely fast response times of less than 1.2 s and a wide effective range from 1 millitorr (0.13 Pa) to 1 atm (760 torr, or 101 kPa).