A packaging technique of pressure sensor for in vivo measurement system

Bodily pressures can provide valuable information for making a diagnosis or health monitoring. The pressure sensor is widely used to obtain bodily pressure, however, sensor drift has severely limited their application in vivo measurement system. In this paper, we report on a packaging technique for improving the stability and accuracy of the pressure sensor. Commercial piezoresistive pressure sensors are enclosed in silicone oil and then encapsulated with silicone membrane and parylene-N. The described method isolates the pressure sensor from the abominable surrounding environment and keeps the pressure in the cavity constant. In vitro tests for 40 days show that the pressure sensor packaged by this method could obtain better stability. The average baseline drift of the pressure sensor was 0.025 mmHg/week after the pressure sensor became stable. As a biocompatible material, silicone membrane is widely used in in vivo devices. Its permeability should be paid more attention to when it is used to isolate body fluids. Parylene is deposited on the silicone membrane, which can greatly reduce the permeability of the silicone membrane. The pressure sensor using this packaging structure has good long-term stability. [Display omitted] •A packaging technique of pressure sensor for in vivo measurement system is proposed.•Silicone membrane deposited with parylene as a whole as a packaging film structure.•This packaging technology can greatly improve the long-term stability of the sensor.