Liquid metal embedded real time microfluidic flow pressure monitoring sensor

Precise monitoring of the fluidic pressure is one of the key factors that are required for microfluidics-based devices to be successfully utilized in various biomedical applications. Although conventional methods based on electrical and optical measurement are widely used, these technologies are unstable due to their complicated fabrication process as well as difficulties in integration with other components. Here, we developed a novel liquid metal embedded microfluidic flow pressure sensor that can be used to monitor the flow pressure changes within the microfluidic channels in real time for an elongated time and with high stability. The developed pressure sensor employed high aspect ratio membranes between a main flow channel and liquid metal filled sensing channels. When the input flow pressure changes, the high aspect ratio membrane deflects and affects dimensions/morphology of the liquid metal in the sensing channel, resulting in the variation of the electrical resistance. The electrical resistance of the liquid metal corresponding to different pressure levels (0−1200 mbar) were characterized, and their long-term reliability was tested as well. The variation electrical resistance in accordance to the pressure changes showed linear correlation with high repeatability and the developed sensor have been validated to work consistently even after 3 weeks.