PDMS microdevice for precise liquid aspiration in the submicroliter range based on the Venturi effect

Abstract

This paper presents the study of a MEMS (microelectromechanical systems) precision aspiration device designed to extract liquids from a reservoir, which could be an animal or human body. The device works by generating a negative pressure, which deflects a membrane and extracts liquid volumes in the submicroliter range. This negative pressure is created inside a closed channel using the Venturi effect. The existence of the membrane prevents the extracted fluid to be mixed or in contact with the actuation fluid, avoiding cross-contamination of the samples. In addition, the microdevice is pneumatically actuated using air, preventing damages in the extracted volumes because of electric fields and minimizing the actuation cost because inert gas sources are not necessary. The device is fabricated in poly-dimethyl-siloxane (PDMS) using an inexpensive fabrication process. A study has been made to determine the influence of several geometrical parameters over the operation. Finally, experiments demonstrate the working of the device providing an aspiration range from 20 to 120 nL with an average sensitivity of extracted volume with respect to actuation pressure of 220 pL/mbar.