A microfluidic based Interstitial Fluid (ISF) transdermal extraction tool made from polydimethylsiloxane (PDMS) was designed to the application of continuous glucose monitoring. Four layers of PDMS fabricated by replica molding process were bonded together using oxygen plasma to construct the device, including a Venturi tube for vacuum generation, chambers for the introduction of ISF and normal saline solution, pneumatic valves for fluid control, and interconnected microchannels. Then, the output vacuum of Venturi tube and the close pressure of pneumatic valve were measured. Finally, the ISF extraction and collection function was tested. Results show that the vacuum pressure is used for fluid manipulation and a 92 kPa (absolute pressure) vacuum is achieved, when 220 kPa (absolute pressure) external pressure is applied to the Venturi tube. Moreover,the normally open pneumatic valves can be closed under the operating pressure less than 65 kPa (relative pressure). Under the control of pneumatic valves, the normal saline injection, ISF extraction and collection function of the tool are implemented by using the vacuum generated from the Venturi tube.