Figure 1.

Schematic of the microfluidic device and working principle of the semi-always-closed valve. (A) The microfluidic device consists of a large central chamber, a fluidic channel and several pneumatic control channels. (B) Close up of the single layer semi-always closed valve. (C) In an unaltered state, the opening to the sides of the microfluidic structural element will allow the medium to pass while blocking the pass of bacteria. (D) When we subject the pneumatic control channels to negative pressure, the membrane deforms allowing the bacteria to pass freely. (E) When we subject the control channels to positive pressure, the membrane will deform cutting off the flow of the medium.