After the SLB was formed in the device, as described in the Materials and methods, the chip was connected to a syringe pump containing Min buffer. A flow of 75−150 µl/h was applied (green traffic light). The application of buffer flow resulted in migration of the SUVs that did not splash during the previous incubation period on the chambers walls along the stream lines. After ∼3 min the valves were closed and the flow was stopped (red traffic light). This resulted in an immediate halt of the SUVs flow, showing that the chambers were isolated from the rest of the chip. In order to show reversibility of the valves operation, after additional ∼1.5 min, the valves were opened (second round of green traffic light). Immediately upon releasing the pressure in the pressure valves, the SUVs started to flow again, showing that the halting of the flow was the result of the valves operation and did not result from, say, stopping the syringe pump operation. Of course, stopping the operation of the syringe pump will also result in a halt of the flow in the microfluidic device. However, due to pressure-difference equilibration, this process usually lasts couple of minutes. In contrast, upon operating the valves, an immediate halt in the flow was observed.