Figure 3

Microfluidic closed-end actuator. (A) The closed-end actuator consists of a lower layer (PDMS I) with channels containing the cells (blue) and an upper layer (PDMS II) with the actuation channels (red). (B) Photograph of the assembled closed-end actuator filled with ink (actuation channel in red and lower channel in blue). (C) The principle of operation for the closed-end actuator. (D) To create the lower layer, PDMS was poured onto the wafer. Then a cover slip was placed across the pattern. This cover slip rests on two other cover slips, which act as spacers that define the height of the PDMS layer (E). This layer will separate the lower and the upper channels. (F) After curing and cutting the PDMS, the middle section was cut out and stored. The first cover slip was replaced by a second cover slip and the cut PDMS piece is placed in its former position to provide stability during plasma cleaning. (G) Illustration of the assembled double layer device. The lower layer (PDMS I) contains the microfluidic channel filled with the cells. The upper layer (PDMS II) contains the closed-end channel which applies pressure to the channel below. The red spots in (G) mark the overlapping areas, in which flattening of the cells occur.