Final Design

The cell stretcher, using the pressure chambers in blue, retracts the membrane into them, therefore stretching the membrane. What is achieved by that is that during the cyclic stretching of 1- 2Hz, the volume of the flow chamber stays the same, which keeps the pressure in the flow chamber stable. Also, with the membrane being stretched, we can see what effect the stretching has on the cells that are placed in the middle.

False Walls

The false walls are a significant component of the device. They hold the membrane steady in the y-axis while the membrane is being stretched. This achieves two things: one, it keeps the volume of the water flowing over the membrane the same, achieving steady flow over the membrane, and two, it maintains a steady shear stress over the cells placed on the membrane, which is crucial for testing. Also, the false walls prevent the flow from leaving the flow chamber, preventing flow disruptions from gaps between the membrane and the flow during stretching. 

Pressure Chambers

The pressure chambers also play a vital role in this device. The holes on the side are connected to a pressure regulator that creates the required pressure to retract the membrane and stretch it as required. the holed on top are screws that will prevent the membrane being stretched in any other direction than the horizontal. Also, these pressure chambers will act as the base of the device.

Membrane

The membrane is placed between the false walls and the pressure chamber. It is sealed on the outside of the pressure chamber by being squished from the false walls cap and the pressure chambers, preventing it from moving in any direction other than the one we need to stretch it. The membrane needs to be biocompatible so that cells can be grown on it. It also needs to be easy to stretch and hard to rupture. So we used PDMS, which is a reliable material that is biocompatible, easy to stretch, and does not rip easily. 

Disclaimer: Some component images shown here are from older iterations of the design, albeit they are very similar to the final design. This is a consequence of the device being difficult to assemble and the team deciding it was best to leave the device fully assembled until after it was showcased during the poster session.