Disposable PDMS diaphragm pumps

In order to include pumps on the prototype blood analyzer cartridges, it was necessary to implement a small pump using the existing knife-cut PDMS layer layup technique. The diaphragm architecture was selected due to ease of operation and minimal additional part requirements.

CAD model of pump in Autodesk Inventor

Bottom view of fabricated pump.

The most complex component of this pump architecture is the PDMS check valves. Multiple popular check valve configurations exist with the suspended “manhole cover” style was implemented here. It is important to note that the valve contact interfaces must be carefully covered prior to ozone treatment in order to prevent the valve from becoming sealed.

Side view of fabricated pump with electromagnetic actuator installed.

It is clear from the video that the valves are imperfect, allowing significant back flow. Oddly enough, this “leaky” valve design may be ideal for the cross-membrane agitation application in this project.

Flow rate test apparatus.

 

Flow rate vs frequency plot. Driving signal was 10V pk-pk sine wave with approximately zero head pressure. Note that a control pump lacking valve covers was created to prove that the pumping is not arising from valveless energy effects.

 

The next step is to fabricate a microfluidic low-pass RC filter to attenuate the pulsatile component of the flow.