Insect-inspired flow control in microfluidic networks*

In earlier work, we incorporated key features of respiratory kinematics in some insect species, in the design of single-channel 3-layer, PDMS-based microfluidic devices and found that they produced unidirectional flows that reversed direction based on the frequency of actuation alone. In the present study, we use the same principles that serve to actuate the tracheal system to design and test four different insect-inspired microfluidic networks. In these devices, a pressure signal from a single source is distributed over the entire network and used to collapse the ceiling of the flow channel at multiple sites. We found that variation in the frequency of actuations can be used to regulate the magnitude of flow rates into different branches of the network. Additionally, we observed that in two networks, changes in actuation frequency drive the flow into a particular branch or completely shut it off, an unexpected finding. This novel feature- pumping selectively into certain branches in the network in a valveless device- has the potential to reduce the actuation overhead in microfluidic devices for applications including microscale chemical analysis, mixing, and cell sorting.