Pressure-driven flow through PDMS-based flexible microchannels and their applications in microfluidics

Flexible microchannels have soft walls which undergo deformation under the influence of fluid flow. The dimensional and flexural similarity of flexible microchannels make them ideal candidates for mimicking biological structures such as blood vessels and air pathway in lungs. The analysis of fluid flow and the dynamics of interaction of cells through flexible arteries provide valuable insights about cardiovascular-related diseases. Flexible microchannels can be instrumental in the in vitro investigation of such diseases. This review discusses the recent developments in pressure-driven flow through flexible microchannels and their applications. Here we present the existing theoretical models that predict the deformation and pressure-flow characteristics of flexible microchannels and the corresponding experimental validations. We compare the models for laminar flow of Newtonian fluids through flexible microchannels with their corresponding experimental validation and enlist their limitations. We discuss in detail the various applications of flexible microchannels and their relevance in cell mechanophenotyping, micropumps, microflow stabilizers, and organ-on-chip devices. The insight into the flow dynamics provided herein will extend using flexible microchannels to develop organs-on-chip and other microfluidic applications.