Designing single-layer PDMS devices for micron to millimeter-scale deformations

TL;DR

This study explores the design parameters of single-layer PDMS microfluidic devices, revealing how geometry influences deformation modes and demonstrating applications like valves and lenses.

Contribution

It provides a comprehensive numerical analysis of 14,336 device variants, identifying key geometric factors affecting deformation and validating these findings experimentally.

Findings

Deformation modes depend on PDMS height, channel width, and air chamber width.

Vertical ceiling deformations range from microns to millimeters.

Validated designs for microfluidic valves and optical lenses.

Abstract

The elasticity of PDMS has played a central role in advancing important microfluidic technologies, ranging from early valves to sophisticated organ-on-a-chip systems. However, most deformable microfluidic devices are based on geometries that require complex multi-layer PDMS architectures and include thin membranes, leading to difficult microfabrication and poor stability. Recently, Jain, Belkadi et al. (Biofabrication 16.3 (2024): 035010) introduced a single-layer device in which a wide and long microfluidic channel was deformed by controlling the pressure in two independent and adjacent air chambers. While they demonstrated the ability to deform the channel ceiling to compress biological materials, the design parameters remain unexplored. Here, we perform a numerical study on 14,336 variants of this device and identify the height of the PDMS layer, the width of the microchannel and the width of the air chamber as the main features that determine the ceiling deformation. Three deformation modes are observed as the geometrical parameters are varied: A U shape with a central minimum, a W shape with two minima and a central maximum, or an inverse U shape with an upward-bulging single maximum. The numerical results are validated in experiments that reproduce the three shapes for the predicted geometries and demonstrate vertical ceiling deformations ranging from a few microns to the millimeter scale. The generality of this approach is demonstrated for two example applications: A fully closing single-layer microfluidic valve and an optical lens of controllable anisotropy. This work leverages the rapid prototyping enabled by 3D printing or micro-milling to open new perspectives in microfluidic actuation.