The deformation of flexible PDMS microchannels under a pressure driven flow

Abstract

Poly(dimethylsiloxane) (PDMS) microchannels are commonly used microfluidic structures that have a wide variety of biological testing applications, including the simulation of blood vessels to study the mechanics of vascular disease. In these studies in particular, the deformation of the channel due to the pressure inside is a critical parameter. We describe a method for using fluorescence microscopy to quantify the deformation of such channels under pressure driven flow. Additionally, the relationship between wall thickness and channel deformation is investigated. PDMS microchannels of varying top wall thickness were created using a soft lithography process. A solution of fluorescent dye is pumped through the channels at constant volume flow rates and illuminated. Pressure and fluorescence intensity are measured at five positions along the length of the channel. Fluorescence measurements are then used to determine deformation, using the linear relationship of dye layer thickness and intensity. A linear relationship between pressure and microchannel deformation is measured. Pressure drops and deformations closely correspond to values predicted by the model in most cases. Additionally, measured pressure drops are found to be up to 35% less than the pressure drop in a rigid-walled channel, and channel wall thickness is found to have an increasing effect as the channel wall thickness decreases.

Static response of deformable microchannels: a comparative modelling study

“…Fluorescence microscopy has been used as a costeffective method to detect deformation of microchannels from their rectangular moulding [20,12,13,14]. Even tough this technique has allowed for the measurement of the maximal cross-sectional displacement of a microchannel, the inherent uncertainties and noisy measurements produced by this technique do not pro- Figure 9.…”

Deformation properties between fluid and periodic circular obstacles in polydimethylsiloxane microchannels: Experimental and numerical investigations under various conditions

“…Also, scaling analysis has been widely used when the applied flow rates are relatively high. The relative equation for the maximum thickness variation of a microchannel at any given position can be described as 22,23,35 FIG. 4.…”

“…It was found that when the flow rates were doubled the pressure drop increased by only 55%. Hardy et al 23 introduced an alternative florescence microscopy method with Rhodamine 6G dye which was pumped through microfluidic channels and created the fluorescent intensity difference based on the deformation of the microchannels. They reported a 65% increase in the pressure drop when the flow rates were doubled.…”

Viscoelasticity of blood and viscoelastic blood analogues for use in polydymethylsiloxane in vitro models of the circulatory system

“…25,26 In microfluidics, polydimethylsiloxane (PDMS) is one of the most widely used polymers to manufacture channels because of its transparency at optically visible wavelengths, biocompatibility, low autofluorescence, low cost, deformability and ability to mold easily among other advantages, which make this polymer a good candidate for manufacturing model vessels to study the dynamics of vascular diseases. [27][28][29] In this work, we develop transparent non-Newtonian blood analogues that exhibit rheological behavior under shear and extension very similar to real whole blood. To this end, we first measured the linear viscoelastic properties of real whole blood, the storage (G 0 ) and loss (G 00 ) moduli, using passive microrheology.…”