Particle/Fluid Interface Replication as a Means of Producing Topographically Patterned Polydimethylsiloxane Surfaces for Deposition of Lipid Bilayers
Microstructured surfaces are common, but their fabrication techniques typically involve some form of photolithography, and the patterning is limited to two-dimensions. In order to achieve patterning in the third dimension, etching is used following the photolithography. Although these techniques can create three dimensional microstructured patterns, they are complex and involve cleanroom or microfabrication facilities. This paper introduces a new method using a particle-studded fluid-fluid interface to produce topographically patterned PDMS surfaces. PDMS is chosen since it is well studied and commonly used in soft lithography to mimic micron to nano scale structures. The advantage of this method is that it does not involve harsh chemicals or cheanroom facilities.
A colloidal monolayer at a fluid/fluid interface is used as the initial template off of which the PDMS pattern is molded. The advantages include 1) these colloids are either commercially available or can be synthesized, 2) the colloidal sizes can be chosen to determine the curvature of the surface features, 3) the entire process can be done in ambient environment.
The above image shows the schematic of the experimental procedure. First, colloidal particles are spread on air-water interface, then PDMS is pour onto the surface and cured. Since now the colloidal particles are embedded in the PDMS, it can be used as a template. An UV-curable epoxy is used to make the mold, and PDMS is poured into the epoxy mold, and finally the PDMS topographically patterned substrate is created.
One of the nice consequence of this method is that surfaces with features of positive, negative, and zero mean curvatures can be obtained. This other advantage is that surface features of exotic geometries can be obtained as well by using non-spherical particles such as ellipsoids, microrods, or carbon nanotube. These are illustrated in the image below