Superhydrophobic Surfaces as an On-Chip Microfluidic Toolkit for Total Droplet Control

Abstract

We propose and outline a novel technique designed to utilize the unique surface repulsion present between aqueous droplets and customizable superhydrophobic surfaces for the on-chip spatial and temporal manipulation of droplets within microfluidic architectures. Through the integration of carefully designed and prepatterned superhydrophobic surfaces into polymer microfluidic chipsets, it is possible to take advantage of this enhanced surface repulsion to passively manipulate droplets on the microscale for a wide range of droplet operations, including but not limited to acceleration, deceleration, merging, and path control. This work aims to help fulfill and stimulate development based around current requirements for additional passive analytical manipulation and detection techniques in order to enable a reduction in experimental design complexity with the goal of facilitating and improving portability for Lab-on-a-chip devices.

Hierarchical micro and nano structured, hydrophilic, superhydrophobic and superoleophobic surfaces incorporated in microfluidics, microarrays and lab on chip microsystems

“…Seo et al used superhydrophobic magnetic elastomer and magnetic forces to control the movement of droplets towards digital microfluidics [146]. Draper et al incorporated prepatterned superhydrophobic surfaces inside microfluidics to allow movement, acceleration, merging and other control functions for droplets [147]. The field of droplet microfluidics (also called digital microfluidics) has been reviewed recently by Sharma et al [148] focusing on dielectrophoresis (DEP) and electrowetting on dielectric (EWOD), while applications in chemistry were reviewed by Choi et al [149].…”

Micro/Nanopatterned Superhydrophobic Surfaces Fabrication for Biomolecules and Biomaterials Manipulation and Analysis

“…Another interesting material for superhydrophobic application is polydimethylsiloxane (PDMS). PDMS is a relatively soft, biocompatible polymer, which has already found a lot of different applications in superhydrophobicity, owing also to the intrinsic hydrophobicity of its surface [74,75]. An important advantage of this material is its versatility, being possible to machine it with top-down and bottom-up approaches, or a combination of the two.…”

Carbon nanotubes in microfluidic lab-on-a-chip technology: current trends and future perspectives

“…CNT wettability may be changed through chemical modification methods such as oxidative treatment of the CNT surface or treating the surface with acids. Modifying the CNT surfaces leads to a significant rise in the wettability of the surface for polar liquids including water and also to more reactive surfaces (Shiu et al 2005; Krupenkin et al 2007; Draper et al 2013). The presence of functional groups not only increases diffusional resistance, but it also changes the adsorption properties of the CNTs.…”