Surface microfluidics fabricated by photopatternable superhydrophobic nanocomposite

Abstract

Surface microfluidics can be of potential use in a variety of emerging applications, including biological and chemical analysis, cellular detection and manipulation, high-throughput pharmaceutical screening, and etc. In comparison with the conventional closed-channel microfluidic system, surface microfluidics shows the distinct advantages of simple construction, direct surface access, no cavitation or interphase obstruction, clear optical path, easy fluidic packaging, and device reusability. In this article, we first present surface microfluidic networks microfabricated by a single-step lithographic process using a novel superhydrophobic photosensitive nanocomposite formula. The photopatternable superhydrophobic nanocomposite (PSN) incorporates PTFE nanoparticles into a SU-8 matrix, in which superhydrophobicity (contact angle of above 160°) is primarily contributed by the extremely low chemical energy and nano-topology of PTFE nanoparticles, while the SU-8 polymer matrix offers photopatternability (lithographic resolution of 10 lm) and substrate adhesion. Moreover, an additive intermediate layer with hydrophilic sidewall considerably reduces flow resistance while improving the substrate adhesion, as a crucial improvement from the previous surface flow configuration. Furthermore, self-propelled microfluidic networks driven by surface tension-induced pressure gradient have been fabricated and characterized to demonstrate the applicability of the novel nanocomposite fabrication approach.

Effects of Micromachining Processes on Electro-Osmotic Flow Mobility of Glass Surfaces

“…In particular, nano fluidic devices that contain nano channels can be used for separation and filtration [21], single-molecule detection [22][23][24][25][26], highly efficient PCR [27], chemical analysis [28,29] and nano-photonic sensors [30], with great help of development of nanofabrication technologies [31][32][33][34][35][36][37][38][39][40][41][42][43]. As the channels are reduced in size, the surface roughness and surface chemistry become dominant in determining the dynamics of flow.…”

Coating method of micro pattern based on microscopic injection system

“…Adhesion work is defined as the energy to separate liquid from solid substrate. And it's described as 1 2 3 w J J J (5) where w denotes adhesion work, 1 J , 2 J and 3 J denote solid surface energy, liquid surface energy and solid-liquid interfacial energy respectively.…”

“…So far, two methods consisting of microcontact printing (μCP) [3] [4] and microfluidic channel (μFC) [5] [6] are generally used to coat substrate material with solution in micro pattern [7]. Both of them are based on techniques of micro fabrication.…”

Magnetic liquid marbles, their manipulation and application in optical probing

“…A guiding wire that directly contacts with the droplet was also employed to direct the droplet movement (Mumm et al 2009;Yoon and You 2008). In addition, surface tensioninduced pressure gradient was used to drive the droplet movement on a superhydrophobic surface (Hong and Pan 2011). Although the droplet microfluidics based on superhydrophobic surfaces can overcome some drawbacks facing to oil-immersed systems, it has an issue in the fast evaporation of liquid from the droplets.…”