Fabrication and characterization of non-linear parabolic microporous membranes

• Published in: Journal of membrane science 2015-01, Vol.473, p.28-35
• Main Authors: Rajasekaran, Pradeep Ramiah, Sharifi, Payam, Wolff, Justin, Kohli, Punit
• Format: Article
• Language: English
• Subjects: energy efficiency; equations; Fluid dynamics; Fluid flow; Fluids; Membranes; Micro-mirrors; Micro-optics; Microfluidics; micropores; microporous membranes; Navier-Stokes equations; Non-linear parabolic pores; Nonlinearity; optics; Parabolic membranes; polydimethylsiloxane; Polydimethylsiloxane membranes; Separation; surface tension; viscoelasticity
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2014.08.042

Large scale fabrication of non-linear microporous membranes is of technological importance in many applications ranging from separation to microfluidics. However, their fabrication using traditional techniques is limited in scope. We report on fabrication and characterization of non-linear parabolic micropores (PMS) in polymer by utilizing flow properties of fluids. The shape of the fabricated PMS corroborated well with simplified Navier–Stokes equation describing parabolic relationship of the form L–t1/2. Here, L is a measure of the diameter of the fabricated micropores during flow time (t). The surface of PMS is smooth due to fluid surface tension at fluid–air interface. We demonstrate fabrication of PMS using curable polydimethylsiloxane (PDMS). The parabolic shape of micropores was a result of interplay between horizontal and vertical fluid movements due to capillary, viscoelastic, and gravitational forces. We also demonstrate fabrication of asymmetric “off-centered PMS” and an array of PMS membranes using this simple fabrication technique. PMS containing membranes with nanoscale dimensions are also possible by controlling the experimental conditions. The present method provides a simple, easy to adopt, and energy efficient way for fabricating non-linear parabolic shape pores at microscale. The prepared parabolic membranes may find applications in many areas including separation, parabolic optics, micro-nozzles/-valves/-pumps, and microfluidic and microelectronic delivery systems. [Display omitted] •We fabricate and characterize single and multiple parabolic pores in polymer.•The experimental data matched well with a simplified Navier–Stokes equation.•Non-symmetric parabolic pores and replica of parabolic pores were synthesized.•The effect of fluid properties on pore shape and size was discussed.