Efficient Nanoporous Silicon Membranes for Integrated Microfluidic Separation and Sensing Systems
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1191-OO09-02
Efficient Nanoporous Silicon Membranes for Integrated Microfluidic Separation and Sensing Systems Nazar Ileri1,2, Sonia E. Létant2, Jerald Britten2, Hoang Nguyen2, Cindy Larson2, Saleem Zaidi3, Ahmet Palazoglu1, Roland Faller1, Joseph W. Tringe2 and Pieter Stroeve1 1
University of California, Davis, Davis, CA 95616, U.S.A. Lawrence Livermore National Laboratory, Livermore, CA 94550, U.S.A. 3 Gratings, Inc., Albuquerque, NM 87107, U.S.A. 2
ABSTRACT Nanoporous devices constitute emerging platforms for selective molecule separation and sensing, with great potential for high throughput and economy in manufacturing and operation. Acting as mass transfer diodes similar to a solid-state device based on electron conduction, conical pores are shown to have superior performance characteristics compared to traditional cylindrical pores. Such phenomena, however, remain to be exploited for molecular separation. Here we present performance results from silicon membranes created by a new synthesis technique based on interferometric lithography. This method creates millimeter sized planar arrays of uniformly tapered nanopores in silicon with pore diameter 100 nm or smaller, ideallysuited for integration into a multi-scale microfluidic processing system. Molecular transport properties of these devices are compared against state-of-the-art polycarbonate track etched (PCTE) membranes. Mass transfer rates of up to fifteen-fold greater than commercial sieve technology are obtained. Complementary results from molecular dynamics simulations on molecular transport are reported.
INTRODUCTION Transport of biomolecules through nanopores is crucial in many biotechnological and biophysical processes [1]. Advances in protein screening, organic and inorganic molecular development, and sensing of toxins/viruses have accelerated the requirement for membranes with uniform pore size and a large dynamic range of biomolecule size selection (~1 nm to 1µm). However, the standard lithographic processes limit the production of membranes with nanometer-scale pore sizes over 1-100’s of mm2 areas needed by most applications. The majority of commercial membranes are made of organic polymers and fabricated by non-lithographic methods [2]. For example, PCTE membranes, produced by ion-track etching through polycarbonate films, have pore sizes in the range ~10 nm to ~µm. Although the scalability of these membranes is good, uniformity and flow rates are limited to ±20% and
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