High-Throughput Continuous-Flow Separation in a Micro Free-Flow Electrophoresis Glass Chip Based on Laser Microfabrication.

Aodong Zhang,Jian Xu,Xiaolong Li,Xin Li,Zhenhua Wang,Ya Cheng,Zijie Lin,Yunpeng Song

doi:10.3390/s22031124

Abstract

Micro free-flow electrophoresis (μFFE) provides a rapid and straightforward route for the high-performance online separation and purification of targeted liquid samples in a mild manner. However, the facile fabrication of a μFFE device with high throughput and high stability remains a challenge due to the technical barriers of electrode integration and structural design for the removal of bubbles for conventional methods. To address this, the design and fabrication of a high-throughput μFFE chip are proposed using laser-assisted chemical etching of glass followed by electrode integration and subsequent low-temperature bonding. The careful design of the height ratio of the separation chamber and electrode channels combined with a high flow rate of buffer solution allows the efficient removal of electrolysis-generated bubbles along the deep electrode channels during continuous-flow separation. The introduction of microchannel arrays further enhances the stability of on-chip high-throughput separation. As a proof-of-concept, high-performance purification of fluorescein sodium solution with a separation purity of ~97.9% at a voltage of 250 V from the mixture sample solution of fluorescein sodium and rhodamine 6G solution is demonstrated.

Highlights

Micro free-flow electrophoresis is a versatile technique for high-efficiency continuous separation and purification of liquid analytes with an electric-field-controlled microfluidic environment [1,2,3,4,5,6]
To assemble a μFFE chip with desirable size, high-precision and high-quality fabrication of the bottom plate of the chip is of vital importance through fs laser-assisted chemical etching since the top plate of the chip was only composed of several vertical ports
A height ratio of ~1:3.3 between the separation chamber and the electrode channel was optimized to enhance the exhaust of bubbles and maintain the stability of the separation processes

Summary

Introduction

Micro free-flow electrophoresis (μFFE) is a versatile technique for high-efficiency continuous separation and purification of liquid analytes with an electric-field-controlled microfluidic environment [1,2,3,4,5,6]. Some representative methods to prepare μFFE chips have been developed [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21] For polymeric materials such as PDMS and ABS plastics, soft-lithography [8] or threedimensional (3D) printing [9] are popularly adopted due to their economy and ease of operation. To ensure the long-term and stable operation of μFFE, the electrolytic bubbles generated around the electrodes need to be timely expelled. Otherwise, those bubbles could severely affect the stability of the separation performance. The manufacture of high-throughput and highly stable μFFE glass chips in a simple fashion remains a challenge in terms of tedious and complex fabrication procedures

Methods

Results

Discussion

Conclusion