Research on forming and application of U-form glass micro-nanofluidic chip with long nanochannels
The forming process of U-form glass micro-nanofluidic chip with long nanochannels is presented in this paper, in which the fabrication of channels and the assembly of plates are included. The micro-nanofluidic chip is composed of two glass plates in which there are microchannels and nanochannels, respectively. This chip can be used for trace sample enrichment, molecule filtration, and sample separation, etc. In fabrication process, the two-step photolithograph on one wafer is often required in early papers, as nano and micro structure designed in one plate have different depths. In this paper, the channels in micro-nanofluidic chip are designed in two glass plates instead of in one wafer. The nanochannels and microchannels are, respectively, formed on plates using wet etching and two-step photolithograph on one wafer is not required. Since the channels are formed, the upper plate and the bottom plate are assembled together by alignment, preconnection and thermal bonding orderly. Firstly these plates are aligned with the cross-marks on an inverted microscope. The aqueous film between plates is controlled to decrease the static friction force for accurate adjustment. Then the adhesion strength of connection is enhanced with semi-dry status for limiting movement from slight inclining and shaking. At last, the bottom plate and the upper one are irreversibly linked together with thermal bonding. The heating period and max temperature of thermal bonding are optimized to eliminate thermal stress gradient and the size shrinking. With the micro-nanofluidic chip, the 1μM fluorescein isothiocyanate in 10mM PBS buffer is concentrated successfully. The sample concentrating factor of light intensity varies from 2.2 to 8.4 with applied voltages between 300 and 2,000V. The switch effect and the instability effect in concentrating process are described and analyzed too.
[Show abstract] [Hide abstract] ABSTRACT: Abstract: This paper studies the flow characteristics in micro/nano-channels subjected to an applied electric field. The nano-channel flow was observed by means of the fluorescence Calcein. A Fluorescence Concentration Gradient Interface (FCGI) was observed across the nano-channel array. The front of the FCGI was shown to have an analogous parabolic shape. The propagation of this inter-face reflects indirectly the induced pressure at the micro/nano-channel junction, where the enrichment-depletion processes are known to take place. This induced pressure was predicted by numerical simulations, and this paper gives the first experimental evidence.0Comments 2Citations
- "Dalian University of Technology. (see Xu et al.  for details). 1.3 Reagents The sodium borate buffer solution was prepared by using Di-water (Millipore company) at a concentration of 0.1 mM and a pH value of 9.2. "
- [Show abstract] [Hide abstract] ABSTRACT: This paper reports a new fabrication method of lithography-free nanochannel array. It is based on the cracking process on the surface of a polystyrene (PS) Petri-dish, one type of thermoplastic that is composed of uni-axial macromolecular chains. Under proper conditions, parallel nanochannels with equal interspaces are obtained. Control over the channel depth from 20 nm to 200 nm is achieved, with the channel length reaching tens of millimetres. The PDMS replication based on PS nanochannel array has been successfully carried out. In combination with the microstructure, both an ion enrichment device and a current rectification device are fabricated, and their quantified characters manifested the applicability of the channel array structure in nanofluidics.0Comments 19Citations
- [Show abstract] [Hide abstract] ABSTRACT: In this study, a simple and economical fabrication technique bridging micro- and nanostructures is proposed. Glass molds with micro-nanostructures are fabricated by glass microlithography. The microlithography provides flexibility for structure design, and the glass etching contributes to transform the micro glass ridge to the nanoscale. Glass ridge structures with triangular cross sections are generated by undercutting, which coupled the isotropic character of glass and the shield effect of the top Cr layer upon HF etching. Further etching induced the height of the glass ridges to shrink from micro- to nanometres due to the edge effects. At the late etching stage, the geometrical change of the glass greatly slows down, which gives better control over the size of the glass ridge. By glass structure mold-copy, well repeatable, mechanically stable and tunable polydimethylsiloxane (PDMS) channels and cones are fabricated. Scanning electron microscopy (SEM) and laser interferometry (LI) are carried out to characterize the micro-nanostructures. To demonstrate their workability, sample preconcentration to a single nanochannel level is carried out.0Comments 14Citations