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Nanofabrication (Publications)

Non-planar nanofluidic devices for single molecule analysis fabricated using nanoglassblowing

“Nanoglassblowing” was developed as a method to fabricate integrated micro- and nanofluidic fused silica devices with wide, shallow nanochannels and areas of gradual channel depth change. Using this method, channels were constructed with out-of-plane curvature of channel covers from over ten micrometers to a few nanometers, nanochannel aspect ratios smaller than 2x10-5:1 (depth:width), and nanochannels as shallow as 7 nm. These low aspect ratios and shallow channel depths are difficult to obtain using other fabrication techniques without collapsing the channel cover. The gradual changes also facilitate loading of double-stranded deoxyribonucleic acid (DNA) molecules. The nanochannel depths and aspect ratios formed by nanoglassblowing allowed measurements of the radius of gyration, , of single l DNA molecules confined to slit-like nanochannels with depths ranging from 11 nm to 507 nm.

Nanochannels fabricated in polydimethylsiloxane using sacrificial electrospun polyethylene oxide nanofibers

We have used electrospun polyethylene oxide (PEO) nanofibers as sacrificial templates to form nanofluidic channels in polydimethylsiloxane (PDMS). By depositing fibers on silicon templates incorporating larger structures, we demonstrate that these nanochannels can be integrated easily with microfluidics. We use fluorescence microscopy to image channels filled with dye solution. The utility of the hybrid micro- and nanofluidic PDMS structures for single molecule observation and manipulation was demonstrated by introducing single molecules of λ DNA into the channels. This nanofabrication technique allows the simple construction of integrated micro- and nanofluidic PDMS structures without lithographic nanofabrication techniques.

Nanofluidic Channels for Biological Manipulation and Analysis

Nanoscale fluid filled channels can be used as tools for manipulating and observing fluorescently labeled DNA molecules. A DNA molecule with a radius of gyration larger than the nanochannel width can be forced into a channel using externally applied electric fields. Once inside, it is subject to confinement induced forces which cause it to elongate in the direction of the nanochannel axis. Here, we report on the dynamics of DNA molecules which initially enter the channel with a looped front end. Such folded molecules are observed to spontaneously unfold over a period of time ranging from seconds to minutes and depending on the length of the initially folded portion.