Non-planar nanofluidic devices for single molecule analysis fabricated usingnanoglassblowing

Abstract

A method termed ‘nanoglassblowing’ is presented for fabricating integrated microfluidicand nanofluidic devices with gradual depth changes and wide, shallow nanochannels. Thismethod was used to construct fused silica channels with out-of-plane curvature of channelcovers from over ten micrometers to a few nanometers, nanochannel aspect ratios smaller than2 × 10−5:1 (depth:width), and nanochannel depths as shallow as 7 nm. These low aspect ratios and shallow channeldepths would be difficult to form otherwise without collapse of the channel cover, and thegradual changes in channel depth eliminate abrupt free energy barriers at the transitionfrom microfluidic to nanofluidic regions. Devices were characterized with atomic forcemicroscopy (AFM), white light interferometry, scanned height measurements, fluorescenceintensity traces, and single molecule analysis of double-stranded deoxyribonucleicacid (DNA) velocity and conformation. Nanochannel depths and aspect ratiosformed by nanoglassblowing allowed measurements of the radius of gyration,Rg, ofsingle λ DNA molecules confined to slit-like nanochannels with depths,d, ranging from 11 nm to 507 nm. Measurements ofRg as afunction of d agreed qualitatively with the scaling law Rg∝d-0.25 predicted by Brochard for nanochannel depths from 36 nm to 156 nm, while measurements ofRg in 11 nm and 507 nm deep nanochannels deviated from this prediction.