A method for nanofluidic device prototyping using elastomeric collapse

Abstract

Nanofluidics represents a promising solution to problems in fields ranging from biomolecular analysis to optical property tuning. Recently a number of simple nanofluidic fabrication techniques have been introduced that exploit the deformability of elastomeric materials like polydimethylsiloxane (PDMS). These techniques are limited by the complexity of the devices that can be fabricated, which can only create straight or irregular channels normal to the direction of an applied strain. Here, we report a technique for nanofluidic fabrication based on the controlled collapse of microchannel structures. As is demonstrated, this method converts the easy to control vertical dimension of a PDMS mold to the lateral dimension of a nanochannel. We demonstrate here the creation of complex nanochannel structures as small as 60 nm and provide simple design rules for determining the conditions under which nanochannel formation will occur. The applicability of the technique to biomolecular analysis is demonstrated by showing DNA elongation in a nanochannel and a technique for optofluidic surface enhanced Raman detection of nucleic acids.concentrator ͉ nanofluidic channel ͉ single molecule manipulation ͉ surface enhanced raman scattering O f the many reasons why nanofluidic (1-8) systems are of interest, the most well developed applications revolve around sensing, detection, and species handling in single or ''few'' molecule environments. Researchers have recently demonstrated unique bioanalytical capabilities in nanofluidic devices including the ability to elongate single DNA molecules (2), concentrate protein samples by more than four orders of magnitude (9), and efficiently separate both large (3, 10) and small (4) biomolecules. As a result of their technological promise, numerous methods have been developed to fabricate these systems, including electron beam lithography (11, 12), focused ion beam milling (13), interference lithography (14), AFM lithography (15), and nano-imprint lithography (2, 16). The significant advantages of these high-end nanofabrication technologies are their high resolution, reproducibility, and flexibility. Despite these advantages, these methods are somewhat limited when it comes to rapid prototyping of nanofluidic systems. To augment these high-resolution techniques, several groups have developed simpler nanofluidic fabrication in polydimethylsiloxane (PDMS) using lower resolution lithography methods. Huh et al. (17) for example used crack formation in a surface oxide layer to make nanochannels with mechanically tunable widths. Similarly, Chung et al. (18) used wrinkles on an elastomeric PDMS surface that, when bonded to another surface, formed discrete nanochannels. While these approaches greatly simplify the fabrication of nanochannels, the complexity of the devices that can be created is relatively low, in that only straight lines orthogonal to the stretching force can be fabricated.An additional challenge of nanofluidic fabrication with soft materials like PDMS is the relatively low stiffness ...

A nanoporous optofluidic microsystem for highly sensitive and repeatable surface enhanced Raman spectroscopy detection

“…Passive concentration has been accomplished by fabricating a single nanofluidic channel to accumulate nanoparticle-analyte conjugates. [24][25][26] These reports show excellent detection performance. However, transport through a single nanochannel potentially limits the throughput and creates opportunities for clogging the channel.…”

3D lithography by rapid curing of the liquid instabilities at nanoscale

“…A wide variety of lithographic techniques have been developed for fabricating 3D structures (1)(2)(3)(4)(5), such as soft lithography (6) that allows one to develop lab-on-chip devices with applications ranging from organic light emitting diode to biology and biochemistry (7). Among others, "capillary-force lithography" is able to nicely pattern polymers at nano-/microscale, but with a very low aspect ratio, in a single step and avoiding the use of external forces (8).…”

Theory, fabrication and applications of microfluidic and nanofluidic biosensors

“…A on May 11, 2018 http://rsta.royalsocietypublishing.org/ Downloaded from A polymer such as PDMS is poured into the master and allowed to cure. Once fully cured, the PDMS mould is detached from the master and the device is ready to be bonded [11,131]. Detachment lithography is a photoresist-based contact printing technique used in the fabrication of three-dimensional structures.…”

“…Typically PDMS devices are bonded to glass covers by placing the glass cover in contact with the PDMS and curing the PDMS while applying pressure [60,131] or by simply applying pressure [122]. PDMS can also be used as an intermediate layer for glass-to-glass bonding.…”