Mixed-scale channel networks including Kingfisher-beak-shaped 3D microfunnels for efficient single particle entrapment

Abstract

Reproducible research results for nanofluidics and their applications require viable fabrication technologies to produce nanochannels integrated with microchannels that can guide fluid flow and analytes into/out of the nanochannels. We present the simple fabrication of mixed-scale polydimethylsiloxane (PDMS) channel networks consisting of nanochannels and microchannels via a single molding process using a monolithic mixed-scale carbon mold. The monolithic carbon mold is fabricated by pyrolyzing a polymer mold patterned by photolithography. During pyrolysis, the polymer mold shrinks by ∼90%, which enables nanosized carbon molds to be produced without a complex nanofabrication process. Because of the good adhesion between the polymer mold and the Si substrate, non-uniform volume reduction occurs during pyrolysis resulting in the formation of curved carbon mold side walls. These curved side walls and the relatively low surface energy of the mold provide efficient demolding of the PDMS channel networks. In addition, the trigonal prismatic shape of the polymer is converted into to a Kingfisher-beak-shaped carbon structure due to the non-uniform volume reduction. The transformation of this mold architecture produces a PDMS Kingfisher-beak-shaped 3D microfunnel that connects the microchannel and the nanochannel smoothly. The smooth reduction in the cross-sectional area of the 3D microfunnels enables efficient single microparticle trapping at the nanochannel entrance; this is beneficial for studies of cell transfection.

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2014–2016)

“…A batch process for casting PDMS with nanostructures was reported by Lee et al. . A monolithic carbon mold was fabricated by UV photolithography followed by pyrolysis.…”

Unconventional micro-/nanofabrication technologies for hybrid-scale lab-on-a-chip

“…To date, many attempts have been made. Among these, it seems that cracking, 94 pyrolysis, 95 and nanowires 17,[96][97][98] are representative approaches to develop simple fabrication techniques for master molds with hybrid-scale patterns or fluidic channels. They have been employed to facilitate large-scale reproducible channel fabrication through a single molding process and thus enable the fabrication of multi-scale LOC devices at a wafer level with advantages seen in the throughput, cost-effectiveness, reliability, and reproducibility.…”

Development of a Novel Gas-Sensing Platform Based on a Network of Metal Oxide Nanowire Junctions Formed on a Suspended Carbon Nanomesh Backbone

“…This approach enables the cost-effective wafer-level fabrication of complex carbon micro/nanostructures simply through the pyrolysis of photoresist structures pre-patterned by photolithography [ 28 , 29 ]. In addition, the pyrolysis is accompanied by a dramatic volume reduction, allowing the tailored fabrication of nanoscale carbon devices without requiring expensive and complex nanofabrication technologies [ 30 , 31 , 32 ]. In this study, suspended carbon mesh backbones were fabricated using C-MEMS processes, as described above.…”