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Open AccessArticle

Increased Flexibility in Lab-on-Chip Design with a Polymer Patchwork Approach

Department of Physics, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
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Nanomaterials 2019, 9(12), 1678; https://doi.org/10.3390/nano9121678
Received: 25 October 2019 / Revised: 19 November 2019 / Accepted: 20 November 2019 / Published: 25 November 2019
Nanofluidic structures are often the key element of many lab-on-chips for biomedical and environmental applications. The demand for these devices to be able to perform increasingly complex tasks triggers a request for increasing the performance of the fabrication methods. Soft lithography and poly(dimethylsiloxane) (PDMS) have since long been the basic ingredients for producing low-cost, biocompatible and flexible devices, replicating nanostructured masters. However, when the desired functionalities require the fabrication of shallow channels, the “roof collapse” phenomenon, that can occur when sealing the replica, can impair the device functionalities. In this study, we demonstrate that a “focused drop-casting” of h-PDMS (hard PDMS) on nanostructured regions, provides the necessary stiffness to avoid roof collapse, without increasing the probability of deep cracks formation, a drawback that shows up in the peel-off step, when h-PDMS is used all over the device area. With this new approach, we efficiently fabricate working devices with reproducible sub-100 nm structures. We verify the absence of roof collapse and deep cracks by optical microscopy and, in order to assess the advantages that are introduced by the proposed technique, the acquired images are compared with those of cracked devices, whose top layer, of h-PDMS, and with those of collapsed devices, made of standard PDMS. The geometry of the critical regions is studied by atomic force microscopy of their resin casts. The electrical resistance of the nanochannels is measured and shown to be compatible with the estimates that can be obtained from the geometry. The simplicity of the method and its reliability make it suitable for increasing the fabrication yield and reducing the costs of nanofluidic polymeric lab-on-chips. View Full-Text
Keywords: nanofluidic device; polydimethylsiloxane; polymeric device; nanochannel; nanofabrication nanofluidic device; polydimethylsiloxane; polymeric device; nanochannel; nanofabrication
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Pezzuoli, D.; Angeli, E.; Repetto, D.; Guida, P.; Firpo, G.; Repetto, L. Increased Flexibility in Lab-on-Chip Design with a Polymer Patchwork Approach. Nanomaterials 2019, 9, 1678.

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