The ability of micro-to nanometer-scale patterning on flexible substrates can enable many new applications in the area of photonics and organic electronics. A major roadblock has remained for many practical applications of patterned nanostructures, which is the throughput of nanopattern replication and the associated cost issues. Among the emerging techniques, nanoimprint lithography (NIL) clearly stands out as a promising technology for high-throughput and highresolution nanometer-scale patterning, [1,2] which can achieve resolutions beyond the limitations set by light diffraction or beam scattering that are encountered in other traditional techniques. Developments in this area have enjoyed great momentum in the past decade and numerous applications, such as in Si electronics, [3,4] organic electronics and photonics, [5,6] magnetics, [7,8] and biology [9][10][11][12] have been exploited by many researchers. On the other hand, the current process and throughput in NIL (on the order of a few minutes per wafer) is still far from meeting the demands of many practical applications, especially in photonics, biotechnology, and organic optoelectronics. The concept of roller imprinting has been pursued by previous investigators as a means to improve speed.[13] However, the procedure was to imprint a small piece of Si mold onto a Si substrate, which is not too different from that of conventional NIL except that a rod is used to apply pressure rather than a flat plate. The reverse nanoimprinting [14] or nanotransfer printing methods [15] produce positive-tone polymer or metal patterns, which in principle can also be applied to roll-to-roll printing processes. In addition, Lee et al. proposed a bilayer transfer process from a ''rigiflex'' mold to a Si wafer, [16] and pointed out that the process can potentially be extended to a roller bilayer transfer process. However, these are yet to be demonstrated.The motivation of this work is to enable continuous printing of nanostructures on a flexible web with drastically increased throughput, and thereby push the nanometer-scale lithography to an entirely new level. The roll-to-roll nanoimprint lithography (R2RNIL) technology presented in this Communication inherits its high-resolution feature from traditional NIL because it is also based on a mechanical embossing approach, but with a speed of nanopatterning increased by at least one or two orders of magnitude.The R2RNIL process primarily targets large-area patterning of nanostructures. In the conventional approach, embossing a large area requires a very large force. Huge contact areas between the mold surface and the imprinted nanostructures also produce significant adhesion force, making the mold-sample separation without damaging the substrates difficult or even impossible. In thermal NIL, if the mold and substrate are made from materials with different thermal expansion coefficients, such as Si mold and polymer substrate, stress can build up during a thermal cycle of such a magnitude that it can even destroy the Si mold during ...

A continuous roll-to-roll nanoimprint lithography (R2RNIL) technique can provide a solution for high-speed large-area nanoscale patterning with greatly improved throughput; furthermore, it can overcome the challenges faced by conventional NIL in maintaining pressure uniformity and successful demolding in large-area imprinting. In this work, we demonstrate large-area (4 in. wide) continuous imprinting of nanogratings by using a newly developed apparatus capable of roll-to-roll imprinting (R2RNIL) on flexible web and roll-to-plate imprinting (R2PNIL) on rigid substrate. The 300 nm line width grating patterns are continuously transferred on either glass substrate (roll-to-plate mode) or flexible plastic substrate (roll-to-roll mode) with greatly enhanced throughput. In addition, the film thickness after the imprinting process, which is critical in optical applications, as a function of several imprinting parameters such as roller pressure and speed, is thoroughly investigated, and an analytical model has been developed to predict the residual layer thickness in dynamic R2RNIL process.

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These results indicate that PMRT and GI were associated with both the improvements in ANV and PNV and in the QoL of patients with breast cancer.