Controllable biaxial and uniaxial nanowrinkles (see figure) are fabricated by a simple two‐step approach — metal deposition and subsequent heating — based on shape memory polymer (prestressed polystyrene) sheets. The wavelengths of the wrinkles can be tuned by controlling the thickness of deposited metal. The ready integration of the nanowrinkles into microchannels and their effectiveness in surface enhanced sensing is demonstrated.

We present a rapid and non-photolithographic approach to microfluidic pattern generation by leveraging the inherent shrinkage properties of biaxially oriented polystyrene thermoplastic sheets. This novel approach yields channels deep enough for mammalian cell assays, with demonstrated heights up to 80 mm. Moreover, we can consistently and easily achieve rounded channels, multi-height channels, and channels as thin as 65 mm in width. Finally, we demonstrate the utility of this simple microfabrication approach by fabricating a functional gradient generator. The whole process-from device design conception to working device-can be completed within minutes.

We present a novel approach for the ultra-rapid direct patterning of complex three-dimensional, stacked polystyrene (PS) microfluidic chips. By leveraging the inherent shrinkage properties of biaxially pre-stressed thermoplastic sheets, microfluidic channels become thinner and deeper upon heating. Design conception to fully functional chips can thus be completed within minutes.

We demonstrate rapid homogenous micromixing at low Reynolds numbers in an easily fabricated and geometrically simple three-dimensional polystyrene vortex micromixer. Micromixing is critically important for miniaturized analysis systems. However, rapid and effective mixing at these small scales remains a persistent challenge. We compare our micromixer's performance against a two-dimensional square-wave design by examining its effectiveness in mixing solutions of dissimilar concentration as well as suspension solutions comprised of microparticles. Numerical simulations confirm our experimental observations and provide insights on the self-rotational mixing dynamics achieved with our simple geometry at low Reynolds numbers. This rapid, robust, and easily fabricated micromixer is amenable readily to large scale integration.

By leveraging the mismatch in stiffness between a stiff thin metal film and heat‐induced shrinkage of prestressed polystyrene sheets, Michelle Khine and co‐workers can rapidly and controllably create tunable nanowrinkles of various sizes and shapes for surface‐enhanced sensing applications, as reported . Because the wrinkles are robustly embedded into the plastic, nanostructures can be integrated into microfluidic channels within minutes. Cover design by Libre Design.