Cellulose-based paper is a versatile material with a diverse array of applications. While paper is not commonly thought of as a material that shrinks, here we present a method for miniaturizing paper via periodate oxidation. Chromatography paper was exposed to varying concentrations of periodate (0.1–0.5 M) over a 96-h period. Following optimization of miniaturization parameters, fourteen different types of paper were miniaturized and reductions in surface area ranging from 60 to 80% were observed. All cellulose paper types, but not cellulose-derivatives, displayed successful miniaturization. Results were highly tunable dependent upon periodate concentration and reaction time. Potential applications of the technique are discussed, including its use as a microfabrication method.
more »
« less
UV‐Micropatterned Miniaturization: Rapid In Situ Photopatterning and Miniaturization of Microscale Features on Shrinkable Thermoplastics
Shrink lithography is a promising top‐down micro/nanofabrication technique capable of miniaturizing patterns/structures to scales much smaller than the initial mold, however, rapid inexpensive fabrication of high‐fidelity shrinkable microfeatures remains challenging. This work reports the discovery and characterization of a simple, fast, low‐cost method for replicating and miniaturizing intricate micropatterns/structures on commodity heat‐shrinkable polymers. Large‐area permanent micropatterning on polystyrene and polyolefin shrink film is attained in one step under ambient conditions through brief irradiation by a shortwave UV pencil lamp. After baking briefly in an oven, the film shrinks biaxially and the miniaturized micropatterns emerge with significantly reduced surface area (up to 95%) and enhanced depth profile. The entire UV‐micropatterned miniaturization process is highly reproducible and achievable on benchtop under a few minutes without chemicals or sophisticated apparatus. A variety of microgrid patterns are replicated and miniaturized with high yield and resolution on both planar and curved surfaces. Sequential UV exposures enable easy and rapid engineering of sophisticated microtopography with miniaturized, multiscale, multidimensional microstructures. UV–ozone micropatterned polystyrene surfaces are well‐suited for lab‐on‐a‐chip analytical applications owing to the inherent biocompatibility and enhanced surface hydrophilicity. Miniaturization of dense, periodic micropatterns may facilitate low‐cost prototyping of functional devices/surfaces such as micro‐optics/sensors and tunable metamaterials.
more » « less- NSF-PAR ID:
- 10457856
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Technologies
- Volume:
- 5
- Issue:
- 6
- ISSN:
- 2365-709X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
Abstract Hydrocyclones are a simple and powerful particle separation technology, widely used in macroscale industrial processes, with enormous potential for miniaturization. Although recent efforts to shrink hydrocyclones to the centimeter scale have shown great promise for passive and high‐throughput microparticle separations, further miniaturization is constrained by limited understanding of the impact of device size scale and design on separation performance, and challenges in realizing the complex internal structures of hydrocyclones at small size scales using conventional microfabrication techniques. Here, fundamental scaling issues for hydrocyclones with sub‐millimeter critical dimensions are investigated, and the first microscale hydrocyclones with critical feature size as small as 250 µm are demonstrated by taking advantages of 3D printing using stereolithography coupled with digital light processing. The resulting devices are shown to provide high separation efficiency for particles as small as 3.7 µm while operating at high flow rates up to 40 mL min−1, with scaling analysis suggesting that sub‐micrometer particle separations can be achieved with further miniaturization, potentially making the technology suitable for the rapid isolation and concentration of both inorganic and biological nanoparticles.
-
more » « less
Abstract Thin polymeric films are being explored for biomedical uses such as drug delivery, biofiltration, biosensors, and tissue regeneration. Of specific interest is the formation of mechanically flexible sheets, which can be formed with controllable thickness for sealing wounds, or as biomimetic cellular constructs. Flexible substrates with precise micro‐ and nanopatterns can function as supports for cell growth with conformal contact at the biointerface. To date, approaches to form free‐standing, thin sheets are limited in the ability to present patterned architectures and micro/nanotextured surfaces. Other materials have a lack of degradability, precluding their application as cellular scaffolds. An approach is suggested using biocompatible and biodegradable films fabricated from silk fibroin. This work presents the fabrication and characterization of flexible, micropatterned, and biodegradable 2D fibroin sheets for cell adhesion and proliferation. A facile and scalable technique using photolithography is shown to fabricate optically transparent, strong, and flexible fibroin substrates with tunable and precise micropatterns over large areas. By controlling the surface architectures, the control of cell adhesion and spreading can be observed. Additionally, the base material is fully degradable via proteolysis. Through mechanical control and directing the adherent cells, it is possible to explore interactions of cells and the microscale geometric topography.
-
more » « less
Abstract The evolution of miniaturization can result in dramatic alterations of morphology, physiology, and behavior; however, the effects of miniaturization on sexual dimorphism remain largely unknown. Here we investigate how miniaturization influences patterns of sexual size dimorphism (SSD) in geckos. Measuring 1,875 individuals from 131 species, we characterized patterns of SSD relative to body size across two families. We found that miniaturized species were more female biased than non-miniaturized species. Additionally, one family that contained many miniaturized species (Sphaerodactylidae) displayed allometric patterns in SSD with body size, where larger species were male biased and smaller species were more female biased. Smaller species in this lineage also produced proportionally larger eggs. By contrast, another family containing few miniaturized species (Phyllodactylidae) displayed a more isometric trend. Together, these observations are consistent with the hypothesis that selection for increased reproductive success in small species of Sphaerodactylidae results in female-biased SSD in these taxa, which in turn drives the positive SSD allometry observed in this lineage. Thus, selection for increased miniaturization in the clade may be offset by selection on maintaining a female size in smaller taxa that ensures reproductive success.
-
more » « less
Abstract This paper describes a tape nanolithography method for the rapid and economical manufacturing of flexible, wearable nanophotonic devices. This method involves the soft lithography of a donor substrate with air-void nanopatterns, subsequent deposition of materials onto the substrate surface, followed by direct taping and peeling of the deposited materials by an adhesive tape. Without using any sophisticated techniques, the nanopatterns, which are preformed on the surface of the donor substrate, automatically emerge in the deposited materials. The nanopatterns can then be transferred to the tape surface. By leveraging the works of adhesion at the interfaces of the donor substrate-deposited material-tape assembly, this method not only demonstrates sub-hundred-nanometer resolution in the transferred nanopatterns on an area of multiple square inches but also exhibits high versatility and flexibility for configuring the shapes, dimensions, and material compositions of tape-supported nanopatterns to tune their optical properties. After the tape transfer, the materials that remain at the bottom of the air-void nanopatterns on the donor substrate exhibit shapes complementary to the transferred nanopatterns on the tape surface but maintain the same composition, thus also acting as functional nanophotonic structures. Using tape nanolithography, we demonstrate several tape-supported plasmonic, dielectric, and metallo-dielectric nanostructures, as well as several devices such as refractive index sensors, conformable plasmonic surfaces, and Fabry-Perot cavity resonators. Further, we demonstrate tape nanolithography-assisted manufacturing of a standalone plasmonic nanohole film and its transfer to unconventional substrates such as a cleaved facet and the curved side of an optical fiber.
