Optical-softlithographic technology for patterning on curved surfaces

Kim, J G; Takama, Nobuyuki; Kim, B J; Fujita, Hiroyuki

doi:10.1088/0960-1317/19/5/055017

Cited by 58 publications

(31 citation statements)

References 9 publications

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“…Traditional techniques for patterning surfaces with spatial wettability contrast include vapor deposition (8), photolithography (3), and soft lithography (54,55). Although photolithography can only be used to pattern flat substrates, soft lithography using flexible molds or masks fabricated via photolithography can work on cylindrical or conical surfaces, i.e., curved surfaces with zero Gaussian curvature (54,55).…”

Section: Resultsmentioning

confidence: 99%

Spontaneous wettability patterning via creasing instability

Chen

McKinley

Cohen

2016

Proc. Natl. Acad. Sci. U.S.A.

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Surfaces with patterned wettability contrast are important in industrial applications such as heat transfer, water collection, and particle separation. Traditional methods of fabricating such surfaces rely on microfabrication technologies, which are only applicable to certain substrates and are difficult to scale up and implement on curved surfaces. By taking advantage of a mechanical instability on a polyurethane elastomer film, we show that wettability patterns on both flat and curved surfaces can be generated spontaneously via a simple dip coating process. Variations in dipping time, sample prestress, and chemical treatment enable independent control of domain size (from about 100 to 500 μm), morphology, and wettability contrast, respectively. We characterize the wettability contrast using local surface energy measurements via the sessile droplet technique and tensiometry.wettability contrast | creasing instability | domain size | morphology | curved surfaces S urfaces that juxtapose local hydrophilic areas with hydrophobic areas show superior performance compared with surfaces with homogeneous wettability in many industrial applications including heat transfer (1), water collecting (2-6), particle separation (7), and microfluidics (8). For instance, developing enhanced water-collecting efficiency has been inspired by the Namib desert beetle, which was reported (2) to have hydrophilic bumps on an overall wax-covered hydrophobic surface. Although the hydrophilic bumps reduce the nucleation/coalescence energy of microdroplets, the overall hydrophobic character of the surface facilitates the spontaneous shedding of water droplets when they grow beyond a certain size.To achieve surfaces with wettability patterning, traditional fabrication methods such as photolithography and soft lithography have been used. However, these methods are generally not cost-effective, not readily scaled up, require multiple process steps, and are difficult to implement on curved surfaces (3, 9). Recently, mechanical instabilities have been explored as a facile self-assembly approach to endow surfaces with superhydrophobicity (10-12), superhydrophilicity (13), or anisotropic wettability (14). Although mechanical self-assembly provides a low cost route for spontaneous generation of surface patterns, explorations to date have been focused on introducing surface roughness via wrinkling and crumpling instabilities. Here we show that surfaces can be spontaneously patterned with chemical patches with small changes in surface roughness by harnessing a reversible creasing instability (15-17).A creasing instability develops when a soft polymer network is placed under mechanical compression beyond a certain critical strain, at which point sharp folds spontaneously develop and grow on the deformable free surfaces (18). This process has been linked to the morphology development of the brain (19,20), electric breakdown of dielectric elastomers (21), and has also been harnessed to prepare switchable surfaces actuated by temperature (22) or electric ...

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Section: Resultsmentioning

confidence: 99%

Spontaneous wettability patterning via creasing instability

Chen

McKinley

Cohen

2016

Proc. Natl. Acad. Sci. U.S.A.

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“…In addition, the soft lithography technology was used to realize patterning on the curved surface in Ref. [12]. Even, in order to fabricate microstructures on the thin cylindrical substrate, an automatic wire bonder was also utilized in the work [13,14].…”

Section: Flexible Implantable Microtemperature Sensormentioning

confidence: 99%

Lab-on-a-Tube Surface Micromachining Technology

Yang¹,

Zhang²

2017

Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets

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In this chapter, the lab-on-a-tube surface micromachining technology will be used to fabricate a flexible implantable microtemperature sensor for hyperthermia application and a three-electrode system on a polymer tube surface for glucose monitoring application. This micromachining process is based on two homemade equipments: a spray coating equipment and a programmable UV 3D projection lithography system with alignment. In the spray coating system, there is a heater nozzle next to the spray nozzle for real-time heating. Pure nitrogen is flowed through the heater nozzle, warmed up and sprayed onto the tube substrate surface. The programmable UV lithography equipment for cylindrical substrate mainly consists of four parts: a uniform illumination system, a reduced projection lithography system, a synchronized motion stage system, and a Charge-Coupled Device (CCD) multilayer alignment system which is used to observe simultaneously the projected mask's patterns and those ever fabricated on the tube. Using the developed labon-a-tube surface micromachining technology, an implantable flexible microtemperature sensor and a three-electrode microstructure are successfully fabricated on the flexible polymer tube with 330 μm outer diameter, respectively. The test temperature coefficient of resistance (TCR) of the temperature sensor is 0.0034/°C. The measured cyclic voltammetry curve shows that the three-electrode system has a good redox property.

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“…Complex antenna arrays with non-planar geometries have been implemented in the past using multiple layers or tiling schemes which may involve intricate and time-consuming assembly steps [130]. Some designs based on canonical geometries have utilized directive deposition through shadow masks [131] or flexible contact masks [132] to mitigate defects such as folding, stretching and cracking that can result from a post-processing step [133]. Masks, however, have been implemented successfully only in single curved surfaces such as cylinders with an added restriction of patterning smooth elements.…”

Section: Conformal Structuresmentioning

confidence: 99%