Discontinuous Dewetting in a Degassed Mold for Fabrication of Homogeneous Polymeric Microparticles

Abstract

Discontinuous dewetting (DD) is an attractive technique that enables the production of large liquid arrays in microwells and is applicable to the synthesis of anisotropic microparticles with complex morphologies. However, such loading of liquids into microwells presents a significant challenge, as the liquids used in this technique should exhibit low mold surface wettability. This study introduces DD in a degassed mold (DM), a simple yet powerful technique that achieves uniform loading of microparticle precursors into large microwell arrays within 1 min. Using this technique, hydrogel microparticles are produced by different polymerization mechanisms with various shapes and sizes, ranging from a few micrometers to hundreds of micrometers. Hydrophobic oil microparticles are produced by the simple plasma treatment of the DM, and agarose microparticles encapsulating bovine serum albumin (in a well-dispersed state) are produced by submerging the DM in fluorinated oil. To demonstrate additional functionality of microparticles using this technique, high concentrations of magnetic nanoparticles are loaded into microparticles for particle-based immunoassays performed in a microwell plate, and the immunoassay performance is comparable to that of ELISA.

Thermally switchable, crystallizable oil and silicone composite adhesives for skin-interfaced wearable devices

“…As an alternative to a uniform, random distribution of oil crystallite throughout the thickness of the composite, patterned architectures of oil confined to the surface can be considered. Here, a process of discontinuous dewetting of heated liquid oil onto the surface of a silicone film with arrays of cylindrical features of bas relief, followed by cooling leaves circular disks of solid oil ( 42 , 43 ) at the surface. As the liquid travels across the mold, it pins on the edge of the wells due to the structural heterogeneity.…”

“…Spin-coating (250 rpm) polydimethylsiloxane (PDMS; Sylgard 184, Dow Corning) on the PDMS well mold, curing at 75°C for 30 min and then removing from the mold yielded silicone elements embossed with recessed wells. A discontinuous dewetting process ( 42 , 43 ) filled the wells with oil. Briefly, plasma treating (30 s) the wells followed by moving the liquid oil horizontally across the wells (24 mm min −1 ) using a glass slide [treated with trichloro(1 H ,1 H ,2 H ,2 H -perfluorooctyl)silane to produce a hydrophobic surface] suspended (1 mm) above the silicone surface (placed on a hot plate at elevated temperature to ensure the oil remained liquid) uniformly filled the wells with oil.…”

Oil-Triggered and Template-Confined Dewetting for Facile and Low-Loss Sample Digitization

“…Dominated by the minimization of the surface energy, such an oil covering triggered the dewetting of the impregnated aqueous sample at narrow well-to-well channels, leading to the isolation of the sample in individual microwells and thus sample discretization. In contrast to traditional discontinuous dewetting, which creates liquid arrays by draining or scraping the excess liquid from a molded or patterned surface, , this method does not require any delicate handling of the liquid or the devices ( e.g. , carefully controlling the draining or scraping speed), thus providing a simple and robust route to sample digitization.…”

“…In contrast to traditional discontinuous dewetting, which creates liquid arrays by draining or scraping the excess liquid from a molded or patterned surface, 32,33 this method does not require any delicate handling of the liquid or the devices (e.g., carefully controlling the draining or scraping speed), thus providing a simple and robust route to sample digitization. More importantly, the primed sample can be transformed into discretized droplets in the NMA chip with nearly zero waste (only wasting a tiny amount of the sample loaded in the main channel).…”

Facile and Low-Waste Self-Digitization of Samples by Oil-Triggered, Template-Confined Dewetting on a Networked Microwell Array

“…Due to its high wettability to PDMS, the oil leaked from the oil reservoir spontaneously spreads over the surface of the microstructure layer to trigger the dewetting of the impregnated aqueous sample at narrow well-to-well channels, leading to the isolation of sample in individual microwells and thus sample discretization. In contrast to traditional discontinuous dewetting which creates liquid arrays by draining or scraping the excess liquid from a molded or patterned surface, 30,31 this method does not require any delicate handling of liquid or devices (e.g., carefully controlling the draining or scraping speed), thus providing a simple and robust route to sample digitization. More importantly, the primed sample can be transformed into discretized droplets in the NMA chip with nearly zero waste (only wasting a tiny sample loaded in the main channel).…”