Interfacial microfluidic transport on micropatterned superhydrophobic textile

Abstract

Textile-enabled interfacial microfluidics, utilizing fibrous hydrophilic yarns (e.g., cotton) to guide biological reagent flows, has been extended to various biochemical analyses recently. The restricted capillary-driving mechanism, however, persists as a major challenge for continuous and facilitated biofluidic transport. In this paper, we have first introduced a novel interfacial microfluidic transport principle to drive three-dimensional liquid flows on a micropatterned superhydrophobic textile (MST) platform in a more autonomous and controllable manner. Specifically, the MST system utilizes the surface tension-induced Laplace pressure to facilitate the liquid motion along the hydrophilic yarn, in addition to the capillarity present in the fibrous structure. The fabrication of MST is simply accomplished by stitching hydrophilic cotton yarn into a superhydrophobic fabric substrate (contact angle 140 ± 3°), from which well-controlled wetting patterns are established for interfacial microfluidic operations. The geometric configurations of the stitched micropatterns, e.g., the lengths and diameters of the yarn and bundled arrangement, can all influence the transport process, which is investigated both experimentally and theoretically. Two operation modes, discrete and continuous transport, are also presented in detail. In addition, the gravitational effect as well as the droplet removal process have been also considered and quantitatively analysed during the transport process. As a demonstration, an MST design has been implemented on an artificial skin surface to collect and remove sweat in a highly efficient and facilitated means. The results have illustrated that the novel interfacial transport on the textile platform can be potentially extended to a variety of biofluidic collection and removal applications.

Exploration of microfluidic devices based on multi-filament threads and textiles: A review

“…17 Most recently, Xing et al fabricated micro-patterns on super hydrophobic textile (MST) for transporting microliter volumes of fluids by means of capillary wicking. 24 They used a hydrophilic cotton yarn stitched into superhydrophobic fabric to create an interfacial transport model by considering the lengths of the yarn and bundle arrangement (Fig. 1).…”

“…In their devices, fluids have been transported using an interfacial principle along the hydrophilic thread in autonomous, controllable, and continues models. 24 …”

“…Li et al conducted a semi-quantitative assay of NO 2 À on stitches of an indicatortreated cotton thread sewn into a polymer film support. They used a desk top scanner to convert the assay results into electronic images and measured the colour density of the stitches of thread and established calibration curves using serially diluted NO 2 À solutions (0, 125, 250, Treatments for increasing hydrophilicity Plasma oxidation 4 Plasma oxidation 30 Boiling 7 Mercerization 6 Washing with sodium carbonate 8 As received 36 Boiling in sodium carbonate (1.5 wt%) and hand soap solution 24 Treatment toward increasing hydrophobicity Mixing ratio controller 5 On/Off switch 18 Human body fluid (simulated/real) Urine 6,8 Whole blood 30,36 Blood plasma 36 Sweat 24,34 Blood plasma 36 …”

Wearable Bio and Chemical Sensors

“…A recent example of a textile-based interfacial micro-fluidic platform was reported by Xing et al [17], in which a 3D micro-fluidic network was fabricated by "stereo-stitching" of cotton yarn on a superhydrophobic textile. Taking advantage of the difference in wettability between the cotton yarn (contact angle 5 0 ) and the superhydrophobic textile (contact angle 5 140 ), a surface tension-driven micro-fluidic system was created in which the flow was inversely proportional to the flow resistance of the hydrophilic yarn.…”

Robust superhydrophilic patterning of superhydrophobic ormosil surfaces for high-throughput on-chip screening applications

“…2 Extreme wettability contrast by combination of superhydrophilic and superhydrophobic regions at the micro scale is desirable for applications such as water harvesting, [3][4][5][6] and microuidics. [7][8][9][10][11][12] In addition, precise control of the wetted and non-wetted patterns on a single surface allows the formation of ordered droplet arrays and easy droplet manipulation as well as immobilization and aliquoting of droplet-dispersed materials including nanoparticles, biomolecules and cells. 13,14 Therefore, patterned superhydrophobic surfaces have attracted signicant research interest for high-throughput biological and chemical screening.…”