Hydrophilic strips for preventing air bubble formation in a microfluidic chamber

Abstract

In a microfluidic chamber, unwanted formation of air bubbles is a critical problem. Here, we present a hydrophilic strip array that prevents air bubble formation in a microfluidic chamber. The array is located on the top surface of the chamber, which has a large variation in width, and consists of a repeated arrangement of super- and moderately hydrophilic strips. This repeated arrangement allows a flat meniscus (i.e. liquid front) to form when various solutions consisting of a single stream or two parallel streams with different hydrophilicities move through the chamber. The flat meniscus produced by the array completely prevents the formation of bubbles. Without the array in the chamber, the meniscus shape is highly convex, and bubbles frequently form in the chamber. This hydrophilic strip array will facilitate the use of a microfluidic chamber with a large variation in width for various microfluidic applications.

Symmetric surficial phaseguides: a passive technology to generate wall-less channels by two-dimensional guiding elements

“…2b). In previous measurements, the angle on ODT declined only by 10 • after one month showing a good stability (Bunge et al 2015).…”

“…11c), so that the blue and the yellow dye cannot mix instantaneously. However, as agarose is porous, the diffusion through the gel occurs as shown previously (Bunge et al 2015).…”

“…In contrast, the concave inner side is always prone to overflow independent of the width and shape of the phaseguides. However, we showed that many 90 • corners can be included in a wall-less channel as shown in Fig. 10b (Bunge et al 2015). Here, two glass plates with gold and ODT-structures were mounted in parallel with a distance of 100 µm.…”

“…Phaseguides consists either of a different material (Choi et al 2015;Vulto et al 2006) or of a different geometry (Phurimsak et al 2014;Podszun et al 2012;PuchbergerEnengl et al 2014;Vulto et al 2010Vulto et al , 2011Xu et al 2015). Phaseguides based on a different material consist usually of thin stripes of SU8 (Vulto et al 2006), Teflon (Vulto et al 2006) or SiO 2 (Choi et al 2015) which are patterned on the top or bottom plate of the chip.…”

“…Phaseguides based on a different material consist usually of thin stripes of SU8 (Vulto et al 2006), Teflon (Vulto et al 2006) or SiO 2 (Choi et al 2015) which are patterned on the top or bottom plate of the chip. In these examples, the surficial phaseguides are used reliably to fill and empty a chamber.…”