A simplified PDMS microfluidic device with a built‐in suction actuator for rapid production of monodisperse water‐in‐oil droplets

Abstract

We previously established an automatic droplet‐creation technique that only required air evacuation of a PDMS microfluidic device prior to use. Although the rate of droplet production with this technique was originally slow (∼10 droplets per second), this was greatly improved (∼470 droplets per second) in our recent study by remodeling the original device configuration. This improvement was realized by the addition of a degassed PDMS layer with a large surface area‐to‐volume ratio that served as a powerful vacuum generator. However, the incorporation of the additional PDMS layer (which was separate from the microfluidic PDMS layer itself) into the device required reversible bonding of five different layers. In the current study, we aimed to simplify the device architecture by reducing the number of constituent layers for enhancing usability of this microfluidic droplet generator while retaining its rapid production rate. The new device consisted of three layers. This comprised a degassed PDMS slab with microfluidic channels on one surface and tens of thousands of vacuum‐generating micropillars on the other surface, which was simply sandwiched by PMMA layers. Despite its simplified configuration, this new device created monodisperse droplets at an even faster rate (>1000 droplets per second).

CO2-Laser-Micromachined, Polymer Microchannels with a Degassed PDMS slab for the Automatic Production of Monodispersed Water-in-Oil Droplets

“…The droplet-production rate initially increased and then slightly decreased. This characteristic of the rate change was also evident for the PDMS/PDMS chip used in the latest study [36] and our other preceding formats of connection-free droplet production chips [24,50,51]. The mechanism of the rate change was discussed in the cited studies in terms of the change in the vacuum level within the sealed, air-trapping outlet void space.…”

“…In the top PDMS slab, 3 through-holes (R1, R2, and R3) were cut. In addition, a two-dimensional array of orthogonal microgrooves (covering an area of 850 mm 2 ) was fabricated on the upper surface of the top PDMS slab using the laser-engraving machine to increase the PDMS surface-area-to-volume (SA/V) ratio inside the air-trapping void space, facilitating the permeation of the entrapped air into the degassed PDMS slab, and thereby increasing the vacuum level in that space [50]. The bottom PMMA and top PDMS slabs were reversibly bonded together on the basis of the viscoelastic properties of PDMS (Figure 1b, left).…”

“…Our previous study suggested that the vacuum level attained with our droplet production microchips is likely to be determined by the PDMS SA/V ratio within the air-trapping void space [50]. Therefore, a simple approach for increasing the droplet-production rate with a fixed PDMS SA/V ratio is to decrease the hydrodynamic resistances of the microfluidic channels.…”

Microfabrication with Very Low-Average Power of Green Light to Produce PDMS Microchips

“…Because of the high patterning resolution, simple processing, and low-cost fabrication method, laser ablation has become an important tool to obtain polymeric microfluidic devices, highlighting poly(dimethyl siloxane) (PDMS) for studies in biological systems [ 18 , 19 , 20 , 21 ]. Frequently, a microfluidic system consists of a polymer-covered transparent glass plate in which a well-defined micro-channels and cavities pattern is engraved to provide an appropriate mechanical and chemical environment for a system of interest [ 22 ].…”

単分散plgaナノ粒子の用時調製技術の開発

“…． 高分子球形晶析法のひとつである「水中エマ ルション溶媒拡散法(Emulsion Solvent Diffusion (ESD) method) 」にて，薬物封入 PLGA ナノ粒 子を作製し (Cohen-Sela et al, 2009;Esmaeili et al, 2007;Murakami et al, 2000) (Murata et al, 2018;Nakatani et al, 2020;Tanaka et al, 2015)…”