Development of small-volume, microfluidic chaotic mixers for future application in two-dimensional liquid chromatography

Abstract

We report a microfluidic chaotic micromixer with staggered herringbone grooves having a geometry optimized for fast mobile-phase modification at the interface of a two-dimensional liquid chromatography system.

Digestion-on-a-chip: a continuous-flow modular microsystem recreating enzymatic digestion in the gastrointestinal tract

“…Micromixer devices were fabricated by micromolding polyIJdimethylsiloxane) (PDMS, Sylgard 184, Dow Corning, Midland, MI, USA) on SU-8 molds, according to a procedure we have described in earlier work. 31 The 300-μm-wide, 51.5mm-long channels contained 16 arrays of cycles of 12 herringbone-shaped grooves each, which greatly enhance mixing in this laminar-flow regime through chaotic advection. 30,31 The channels were 60 μm deep, and 50 μm deeper Table 1 Optimized composition of the artificial digestive juices, dissolved in ultrapure water (adapted from Walczak et al 27 in the groove regions for optimal mixing characteristics.…”

“…Each compartment was decoupled from the rest of the system and studied individually to study the enzyme kinetics of that compartment. Therefore, devices containing a single micromixer (two inlets, one outlet, as described by Ianovska et al 31 ) were used to demonstrate enzymatic function in the separate compartments. Two syringe pumps (Harvard Apparatus, Pump 11 Pico Plus Elite, Holliston, MA, USA) were used with glass syringes (250 μL, Kloehn, Whittier, CA, USA) or plastic syringes (1 mL, Braun, Melsungen, Germany), containing either the digestive juice or the solution containing the compound to be digested.…”

“…herringbone-shaped grooves in an earlier study. 31 The output from the first (mouth) stage was transferred to the second (stomach) stage using a short (2 cm) piece of tubing. We observed that the fluorescence disappears within one cycle of grooves upon mixing with gastric juice.…”

“…This flow rate was chosen for two reasons: 1) the inlet flow rates used (ranging from 1-12 μL min −1 ) are low enough to save valuable artificial digestive juices and samples with respect to larger-scale in vitro digestions, but high enough to maintain steady-state flow conditions by using syringe pumps; and 2) we found in earlier work that mixing is very fast and efficient at these low flow rates, occurring within the first section of the micromixer channels (vide infra for a description of these micromixer channels containing cycles of herringbone-shaped grooves). 31 The ratios of the inlet flow rates (1 + 4 + 8 + 12 μL min −1 ) in our system were chosen to approximate the volumetric ratios of digestive juices in vivo (Fig. 1).…”

Towards the Spectrochrom automation with ADC & omics-oriented DSP analysis

“…Нами предлагается использовать для этого данные, снимаемые со спектрального / спектрофотометрического детектора типа «Gilson Spectrochrom M». Капиллярный ввод, используемый большинством пользователей без перестройки тракта, по уровню потока совместим с микрофлюидными помпами и смесителями для хроматографии на чипе [ 43 ] (а также с соответствующими микрофлюидно-хроматографическими интерфейсами для совмещения микроэкстракции и жидкостной хроматографии [ 44 ]). Детекторы этой марки, преимущественно, без конструктивных изменений, широко использовались (с 1960-х гг.…”