Active Continuous-Flow Micromixer Using an External Braille Pin Actuator Array

Abstract

Abstract:We present a continuous-flow active micromixer based on channel-wall deflection in a polydimethylsiloxane (PDMS) chip for volume flows in the range up to 2 μL s −1 which is intended as a novel unit operation for the microfluidic Braille pin actuated platform. The chip design comprises a main microchannel connected to a series of side channels with dead ends aligned on the Braille pins. Computer-controlled deflection of the side-channel walls induces chaotic advection in the main-channel, which substantially accelerates mixing in low-Reynolds number flow. Sufficient mixing (mixing index MI below 0.1) of volume flows up to 0.5 μL s −1 could be achieved within residence times ~500 ms in the micromixer. As an application, continuous dilution of a yeast cell sample by a ratio down to 1:10 was successfully demonstrated. The mixer is intended to serve as a component of bio-analytical devices or as a unit operation in the microfluidic Braille pin actuated platform.

A Review on Micromixers

“…Active micromixers depend on different external energy sources to disturb the fluids, increase the contact area, or induce the chaotic advection, thus enhancing the mixing effect. Based on the types of external energy sources, the active micromixers can be further categorized as pressure field driven [ 7 , 13 , 14 , 15 , 16 ], electrical field driven [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ], sound field driven [ 6 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ], magnetic field driven [ 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ], and thermal field driven [ 58 ,…”

Mixing in an enclosed microfluidic chamber through moving boundary motions

“…With this structure, flows are made with a 90° rotation between each recombination and splitting. Abbas et al (2013) developed a continuous-flow micromixer based on the channel deflection. Further by generating a chaotic advection using the channel deflection, the mixing efficiency was enhanced significantly.…”

Switching Modes of Mixing Due to an Adjustable Gap in a Continuous-Flow Microreactor

“…Furthermore, various techniques have been developed for mixing typically laminar flows in the CFMR. Among them are passive methods, where the mixing effect is introduced by geometry [16] or using bas-relief structures on the bottom of the channel [17] and active methods using an external Braille pin actuator array [18]. Further micromixer working principles are based on fluidic dielectrophoresis [19] or centrifugal action [20].…”