On-demand acoustic droplet splitting and steering in a disposable microfluidic chip

Abstract

On-chip droplet splitting is one of the fundamental droplet-based microfluidic unit operations to control droplet volume after production and increase operational capability, flexibility, and throughput. Various droplet splitting methods have been proposed, and among them the acoustic droplet splitting method is promising because of its label-free operation without any physical or thermal damage to droplets. Previous acoustic droplet splitting methods faced several limitations: first, they employed a cross-type acoustofluidic device that precluded multichannel droplet splitting; second, they required irreversible bonding between a piezoelectric substrate and a microfluidic chip, such that the fluidic chip was not replaceable. Here, we present a parallel-type acoustofluidic device with a disposable microfluidic chip to address the limitations of previous acoustic droplet splitting devices. In the proposed device, an acoustic field is applied in the direction opposite to the flow direction to achieve multichannel droplet splitting and steering. A disposable polydimethylsiloxane microfluidic chip is employed in the developed device, thereby removing the need for permanent bonding and improving the flexibility of the droplet microfluidic device. We experimentally demonstrated on-demand acoustic droplet bi-splitting and steering with precise control over the droplet splitting ratio, and we investigated the underlying physical mechanisms of droplet splitting and steering based on Laplace pressure and ray acoustics analyses, respectively. We also demonstrated droplet tri-splitting to prove the feasibility of multichannel droplet splitting. The proposed on-demand acoustic droplet splitting device enables on-chip droplet volume control in various droplet-based microfluidic applications.

Enhancing rate of water absorption in seeds via a miniature surface acoustic wave device

“…SAW devices have been used extensively for microfluidic operations and applications such as droplet transport and manipulation [13–16], fluid mixing [17,18], particle concentration [19–21], particle trapping and manipulation [22–25], liquid jetting [26] and atomization [27–30], cooling [31], heating [32], drug delivery [33,34] and nanofiltration [35]. When SAWs travel on the piezoelectric substrate, the surface displacement amplitude of the substrate is in the order of 10 −9 m, and the amplitude decays exponentially with increasing distance from the substrate surface.…”

Microfluidics for Biosynthesizing: from Droplets and Vesicles to Artificial Cells

“…The process was done in a straight channel without any special treatments, and provides plenty of advantages, such as high‐throughput, biologically compatibility, on‐demand droplet merging. Sung and his colleagues reported the on‐demand splitting and steering of droplets by a parallel‐type, disposable microfluidic chip . This newly developed acoustofluidic device is a promising on‐chip tool for droplet steering and splitting with volume control.…”

Droplet‐based microreactor for the production of micro/nano‐materials

“…Therefore, we describe two kinds of the most widely used microfluidic devices, including lithographically fabricated poly(dimethylsiloxane) (PDMS) devices and glass capillary devices for generating various kinds of emulsion droplets. Then, varieties of manipulation methods of droplets are also introduced, such as coalescence , split , and pico‐injection .…”