Noncontact Charge Shielding Knife for Liquid Microfluidics

Abstract

Multibehavioral droplet manipulation in a precise and programmed manner is crucial for stoichiometry, biological virus detection, and intelligent lab-on-a-chip. Apart from fundamental navigation, merging, splitting, and dispensing of the droplets are required for being combined in a microfluidic chip as well. Yet, existing active manipulations including strategies from light to magnetism are arduous to use to split liquids on superwetting surfaces without mass loss and contamination, because of the high cohesion and Coanda effect. Here, we demonstrate a charge shielding mechanism (CSM) for platforms to integrate with a series of functions. In response to attachment of shielding layers from the bottom, the instantaneous and repeatable change of local potential on our platform achieves the desired loss-free manipulation of droplets, with a wide-ranging surface tension from 25.7 mN m–1 to 87.6 mN m–1, functioning as a noncontact air knife to cleave, guide, rotate, and collect reactive monomers on demand. With further refinement of the surface circuit, the droplets, just as the electron, can be programmed to be transported directionally at extremely high speeds of 100 mm s–1. This new generation of microfluidics is expected to be applied in the field of bioanalysis, chemical synthesis, and diagnostic kit.

Droplet Manipulation on Lubricant Self-Mediating Slippery PDMS Films

“…Controllable droplet transport and droplet splitting on W-LSSPF can be applied in fields such as drug detection and screening. − As shown in the schematic diagram in Figure , two simulated chip laboratories with separated chambers are used for micro reaction systems. The chamber is cut from polytetrafluoroethylene sheets.…”

Charge-Powered Electrotaxis for Versatile Droplet Manipulation

“…Accordingly, introducing the external force source, such as electricity, to actively evoke the taxis property of droplets might be a more promising means for droplet manipulation. Various electricity-based strategies, such as electrowetting, , electrodewetting, dielectrophoresis, − surface charge printing, , Coulomb attraction/repulsion, − and so on, − have been widely used in droplet manipulation. Despite great improvement in droplet manipulating performance, these methods still suffer from several limitations, such as the complexity of the manipulation platform, instability of droplet motion, and so on.…”

Integrated Microwell Array-Based Microfluidic Chip with a Hand-Held Smartphone-Controlled Device for Nucleic Acid Detection

“…In the past 30 years, microfluidic chips have led to significant advances in chemistry, biology, and medicine. − As many structures and functions can be integrated into miniaturized devices, microfluidic chips have been developed as important platforms for biochemical reactions, − especially in the point-of-care testing (POCT) applications. − …”