A Biocompatible Vibration‐Actuated Omni‐Droplets Rectifier with Large Volume Range Fabricated by Femtosecond Laser

Abstract

High‐performance droplet transport is crucial for diverse applications including biomedical detection, chemical micro‐reaction, and droplet microfluidics. Despite extensive progress, traditional passive and active strategies are restricted to limited liquid types, small droplet volume ranges, and poor biocompatibilities. Moreover, more challenges occur for biological fluids due to large viscosity and low surface tension. Here, a vibration‐actuated omni‐droplets rectifier (VAODR) consisting of slippery ratchet arrays fabricated by femtosecond laser and vibration platforms is reported. Through the relative competition between the asymmetric adhesive resistance originating from the lubricant meniscus on the VAODR and the periodic inertial driving force originating from isotropic vibration, the fast (up to ≈60 mm s−1), programmable, and robust transport of droplets is achieved for a large volume range (0.05–2000 µL, Vmax/Vmin ≈ 40 000) and in various transport modes including transport of liquid slugs in tubes, programmable and sequential transport, and bidirectional transport. This VAODR is general to a high diversity of biological and medical fluids, and thus can be used for biomedical detection including ABO blood‐group tests and anticancer drugs screening. These strategies provide a complementary and promising platform for maneuvering omni‐droplets that are fundamental to biomedical applications and other high‐throughput omni‐droplet operation fields.

A review on control of droplet motion based on wettability modulation: principles, design strategies, recent progress, and applications

“…Zhang et al aimed for high-capacity transport of any biocompatible liquid free from electrical damage, thermal (high temperature) damage, and contamination from magnetic nanoparticle doping [ 211 ]. A vibration-actuated omni-droplet rectifier (VAODR) consisting of a slippery ratchet array was developed using a femtosecond laser and vibration platform.…”

Meniscus-Induced Directional Self-Transport of Submerged Bubbles on a Slippery Oil-Infused Pillar Array with Height-Gradient

“…Similarly, the hydrophyte seeds floating on the water could be captured and collected by the meniscus around emersed plants (Figure a). , Inspired by these intriguing phenomena, useful strategies are proposed to transport or self-assemble floating objects via constructing menisci, such as interface deformation induced by bubbles and pillars − or deformed paramagnetic liquid by magnet . Recently, researchers have further extended it to the Nepenthes-inspired LIPS, featuring the advantage of excellent liquid-repellency and low contact angle hysteresis. − Under the effect of the capillary action, the meniscus can form around the fixed or mobile pillars on the LIPS for droplet self-transport and water collection. − The self-transport properties are closely related to the meniscus profile, which are further determined by the characteristics of the solid pillar and infused oil. , However, current pillar-powered strategies mainly utilize the centrosymmetric meniscus around a single pillar. The meniscus profile is approximately described as an exponential function, which is difficult to adjust except by changing the contact angle of oil on the pillar. − To further explore the driving effect of the meniscus, it is necessary to consider the unconventional meniscus shape.…”

Robust and Transparent Lossless Directional Omniphobic Ultra-Thin Sticker-Type Film with Re-entrant Micro-Stripe Arrays

“…To demonstrate the conventional directional droplet-sliding omniphobic surface, several remarkable findings, such as anisotropic inorganic re-entrant structures, ,,− external stimuli-induced/actuated surfaces, − and slippery liquid-infused porous/textured surfaces, ,− have been reported in recent years. However, there are still some limitations in the development of robust and transparent thin sticker-type directional omniphobic films.…”