Liquid droplets move readily under the influence of surface tension gradients on their substrates. Substrates decorated with parallel microgrooves, or striations, presenting the advantage of homogeneous chemical properties yet varying the topological characteristics on either side of a straight-line boundary are considered in this study. The basic type of geometry consists of hydrophobic micro-striations/rails perpendicular to the boundary, with the systematic variation of the width to spacing ratio, thus changing the solid-liquid contact fraction and inducing a well-defined wettability contrast across the boundary. Droplets in the Cassie-Baxter state, straddling the boundary, move along the wettability contrast in order to reduce the overall surface free energy. Results show the importance of average solid fraction and contrasting fraction in a wide range for given geometries across the boundary on droplet motion. A unified criterion for contrasting striated surfaces, which describes the displacement and the velocity of the droplets, is suggested, providing guidelines for droplet manipulation on microstriated/railed surfaces.
Vibrio parahaemolyticus is usually
spread via consumption of contaminated seafood and causes vibriosis.
By combination of digital microfluidic (DMF) and loop-mediated isothermal
amplification (LAMP), we provided an automated instrumentation-compact
DMF–LAMP device for sample-to-answer detection of V. parahaemolyticus. For the first time, how much
the proper mixing might facilitate the DMF–LAMP process is
explored. The results illustrated that increasing the number of flow
configurations and decreasing the fluid-reversibility will extend
the interfacial surface available for diffusion-based mass transfer
within a droplet microreactor, thus contributing to the overall amplification
reaction rate. Noticeably, the DMF–LAMP amplification plateau
time is shortened by proper mixing, from 60 min in static mixing and
traditional bulk LAMP to 30 min in 2-electrode mixing and 15 min in
3-electrode mixing. The device achieved much higher detection sensitivity
(two copies per reaction) than previously reported devices. V. parahaemolyticus from spiked shrimps is detected
by Q-tip sampling associated with 3-electrode mixing DMF–LAMPs.
The detectable signal occurs within only 3 min at a higher concentration
and, at most, is delayed to 18 min, with a detection limit of <0.23
× 103 CFU/g. Thus, the developed DMF–LAMP device
demonstrates potential for being used as a sample-to-answer system
with a quick analysis time, high sensitivity, and sample-to-answer
format.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.