Simultaneous Multidrop Creation with Superhydrophobic Wells for Field Environmental Sensing of Nanoparticles.

Facile creation of multiple drops at appropriate volumes on surfaces without the use of sophisticated instrumentation facilitates downstream evaporative preconcentration of liquid samples for analytical purposes. In this work, a superhydrophobic (SH) substrate comprising wells with a perforated mesh base was developed for simultaneous drop creation in a quick and convenient manner. In contrast to the method of pouring liquid directly over the SH wells, consistent liquid filling was readily achieved by a simple immersion approach.

Living specimens under field immobilization and smartphone microscopic observation.

In this work a single glycerol-water mixture, determined to be most apt at 30% (wt/vol), was used to immobilize Drosophila samples as well as to create a liquid lens for smartphone magnification viewing. This provides the advantage of being able to observe immobilized insects directly in the field rather than in the laboratory. In order to avoid having bubbles in the liquid lens and immobilizing medium that hinder visibility, an approach was developed where a stable pendant drop is moved in tandem with the dispensing tip by gravity and stopped abruptly so that sufficient momentum is transferred to the drop for its dislodgement.

Antibody drop based handling with near-superhydrophobic mesh substrates overcomes condensation sticking.

Superhydrophobic substrates facilitate low adhesion for biological liquid handling but are hampered by wetting state changes due to condensation. Here, meshed near-superhydrophobic substrates, that are easier to produce than two-tiered architecture substrates, are shown to provide good immunity to wetting state changes while imbuing high positional resistance to roll-off by tilting when tested with 5 and 10 μL volume drops (18° and 13° respectively) of human IgG antibodies in aqueous solution at both room temperature and 4 °C. Pneumatic actuation was applied to elicit horizontal drop movement over the near-SH surface without any fragmentation, wherein higher velocities can be achieved when smaller drops and higher air pressures are used (0.