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.

Linear Stepper Actuation Driving Drop Resonance and Modifying Hysteresis.

In this work, 2 μL water drops are placed on substrates that are created to have a circular hydrophilic region bounded by superhydrophobicity so that they exhibit high contact angles. When the substrate is translated by a linear stepper actuator, the random force components present in the actuator are shown to cause the drop to rock resonantly. When the substrate is translated downward at inclination angles of up to 6° with respect to the horizontal, the contact angle hysteresis increases progressively to a limiting condition.

Controlled transport of captive bubbles on plastrons.

Captive bubbles that reside on superhydrophobic surfaces with plastrons move uncontrollably when tilted. A system based on creating moveable local apexes on flexible superhydrophobic foils is shown to allow controlled transport. Simulations done reveal that specific bubble transport speeds are needed to form concentration gradients suited for aerotaxis study and sensing.

Particles replaced axially in an optical trap.

Flow-based measures to automate optical trapping have significant limitations. A scheme is advanced here where a spherical bead is first located in a trap, and a second bead below the focus point is selectively drawn into the trap to replace the original particle. Experimentation conducted showed that it was possible to do so with little perturbation of other surrounding particles.

A direct heating model to overcome the edge effect in microplates.

Array-based tests in a microplate format are complicated by the regional variation in results of the outer against the inner wells of the plate. Analysis of the evaporation mechanics of sessile drops showed that evaporation rate increase with temperature was due to changes in the heat of vaporization, density and diffusion coefficient. In simulations of direct bottom heating of standard microplates, considerable heat transfer via conduction from the side walls was found to be responsible for lower temperatures in the liquid in wells close to the edge.

Transparency microplates under impact.

Transparency microplates enable biochemical analysis in resource-limited laboratories. During the process of transfer, the analytes tittered into the wells may undergo spillage from one well to another due to lateral impact. Sidelong impact tests conducted found the absence of non-linear effects (e.

Optical stirring in a droplet cell bioreactor.

In the context of a bioreactor, cells are sensitive to cues from other cells and mechanical stimuli from movement. The ability to provide the latter in a discrete fluidic system presents a significant challenge. From a prior finding that the location of the focus of a laser below particles relative to the beam axis producing a pushing effect in a predominant lateral sense, we advance an approach here that generates a gentle and tunable stirring effect.

Graphite flake self-retraction response based on potential seeking.

The high elastic modulus and interlayer strengths of graphite flakes make them a durable solid superlubricant. Apart from this, they have configurable electrical properties, exhibit quantum Hall effects, and possess a myriad of useful photonic properties. The self-retraction behavior of graphite flakes can have significant impact on the creation of ordered stacks for various applications because any accidental or intentional displacement of the top flake over the stacks below may result in a misalignment of the carbon-carbon atomic arrangement which, in turn, can have influence over the electrical and photonic properties.