Towards a Robotically Steerable Laser Ablation Probe.

In this paper, we present a robotically steerable laser ablation probe with application to interstitial thermal therapy. Existing laser interstitial thermal therapy (LITT) methods utilize a straight probe to deliver laser energy around the tip or to the side of the tip. These methods are inadequate to provide effective treatment for large, irregularly shaped tumors.

In-vitro evaluation of the evaporation retardation by Meibomian lipids in homogeneous and non-homogeneous evaporation.

Hypothesis: An important function of the Tear Film Lipid Layer (TFLL) is the retardation of evaporation. We propose two micro-scaled systems to quantify the influence of the TFLL in evaporation for single patients, which may contribute as an improvement on the diagnosis of Meibomian Gland Dysfunctions (MGD).

Experiments: Meibum was extracted from 10 patients with hypersecretory MGD and 9 healthy controls.

Particle/wall electroviscous effects at the micron scale: comparison between experiments, analytical and numerical models.

We report a experimental study of the motion of 1 m single particles interacting with functionalized walls at low and moderate ionic strengths conditions. The 3D particle's trajectories were obtained by analyzing the diffracted particle images (point spread function). The studied particle/wall systems include negatively charged particles interacting with bare glass, glass covered with polyelectrolytes and glass covered with a lipid monolayer.

Photomechanical Polymer Nanocomposites for Drug Delivery Devices.

We demonstrate a novel structure based on smart carbon nanocomposites intended for fabricating laser-triggered drug delivery devices (DDDs). The performance of the devices relies on nanocomposites' photothermal effects that are based on polydimethylsiloxane (PDMS) with carbon nanoparticles (CNPs). Upon evaluating the main features of the nanocomposites through physicochemical and photomechanical characterizations, we identified the main photomechanical features to be considered for selecting a nanocomposite for the DDDs.

Transport of Colloids along Corners: Visualization of Evaporation-Induced Flows beyond the Axisymmetric Condition.

Nonhomogeneous evaporation fluxes have been shown to promote the formation of internal currents in sessile droplets, explaining the patterns that suspended particles leave after the droplet has dried out. Although most evaporation experiments have been conducted using spherical-cap-shaped drops, which are essentially in an axisymmetric geometry, here we show an example of nonhomogeneous evaporation in asymmetric geometries, which is visualized by following the motion of colloidal particles along liquid fingers forming a meniscus at square corners. It is found that the particle's velocity increases with the diffusive evaporation factor [Formula: see text] for the three tested fluids: water, isopropyl alcohol (IPA), and ethanol (EtOH).

On the Motion of Carbon Nanotube Clusters near Optical Fiber Tips: Thermophoresis, Radiative Pressure, and Convection Effects.

We analyze the motion of multiwalled carbon nanotubes clusters in water or ethanol upon irradiation with a 975 and 1550 nm laser beam guided by an optical fiber. Upon measuring the velocities of the nanotube clusters in and out of the laser beam cone, we were able to identify thermophoresis, convection and radiation pressure as the main driving forces that determine the equilibrium position of the dispersion at low optical powers: while thermophoresis and convection pull the clusters toward the laser beam axis (negative Soret coefficient), radiation pressure pushes the clusters away from the fiber tip. A theoretical solution for the thermophoretic velocity, which considers interfacial motion and a repulsive potential interaction between the nanotubes and the solvent (hydrophobic interaction), shows that the main mechanism implicated in this type of thermophoresis is the thermal expansion of the fluid, and that the clusters migrate to hotter regions with a characteristic thermal diffusion coefficient D(T) of 9 × 10(-7) cm(2) K(-1) s(-1).

An optopneumatic piston for microfluidics.

We demonstrate an optopneumatic piston based on glass capillaries, a mixture of PDMS-carbon nanopowder, silicone and mineral oil. The fabrication method is based on wire coating techniques and surface tension-driven instabilities, and allows for the assembly of several pistons from a single batch production. By coupling the photothermal response of the PDMS-carbon mixture with optical excitation via an optical fiber, we demonstrate that the piston can work either as a valve or as a reciprocal actuator.

Thermocapillary flow in glass tubes coated with photoresponsive layers.

Thermocapillary flow has proven to be a good alternative to induce and control the motion of drops and bubbles in microchannels. Temperature gradients are usually established by implanting metallic heaters adjacent to the channel or by including a layer of photosensitive material capable of absorbing radiative energy. In this work we show that single drops can be pumped through capillaries coated with a photoresponsive composite (PDMS + carbon nanopowder) and irradiated with a light source via an optical fiber.

Viscous pumping inspired by flexible propulsion.

Fluid-suspended microorganisms have evolved different swimming and feeding strategies in order to cope with an environment dominated by viscous effects. For instance, ciliated organisms rely on the collective motion of flexible appendages to move and feed. By performing a non-reciprocal motion, flexible filaments can produce a net propulsive force, or pump fluid, in the absence of inertia.