Dash, Susmita. Ph.D., Purdue University, December 2014. Droplet Behavior on Superhydrophobic Surfaces: Interfaces, Interactions, and Transport. Major Professor: Suresh V. Garimella, School of Mechanical Engineering. The primary objective of the present work is to study droplet dynamics on smooth hydrophobic and textured superhydrophobic surfaces, and to understand the dependence of interfacial ...

In this paper, we investigated the temperature-dependent viscoelastic behavior of dielectric elastomers (DEs) and the effects of viscoelasticity on the electro-actuation behavior. We performed dynamic thermomechanical analysis to measure the master curve of the stress relaxation function and the temperature dependence of the relaxation time of VHB 4905, a commonly used DE. The master curve was ...

A MEMS varactor using torsional beams for actuation is proposed. Analytical expression for electrostatic torque developed is derived. The structure is compared with existing structures for dynamic range and actuation voltage. It is demonstrated that the proposed varactor outperforms the other structures in terms of wide dynamic range and lower actuation voltage, coupled with ease of fabrication...

Digital microfluidics (DMF) is a popular alternative to traditional in-channel microfluidics, which allows precise control of individual droplets. Most commonly used droplet manipulation methods for DMF are electrowetting on dielectric (EWOD) and magnetic actuation. Both methods require high surface hydrophobicity to facilitate droplet movement, and often superhydrophobic surfaces are used to f...

An ionic polymer-metal composite (IPMC) consisting of a thin perfluorinated ionomer (usually, Nafion or Flemion) strip, platinum and/or gold plated on both faces, undergoes large bending motion when a small electric field is applied across its thickness. When the same membrane is suddenly bent, a small electric potential of the order of millivolts is produced across its surfaces. This actuation...

This paper examines the limits of performance in systems with periodic irregular sampling rate when the actuation is not necessarily synchronized with the sampling. For such a system, three sampling and actuation schemes are considered: when the sampling and control rate are both regular, when they are both irregular, and when the sampling rate is irregular while the control rate is regular. To...

The uniqueness of microelectromechanical system (MEMS) devices, with their multiphysics characteristics, presents some limitations to the borrowed test methods from traditional integrated circuits (IC) manufacturing. Although some improvements have been performed, this specific area still lags behind when compared to the design and manufacturing competencies developed over the last decades by t...

Nanoscale actuators are essential components of the NEMS (nanoelectromechanical systems) and nanorobots of the future, and are expected to become a major area of development within nanotechnology. This paper demonstrates for the first time that individual polypyrrole (PPy) nanowires with diameters under 100 nm exhibit actuation behavior, and therefore can potentially be used for constructing na...

A new multi-objective topology optimization method is proposed in this study for systematic design of multi-phase piezoelectric actuators. The actuator under consideration is composed of a compliant host structure equipped with piezoelectric elements, where the host structure serves as a compliant amplifier to enlarge the small stroke output generated by the actuation force of piezoelectric mat...

This paper investigates potential improvements that can be accomplished by integral twist-actuated rotor blades regarding helicopter performance and its vibration. The twist deformation is obtained using anisotropic piezocomposite actuators embedded in the composite blade construction. A four-bladed fullyarticulated Active Twist Rotor (ATR) system was built and tested at Langley Transonic Dynam...