Improved Electromechanical Transduction for PiezoMUMPS HBAR Impedance Sensors

Dielectric elastomers are an emerging class of highly deformable electro-active materials employed for electromechanical transduction technology. For practical applications, the design of such transducers requires a model accounting for insulation of the active membrane, non-perfectly compliant behavior of the electrodes, or interaction of the transducer with a soft actuated body. To this end, a three-layer model, in which the active membrane is embedded between two soft passive layers, can be formulated. In this article, the theory of non-linear electro-elasticity for heterogeneous soft dielectrics is used to investigate the electromechanical response of multilayer electro-active tubes—formed either by the active membrane only ( single-layer tube) or by the coated active membrane ( multilayer tube). Numerical results showing the influence of the mechanical and the geometrical properties of the soft coating layers on the electromechanical response of the active membrane are presented for different constraint conditions.

Download Full-text

Properties of a Dielectric Elastomer Actuator Modified by Dispersion of Functionalised Carbon Nanotubes

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.79.41 ◽

2012 ◽

Vol 79 ◽

pp. 41-46 ◽

Cited By ~ 1

Author(s):

Fabia Galantini ◽

Sabrina Bianchi ◽

Valter Castelvetro ◽

Irene Anguillesi ◽

Giuseppe Gallone

Keyword(s):

Carbon Nanotubes ◽

Dielectric Constant ◽

Mechanical Performance ◽

Broad Class ◽

Dielectric Elastomer ◽

Low Dielectric ◽

Dielectric Elastomer Actuators ◽

Electromechanical Transduction ◽

The Matrix ◽

Simple Matrix

Among the broad class of electro-active polymers, dielectric elastomer actuators represent a rapidly growing technology for electromechanical transduction. In order to further develop this applied science, the high driving voltages currently needed must be reduced. For this purpose, one of the most promising and adopted approach is to increase the dielectric constant while maintaining both low dielectric losses and high mechanical compliance. In this work, a dielectric elastomer was prepared by dispersing functionalised carbon nanotubes into a polyurethane matrix and the effects of filler dispersion into the matrix were studied in terms of dielectric, mechanical and electro-mechanical performance. An interesting increment of the dielectric constant was observed throughout the collected spectrum while the loss factor remained almost unchanged with respect to the simple matrix, indicating that conductive percolation paths did not arise in such a system. Consequences of the chemical functionalisation of carbon nanotubes with respect to the use of unmodified filler were also studied and discussed along with rising benefits and drawbacks for the whole composite material.

Download Full-text

Enabling electromechanical transduction in silicon nanowire mechanical resonators fabricated by focused ion beam implantation

Nanotechnology ◽

10.1088/0957-4484/25/13/135302 ◽

2014 ◽

Vol 25 (13) ◽

pp. 135302 ◽

Cited By ~ 24

Author(s):

J Llobet ◽

M Sansa ◽

M Gerbolés ◽

N Mestres ◽

J Arbiol ◽

...

Keyword(s):

Focused Ion Beam ◽

Ion Beam ◽

Silicon Nanowire ◽

Mechanical Resonators ◽

Electromechanical Transduction ◽

Ion Beam Implantation

Download Full-text

Interfacial gating triad is crucial for electromechanical transduction in voltage-activated potassium channels

The Journal of General Physiology ◽

10.1085/jgp.201411185 ◽

2014 ◽

Vol 144 (5) ◽

pp. 457-467 ◽

Cited By ~ 12

Author(s):

Sandipan Chowdhury ◽

Benjamin M. Haehnel ◽

Baron Chanda

Keyword(s):

Potassium Channels ◽

Conformational Changes ◽

Electromechanical Coupling ◽

Structural Integrity ◽

Voltage Sensor ◽

Amino Acid Residues ◽

Kv Channel ◽

Electromechanical Transduction ◽

Voltage Dependent ◽

Graph Theoretical Approach

Voltage-dependent potassium channels play a crucial role in electrical excitability and cellular signaling by regulating potassium ion flux across membranes. Movement of charged residues in the voltage-sensing domain leads to a series of conformational changes that culminate in channel opening in response to changes in membrane potential. However, the molecular machinery that relays these conformational changes from voltage sensor to the pore is not well understood. Here we use generalized interaction-energy analysis (GIA) to estimate the strength of site-specific interactions between amino acid residues putatively involved in the electromechanical coupling of the voltage sensor and pore in the outwardly rectifying KV channel. We identified candidate interactors at the interface between the S4–S5 linker and the pore domain using a structure-guided graph theoretical approach that revealed clusters of conserved and closely packed residues. One such cluster, located at the intracellular intersubunit interface, comprises three residues (arginine 394, glutamate 395, and tyrosine 485) that interact with each other. The calculated interaction energies were 3–5 kcal, which is especially notable given that the net free-energy change during activation of the Shaker KV channel is ∼14 kcal. We find that this triad is delicately maintained by balance of interactions that are responsible for structural integrity of the intersubunit interface while maintaining sufficient flexibility at a critical gating hinge for optimal transmission of force to the pore gate.

Download Full-text

Stretchable, Transparent, Ionic Conductors

Science ◽

10.1126/science.1240228 ◽

2013 ◽

Vol 341 (6149) ◽

pp. 984-987 ◽

Cited By ~ 843

Author(s):

Christoph Keplinger ◽

Jeong-Yun Sun ◽

Choon Chiang Foo ◽

Philipp Rothemund ◽

George M. Whitesides ◽

...

Keyword(s):

Electrochemical Reaction ◽

Transparent Conductors ◽

Large Strains ◽

Stretchable Electronics ◽

Ionic Conductors ◽

Sensors And Actuators ◽

Electromechanical Transduction ◽

Highly Stretchable ◽

Electronic Conductors ◽

Lower Sheet Resistance

Existing stretchable, transparent conductors are mostly electronic conductors. They limit the performance of interconnects, sensors, and actuators as components of stretchable electronics and soft machines. We describe a class of devices enabled by ionic conductors that are highly stretchable, fully transparent to light of all colors, and capable of operation at frequencies beyond 10 kilohertz and voltages above 10 kilovolts. We demonstrate a transparent actuator that can generate large strains and a transparent loudspeaker that produces sound over the entire audible range. The electromechanical transduction is achieved without electrochemical reaction. The ionic conductors have higher resistivity than many electronic conductors; however, when large stretchability and high transmittance are required, the ionic conductors have lower sheet resistance than all existing electronic conductors.

Download Full-text

Mechanical energy harvesting using polyurethane/lead zirconate titanate composites

Journal of Composite Materials ◽

10.1177/0021998317722401 ◽

2017 ◽

Vol 52 (9) ◽

pp. 1171-1182 ◽

Cited By ~ 5

Author(s):

Abdelkader Rjafallah ◽

Abdelowahed Hajjaji ◽

Fouad Belhora ◽

Daniel Guyomar ◽

Laurence Seveyrat ◽

...

Keyword(s):

Energy Harvesting ◽

Lead Zirconate Titanate ◽

Microelectromechanical Systems ◽

Volume Fraction ◽

Mechanical Energy ◽

Mechanical Strain ◽

Lead Zirconate ◽

Inorganic Materials ◽

Zirconate Titanate ◽

Electromechanical Transduction

The microelectromechanical systems invade gradually the market with applications in many sectors of activity. Developing these micro-systems allows deploying wireless sensor networks that are useful to collect, process and transmit information from their environments without human intervention. In order to keep these micro-devices energetically autonomous without using batteries because they have a limited lifespan, an energy harvesting from ambient vibrations using electrostrictive polymers can be used. These polymers present best features against inorganic materials, as flexibility and low cost. The aims of this paper are manifold. First of all, we made elaboration of the polyurethane/lead zirconate titanate films of 100 µm thickness using a lead zirconate titanate–volume fraction of [Formula: see text]%. Therefore, we did an observation of the lead zirconate titanate grains dispersion and the electrical characterization of the polyurethane–50 vol% lead zirconate titanate composites. Finally, a detailed study of the electromechanical transduction, for the polyurethane–50 vol% lead zirconate titanate unpolarized and polarized composites sustained to the sinusoidal mechanical strain with amplitude of 1.5% and at very low frequencies ( f = 2 [Hz] and f = 4 [Hz]) and static electric field ( Edc = 10 [ V/µm]) or without it ( Edc = 0 [ V/µm]) has been presented.

Download Full-text

Nondestructive Detection of Cartilage Degeneration Using Electromechanical Surface Spectroscopy

Journal of Biomechanical Engineering ◽

10.1115/1.2895788 ◽

1994 ◽

Vol 116 (4) ◽

pp. 384-392 ◽

Cited By ~ 21

Author(s):

Scott I. Berkenblit ◽

Eliot H. Frank ◽

Evan P. Salant ◽

Alan J. Grodzinsky

Keyword(s):

Stress Amplitude ◽

Excitation Frequency ◽

Piezoelectric Sensor ◽

Cartilage Degeneration ◽

Surface Probe ◽

Electromechanical Transduction ◽

Measured Stress ◽

Surface Spectroscopy ◽

Surface Measurements ◽

Poroelastic Model

We have constructed an electrokinetic surface probe capable of applying small sinusoidal currents to the surface of articular cartilage and measuring the resulting current-generated stress with a piezoelectric sensor. Using the probe, we have characterized the electromechanical response of excised discs of normal and chemically modified adult bovine femoropatellar groove cartilage. The measured stress amplitude was proportional to the applied current density and inversely proportional to the excitation frequency, consistent with a poroelastic model. As a function of bath pH, the stress amplitude exhibited a minimum in the range pH 2.4–2.8 and the phase underwent an abrupt 180° transition in the same range, consistent with an electrokinetic mechanism as the origin of the current-generated mechanical stress. Digestion of the tissue with trypsin resulted in a progressive loss of highly charged proteoglycan molecules from the tissue, with a concomitant decrease in the measured stress amplitude. These results support the feasibility of surface measurements as a means of assessing electromechanical transduction in cartilage and of detecting subtle molecular-level degradative changes in the extracellular matrix. This technique of surface spectroscopy provides a new means of nondestructively measuring the material properties of cartilage on intact joints and detecting degradative changes such as those seen in the earliest stages of osteoarthritis.

Download Full-text