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Hiding the squid: patterns in artificial cephalopod skin.

Fishman A, Rossiter J, Homer M - J R Soc Interface (2015)

Bottom Line: Cephalopods employ their chromomorphic skins for rapid and versatile active camouflage and signalling effects.The proposed system achieves dynamic pattern generation by imposing simple local rules into the artificial chromatophore cells so that they can sense their surroundings in order to manipulate their actuation.By modelling sets of artificial chromatophores in linear arrays of cells, we explore the capability of the system to generate a variety of dynamic pattern types.

View Article: PubMed Central - PubMed

Affiliation: Department of Engineering Mathematics, University of Bristol, Bristol BS8 1UB, UK uk.afishman@gmail.com.

No MeSH data available.


Related in: MedlinePlus

Schematic of the actuation of uniaxial DEs. Applying a potential difference across the dielectric medium causes charge to build on the electrodes. The resulting Maxwell stress on the plates, P, caused by Coulomb attraction between the opposing charges on the plates, creates an expansion normal to the plane of the electrodes. The incompressibility of the elastomer forces the DE film to contract in the thickness direction 3 and expand in the longitudinal direction 1. Deformation in direction 2 is prevented by stiff fibres embedded onto the surface of the membrane. (Online version in colour.)
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RSIF20150281F3: Schematic of the actuation of uniaxial DEs. Applying a potential difference across the dielectric medium causes charge to build on the electrodes. The resulting Maxwell stress on the plates, P, caused by Coulomb attraction between the opposing charges on the plates, creates an expansion normal to the plane of the electrodes. The incompressibility of the elastomer forces the DE film to contract in the thickness direction 3 and expand in the longitudinal direction 1. Deformation in direction 2 is prevented by stiff fibres embedded onto the surface of the membrane. (Online version in colour.)

Mentions: When coated with a compliant electrode, sheets of DE store charge, much like a parallel plate capacitor. The build-up of charge induces Maxwell stresses within the material. For incompressible elastomers, this causes the material to expand in the plane of the electrodes and contract in the direction normal to the electrodes. For simplicity, we consider a situation in which the DE is constrained in one direction by light, stiff, parallel fibres added to the surface of the membrane in the plane of the electrodes [11]. The effect of the fibre constraint is to fix the length of the membrane in the direction of the fibres, so the expansion of the DE is uniaxial, normal to the fibre constraints, as illustrated in figure 3. It is known that a membrane subjected to uniaxial force along its length can achieve large deformation when the width direction is constrained [12]. Material undergoing such electrostatic expansion is defined as active and is passive otherwise. It has been shown [13] that the Maxwell stress, P, relates to the thickness of the elastomer, d, with applied voltage, V, by3.1where ɛd = ɛrɛ0, ɛ0 is the permittivity of free space (approx. 8.85 × 10−12 Fm−1) and ɛr is the relative permittivity of the dielectric (typically around 4). We define active material that has approached steady state to be actuated and is unactuated otherwise.Figure 3.


Hiding the squid: patterns in artificial cephalopod skin.

Fishman A, Rossiter J, Homer M - J R Soc Interface (2015)

Schematic of the actuation of uniaxial DEs. Applying a potential difference across the dielectric medium causes charge to build on the electrodes. The resulting Maxwell stress on the plates, P, caused by Coulomb attraction between the opposing charges on the plates, creates an expansion normal to the plane of the electrodes. The incompressibility of the elastomer forces the DE film to contract in the thickness direction 3 and expand in the longitudinal direction 1. Deformation in direction 2 is prevented by stiff fibres embedded onto the surface of the membrane. (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4528594&req=5

RSIF20150281F3: Schematic of the actuation of uniaxial DEs. Applying a potential difference across the dielectric medium causes charge to build on the electrodes. The resulting Maxwell stress on the plates, P, caused by Coulomb attraction between the opposing charges on the plates, creates an expansion normal to the plane of the electrodes. The incompressibility of the elastomer forces the DE film to contract in the thickness direction 3 and expand in the longitudinal direction 1. Deformation in direction 2 is prevented by stiff fibres embedded onto the surface of the membrane. (Online version in colour.)
Mentions: When coated with a compliant electrode, sheets of DE store charge, much like a parallel plate capacitor. The build-up of charge induces Maxwell stresses within the material. For incompressible elastomers, this causes the material to expand in the plane of the electrodes and contract in the direction normal to the electrodes. For simplicity, we consider a situation in which the DE is constrained in one direction by light, stiff, parallel fibres added to the surface of the membrane in the plane of the electrodes [11]. The effect of the fibre constraint is to fix the length of the membrane in the direction of the fibres, so the expansion of the DE is uniaxial, normal to the fibre constraints, as illustrated in figure 3. It is known that a membrane subjected to uniaxial force along its length can achieve large deformation when the width direction is constrained [12]. Material undergoing such electrostatic expansion is defined as active and is passive otherwise. It has been shown [13] that the Maxwell stress, P, relates to the thickness of the elastomer, d, with applied voltage, V, by3.1where ɛd = ɛrɛ0, ɛ0 is the permittivity of free space (approx. 8.85 × 10−12 Fm−1) and ɛr is the relative permittivity of the dielectric (typically around 4). We define active material that has approached steady state to be actuated and is unactuated otherwise.Figure 3.

Bottom Line: Cephalopods employ their chromomorphic skins for rapid and versatile active camouflage and signalling effects.The proposed system achieves dynamic pattern generation by imposing simple local rules into the artificial chromatophore cells so that they can sense their surroundings in order to manipulate their actuation.By modelling sets of artificial chromatophores in linear arrays of cells, we explore the capability of the system to generate a variety of dynamic pattern types.

View Article: PubMed Central - PubMed

Affiliation: Department of Engineering Mathematics, University of Bristol, Bristol BS8 1UB, UK uk.afishman@gmail.com.

No MeSH data available.


Related in: MedlinePlus