Arrays of EAP micro-actuators for single-cell stretching applications

Akbari, Samin; Niklaus, Muhamed; Shea, Herbert

doi:10.1117/12.847125

Cited by 14 publications

(20 citation statements)

References 15 publications

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“…Ability to miniaturize: It should be possible to miniaturize DE devices, this will open the door to new micro-applications that already include tunable diffraction gratings, 128 tunable lenses, 129 and research devices for delivering mechanical stimulation to individual cells, 130 to name a few. To meet these needs, the electro-active polymer research community needs to explore a wide range of different materials and processes.…”

Section: Multi-functional Smart Muscle Systems With Fully Integratmentioning

confidence: 99%

Multi-functional dielectric elastomer artificial muscles for soft and smart machines

Anderson

Gisby²,

McKay³

et al. 2012

Journal of Applied Physics

559

314

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Dielectric elastomer (DE) actuators are popularly referred to as artificial muscles because their impressive actuation strain and speed, low density, compliant nature, and silent operation capture many of the desirable physical properties of muscle. Unlike conventional robots and machines, whose mechanisms and drive systems rapidly become very complex as the number of degrees of freedom increases, groups of DE artificial muscles have the potential to generate rich motions combining many translational and rotational degrees of freedom. These artificial muscle systems can mimic the agonist-antagonist approach found in nature, so that active expansion of one artificial muscle is taken up by passive contraction in the other. They can also vary their stiffness. In addition, they have the ability to produce electricity from movement. But departing from the high stiffness paradigm of electromagnetic motors and gearboxes leads to new control challenges, and for soft machines to be truly dexterous like their biological analogues, they need precise control. Humans control their limbs using sensory feedback from strain sensitive cells embedded in muscle. In DE actuators, deformation is inextricably linked to changes in electrical parameters that include capacitance and resistance, so the state of strain can be inferred by sensing these changes, enabling the closed loop control that is critical for a soft machine. But the increased information processing required for a soft machine can impose a substantial burden on a central controller. The natural solution is to distribute control within the mechanism itself. The octopus arm is an example of a soft actuator with a virtually infinite number of degrees of freedom (DOF). The arm utilizes neural ganglia to process sensory data at the local “arm” level and perform complex tasks. Recent advances in soft electronics such as the piezoresistive dielectric elastomer switch (DES) have the potential to be fully integrated with actuators and sensors. With the DE switch, we can produce logic gates, oscillators, and a memory element, the building blocks for a soft computer, thus bringing us closer to emulating smart living structures like the octopus arm. The goal of future research is to develop fully soft machines that exploit smart actuation networks to gain capabilities formerly reserved to nature, and open new vistas in mechanical engineering.

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Section: Multi-functional Smart Muscle Systems With Fully Integratmentioning

confidence: 99%

Multi-functional dielectric elastomer artificial muscles for soft and smart machines

Anderson

Gisby²,

McKay³

et al. 2012

Journal of Applied Physics

559

314

View full text Add to dashboard Cite

show abstract

“…We have previously reported the design principle [25], and microfabrication and characterization of an array 100 m × 200 m DEA actuators generating up to 5% uniaxial strain for single cell stretching [26]. That first generation of devices consisted of a non-prestretched PDMS membrane bonded to a Pyrex chip with 200 m wide trenches to ensure uniaxial deformation.…”

Section: Introductionmentioning

confidence: 99%

An array of 100μm×100μm dielectric elastomer actuators with 80% strain for tissue engineering applications

Akbari

Shea

2012

Sensors and Actuators A: Physical

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a b s t r a c tBiological cells modulate their behavior, express genes, proliferate or differentiate in response to mechanical strains ranging from 1% to 20%. There currently exists no technique to apply strain to many targeted individual cells in a larger culture in order to perform parallelized high throughput testing. Dielectric elastomer actuators (DEAs) are compliant devices capable of generating large percentage strains with sub-second response time, ideally suited by their compliance for cell manipulation. We report an array of 100 m × 100 m DEAs reaching up to 80% in-plane strain at an electric field of 240 V/m. The miniaturized DEAs are made by patterning 100 m wide compliant ion-implanted gold electrodes on both sides of a 30 m thick polydimethylsiloxane (PDMS) membrane. We report the important effect of uniaxial prestretch of the membrane on the microactuators' performance; the largest strain is achieved by prestretching uniaxially by 175%. Each actuator is intended to have a single cell adhered to it in order to periodically stretch the cells to study the effect of mechanical stimulation on its biochemical responses. To avoid short-circuiting all the top electrodes by the conductive saline cell growth medium, a 20 m thick biocompatible PDMS layer is bonded on the actuators. In this configuration, 37% strain is achieved at 3.6 kV with sub-second response. This device can be used as a high throughput single cell stretcher to apply relevant biological periodic strains to individual cells in a single experiment.

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“…Size of the actuator defined by width of the microelectrode and width of the trench has a minor effect on its actuation strain as previously reported by the authors [30]. The actuator's size is designed close to the size of the single cells, which vary from 10 to 50 μm depending on the cell type.…”

Section: Design Considerationsmentioning

confidence: 69%

“…The geometrical optimization of the actuator has been previously reported by the authors using a simplified finite element method (FEM) model [30]. In this study, we have performed more accurate simulations on the optimized geometry using similar material properties as the fabricated device.…”

Section: Finite Element Analysismentioning

confidence: 99%

See 1 more Smart Citation

Microfabrication and characterization of an array of dielectric elastomer actuators generating uniaxial strain to stretch individual cells

Akbari¹,

Shea²

2012

J. Micromech. Microeng.

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Cells regulate their behavior in response to mechanical strains. Cell cultures to study mechanotransuction are typically cm 2 in area, far too large to monitor single cell response. We have developed an array of dielectric elastomer microactuators as a tool to study mechanotransduction of individual cells. The array consists of 72 100 μm × 200 μm electroactive polymer actuators which expand uniaxially when a voltage is applied. Single cells will be attached on each actuator to study their response to periodic mechanical strains. The device is fabricated by patterning compliant microelectrodes on both sides of a 30 μm thick polydimethylsiloxane membrane, which is bonded to a Pyrex chip with 200 μm wide trenches. Low-energy metal ion implantation is used to make stretchable electrodes and we demonstrate here the successful miniaturization of such ion-implanted electrodes. The top electrode covers the full membrane area, while the bottom electrodes are 100 μm wide parallel lines, perpendicular to the trenches. Applying a voltage between the top and bottom electrodes leads to uniaxial expansion of the membrane at the intersection of the bottom electrodes and the trenches. To characterize the in-plane strain, an array of 4 μm diameter aluminum dots is deposited on each actuator. The position of each dot is tracked, allowing displacement and strain profiles to be measured as a function of voltage. The uniaxial strain reaches 4.7% at 2.9 kV with a 0.2 s response time, sufficient to stimulate most cells with relevant biological strains and frequencies.

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Arrays of EAP micro-actuators for single-cell stretching applications

Cited by 14 publications

References 15 publications

Multi-functional dielectric elastomer artificial muscles for soft and smart machines

Multi-functional dielectric elastomer artificial muscles for soft and smart machines

An array of 100μm×100μm dielectric elastomer actuators with 80% strain for tissue engineering applications

Microfabrication and characterization of an array of dielectric elastomer actuators generating uniaxial strain to stretch individual cells

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