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

Abstract

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.

Improved electromechanical behavior in castable dielectric elastomer actuators

“…5. We have observed that the electric field strength of the elastomer is enhanced from 100 V/lm for nonstretched films 4,16,18 to 250 V/lm by 1.75 biaxial prestretch.…”

“…They combine large actuation strain and high energy density offering an appealing alternative to more conventional actuators. [1][2][3][4] DEAs consist of a soft elastomeric membrane with compliant electrodes patterned on both sides. When a voltage is applied to the electrodes, the membrane is squeezed in thickness and expands in plane due to the electrostatic pressure.…”

Towards materials with enhanced electro-mechanical response: CaCu3Ti4O12–polydimethylsiloxane composites

“…1 Given their excellent properties, this class of materials enable a wide range of interesting applications, such as arm-wrestling robots, 2 fish-like propellers in airships, 3 refreshable tactile displays 4 or microactuators for mecano-transduction of individual cells, 5 to name but a few.…”

Large, uni-directional actuation in dielectric elastomers achieved by fiber stiffening

“…[9][10][11] Within the family of EAP actuators, such as those made of polymer gels, 12 ionic polymer-metal composites, 13 conjugated polymers, 14 carbon nanotubes, 15 electrostrictive polymers 16 and liquid crystal elastomers, 17 dielectric elastomer actuators are considered particularly attractive because they resemble natural muscles, producing fast and large deformation in response to applied voltage. 18 Achieving large voltage-induced deformation, however, is a practical challenge.…”