Ultrafast All‐Polymer Electrically Tunable Silicone Lenses

Abstract

Dielectric elastomer actuators (DEA) are smart lightweight flexible materials integrating actuation, sensing, and structural functions. The field of DEAs has been progressing rapidly, with actuation strains of over 300% reported, and many application concepts demonstrated. However many DEAs are slow, exhibit large viscoelastic drift, and have short lifetimes, due principally to the use of acrylic elastomer membranes and carbon grease electrodes applied by hand. We present here a DEA-driven tuneable lens, the world's fastest capable of holding a stable focal length. By using low-loss silicone elastomers rather than acrylics, we obtain a settling time shorter than 175 μs for a 20% change in focal length. The silicone-based lenses show a bandwidth 3 orders of magnitude higher compared to lenses of the same geometry fabricated from the acrylic elastomer. Our stretchable electrodes, a carbon black and silicone composite, are precisely patterned by pad-printing and subsequently cross-linked, enabling strong adhesion to the elastomer and excellent resistance to abrasion. The lenses operated for over 400 million cycles without degradation, and showed no change after more than two years of storage. This lens demonstrates the unmatched combination of strain, speed and stability that DEAs can achieve, paving the way for complex fast soft machines.

Printing low-voltage dielectric elastomer actuators

“…Actuation strains greater than 100% (Ref. 1) and sub-ms response time 2 can be achieved with DEAs, which find applications in a wide range of fields including soft-robotics, [3][4][5] optics, 2,6,7 and microfluidics. [8][9][10] DEAs are well suited to miniaturisation, as power density is high, 1 and complex shapes and systems can be made using simple architectures.…”

“…In addition, a lateral strain of 7.5% is enough to meet the requirements of many DEA applications. 2,9 Two main effects can explain reduced actuation strain for the 3 lm-DEA. The first one is non-uniformities in the membrane leading to premature local dielectric breakdown.…”

Stimulus-active polymer actuators for next-generation microfluidic devices

“…They achieved a maximum flow rate and back pressure of 77.4 ll/min and 8.45 kPa, respectively. Other examples are the utilization for active tuning of channel geometry [67], the incorporation as an active valve into a microchip [68], or the realization of DEA-based tunable lenses [69][70][71]. However, Lamberti et al [72] presented a comprehensive study on the durability of the electromechanical properties of PDMS for use in DEA actuators.…”

A liquid progressive multifocal lens adjusted by the deformation of a non-uniform elastic membrane due to the variation of liquid pressure

“…In addition, a liquid-filled tunable focus microlens was designed by using a membrane with different thickness between the central and peripheral region [8]. Besides, many kinds of liquid-filled lens with different actuators or control strategies were also designed in recent years, furthermore, the liquid tunable aspherical lenses are formed by liquid sealed with a non-uniform thickness membrane which could alleviate the edge clamping effect and reduce spherical aberration [9][10][11][12][13][14][15]. In order to decrease the influence of gravity to the performance of liquid lens, one of a method is using an in-plane pretention force to a membrane to take the place of surface tension and the other is using a non-uniform thickness profile of the flexible membrane [16,17].…”