Articles written in Bulletin of Materials Science
Volume 44 All articles Published: 3 April 2021 Article ID 0078
Electrically tunable lenses could change focus without motor-controlled translations of stiff lenses. Firstly, the lens system is enabled by stable polyacrylamide (PAM) hydrogel electrodes that are synthesized containing silicone oil, sodium chloride, etc. Two layers of the hydrogel are used as ionic conductors to sandwich a dielectric elastomer membrane. The maximum rupture stretch of the hydrogel was around 20 and the small strain Young’s modulus was about 0.5 kPa in experiments. Secondly, compact computational models are proposed based on the assumption of homogeneous deformation on materials, and the application of energy methods. Thickness-stretch curves of the PAM hydrogel are calculated, and the relation between electric field and stretch of a lens actuator is obtained by using the built mathematic models. Thirdly, a soft solid-body lens is described to obtain compact tunable results. The relationship between the applied voltage and the focus has also been given based on the derived equations. An increase in lens size produced larger tunable range variation. The new lens could find application in systems requiring large variations of focus with silent operation, low weight, shock tolerance, etc.
Volume 44 All articles Published: 24 May 2021 Article ID 0148
In order to simulate the auto-focusing function of human eyes, a liquid lens is proposed based on dielectric elastomer actuator (DEA). The lens could realize rapid focusing under voltages. The structure and principle of the lens are described in detail. A novel fabricating method is presented for the lens, which is inspired by the negative pressure technology. A negative pressure region is made in the centre of the dielectric elastomer (DE) membrane, and the liquid is filled. Then the other layer of membrane is covered to seal the liquid. Around the lens is the DEA coupling carbon grease electrodes. The finite element analysis and simulation of the lens deformation are carried out by using the software of Abaqus. The relationship is explored among lens diameter, volume, pretension ratio, actuating voltage and focal length. Itis found that when the liquid volume is fixed in the soft lens, the larger the pre-stretching ratio is, the greater the lens deformation is. At the condition of the same lens diameter, focal-length changes are inversely proportional to the liquid volume. The correctness of built theoretical models is verified by experiments in the end.
Volume 45, 2022
Continuous Article Publishing mode
Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020
Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
Physical Sciences 2020
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