Adaptive mechanical-wetting lens actuated by ferrofluids

We report an adaptive mechanical-wetting lens actuated by ferrofluids. The ferrofluids works like a piston to pump liquids in and out from the lens chamber, which in turn reshapes the lens curvature and changes the focal length. Both positive and negative lenses are demonstrated experimentally. The ferrofluid-actuated mechanical-wetting lens exhibits some attractive features, such as high resolution, fast response time, low power consumption, simple structure and electronic control, weak gravity effect, and low cost. Its potential applications in medical imaging, surveillance, and commercial electronics are foreseeable. ► The focal length is changed by the electronic-controlled ferrofluids piston. ► Relation between ferrofluids displacement and back focal distance is investigated. ► The methods to widen the lens’s dynamic range are discussed. ► The lens’ fast response time and low power consumption is confirmed by measurements.