Scientists create low-cost liquid lenses

A Filipino research team has discovered a simple, affordable way to make dynamically adjustable water-based lenses that have a wide variety of potential future applications — from classrooms and research labs to cameras and even wearable gadgets. Their findings have been published in the journal Results in Optics.

By coating an ordinary glass slide with specially prepared polyvinyl chloride (PVC) plastic, the researchers were able to create a hydrophobic surface that could hold a water droplet in a dome shape similar to a magnifying glass. And by adding or removing water from the droplet, they were able to change and control the magnifying power of this liquid lens with minimal loss or distortion.

In a process called ‘electrospinning’, the researchers melted the PVC in an electric field, which stretches out and deposits the plastic onto the glass slide as very fine microfibres. This makes the surface of the slide more water-repellent, and the result is that water droplets stay in a spherical dome shape instead of flattening out.

By placing droplets of different sizes on this surface and shining a laser through them, the researchers observed that the light beam widened or narrowed depending on the droplet’s size. Larger droplets acted like lenses with longer focal lengths, while smaller droplets behaved like close-up lenses, with the laser maintaining a clean and undistorted beam.

Because it is low-cost, simple to make and easy to use, the team’s discovery has multiple potential practical applications. It could be used in science classrooms to teach optics, particularly in schools with limited lab equipment; in remote or low-resource areas, it could help build basic optical tools for experiments or diagnostics; and even in research labs, it offers a quick way to adjust laser beams. It also lays the groundwork for more advanced liquid lenses for possible use in cameras, microscopes and even wearable tech. With further development, it might also be used in portable diagnostic devices or small projection and lighting systems.

Image caption: A glass slide coated with a substrate made of electrospun PVC fibres (inset) makes for a hydrophobic surface where water droplets can form spherical domes. Image has been cropped from the original and is courtesy of the study authors under CC BY-NC 4.0