Water are you looking at? Pinoy Scientists Invent Low-Cost Adjustable Liquid Lenses - FlipScience

electrospinning, microdroplets, liquid lenses

Water droplets maintain their spherical shape and optical properties when placed on a hydrophobic surface made by coating a glass slide with electrospun PVC fibers. The optical properties can be changed simply by adjusting the volume of water in the droplet. (SOURCE: Budlayan et al., 2025)

Filipino scientists have discovered a simple and affordable way to make dynamically adjustable water-based lenses that have a wide variety of potential future applications, from classrooms and research laboratories to cameras and even wearable devices.

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 dome-shaped drop of water similar to a magnifying glass. And by adding or removing water from the drop, they were able to change and control the magnifying power of this liquid lens with minimal loss or distortion.

A schematic diagram of the experimental setup and a photograph (inset) of the actual setup in action. A glass slide coated with a substrate made of electrospun PVC fibers creates a hydrophobic surface where water droplets can form spherical domes with useful optical properties. (SOURCE: Budlayan et al., 2025)

In a process called electrospinning, the researchers melted the PVC in an electric field, which stretched and deposited the plastic on the glass slide in the form of very fine microfibers. This makes the surface of the slide more water repellent and the result is that the water droplets remain in a spherical dome shape rather than flattening out.

By placing droplets of different sizes on this surface and passing a laser through them, the researchers observed that the light beam widened or narrowed depending on the size of the droplet. The larger droplets acted as lenses with longer focal lengths, while the smaller droplets behaved as close-up lenses, and the laser maintained a clean, distortion-free beam.

In the inset you see PVC microfibers that make the surface of the glass slide hydrophobic. The researchers were able to observe the effect of the volume of the water drop on its optical properties, in particular its magnifying power. By understanding this relationship, they will be able to better control and adjust the liquid lens to meet the needs of a given application. (SOURCE: Budlayan et al., 2025)

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

The research was led by Ateneo de Manila University College of Science and Engineering Department of Physics researchers Mr. Marco Laurence M. Budlayan and Dr. Raphael A. Guerrero, along with colleagues from Caraga State University, Pangasinan State University and the University of the Philippines – Diliman.

Their findings are published in the May 2025 issue of Results in Optics.—ADMU OAVP-RCWI Research Communications/MF Press Release

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