New method makes inexpensive, high-quality lenses by hanging droplets of transparent silicone and curing them in an oven
A droplet of clear liquid can bend light, acting as a lens. Now, by exploiting this well-known phenomenon, researchers have developed a new process to create inexpensive high quality lenses that will cost less than a penny apiece.
A single droplet lens suspended on a fingertip.
Image credit: Stuart Hay
Because they're so inexpensive, the lenses can be used in a variety of applications, including tools to detect diseases in the field, scientific research in the lab and optical lenses and microscopes for education in classrooms.
"What I'm really excited about is that it opens up lens fabrication technology," says Steve Lee from the Research School of Engineering at Australian National University (ANU) of the new technique, which he and his colleagues describe in a paper published today in The Optical Society’s (OSA) open-access journal Biomedical Optics Express.
Drop, Bake, Repeat
Many conventional lenses are made the same way lenses have been made since the days of Isaac Newton—by grinding and polishing a flat disk of glass into a particular curved shape. Others are made with more modern methods, such as pouring gel-like materials molds.
But both approaches can be expensive and complex, Lee says. With the new method, the researchers harvest solid lenses of varying focal lengths by hanging and curing droplets of a gel-like material—a simple and inexpensive approach that avoids costly or complicated machinery.
"What I did was to systematically fine-tune the curvature that's formed by a simple droplet with the help of gravity, and without any molds," he explains.
Although people have long recognized that a droplet can act as a lens, no one tried to see how good a lens it could be. Now, the team has developed a process that pushes this concept to its limits, Lee says.
All that's needed is an oven, a microscope glass slide and a common, gel-like silicone polymer called polydimethylsiloxane (PDMS). First, drop a small amount of PDMS onto the slide. Then bake it at 70 degrees Celsius to harden it, creating a base. Then, drop another dollop of PDMS onto the base and flip the slide over. Gravity pulls the new droplet down into a parabolic shape. Bake the droplet again to solidify the lens. More drops can then be added to hone the shape of the lens that also greatly increases the imaging quality of the lens. "It's a low cost and easy lens-making recipe," Lee says.
The researchers made lenses about a few millimeters thick with a magnification power of 160 times and a resolution of about 4 microns (millionths of a meter)—two times lower in optical resolution than many commercial microscopes, but more than three orders of magnitude lower in cost. “We're quite surprised at the magnification enhancement using such a simple process," he notes.
A 3-D Printed Microscope for $2
Their low cost—low enough to make them disposable—allows for a host of uses, he says. In particular, the researchers have built a lens attachment that turns a smartphone camera into a dermascope, a tool to diagnose skin diseases like melanoma.
While normal dermascopes can cost $500 or more, the phone version costs around $2. The new dermascope, which was made using a 3-D printer and is designed for use in rural areas or developing countries, is slated to be commercially available in just a few months, Lee says. A similar smartphone-based tool can also help farmers identify pests out in their fields.
Lee also envisions that the lenses could be used in the lab as implantable lenses that biologists can use to study cells in vivo. The high cost of conventional lenses usually dissuades scientists from implanting them into mice, he says.
The lenses would also be ideal for hobbyists or as part of low cost mobile microscopes that can be distributed to kids and other members of the public for educational or outreach purposes, he adds. "Simple optics can be very powerful.”
So far, the researchers can't make lenses much bigger than half an inch in diameter. But to expand the range of applications, the team is now refining the process to make lenses as large as two inches and increasing the lens’s optical performance.
Paper: “Fabricating Low Cost and High Performance Elastomer Lenses using Hanging Droplets,” W. M. Lee et al., Biomedical Optics Express, Vol. 5, Issue 5, pp. 1626-1635 (2014).
EDITOR’S NOTE: High-resolution images, a pre-edited video package and b-roll footage are available to members of the media upon request. Contact Angela Stark, email@example.com.
About Biomedical Optics Express
Biomedical Optics Express is OSA’s principal outlet for serving the biomedical optics community with rapid, open-access, peer-reviewed papers related to optics, photonics and imaging in the life sciences. The journal scope encompasses theoretical modeling and simulations, technology development, and biomedical studies and clinical applications. It is published by The Optical Society and edited by Joseph A. Izatt of Duke University. Biomedical Optics Express is an open-access journal and is available at no cost to readers online at www.OpticsInfoBase.org/BOE.
Founded in 1916, The Optical Society (OSA) is the leading professional society for scientists, engineers, students and business leaders who fuel discoveries, shape real-world applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership programs, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of professionals in optics and photonics. For more information, visit www.osa.org.
Angela Stark | Eurek Alert!
Tiny Drops of Early Universe 'Perfect' Fluid
02.09.2015 | Brookhaven National Laboratory
02.09.2015 | European Southern Observatory ESO
China's Loess Plateau was formed by wind alternately depositing dust or removing dust over the last 2.6 million years, according to a new report from University of Arizona geoscientists. The study is the first to explain how the steep-fronted plateau formed.
China's Loess Plateau was formed by wind alternately depositing dust or removing dust over the last 2.6 million years, according to a new report from...
The leaves of the lotus flower, and other natural surfaces that repel water and dirt, have been the model for many types of engineered liquid-repelling surfaces. As slippery as these surfaces are, however, tiny water droplets still stick to them. Now, Penn State researchers have developed nano/micro-textured, highly slippery surfaces able to outperform these naturally inspired coatings, particularly when the water is a vapor or tiny droplets.
Enhancing the mobility of liquid droplets on rough surfaces could improve condensation heat transfer for power-plant heat exchangers, create more efficient...
Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.
"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...
A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.
The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...
A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).
Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...
20.08.2015 | Event News
20.08.2015 | Event News
19.08.2015 | Event News
02.09.2015 | Physics and Astronomy
02.09.2015 | Life Sciences
02.09.2015 | Awards Funding