The lens can work as a microscope, and the cost and ease of using it – it attaches directly to a smartphone camera lens, without the use of any additional device – make it ideal for use with younger students in the classroom.

It also could have clinical applications, allowing small or isolated clinics to share images with specialists located elsewhere.

The lens is made of polydimethylsiloxane (PDMS), a polymer with the consistency of honey, dropped precisely on a preheated surface to cure. Lens curvature depends on how long and at what temperature the PDMS is heated. The resulting lenses are flexible, similar to a soft contact lens, although they are thicker and slightly smaller.

“Our lens can transform a smartphone camera into a microscope by simply attaching the lens without any supporting attachments or mechanism,” Dr Sung and co-authors said.

“The strong, yet non-permanent adhesion between PDMS and glass allows the lens to be easily detached after use. An imaging resolution of 1 micrometer with an optical magnification of 120x has been achieved.”

Conventional lenses are produced by mechanical polishing or injection molding of materials such as glass or plastics.

Liquid lenses are available, too, but those that aren’t cured require special housing to remain stable. Other types of liquid lenses require an additional device to adhere to the smartphone.

“This lens attaches directly to the phone’s camera lens and remains attached. It is reusable,” Dr Sung said.

For the study, the scientists captured images of a human skin-hair follicle histological slide with both the smartphone-PDMS system and an Olympus IX-70 microscope.

At a magnification of 120, the smartphone lens was comparable to the Olympus microscope at a magnification of 100, and software-based digital magnification could enhance it further.

“I put it on my phone, and it turns out it works,” Dr Sung said. That 1 cent covers the cost of the material; he and his colleagues estimate that it will cost about 3 cents to manufacture the lenses in bulk. A conventional, research quality microscope, by comparison, can cost USD 10,000.

“A microscope is much more versatile, but of course, much more expensive,” said Dr Sung, first author on the paper published in the Journal of Biomedical Optics.