Three-cent lens turns smartphone into microscope

Researchers have created an inexpensive optical lens that turns a smartphone into a microscope which can magnify images by a magnitude of 120, all for just 3 cents a lens.
The lens attaches directly to a smartphone camera lens, without the use of any additional device and could provide schools and clinics with low-cost alternative to conventional equipment.
It could allow small or isolated clinics to share images with specialists located elsewhere, according to Wei-Chuan Shih, assistant professor of electrical and computer engineering at the University of Houston.
The lens is made of polydimethylsiloxane (PDMS), a polymer with the consistency of honey, dropped precisely on a preheated surface to cure.

Lens curvature - and therefore, magnification - depends on how long and at what temperature the PDMS is heated, Yu-Lung Sung, first author of the study, said.
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," the researchers 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 (micrometre) with an optical magnification of 120X has been achieved," they said.

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.
The new lens attaches directly to the phone's camera lens and remains attached, and is reusable, researchers said.
For the study, researchers 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, researchers said.

"I put it on my phone, and it turns out it works," Sung said. The resulting microscope came from "a USD 20 phone and a one cent lens."
Sung and Shih estimate that it will cost about three cents to manufacture the lenses in bulk.
A conventional, research quality microscope, by comparison, can cost USD 10,000.
The research was published in the Journal of Biomedical Optics.