Medical Device Daily

Researchers at the University of California at Los Angeles (UCLA) have built a compact, light-weight, dual-mode microscope that uses holograms instead of lenses. The device can help physicians and clinicians serve patients in remote areas of the world.

“We're trying to get some of the conventional aspects of microscope design, that is behind their improved performance in terms of looking at large scale objects with a decent resolution,“ Aydogan Ozcan, an associate professor of electrical engineering and bioengineering at UCLA and senior author of the paper told Medical Device Daily. “So one of the reasons why conventional microscope designs are not optimum is because they are composed of many components which make their information gathering capacity limited.“

He added, “our approach is to replace lenses in an optic microscope design.“

The prototype weighs about as much as a medium-sized banana and fits in the palm of a hand. Since it relies in part on mass-produced consumer electronics, all the materials to make it add up to between $50 and $100.

It also has a two-in-one feature: a transmission mode that can be used to probe relatively large volumes of blood or water, and a reflection mode that can image denser, opaque samples. The spatial resolution for both modes is less than two micrometers – comparable to that achieved by bulkier microscopes with low- to medium-power lenses.

Ozcan and his team describe the new device in a paper published in the Optical Society's (OSA; Washington) open-access journal Biomedical Optics Express this month.

Part of the device's success is the weight it shed when researchers got rid of the bulkier, heavier, more expensive pieces that most microscopes rely on for collecting and focusing light: the lenses. Instead of lenses, this microscope uses holograms.

Holograms are formed when light bouncing off (or passing through) a three-dimensional object is made to interfere with a “reference beam,“ or light that has not hit the object.

Researchers say to understand how the technology works one must consider this analogy: drop a stone into a still pond and the ripples will move outward in a circle.

Drop two stones and the circular ripples will interfere with each other, making a new pattern of crests and troughs. A person (or computer) analyzing the interference pattern created by those two stones could trace the source back to the stones and recreate what had happened to make the waves.

The UCLA team's device uses a similar principle to recreate images from interfering light waves.

The inexpensive light source is divided into two beams – one that interacts with microscopic cells or particles in the sample, and the other that does not. The beams then pass to an adjacent sensor chip, where their interference pattern is recorded.

Software then analyzes that pattern and recreates the path taken by the light that passed through or bounced off of the objects being imaged.

Each component of the device is fairly inexpensive according to researchers. The laser light could come from a $5 laser pointer. The sensor chip that collects that light is the same as the ones in the backs of iPhones and Blackberrys and costs less than $15 per chip. Researchers say that the whole image-collecting system runs on two AA batteries.

Where the researchers have reduced weight and expense in doing away with lenses, they have added the power of the cloud.

The microscope captures raw data; but a computer is required to reconstruct the images. Workers in the field could use their laptops to process the information or send it over the Internet or mobile phone networks to a remote server. Mobile phones could also have sufficient processing power to do the analysis on the spot.

The next steps for Ozcan's team include commercializing the device. Ozcan says he has founded a company that is developing this technology, trying to make a version of the microscopes that can be manufactured and sold to healthcare workers and hobbyists.

The device could be useful in monitoring the immune system of an HIV patient, or looking at the pathology of a patient suffering from malaria.

“It could be used in a variety of different settings depending on the need,“ he said. “The main advantage [of the device] is that it's a platform that can do microscopy analysis.“

Omar Ford, 404-262-5546