Researchers at UCLA have built a compact, light-weight, dual-mode microscope that uses holograms instead of lenses, and which they say is ideal for use in developing countries. The prototype fits in the palm of a hand, and has a materials cost of under $100.
It has two modes: a transmission mode that can 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 far bulkier microscopes with low- to medium-power lenses.
"This is the first demonstration of essentially a hand-held version of a microscope that can do dual-mode imaging within a very compact and cost-effective form," says associate professor of electrical engineering and bioengineering Aydogan Ozcan.
The microscope could help ensure water quality, test patients' blood for harmful bacteria, and also prove useful in health crises such as the recent outbreak of E coli in Europe.
"It's a very challenging task to detect E. coli in low concentrations in water and food," Ozcan says. "This microscope could be part of a solution for field investigation of water, or food, or maybe pathogens in blood."
Instead of lenses, this microscope uses holograms. An inexpensive light source is divided into two beams — one that interacts with microscopic cells or particles in the sample, and another that does not. The beams then pass to an adjacent sensor chip, where their interference pattern is recorded.
Software analyzes that pattern and recreates the path taken by the light. The raw data is then processed on a laptop to reconstruct the images.
Ozcan says he has founded a company aimed at commercializing the device.