Mobile phone attachment costing US$10 could be used for CD4 counting

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A US engineering professor says that a mobile phone attachment developed in his laboratory could be used to monitor CD4 counts within a few years, at a cost of less than US$10 per device.

Aydogan Ozcan, assistant professor of electrical engineering at UCLA's Henry Samueli School of Engineering and Applied Science, recently received a prestigious New Innovator Award from the US National Institutes of Health, granting him funding of $1.5 million over five years to pursue the invention.

Point-of-care tests which can be used in resource-limited settings with a minimum of training are needed, in order to determine whether patients are eligible for antiretroviral therapy.



Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).

point-of-care test

A test in which all stages, including reading the result, can be conducted in a doctor’s office or a community setting, without specialised laboratory equipment. Sometimes also described as a rapid test.

Researchers are pursuing a variety of platforms to enable low-cost CD4 counts to be made more widely available.

In Ozcan's lab, a prototype mobile phone diagnostic unit has been constructed that uses LUCAS, an innovative lens-free, high-throughput imaging platform.

LUCAS (Lensless Ultra-wide-field Cell Monitoring Array platform based on Shadow imaging) first uses a light source to illuminate a sample of blood, saliva or other fluid. Then, with a sensor array, a "shadow image" – essentially a diffraction pattern – is obtained of the microparticles in the sample, such as red blood cells.

Because red blood cells and other microparticles have a distinct diffraction pattern, they can be identified and counted virtually instantaneously by LUCAS using a custom-developed "decision algorithm" that compares the captured shadow images to a library of images.

Data collected by LUCAS can then be sent to a hospital for analysis and diagnosis using the phone, or transferred by USB to a computer for transmission to a hospital.

The compact, lightweight and portable nature of LUCAS makes the potential impact of Ozcan's mobile lab very wide-reaching.

Currently, microscopes and advanced medical lab equipment, like flow cytometers, represent the standard for examining, identifying and counting cells. But they are bulky, cost tens of thousands of dollars and require trained technicians to operate.

"With LUCAS, we were able to simplify the imaging device. And because LUCAS does not require a lens, we were also able to increase the visual field to a few hundred times larger than the area that can be seen under a microscope," Ozcan said. "LUCAS really provides a capability that doesn't exist today."

According to Ozcan, the LUCAS platform can be produced rather inexpensively – parts cost less than $10 – and all one needs is a simple camera phone. In developed nations like the United States, point-of-care testing can potentially be done by LUCAS as well, reducing the cost and frequency of visits to the doctor's office and to labs.

Further work will be needed to refine the device, test its accuracy in the field and determine the manufacturing requirements before the device can be made available.

You can watch Aydogan Ozcan talking about his team’s invention in a YouTube video



Adapted from a University of California Los Angeles press release.