Medical sampling in a spin

Research at Ohio State University may pave the way for doctors to conduct blood tests and other diagnostic analysis using a compact disc and CD player.

It is envisioned that patients may be able to own a CD that containing sensors and other devices that can analyse drops of their blood, said Marc Madou, professor of materials science and engineering at Ohio State University. The same CD could provide information on how to run medical tests and how to interpret the tests based on their own medical history.

Madou described his latest research efforts earlier this year in a keynote address at the Eurosensors XIV conference in Copenhagen.

Madou is working with L James Lee, professor of chemical engineering at Ohio State University, to perfect the shape of tiny reservoirs and channels on the surface of a CD to allow medical samples and other chemicals to mix while the disc spins.

As the CD spins inside a CD player, centrifugal force pushes liquid medical samples from the inner channels out to the edge, where it mixes with tiny pools of chemicals for testing. All types of analytical functions necessary for the test take place at that time.

‘We found that if you control the size of the channels and the chambers you micromachine inside the plastic surface of the CD, you can basically build any analytical laboratory on a CD,’ said Madou.

Madou claims the CD can merge medical information and diagnostic equipment in one fluidics platform.

In one new development, the researchers crafted a sensor calibration unit into the surface of the CD. Madou and his colleagues designed the pools and channels in the CD so that steps to carry out such a sensor calibration can be controlled by changing the speeds at which the CD spins.

In his address, Madou played a video of a prototype CD spinning slower and then faster to accurately time the release of the different chemicals required for calibrating an optical sensor fitted on the CD.

The optical sensor on the CD changed colour during each step, revealing information about the concentration of substances within it. Madou explained that a computer could be designed to ‘read’ the colour of the sample with a laser to measure the amount of an anomalous substance in a patient’s blood, saliva, or urine.

What really makes this technology unique, said Madou, is that such CDs could store not only medical samples and chemicals for analysis, but also digital information giving a person’s medical history.