Nemoslab Project is an EU-funded initiative to create a new lab-on-a-chip device that can detect the presence of certain chemicals, and may serve as a diagnostic modality for all sorts of disease markers. Currently the NEMOSLAB device is being tested to detect fertility hormones, as well the BRCA1 gene that has a role in breast and ovarian cancers.
NEMOSLAB uses an optical technique to recognise the presence of selected biological molecules. Light passes down a silicon nitride waveguide – a flat rectangular pipe about 8 micrometres wide and 0.15 micrometres thick – to a detector which turns it into an electrical signal.
The waveguide is coated with a probe molecule that can recognise target molecules by binding to them. This could be an antibody, which will bind with a specific protein, or a strand of DNA that will bind with a complementary strand in the sample fluid.
“We chose the probes to be very selective for the molecules we want to detect,” says Dr Sotiris Kakabakos who is working with Misiakos. “They have been tested right on the chip but also with conventional methods which select those probes to be very specific for the analyte to be determined.”
A microfluidics system within the chip passes the sample – normally blood serum – over the waveguide. When a target molecule in the sample binds to the surface of the waveguide the optical properties are changed and the amount of light arriving at the detector also changes. The step in the signal is distinctive.
Each NEMOSLAB chip contains nine waveguides which are exposed to the sample at the same time and can be primed to detect different molecules. The entire chip is fabricated as a single unit.
An electronics package collects the signals from the waveguides and produces the results within a few minutes of the sample being introduced.
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Top image: Three dimensional representation of the optocoupler device. The recognition biomolecules are immobilized on the exposed waveguide surface. Shown are (1) the emmiting avalance junction, (2) the waveguide, (3) the photodetector p/n junction, (4) the silicon dioxide spaceres, (5) the cladding layer.
