Lab-on-chip developments pave the way for on-the-spot medical diagnoses

Labs-on-chips rely on microfluidics - tiny volumes of sample liquids that move along microscopic channels cut into a variety of substances including silicon, glass and plastic. It is now possible to separate samples at the molecular level on a chip the size of a postage stamp. However, until now, large scale equipment is required to detect and identify the molecules flowing inside the microfluidic chips. The EU funded HIBISCUS consortium now claims to be able to 'inscribe' features into microfluidic chips, making integrated optical detection a possibility for the first time. The team has used a technique called femtosecond laser micromachining. The femtosecond laser emits extremely short light 'flashes' – each lasting no more than a few millionths of a billionth of a second. This pulsation makes the laser beam extremely intense, and can alter materials in unusual ways. By focusing the beam the laser can be used like a microscopic tool or pen and 'draw' physical features in three dimensions into a thin wafer of glass. Using this micromachining technique the HIBISCUS team was able to inscribe tracks, called waveguides, into labs-on-chips. The waveguides channel light through the chip, across the microfluidic channels and back out of the chip where it is detected. They could also use the laser to produce the microfluidic channels themselves. It is now possible to shine a light source (usually a laser) into the sample fluid and detect its absorption or other optical activity directly in the chip, rather than having to take a sample from the chip and analyse it with laboratory equipment. Giulio Cerullo who coordinated the project, suggests that the lab-on-chip could help doctors perform virtually immediate medical diagnoses in their own practices. They could take a sample from a patient and immediately run it through a small device, which would be able to detect marker molecules – protein markers for a disease or the telltale DNA sequence of a genetic disorder. Cerullo said: "Once you make detection part of the lab-on-chip, you have miniaturisation of an entire analytical laboratory. It brings diagnosis to the point of care. A patient goes home without that awful sense of uncertainty hanging over them until they get their test results back. Or they can receive urgent medical treatment – a day or two's advance on treatment can mean life or death for some cancer patients." The HIBISCUS consortium includes three commercial SME partners - High Q Laser, Lionix and Dutch firm Zebra Bioscience.