Diagnosis delivered

A microfluidic device to reduce the risk of miscarriage associated with some Down's Syndrome tests in foetuses is being developed by scientists at

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It is one of a range of health and condition-monitoring microsystems that the manufacturing research centre will investigate over the next three years. Another device under development is a sensor that can monitor the status of wiring systems in aircraft.

In Down's Syndrome tests such as amniocentesis, there is a one per cent chance of miscarriage when a sample of the amniotic fluid surrounding the unborn baby is taken for laboratory testing. In an attempt to find a less invasive method of diagnosis, the Cranfield team will explore methodologies for creating a microfluidic device that can carry out the process from start to finish.

'We're trying to make something that can take a pin-prick sample of blood from a pregnant woman, and this device would separate the foetus's DNA from the mother's and detect in that DNA for things like Down's Syndrome. This would be done in a non-intrusive way instead of taking it directly from the foetus,' said Dr Jeffrey Alcock, a materials specialist at Cranfield.

According to Alcock, the device could be self-administered and inform the mother whether or not her child would be born with a particular condition.

'The long-term plan is for everything to be done in the device, giving you the information such as 'yes, your child has something' or 'no, your child won't have something', said Alcock. 'This would particularly benefit people in Third World countries, where they do not have the medical teams or laboratories to do the analyses.'

Alcock acknowledges that ethical issues could constrain the characteristics of the device. 'One thing you might want to think about is how the device would work in terms of it generating a false negative or a false positive because each could have significant consequences. If your child has Down's Syndrome and there is a false reading, you have to take the ethical considerations into account, rather than treating it as just a technological problem,' he said.

Nevertheless, Alcock was able to indicate how the microfluidic system could look and function. 'This device would effectively be a lab on a chip. Physically, the dimensions are probably constrained by the manufacturing methods used, so you're probably talking about less than five cm3,' he said.

'Essentially in the device you will have a separation stage to separate the foetal DNA from the blood, an amplification stage to amplify the DNA to a quantity that you can actually measure, and then the information extraction stage. There are a number of possible technologies for each stage in the laboratory but these do not exist on a chip.'

One technology that could be integrated onto the device is the use of polymerase chain reaction to amplify the foetal DNA. This is because in a pregnant woman's blood sample, according to Alcock, there are only three foetal cells for every one million cells belonging to the mother.

Alcock said genetic markers could also be used in the information extraction phase. 'Genetic markers such as magnetic beads or phosphorescence could be anchored onto the extra chromosome 21 (which is present in Down's Syndrome babies) and you can then read the magnetic or light signal to make a diagnosis.'

In an associated project the team also plans to develop a microsystem for aerospace applications.

'The problem with aircraft wiring systems is that they were not designed for monitoring the health of the wires,' said Alcock. 'In particular, there is nothing to diagnose intermittent faults, which is significant from a safety, but also a cost point of view. So the aircraft takes off, there is vibration and a wire stops contacting, but when you come back down to ground there is nothing to tell you where the problem comes from and why you've just grounded your aircraft.'

One system that would constantly monitor the wiring in the fuselage or the wings of an aircraft could be powered by using vibration harvesting or a more passive method. 'We want to install a clip-on device with a sensor in the wiring loom. The sensor would measure the current of the wiring loom to tell you where the signal is disrupted, and then the device would take the data and monitor it.'

While the device would be an auxiliary component for existing aircraft, Alcock said it could be readily integrated into new aircraft.