Hamburg - A new chip-based mobile blood test allows doctors in the field to detect pathogens in blood within minutes, no longer necessitating time-consuming lab results, according to a team of German researchers working together with Egyptian experts.

In Egypt doctors collect much-needed blood for clinics and hospitals by travelling to towns and villages and conducting blood donation sessions in a laboratory bus.

The problem is that 25 per cent of the samples taken contain pathogens, including HIV, hepatitis and syphilis. As these diseases can be passed on in transfusions, the contaminated blood cannot be used.

Conventional fast tests are not suitable in most cases for mobile use.

The Egyptian experts and the German scientists say they have developed an improved marker-free technique which provides the basis for faster analysis, whether in a hospital or for mobile blood donations.

A few drops of blood could be tested in the bus to check whether it can be used. Only if the result is positive will the doctors take a larger quantity from the donor.

The basis for this has been provided by research scientists at the Fraunhofer Institute for Biomedical Engineering (IBMT) in Sankt Ingbert, Germany, under a European Union project also involving the Egyptian company VACSERA.

"Our consortium has developed a glass chip which has antibodies on it. Tiny surface oscillations are induced in the chip. If the relevant virus binds with an antibody, the oscillation changes," explains Dr Thomas Velten, Head of Department at the IBMT.

The technique is not new, but the chip that has been developed offers advantages. Usually there is only one measurement field and a reference field next to it, positioned a just a few millimetres apart. But the temperature there can be different.

On the new chip, the measurement and reference fields are divided into narrow strips which in each case are located right next to each other. As a result the chip is more resistant to fluctuations in temperature.

What's more, the new chip consists of four analysis squares, which means that the blood can be examined for four different pathogens during each test.

It has also been difficult up till now for laboratory workers to avoid contact with the blood and protect themselves from infections while conducting tests in the bus. The researchers at the IBMT have therefore encapsulated the chip. This makes the blood follow a defined course on the chip, protecting the user.

A first prototype of the measurement device is being presented at the Medica trade fair from November 18 to 21 in Dusseldorf. Dr Velten estimates that the device could come onto the market in about three years' time. (dpa)