A credit card-sized “lab-on-a-chip” which can diagnose infections within minutes has the potential to transform blood testing and medical care in remote parts of the world.

The £60 plastic device contains an array of miniature pipes and test tubes and only requires a finger-prick of blood.

US scientists reported how the “mChip” (mobile microfluidic chip) was successfully used to test for HIV and syphilis in Rwanda. The combined test took less than 15 minutes and achieved respective accuracies of 95 per cent and 76 per cent.

A version of the mChip has also been developed to test for prostate cancer. The transparent device is a miniaturised version of the enzyme-linked immuno-sorbent assay test, which is normally bench-top size. Being so small, it can easily be transported to remote, rural areas far from any hospitals or clinics.

Each chip uses tiny amounts of antibodies to carry out a series of multi-step tests. “Positive” and “negative” results are obtained from silver signals which can either be read by eye or with a low-cost photo-detector.

Biomedical engineer Samuel Sia, who led the design team at Columbia University, New York, said: “We have engineered a disposable credit card-sized device that can produce blood-based diagnostic results in minutes.