Blood flow examined close up

The device is tiny, but produces very detailed images

A tiny measurement system that incorporates a lens as thick as two human hairs has been developed by researchers to investigate blood flow.

The device is able to examine the force exerted on the wall of an artery as blood whooshes past.

The acoustical lens focuses the sound waves similar to how a camera lens focuses a picture

Dr Robert Keynton

The aim is to investigate how the dragging force of the blood - known as shear stress - may be linked to the development of cardiovascular disease, and to the re-blocking of coronary artery bypass grafts after surgery.

Researchers also hope to use the technology to investigate skin cancers. Potentially, it can help a surgeon determine how deep a tumour is, and where its edges are before surgery takes place.

The device is known technically as an integrated miniature acoustical lens-transducer system.

Sophisticated technology

It consists of an extremely small lens directly attached to a transducer, ceramic material which converts electrical energy into sound wave and vice versa.

It works by focusing very high frequency sound very precisely, enabling medical researchers to look at very fine detail.

Very accurate imaging systems that use high-frequency ultrasound generated by a transducer are widely used in medical diagnostics.

But the new system, developed by researchers from the University of Louisville in Kentucky and Michigan Technological University, takes the technique one stage further by using more intense ultrasound waves.

This means that a smaller region can be examined to obtain much more detailed information - and a sharper image.

'Better understanding'

Researcher Dr Robert Keynton told BBC News Online: "The acoustical lens focuses the sound waves similar to how a camera lens focuses a picture.

"When used to measure the forces exerted on the walls of an artery, the higher resolution enables us to measure the dragging force of the blood more closely to the artery wall which will give us a better understanding of the forces that the cells inside the blood vessel are experiencing.

"Researchers have shown that cells respond to forces exerted by the blood, only sometimes these responses are not favourable and lead to cardiovascular disease.

"For imaging applications, this system produces a sharper, clearer image so we can see features in the body of very small sizes that we are normally unable to see."

The research is published in the Institute of Physics publication Journal of Micromechanics and Microengineering.