Flow chart

A wireless implant designed to give advance warning of clogged arteries has been successfully tested in the US.

The tiny implant, the Stentenna, is the first to combine electronic sensing of blood flow with the biological function of keeping the artery open and free from plaque.

The Stentenna, designed by researchers at the University of Michigan, consists of two silicon pressure sensors and micro scaffolding, known as a stent.

The stent expands in the artery to keep the blood vessel open, but also acts as an antenna to transmit the necessary information, and an electrical inductor to allow the device to be battery-free.

It is envisaged that patients who have undergone surgery will keep track of their blood flow or pressure by using a hand-held RF device, which will pick up information transmitted by the stent.

To test the device, the researchers set up an experiment using a silicone mock artery with a fake blockage and performed an ‘operation’ using a conventional surgical method known as balloon angioplasty.

The Stentenna, which is 20mm long with a diameter of 3.5mm, was placed inside a deflated balloon, which in turn was inserted into the mock artery. Inside the artery, the balloon was inflated, allowing the deployment of the stent.

With sensors monitoring the blood flow, and the stent transmitting data and propping the artery open, it proved possible to maintain a continuous check on the flow through the artery.

During the experiment the device showed a hundred-fold increase in sensitivity and flow-sensing capabilities on previous tests, said Professor Yogesh Gianchandani, associate professor in electrical engineering and computer science at the university, who is leading the research.

‘We have, for the first time, provided electrical functionality to the stent and coupled sensors to it. The overall device can be interrogated wirelessly for pressure and flow information,’ he said.

Gianchandani’s team had previously innovated stent production by introducing a lithography-based manufacturing process using thin layers of foil. Earlier versions of the stent were manufactured from stainless steel tubes and laser machining.

This new process has made cheap mass production commercially viable, and the researchers hope that the Stentenna will be in production within five years.