Soft skin patch could provide early warning for strokes, heart attacks - Science Daily

Engineers at the University of California San Diego developed a soft and stretchy ultrasound patch that can be worn on the skin to monitor blood flow through major arteries and veins deep inside a person's body.

The new ultrasound patch developed at UC San Diego can continuously monitor blood flow -- as well as blood pressure and heart function -- in real time.

Each is individually controlled by a computer -- this type of array is known as an ultrasound phased array.

The phased array offers two main modes of operation.

"With the phased array technology, we can manipulate the ultrasound beam in the way that we want," said Muyang Lin, a nanoengineering Ph.D.

The phased array consists of a 12 by 12 grid of ultrasound transducers.

When the ultrasound waves penetrate through a major blood vessel, they encounter movement from red blood cells flowing inside.

This movement changes or shifts how the ultrasound waves echo back to the patch -- an effect known as Doppler frequency shift.

This shift in the reflected signals gets picked up by the patch and is used to create a visual recording of the blood flow.

The standard blood flow exam itself can be time consuming and labor intensive.

A trained technician presses a handheld ultrasound probe against a patient's skin and moves it from one area to another until it's directly above a major blood vessel.

In tests, the patch performed as well as a commercial ultrasound probe used in the clinic.

It accurately recorded blood flow in major blood vessels such as the carotid artery, which is an artery in the neck that supplies blood to the brain.