Most of us don't ponder our pulses outside of the gym. But doctors use the human pulse as a diagnostic tool to monitor heart health.
Zhenan Bao, a professor of chemical engineering at Stanford, has developed a heart monitor thinner than a dollar bill and no wider than a postage stamp. The flexible skin-like monitor, worn under an adhesive bandage on the wrist, is sensitive enough to help doctors detect stiff arteries and cardiovascular problems.
The devices could one day be used to continuously track heart health and provide doctors a safer method of measuring a key vital sign for newborn and other high-risk surgery patients.
"The pulse is related to the condition of the artery and the condition of the heart," said Bao, whose lab develops artificial skin-like materials. "The better the sensor, the better doctors can catch problems before they develop."
To find your pulse, press your index and middle finger into the underside of your opposite wrist. You should feel the steady rhythm of your heart as it pumps blood through your veins.
Each beat you feel is actually made up of two distinct peaks, even though you can't tell them apart with just your fingers. The first, larger peak is from your heart pumping out blood. Shortly after a heartbeat, your lower body sends a reflecting wave back to your artery system, creating a smaller second peak.
The relative sizes of these two peaks can be used by medical experts to measure your heart's health.
"You can use the ratio of the two peaks to determine the stiffness of the artery, for example," said Gregor Schwartz, a post-doctoral fellow and a physicist for the project. "If there is a change in the heart's condition, the wave pattern will change. Fortunately, when I tested this on myself, my heart looked fine."
To make the heart monitor both sensitive and small, Bao's team uses a thin middle la
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