At the University of Missouri, a team of researchers developed a custom finger clip device that can continuously measure a variety of vitals, including blood pressure. The new device represents a new way of measuring vital elements and contains two commercial photoplethysmography (PPG) sensors that operate at two different points on the finger. This approach allows researchers to simultaneously calculate the speed of the pulse wave and also measure blood oxygen saturation, body temperature, heart rate, and respiratory rate.
Ongoing blood pressure measurements can reveal trends that a single measure can miss. In addition, measuring a person’s blood pressure in a doctor’s office can increase their anxiety, causing a change in their blood pressure, in a phenomenon known as “white coat syndrome.” “. Clearly, continuous monitoring that is non-invasive and unobtrusive takes action throughout the day is preferable.
“Typically, calculating a person’s blood pressure in a hospital or clinic involves using an inflatable fist around the arm, but there are three issues with this method: it can cause damage to someone’s arteries if done repeatedly in a in a short period of time, people’s blood pressure may increase due to nervousness, and it may take up to 30 seconds to complete, “said Richard Byfield, one of the leaders in the development of the new device. “Our device can record someone’s blood pressure in five seconds using optical sensors placed at their fingertips that measure the amount of light reflected by blood vessels below the surface of the skin.”
Once the clip obtains the pulse wave speed data, it transmits it wirelessly to a computer, where machine learning algorithms interpret it and calculate blood pressure. So far, in tests with volunteers, the clip has shown that it can measure systolic blood pressure with an accuracy of approximately 90%, and diastolic pressure with an accuracy of 63%.
The robust nature of the clip is key to making sure PPG data is reliable. “Normally, there are some issues with PPG sensors,” Byfield said. “One is called artifact movement: moving a PPG sensor while reading can affect the waves being recorded. In addition, we found that pressure differences can alter the waves, but with a clip design. finger spring provides constant pressure.Another reason why this method has not been explored long before is that these finger clips only have one sensor, but we have two sensors in our device.
Study a IEEE Sensors Journal: Towards a robust estimate of blood pressure from the pulse wave rate measured by photoplethysmography sensors