Thursday, April 18, 2024

Simple, low-cost BPClip brings blood pressure monitoring to your fingertips

Hypertension, also known as high blood pressure, is a global public health problem. According to World Health Organization (WHO), it is one of the major causes of premature death worldwide, killing nearly 8 million people every year, and the problem is growing.

The key areas where low-cost BP monitors can make a significant impact are low-income and disadvantaged communities. These communities often face barriers to accessing healthcare services, which can lead to a lack of preventative care and increased risk for chronic diseases like hypertension.

In an effort to increase accessibility to this vital measurement, engineers at the University of California San Diego have developed BPClip, a simple, low-cost clip that enables smartphones to measure blood pressure. The device uses a smartphone’s camera and flash to monitor blood pressure at the user’s fingertip.

The innovative clip works with a custom smartphone app and currently costs about 80 cents to make. The researchers estimate that the cost could be as low as 10 cents apiece when manufactured at scale. It has the potential to revolutionize routine blood pressure monitoring and make it easy, affordable, and accessible to people in resource-poor communities.

Other blood pressure monitors developed for smartwatches and smartphones require obtaining a separate set of measurements with a cuff so that their models can be tuned to fit these measurements. On the other hand, the clip does not need to be calibrated to a cuff. This means the user can just use the device without touching another blood pressure monitor to get a trustworthy blood pressure reading.

The BPClip is a 3D-printed plastic attachment that fits over a smartphone’s camera and flash. It features an optical design similar to that of a pinhole camera.

When the user presses on the clip, the smartphone‘s flash lights up the fingertip. The generated light is transmitted to the camera through a pinhole-sized channel, creating a picture of a red circle. A spring inside the clip allows the user to press with different levels of force.

By looking at the size of the circle, the smartphone app can measure the amount of pressure that the user’s fingertip applies. And by looking at the brightness of the circle, the app can also measure the volume of blood going in and out of the fingertip. An algorithm then converts this information into systolic and diastolic blood pressure readings.

Researchers tested their innovative BPClip on 24 volunteers from the UC San Diego Medical Center, and the results were comparable to those taken by a blood pressure cuff.

“Because of their low cost, these clips could be handed out to anyone who needs them but cannot go to a clinic regularly,” said senior study author Edward Wang, a professor of electrical and computer engineering at UC San Diego and director of the Digital Health Lab. “A blood pressure monitoring clip could be given to you at your checkup, much like how you get a pack of floss and toothbrush at your dental visit.”

While the team has only proven the solution on a single smartphone model, researchers say the clip’s current design should theoretically work on other phone models. The team next plans to make the technology more user-friendly, especially for older adults, test its accuracy across different skin tones and create a universal design.

Journal reference:

  1. Yinan Xuan, Colin Barry, Jessica De Souza, Jessica H. Wen, Nick Antipa, Alison A. Moore and Edward J. Wang. Ultra-low-cost mechanical smartphone attachment for no-calibration blood pressure measurement. Scientific Reports, 2023; DOI: 10.1038/s41598-023-34431-1