Engineers at the University of California, San Diego have developed a cheap clip that uses the smartphone’s camera and flash to take the user’s blood pressure at the tip of their finger.
This ground-breaking clip, which can be mass-produced for as cheap as 10 cents, has the power to transform routine blood pressure monitoring and make it easily accessible even to people with limited access to healthcare. The attachment can be used with most smartphones as long as they can install the special application and have a flash LED and camera.
Here is how the smartphone attachment works
The so-called BPClip is a device that measures blood pressure by sensing oscillometry at the fingertip. A mobile pinhole projection that gets closer to the camera as the user presses down on the clip harder enables a smartphone to detect the pressure placed on the digital artery. The spring-loaded mechanism contracts as the user applies more force to the device.
Thus, the pinhole’s size encodes the amount of pressure placed on the finger. In addition, the amplitude of the arterial pulse correlates with the brightness variation of the pinhole projection. With just a cheap plastic clip and an app, a smartphone can assess a user’s blood pressure by capturing the size and brightness of a pinhole projection.
In contrast to previous methods, which relied on pulse transit time and pulse wave analysis for user-specific calibration, this system does not call for a blood pressure cuff measurement. Additionally, the system does not require particular smartphone models with unique sensors.
The preliminary feasibility finding shows that the BPClip system can achieve a mean absolute error of 8.72 and 5.49 for systolic and diastolic blood pressure, respectively, in a validation study with 29 subjects with systolic blood pressures ranging from 88 to 157 mmHg.
