Engineers at the University of California, San Diego have created a low-cost solution to lower the threshold for blood pressure monitoring. They have developed a simple, low-cost clip that uses a smartphone's camera and flash to monitor the user's fingertip blood pressure. This clip can be used in conjunction with customized smartphone applications. The relevant paper was published in the May 29th issue of the journal Scientific Reports. The current production cost of this clip is approximately 80 cents. Researchers estimate that if produced on a large scale, the cost may be as low as 10 cents per unit. This helps to make routine blood pressure monitoring low-cost, easy, and convenient for people in resource scarce areas. In addition to its low cost, another key advantage of this clip compared to other blood pressure detectors is that it does not require calibration based on the cuff. The researchers explained that the system is calibration free, which means that the subjects only need to clamp the clip at their fingertips, and a customized smartphone application can guide users on the force and time of pressing during the measurement process. This clip is a 3D printed plastic accessory that can be installed on the camera and flash of a smartphone. Its optical design is similar to a pinhole camera. When the user presses the clip, the smartphone's flash illuminates the fingertips. Then, the light is projected onto the camera through a pinhole sized channel, forming a red circular image. The spring inside the clamp allows the user to press with different forces. The harder the user presses, the larger the red circle that appears on the camera. By observing the size of the circle, this application can measure the pressure exerted by the user's fingertips. By observing the brightness of the circle, it can measure the amount of blood entering and exiting the fingertips, and then convert this information into systolic and diastolic blood pressure readings through algorithms. The researchers tested the clip on 24 volunteers at the University of California San Diego Medical Center, and the results were comparable to those measured with a sphygmomanometer. (New News Agency)