Turning Cell Phones Into Blood Pressure Monitors

Mar 28, 2018

High blood pressure can be a killer, and millions of people don’t know they have it. Knowing that you have hypertension and treating it with lifestyle changes and-or medication can prevent heart attacks and strokes. Researchers at Michigan State University are developing a device that they hope will one day make it easier to monitor blood pressure.

Checking your blood pressure usually means a visit to your doctor’s office or maybe a pharmacy. Some people buy their own blood pressure devices. Those options, though, leave many people not keeping an eye on their blood pressure like they should.

MSU Electrical and Computer Engineering professor Ramakrishna Mukkamala and Ph.D student Anand Chandrasekhar think there could be a better way, and the entrance to that better way might be in your pocket right now: your smart phone. Mukkamala says "we created a sensor unit and accompanying circuitry and we put it in a casing, and we fixate it to the back of the phone. The data recorded by the sensing unit is sent to the phone by bluetooth."

Mukkamala explains that instead of a blood pressure cuff, you simply place your fingertip on the device for a few moments. Visual indicators guide you through that placement. You hold the phone at heart level and look at the screen and watch a cursor moving between two blue lines. You then have to keep the cursor moving between those lines. When enough data has been collected, your blood pressure appears on the screen.

The device also records your heart rate, and if you forget to test your blood pressure for a while, the app can text you a reminder.

Anand Chandrasekhar says most test subjects get the hang of using this blood pressure monitor quickly. "We did this study in around 60 subjects," he states, "and they could do it quite well."

If the test fails, your phone alerts you to try again.

The prototype currently being tested is about double the thickness of the smart phone. Mukkamala hopes to make it much smaller, perhaps only one millimeter thick. That, he says, would allow it to be easily built into a phone or a smart phone case.

The patent application process is underway, but the device needs to be validated according to regulatory protocalls. Mukkamala says that validation requires studying subject populations with a diverse range of blood pressure levels. "If you could satisfy the accuracy limits that the regulatory bodies set forth," he concludes, "then everybody could have an FDA-approved medical device in their pockets."

One other advantage to more frequent blood pressure checks is that averaging results over time diminishes fluctuations in readings attributed to factors like stress, exercise, or meals.