Apple has applied for a patent (number 20220015652) for an “integrated flexible sensor for blood pressure measurements.” It suggests the tech giant is considering devices beyond the Apple Watch that integrate with its Health app.
About the patent filing
The patent filing involves glexible sensors that can be integrated with a blood pressure cuff and used to estimate a blood pressure of a user.
A user may monitor one or more of his or her physiological parameters by attaching a monitoring device, such as a blood pressure monitor, to one of his or her limbs.
The blood pressure monitor may include an inextensible cuff that secures an inflatable bladder against a limb of the user. The inflatable bladder can be expanded and the inextensible cuff may cause the bladder to compress the limb, thereby compressing one or more blood vessels in the limb and restricting and/or stopping blood flow through the vessels. The various pressures in the inflatable bladder that restrict and/or stop blood flow through the vessels in the limb may be measured and used to determine one or more physiological parameters of a user such as a blood pressure of the user.
Techniques for determining blood pressure metrics, such as mean pressure, diastolic pressure and/or systolic pressure, include monitoring oscillatory pressure changes within the cuff due to changes in blood flow through a user’s limb. However, Apple says that, in isolation, such oscillatory measurement may not be as accurate as desirable in determining some metrics such as systolic pressure and/or diastolic pressure.
The tech giant’s idea is for a blood pressure cuff with piezoelectric sensor and a processor. They could “filter the signal [from the cuff]to identify a first sound that corresponds to a change in the blood flow due to a partial collapse of a blood vessel within the limb, identify a second sound that corresponds to a stoppage of the blood flow in the blood vessel within the limb, and determine a blood pressure of the user at least partially based on the identified first and second sounds.
Summary of the patent filing
Here’s Apple’s abstract of the patent filing: “Embodiments are directed to a blood pressure measurement device including a cuff that is operative to wrap around a limb of a user, a bladder coupled to the cuff and operative to compress the limb of the user when inflated, and a piezoelectric sensor coupled to the cuff and operative to detect blood flow through the limb of the user and output a signal indicative of the blood flow.
“The blood pressure measurement device can also include a processor coupled with the piezoelectric sensor that is operative to filter the signal to isolate sounds corresponding to changes in the blood flow through the limb due to inflation of the bladder, correlate the isolated sounds with a pressure inside the bladder, and determine a blood pressure of the user at least partially based on correlating the isolated sounds with the pressure.”