The focus of Apple Watch over the years has been ever increasingly towards a health device. For Apple Watch 7, Apple’s webpage markets points to Apple Watch being “The Future of Health” with sensors for measuring blood oxygen and the ability to take an ECG at any time. One of the possible next health related features that Apple is working on is measuring blood pressure, with or without a blood pressure cuff. Patently Apple has covered a number of Apple’s patent on this starting in 2018: 01, 02, 03, 04, 05, 06, 07 and more.
Today the US Patent & Trademark Office published a patent application from Apple that relates to blood pressure measurement devices, and more particularly, the present embodiments relate to blood pressure measurement devices including a liquid filled sensor.
In Apple’s patent background they note that a user may monitor one or more of their physiological parameters by attaching a monitoring device such as a blood pressure monitor to one of their limbs. The blood pressure monitor may include a cuff that secures an inflatable bladder against a limb of the user. The bladder can be inflated 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 inflated 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 blood pressure of the user. The accuracy of correlating changes in air pressure within the bladder to blood pressures in the arm may vary based on a variety of factors including inflation and deflation rates, the volume of the cuff, and/or the material of the cuff among others. It may be desirable to reduce some of these variations and/or increase the sensitivity of the pressure measurements to help increase the accuracy or precision of measurements taken by blood pressure monitors.
Apple’s invention is directed to a blood pressure measurement device that includes a strap configured to couple the blood pressure measurement device to a user, an air pump coupled to the strap and having a housing defining a surface facing the user, and an inflatable chamber positioned on the surface of the air pump and fluidly coupled to the air pump. The inflatable chamber can be positioned between the air pump and the user when the blood pressure measurement device is worn by the user, and expand towards the user when inflated. The blood pressure measurement device can also include a pressure sensing chamber coupled to the inflatable chamber and positioned between the inflatable chamber and the user when the blood pressure measurement device is worn by the user. The pressure sensing chamber can include a liquid volume and a pressure sensing device configured to detect a pressure of the liquid volume.
Embodiments are also directed to a blood pressure measurement device that includes a strap configured to at least partially extend around a limb of a user, an air pump coupled to the strap and defining a surface that faces the user when the blood pressure measurement device is worn by the user, and an inflatable chamber positioned on the surface, fluidly coupled to the air pump, and configured to expand towards the user when inflated. The blood pressure measurement device can include a support plate coupled to the inflatable chamber, positioned between the user and the inflatable chamber when the blood pressure measurement device is worn by the user, and configured to move toward the user when the inflatable chamber is inflated.
The blood pressure measurement device can also include a fluid chamber coupled to the support plate, positioned between the user and the support plate when the blood pressure measurement device is worn by the user, and comprising a pressure sensor configured to measure pressures of liquid within the fluid chamber.
Apple’s patent FIG. 1A illustrates an example blood pressure measurement device being worn by a user.
Apple’s FIG. 1B above shows a cross-sectional view taken along section A-A shown in FIG. 1A of an example blood pressure measurement device 100 being worn by a user #101. The blood pressure measurement device (Apple Watch or ‘Health monitoring device #100) can be operated to measure the blood pressure in a blood vessel #103 of a user. The pressure sensing stack #102 can be configured such that the pressure sensing mechanism #110 is positioned between the expansion mechanism #108 and the user.
The expansion mechanism can be configured to press the pressure sensing mechanism against the user to collapse the blood vessel. In some cases, the expansion mechanism can include an air pump #120 and an inflatable chamber #122 that is fluidly coupled to the air pump. The term “fluidly coupled” is used to describe components that can exchange air using one or more sealed passages. The air pump can be attached to the strap #104 and can form a rigid structure such that as the inflatable chamber is filled with air, it primarily expands towards the user. Accordingly, expansion of the inflatable chamber pushes the pressure sensing mechanism against the user to collapse the blood vessel. In this regard, the strap and air pump can be configured to have sufficient rigidity such that as the inflatable chamber expands, the primary motion of this expansion is toward the user.
The expansion mechanism can be implemented in various ways. In some cases, the expansion mechanism can be configured to tighten the strap around the user thereby compressing the pressure sensing mechanism against the skin of the user to collapse the blood vessel. In these cases, the expansion mechanism can tighten the strap using a ratcheting mechanism, a screw-based mechanism, gears, friction, a magnetically-actuating element, a piezoelectric element or other suitable system that tightens the strap around the user. In other cases, the expansion mechanism can expand toward the user using a piezoelectric actuator, pneumatic actuator, an electromechanical actuator or combination thereof.
The pressure sensing mechanism can include a sealed chamber that contains a volume of liquid and a pressure sensing device that is configured to detect pressure changes of the liquid volume. In this regard, as the pressure sensing mechanism is pressed against the user, blood pressures within the blood vessel can be transferred to the liquid volume and detected by the pressure sensing device.
Apple’s patent FIG. 6 below illustrates an example process for operating a blood pressure measurement device; and FIG. 7 shows an example system diagram for a blood pressure measurement device.
For more details, review Apple’s patent application number 20220240803.
