A Major series of patents from Apple reveal a next-gen Force Sensor System coming to devices known and yet to Surface
On Thursday the US Patent & Trademark Office published a major series of patents that cover a wide array of devices. The patent focuses on next-gen force touch technology. Apple points to their new technology applying to Apple Watch and smart-bands, a new wrist-band device for "patients," headphones, AirPods, smart cuffs, smart glasses), personal medical devices (e.g., at-home health monitors, wearable medical devices, sleep tracking devices, activity tracking devices, sport devices and more.
More importantly, Apple's invention covers a next-generation of force sensor system designed for small form factor devices. Apple notes that the new interface pressure sensor can be used for applanation tonometry. Further, new infill material defines a sensing surface that, when pressed, can impart a force that is detectable by a fluid pressure sensor.
Apple notes in their patent background that an electronic device can include a force sensor. Conventional force sensors are typically implemented with compressible capacitive plates, piezoelectric materials, piezoresistive materials, strain-sensitive materials, and the like. However, in part as a direct result of these architectures and materials, conventional force sensors reserve substantial volume and/or area with an electronic device housing, and may not be readily or efficiently incorporated into portable or low-profile applications.
In addition, conventional force sensors typically have structurally-limited and/or nonlinear force sensitivity that render such sensors unable to accurately or precisely detect small or gradual changes in force.
Further still, many conventional high precision and high accuracy force sensors (which may be used in medical, scientific, or industrial applications) are typically delicate and/or expensive, requiring specialized training to install, service, and operate.
Due to these and other shortcomings, conventional force sensors are often not suitable for one or more of: (1) small form factor applications, such as in wearable electronic devices; (2) low-cost applications requiring durability, such as in sports equipment; or (3) high precision and high accuracy applications, such as in noninvasive medical devices.
Apple's patent covers an interface pressure sensor system defines a sensing surface configured to receive a normal force. The sensing surface forms a portion of a potting, infill, or encapsulation material disposed over, and enclosing, a microelectromechanical fluid pressure sensor. As a result of this construction, when the sensing surface receives a force, the encapsulation material transits that force, or at least a portion thereof, to a microelectromechanical force or pressure sensitive structure that deforms in response.
A property of an electrical circuit conductively coupled to the microelectromechanical sensor can be converted into a force applied to the sensing surface. A surface area of the sensing surface can also be leveraged to determine a pressure applied to the interface pressure sensor system. In another phrasing, a force detected by the interface pressure sensor system can be divided by the surface area of the sensor to obtain a pressure measurement.
In many embodiments, an interface pressure sensor system includes a rigid module enclosure defining an interior volume. A (microelectromechanical) barometric or other fluid pressure sensor is disposed within the interior volume. In addition, an infill material (e.g., thermoset polymer, bismaleimide-triazine resin, other resins, plastics, epoxies, silica, silicone, polyimide, and so on) is disposed over the pressure sensor so as to fill the interior volume, encapsulate and protect the fluid pressure sensor, and to define an interface surface to receive pressure input.
Today's patent report only covers a few of the devices presented in the patent filing that includes Apple Pencil, AirPods and a device that we covered on Thursday relating to a new Beddit application for sensing a user's body temperature.
In Apple's patent FIG. 1E below we're able to see an Apple Watch which Apple – though the patent later references and illustrates a "wearable health monitor" for "patients."
In this particular construction an interface pressure sensor system or more than one interface pressure sensor systems can be used to receive user input and/or to characterize or quantify a heath parameter of the user/wearer.
For example, in the illustrated embodiment below, an input-configured interface pressure sensor system can be disposed, at least partially, within a button 136. More specifically, a pressure sensor module 138 can be disposed within the button 136 in order to determine a pressure/force input applied to the button 136 by a user/wearer of the electronic device (Apple Watch).
In addition, Apple Watch can include a band (#140) that can include an interface pressure sensor system within a body of the band. In many embodiments, the interface pressure sensor system is disposed such that a sensing surface of the interface pressure sensor system interfaces/touches an interior surface of the user/wearer's wrist. More particularly, the band can have insert molded therein at least one pressure sensor module or pressure sensor module group #142 that, as a result of the positioning within the band #140 (e.g., at least partially diametrically opposite the housing #132), can be configured to detect pressure waves that result from the user's cardiac cycle.
More specifically, the interface pressure sensor system of this example embodiment can be positioned such that at least one pressure sensor module (as described herein) of the interface pressure sensor system is placed in contact with the user/wearer's radial artery. As with preceding embodiments, pressure wave information obtained a result of interfacing a user/wearer's radial artery can be used to determine, without limitation: blood pressure; pulse transit time; augmentation index; arterial age; stressor state; heart rate; pressure wave velocity; and so on.
Wrist-Worn Device for "Patients"
In a secondary example, Apple references a wrist-worn device for "patients" that could be used for detecting blood pressure and more. In this example, having a linear sensitivity of 48 mm dramatically improves the likelihood that at least one pressure sensor module will be aligned over a patient's radial artery.
As a result of reliable alignment of at least one pressure sensor module, the wrist-worn device 510 can be configured to reliably obtain one or more health parameters from the user/wearer/patient, such as blood pressure, heart rate, augmentation index, pulse wave velocity, pulse transit time, and so on.
Apple's patent FIG. 2 depicts a system diagram of an example electronic device including an interface pressure sensor system; FIG. 5B depicts a wearable electronic device incorporating the interface pressure sensor system.
Apple's patent FIG. 5C depicts another wearable electronic device incorporating the interface pressure sensor system.
Apple's patent FIG. 8 below is a flowchart depicting example operations of a method of leveraging output from an interface pressure sensor system to determine a health parameter or to receive user input.
Apple's patent FIG. 12 above is a flowchart depicting example operations of a method of non-invasively determining blood pressure of a user by leveraging an output of an interface pressure sensor system; IG. 14 is a flowchart depicting example operations of a method of leveraging output of an interface pressure sensor system.
New Trackpad for Future MacBooks
Apple's patents also point to MacBook trackpads being another candidate for their next-gen force sensor system as noted in the patent figures below.
(Click on image below to enlarge)
The pressure sensor module (#300) includes a fluid pressure sensor #302 which may be a microelectromechanical fluid pressure sensor, such as a high-precision barometric sensor. Apple tries to hide the fact that figs. 3B&C are for a trackpad, but the materials of the top cover are glass and fiberglass, which is used in MacBook Trackpads and FIG. 1 clearly shows how their new sensor system applies to future MacBooks.
New Force Sensing System Possibly for Future iPhones & iPads
Apple's patent FIG. 4A above depicts an assembly diagram of a group of multiple pressure sensor modules; FIG. 4D depicts the group of FIG. 4B, encapsulated with an encapsulation material, potting, or infill material. in some cases, groups of pressure sensor modules can be arranged in arrays to further increase sensing area. The sensing surface defined by the encapsulation #412 is configured to receive pressure/force input primarily along a direction normal to that surface.
Apple's series of patents cover a tremendous volume of detail that can't be captured in this report. For greater detail, review the 6 in-depth patent applications from Apple listed below:
20220087541 - Pressure Sensor Module for Wearable Applanation Tonometer
20220087551 – Sensing Structure for Pulse-Wave Velocity Measurement
20220087552 - Wearable Device Sensing System for Determining Pulse Transit Time of Wearer
20220087553 - Pressure Sensing in Portable Electronic Devices
20220091569 – Wearable Acoustic Device with Through-Enclosure Pressure and Barometric Sensing
20220090973 - Interface Pressure Sensor System for Electronic Device
It should be noted that all patents share the same patent figures.