Apple acquired the sleep tracking app company 'Beddit' back in 2017. Since that time, Apple's engineers have filed a series of patents shown to be advancing the Beddit system or devising a new an alternative sleep tracking system: 01, 02 and 03. Last Thursday, the US Patent & Trademark Office published a patent application from Apple that once again appears to advance the Beddit system.

More specifically, Apple's patent covers force sensors, vibration sensors, piezoelectric sensors, and/or to a sensor system including such sensors. The sensor or sensor system may be or include a piezoelectric force sensor and may be used on a bed or elsewhere to sense vibrations, including vibrations generated through sounds. The sensed vibrations may include biological vibrations or sounds made by a user, such as heart vibrations and/or lung vibrations. In particular, a force sensor may include resonating microstructures to mechanically amplify vibrational signals within specific biological ranges of interest while the vibrational signals are being collected.

Piezoelectric Sensor with Resonating Microstructures

Apple's new sensor system invention may comprise a sensor stack. The sensor stack may comprise a piezoelectric film having a first side opposing a second side and comprising an array of microstructures, each microstructure of the array of microstructures being tuned to resonate within a biological range of interest corresponding to the biological vibration, a first electrode connected to the first side of the piezoelectric film, and a second electrode connected to the second side of the piezoelectric film, the first electrode and the second electrode converting the biological vibration detected by at least one microstructure of the array of microstructures into electrical signals.

In some embodiments, each microstructure of the array of microstructures may have a cantilever structure and the cantilever structure may be tuned to amplify detection of the biological vibration.

In some embodiments, the sensor stack further comprises a first shielding film coupled to the first electrode and a second shielding film coupled to the second electrode. The first electrode may be disposed between the piezoelectric film and the first shielding film and the second electrode may be disposed between the piezoelectric film and the second shielding film.

In some embodiments, the array of microstructures may be a first array of first microstructures. The biological range of interest may be a first biological range of interest. The piezoelectric film may further comprise a second array of second microstructures. Each of the second array of second microstructures may be tuned to a second biological range of interest. The second biological range of interest may be different from the first biological range of interest.

The first biological range of interest may correspond to lung vibrations in a first range of 50 Hertz to 2500 Hertz. The second biological range of interest may correspond to heart vibrations in a second range of 20 Hertz to 500 Hertz.

A sensor system for monitoring biological vibrations generated by a user may be provided. The sensor system may comprise a flexible sensor detecting the biological vibrations from the user while the user is in contact with the flexible sensor. The flexible sensor may comprise a flexible piezoelectric film comprising an array of microstructures, each microstructure of the array of microstructures defining a respective hole of the flexible piezoelectric film and having a respective cantilevered structure amplifying detected vibrations within a biological range of interest, a first electrode and a second electrode, respectively connected to a first surface of the piezoelectric film and a second surface of the piezoelectric film, the first surface opposing the second surface, and a differential amplifier electrically connected to the first electrode and the second electrode and providing a differential output indicative of the detected vibrations sensed by the array of microstructures of the piezoelectric film.

Apple's patent FIG. 1 below depicts an example sensor system, including a force sensor, that may be used to detect and monitor biological vibrations; FIG. 2 depicts a chart including examples of different types of biological vibrations along with approximate biological ranges of interest corresponding to each depicted type of biological vibration; FIG. 3 depicts an example force sensor that may be used to detect biological vibrations; FIG. 4 depicts an example piezoelectric film including an array of microstructures, which may be used as a part of a force sensor such as described in FIG. 3.

In one example, Apple notes that a microstructure #450 may be tuned to a specific frequency, such as a frequency of 500 Hz to primarily amplify sounds and/or biological frequencies that oscillate at or around 500 Hz. In additional or alternative cases, a given microstructure is tuned across a range wider than a particular biological range of interest, such as between 100 Hz to 6 kHz. This expanded biological range of interest generally corresponds to any vibrations and/or sounds arising from a user's lungs. In such cases, the microstructure amplifies any sounds or vibrations coming from a person's lungs.

For more details, review Apple's patent application number US 20220409095 A1. One of Apple's inventors is Zheng Zeng: OS Power Engineering Manager.