Multifunctional health and activity tracker for wearable, under-mattress, and tactical use

Abstract

A physiological monitoring device, the device having a housing formed by two rigid structural elements, a soft elastomeric part mechanically locked between the two rigid elements, an electromechanical film sensor assembly positioned beneath the soft part, and a conductive electrode that is arranged above the electromechanical film. The electrode includes electrical connection routed to the printed circuit board (PCB), and the device includes electronics for signal processing, wireless communication, and power management.

Description

MULTIFUNCTIONAL HEALTH AND ACTIVITY TRACKER FORWEARABLE, UNDER-MATTRESS, AND TACTICAL USECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to provisional application U.S. Serial No. 63 / 657,105, which is pending, which was filed June 6, 2024, and which is hereby incorporated by reference in its entirety for all purposes.

[0002] This application claims priority to provisional application U.S. Serial No. 63 / 657,106, which is pending, which was filed June 6, 2024, and which is hereby incorporated by reference in its entirety for all purposes.FIELD OF THE INVENTION

[0003] This invention relates to wearable and non-contact-based sensors for monitoring sleep and daily activity, including the tracking of vital signs such as heart rate, heart rate variability, and respiration. The sensor can be worn on the body or placed under a mattress or pillow during sleep, enabling non-contact measurements through clothing or bedding. The invention is suitable for both consumer wellness and clinical-grade monitoring.

[0004] Additionally, the invention qualifies as dual-use technology with military and tactical applications. In such settings, the device can be used simultaneously for continuous health and vital sign monitoring, while also detecting and characterizing high- pressure acoustic or shockwave events — such as blast exposures — occurring near the user.BACKGROUND OF THE INVENTION

[0005] A dielectric cellular or porous electret film and its manufacturing process, when permanently charged and applicable for use as a transducer (electromechanical film) in multifunction health tracker as in question, is described in U.S. Patent No. 4,654,546. Additionally, it is beneficial to make it swelled in the method, as explained in WO publication 96 / 06718. This dielectric film comprises a permanently charged, biaxially oriented, foamed, typically homogeneous film layer containing flat lens-like, shredded, or cavitated gas bubbles, which may also be called voids or cells.

[0006] WO publication 96 / 06718 outlines a process for pressure inflation of pre-foamed plastic film, enabling the manufacture of highly foamed film products characterized by a substantial foaming degree. These are known as 'dielectric swelled cellular electret film' or 'pressure inflated pre-foamed cellular electret film'. The method taught by WO publication 96 / 06718 allows for increasing the thickness of the product without a corresponding increase in the amount of plastic material utilized. An enhancement observed is the increased velocity of gas voids within the film, ranging from 30% to 60% and even up to 70% of the thickness. This improvement leads to an electromechanical response up to 10 times stronger, resulting in a significantly improved signal-to-noise ratio.

[0007] The electret field, or the quasi-permanent electric charge, is established by subjecting the dielectric cellular film to a high DC voltage, typically in the range of 20-25 kilovolts. During this process, the film is placed against or between electrodes, one of which is formed by a layer of resistive (i.e., semi-conductive) material that serves as a ground reference. This arrangement enables the injection and trapping of charges within the internal voids and surfaces of the dielectric structure, creating a stable and long- lasting internal electric field.

[0008] The term dielectric cellular electret film is used herein to describe electromechanical films of a generally cellular morphology that retain a permanent or quasi-permanent electric charge. These films typically consist of a biaxially oriented, foamed plastic layer containing lens-shaped, shredded, or cavitated gas bubbles — referred to as voids or cells — that improve the film’s electromechanical response and contribute to its sensitivity across a broad frequency range.

[0009] The presence of flat lens-like gas bubbles within the electret film effectively impedes the mobility of electret charges within the dielectric material. This is due to the remarkably low electric resistance of gases, which surpasses that of even the most superior solid insulating materials by five orders of magnitude. In contrast to the rigid structure of piezoelectric materials, these gas bubbles serve as an elastic, soft layer during the conversion process — such as transforming heart and lung sounds and vibrations into electric signals — permitting microscopic changes in thickness induced by pressure variations caused by vibrations.

[0010] As the thickness changes, the opposite charges on the opposite sides of the voids either draw closer together or move farther apart, generating so-called mirrorcharges across the electrodes positioned above the cellular electret film. Consequently, this produces a measurable electrical output voltage proportional to the force change.

[0011] Due to the elastic, swelled cellular core, the cellular electret film transducer's Young's modulus is significantly reduced. This leads to improved impedance matching, particularly with picking vibrations and sounds from a human body. As a result, there is a cleaner signal output, which is particularly noticeable in electronic phonocardiogram or stethoscope use, producing more clear sound.

[0012] A previous approach to creating contact microphones with ferroelectret film is outlined in U.S. Patent No. 6,689,948 B2. This method involves producing acoustic guitar pickups by screen-printing electrodes onto sheets of dielectric film, such as polyester, or directly onto cellular electret film. During screen-printing, electrodes are arranged adjacently on a single sheet. The process includes laminating these electrodeprinted sheets together with additional sheets of dielectric cellular electret film. Crucially, the charged dielectric cellular electret film is carefully positioned only on specific areas at one end of the sheet. The opposite end contains a connector part, where different electrode layers are organized side by side. The final product is a laminated sheet from which individual transducers are formed, typically through a punching process. Connectors, like Crimpflex™ from NICOMATIC®, are then mechanically crimped to the electrode sections at the connector end of the transducer.

[0013] One drawback of electromechanical film transducers using ferro-electret cellular film is its (prior art) manufacturing process. The problem is the accumulation of charges in the reel-to-reel DC charging process. When in reel-to-reel charging process rolled layers increase, charges accumulate, causing discharges through layers. This causes areas with no charges or even opposite charges to appear. Such is a severe quality issue in the final product and is difficult to detect before electrodes are printed and sheets are die-cut into individual pickups, which are also crimped. Hence, the quality problem and unwanted discharges at the reel-to-reel charging can cause severe economic losses.

[0014] Another typical drawback of electromechanical film transducer elements for a ballistocardiogram’s sensor and phonocardiogram’s microphone is the complexity of the transducer fabrication, which contributes to higher manufacturing costs. Much of the assembly process requires manual labor. Furthermore, prior art structures often include separate transducer components and connection cables, necessitating the establishment of connections to the preamplifier either through soldering or by solderinga mini plug onto the cable. This reliance on manual labor significantly increases production costs.

[0015] Other major drawbacks of the prior art transducers suitable for innovation in question are, for example method explained in U.S. Patent No. 6,689,948 B2 and their complicated manufacturing process. In it, materials are handled several times before a laminate is ready for die-cutting. The design involves several sheets laminating together, which means more materials, including adhesives and handwork than is economically possible today for the end value of a ready product. Typically, one manufacturer has machinery for manufacturing charged electret material and laminations, and another can screen-printing and die- or laser-cutting. The method also tends to produce bulkier (thicker) transducers and does not prioritize creating a ultra thin, lightweight structure, to ensure highest possible output for better signal-to-noise ratio.

[0016] In the prior-art patent 6,689,948 B2, there is a description of a method for printing electrodes directly onto charged cellular film. However, practical applications have demonstrated that this method is unfeasible. The polypropylene-based, biaxially oriented, and swelled electret material used is extremely fragile. A significant issue arises with the curing temperature required for silver paste printing, which is at least 80 degrees Celsius. At this temperature, the polypropylene-based material tends to shrink, complicating the process of printing electrodes on both sides. Misalignment occurs because it is difficult to achieve the necessary precision across opposite sides. This misalignment can lead to electromagnetic interference, typically at 50 Hz or 60 Hz, and create shorts along the edges when the material is cut into individual contact microphones.

[0017] Another major problem is that the PP-based material alone is so thin and fragile that printed electrodes too easily get wrinkles. This causes significant resistance between signal area picking vibrations and crimped contact, taking the sound further to the signal preamplifier.

[0018] One drawback of prior art contact transducers using ferro electret cellular film lies in its (prior art) manufacturing process. The problem is the accumulation of charges in the reel-to-reel DC charging process. When in reel-to-reel DC charging process the number of winded layers increases, the charges accumulate and cause discharges through layers. This causes areas to appear with no charges or even opposite charges. Such is a severe quality issue in the final product and is difficult to detect before electrodes are printed and sheets are die-cut into individual pickups, which are alsocrimped. Hence, the quality problem and unwanted discharges at the reel-to-reel charging can cause severe economic losses.

[0019] As elucidated in U.S. Patent No. 6,689,948, a dielectric cellular or porous electret film, along with its manufacturing process, applicable for use as a transducer in contact microphone for listening to body sounds, is described in U.S. Patent No. 4,654,546. Additionally, it is beneficial to make it swelled in the method, as explained in WO publication 96 / 06718. This dielectric film comprises a permanently charged, biaxially oriented, foamed, typically homogeneous film layer containing flat lens-like, shredded, or cavitated gas bubbles, which may also be called voids or cells. The electret field, or the permanent electric charge, is established by injecting charges into the dielectric material by applying a very high, in class of 20 - 25 KV DC charge on the cellular film, applied against resistive material. The term 'dielectric cellular electret film' is employed herein to denote electromechanical films of a generally cellular nature possessing a permanent electric charge.SUMMARY OF THE INVENTION

[0020] The object of the present invention is to eliminate the drawbacks associated with prior-art health tracking devices, including manufacturing complexity, production cost, sensitivity to handling damage during installation, limited dynamic range, and the need for multiple separate components or wiring. Additionally, the invention aims to minimize device size and weight, enabling discreet, continuous use in both wearable and undermattress configurations.

[0021] Another object of the invention is to provide a dynamic force and vibration contact transducer for pressure changes, sounds and vibrations sensing, capable of operating across a very wide frequency and dynamic range, without requiring an air gap, separate housing, or separately connected wiring for signal transmission. The transducer structure integrates electrodes and mechanical layers into a unified and flexible assembly.

[0022] Yet another object is to realize a ballistocardiographic and phonographic transducer element with a monolithic, flexible construction that is:

[0023] • Robust during handling and installation,

[0024] • Shielded against electromagnetic interference,

[0025] • Capable of producing a high signal level with excellent signal-to-noise ratio,

[0026] • And mechanically matched to soft tissue or bedding environments.

[0027] The invention also provides a manufacturing method that enables cost-effective, high-yield fabrication of ultra-thin, lightweight transducers from permanently charged, biaxially oriented swelled ferroelectret film. Electrodes in the active sensing region extend seamlessly to the connector region, allowing secure electrical contact via mechanical crimping or printed conductors, without soldering or adhesives.

[0028] In one embodiment, the transducer is positioned on the outer surface of the device housing, optionally under a flexible cover, to enable direct coupling to the environment. In a later-developed embodiment, the transducer is integrated inside the device, compressed between a reference electrode and a signal electrode on a printed circuit board. This structure is enclosed by two rigid plastic parts that mechanically lock a soft elastomeric interface in place, resulting in a compact, sealed, and replaceable assembly. This arrangement simplifies assembly, enhances durability, and enables servicing and recycling even after years of use — reducing electronic waste and supporting sustainability goals.

[0029] The device may also include components for analog filtering, analog-to-digital conversion, wireless communication, motion sensing, and temperature measurement, forming a fully integrated platform for continuous physiological monitoring.

[0030] In an additional use case, the same transducer element may be employed to detect and characterize high-intensity pressure waves, such as those resulting from nearby explosions. This application is particularly useful in military or industrial settings, where the system can:

[0031] • Log the occurrence and intensity of such events,

[0032] • T rack cumulative blast exposure,

[0033] • And initiate post-event health surveillance of the individual.

[0034] This dual-use capability is made possible by the extremely wide dynamic range and mechanical robustness of the ferroelectret sensor, allowing for both subtle physiological signals and extreme pressure events to be accurately recorded using the same structure.

[0035] An additional advantage of the invention lies in the fact that, unlike ECG or PPG- based systems, the sensor does not require direct skin contact to measure physiological signals such as heart rate or respiration. The ferroelectret transducer is capable of detecting ballistocardiographic signals and breathing-induced motion through one or more layers of clothing, including materials such as cotton or wool.

[0036] This provides significantly improved comfort and wearability — especially during sleep, when the user does not need to wear a wristband or ring, and is not disturbed by optical light emission typical of many PPG-based trackers. The under-mattress use enables seamless, passive night-time tracking, improving user adherence and overall sleep experience.

[0037] The device can serve as a 24 / 7 multi-function monitor: worn during the day to detect activity and abnormal events such as epileptic seizures or falls, and placed under the mattress at night for sleep and respiration monitoring. In elderly care, the same device can act as a bed-exit monitor and alert system — detecting if a person remains out of bed too long and notifying caregivers. In neonatal applications, the device may be placed under an infant’s mattress to track breathing patterns without contact or wearables.

[0038] The present invention thus introduces a highly versatile, manufacturable, and high-performance solution for continuous health and environmental monitoring across a wide range of user scenarios — from civilian wellness and sleep tracking to defense and critical care use cases.

[0039] Main Items

[0040] Item 1 . A physiological monitoring device, comprising:

[0041] • a housing formed by two rigid structural elements (800, 801),

[0042] • a soft elastomeric part (802) mechanically locked between the rigid elements,

[0043] • a electromechanical film sensor assembly (804) positioned beneath the soft part (802), the assembly comprising:

[0044] ° one conductive electrode (805) arranged above the electromechanical film,

[0045] • wherein the electrode (805) includes electrical connection routed to the PCB,

[0046] • and wherein the device further comprises electronics for signal processing, wireless communication, and power management.

[0047] Item 2. A method of manufacturing a transducer assembly for use in a physiological monitoring device, comprising:

[0048] • providing electromechanical film,

[0049] • applying a conductive layer to at least one side of the electromechanical film to form one electrode,

[0050] • arranging the electromechanical film within a mechanical housing such that it is compressed between a soft elastomeric layer and a PCB-mounted another electrode,

[0051] • establishing electrical contact on the said electrodes,

[0052] • and enclosing the assembly using mechanically joined rigid housing parts.

[0053] Item 3. A method of monitoring physiological or environmental signals, comprising:

[0054] • positioning the device according to item 1 on a user’s chest, hip or thigh,

[0055] • detecting ballistocardiographic and respiratory signals through one or more layers of clothing,

[0056] • and optionally detecting high-amplitude pressure events, such as explosive blast waves, using the same sensor assembly.

[0057]

[0058] Sub items

[0059] Item 4. The device of item 1 , wherein the rigid housing parts are made of ABS plastic.

[0060] Item 5. The device of item 1 , wherein at least one of the rigid parts is made of metal or ceramic.

[0061] Item 6. The device of item 1 , wherein the soft elastomeric part (802) is made of silicone or thermoplastic polyurethane (TPU).

[0062] Item 7. The device of item 1 , wherein the reference electrode (805) is formed of aluminum on PET or printed silver ink.

[0063] Item 8. The device of item 1 , further comprising a USB-C charging port integrated into the soft part.

[0064] Item 9. The device of item 1 , further comprising a temperature sensor, an accelerometer, and a gyroscope.

[0065] Item 10. The device of item 3, wherein the system is configured to detect and log blast wave events and calculate cumulative exposure over time.

[0066] Item 11. The method of item 2, wherein the ferroelectret laminate comprises a PET-PP-PET structure with silver paste printed electrodes.

[0067] Item 12. The method of item 2, wherein no adhesive is used between the ferroelectret film and the reference electrode.

[0068]

[0069] Main Items

[0070] Item 1 . A physiological monitoring device comprising:

[0071] • a flexible outer interface part configured to deform under external pressure or vibration;

[0072] • an electromechanical sensing film positioned beneath said flexible part, the sensing film being selected from the group consisting of:(a) a swelled and permanently charged ferroelectret film,(b) a piezoelectric PVDF film, and(c) a printed piezoelectric material; wherein the sensing film is configured to detect mechanical vibrations or pressure changes when the device is placed under a mattress, cushion, or worn on a user’s body, including through one or more layers of clothing; and wherein the sensing film is configured to produce signals corresponding to at least one of: a ballistocardiogram or a phonocardiogram.

[0073] Item 2. The device of item 1 , wherein the flexible outer part comprises an elastomeric material selected from silicone, polyurethane, or thermoplastic polyurethane (TPU).

[0074] Item 3. The device of item 1 , wherein the device is configured to operate while placed in contact with or near the user's chest, waist, hip, or thigh.

[0075] Item 4. The device of item 1 , wherein the device is operable when worn under a waistband or belt, or when carried in a trouser pocket.

[0076] Item 5. The device of item 1 , wherein the electromechanical sensing film comprises a laminated stack of a ferroelectret layer and a conductive reference layer, mechanically retained without adhesives.

[0077] Item 6. The device of item 1 , wherein the sensing film is capable of detecting both cardiac and respiratory mechanical signals.

[0078] Item 7. The device of item 1 , wherein the device is configured for both wearable and contactless use, including operation through multiple layers of clothing.

[0079]

[0080] Independent method item:

[0081] Item 8. A method for monitoring physiological signals, comprising:

[0082] • positioning a monitoring device on or near a user’s body, wherein the device comprises a flexible outer interface and an electromechanical sensing film selected from the group consisting of:(a) a swelled and permanently charged ferroelectret film,(b) a piezoelectric PVDF film, and(c) a printed piezoelectric material;

[0083] • allowing the sensing film to detect mechanical forces or vibrations caused by physiological activity;

[0084] • and extracting at least one of: a ballistocardiogram or a phonocardiogram signal from the measured data; wherein the device is operable through at least one layer of clothing and is placed at a location selected from the group consisting of: the chest, waist, hip, thigh, under a waistband or belt, or inside a pocket

[0085] Item 9. The method of claim 8, wherein the sensing of physiological signals is performed without direct skin contact, through one or more layers of textile material.

[0086] Item 10. The method of claim 8, wherein the sensing film operates independently of optical or electrode-based measurement methods requiring direct skin contact.

[0087]

[0088] Dependent Items - Blast Monitoring and Military Use Case

[0089] Sub-item 1. The device according to any of claims 1-10, wherein the electromechanical sensor is configured to detect not only low-amplitude physiological signals, such as heartbeats and respiratory movements, but also high-amplitude mechanical impulses caused by blast pressure waves.

[0090] Sub-item 2. The device according to item 1 , wherein at least one analog signal path comprises a signal limiting circuit or a dedicated attenuated channel, enabling detection of extreme force levels without saturating the sensing electronics.

[0091] Sub-item 3. The device according to any preceding item, wherein the device is configured to timestamp and log blast exposure events, including magnitude and duration, for later review.

[0092] Sub-item 4. The device according to any preceding claim, wherein the cumulative mechanical exposure is tracked to estimate a daily or long-term "blast dose" experienced by the wearer, with thresholds to trigger alerts or flag for medical evaluation.

[0093] Sub-item 5. The device according to any preceding item, wherein the device further monitors heart rate variability (HRV), breathing rate, or other physiological indicators before and after a detected blast exposure to assess acute or chronic physiological stress.

[0094] Sub-item 6. The device according to any preceding item, wherein the device is worn on or near the chest, waist, or thigh region of a uniformed professional, and operates through layers of military-grade clothing including cold-weather or ballistic gear.

[0095] Sub-item 7. The device according to any preceding item, wherein blast data and physiological metrics are transmitted wirelessly to a central monitoring station or stored locally for secure later retrieval.

[0096] Sub-item 8. A system of any item above, wherein the analog front-end further comprises a signal attenuation stage for enabling measurement of high-pressure blast waves, and wherein the system is configured to log such events and calculate cumulative exposure.BRIEF DESCRIPTION OF DRAWINGS

[0097] The invention is described in more detail with the aid of examples by referring to the following drawings:

[0098] Fig. 1 A is an isometric top view, and Fig. 1 B is an isometric bottom view of a microphone in accordance with one or more embodiments of the presently claimed invention.

[0099] Fig. 2 is an exploded view of a ballistocardiogram with an integrated microphone in accordance with one or more embodiments of the presently claimed invention.

[0100] Fig. 3A is a planar view of a ballistocardiogram device, and Fig. 3B is a cross- sectional view taken at section A-A.

[0101] Fig. 4A is a top view, from the signal electrode side, of the transducer of Fig. 4C (before any folding step, release paper still attached) in accordance with one or more embodiments of the presently claimed invention.

[0102] Fig. 4B is the same but in a partly folded status.

[0103] Fig. 4C is an isometric view of a transducer in accordance with one or more embodiments of the presently claimed invention.

[0104] Fig. 5 is an exploded view of the innovation’s transducer (sensor) in accordance with one or more embodiments of the presently claimed invention.

[0105] Fig. 6 is a plan view of a plurality of transducer’s signal electrodes and a plurality of connector traces having respective contact areas printed on one side of a sheet in accordance with one or more embodiments of the present invention.

[0106] Fig. 7 is a plan view of a plurality of transducer’s signal electrodes printed on one side of a sheet in accordance with one or more embodiments of the present invention.

[0107] Fig. 8 is a plan view of a plurality of transducer’s ground electrodes, and connector traces having respective contact areas printed on one side of a sheet in accordance with one or more embodiments of the presently claimed invention.

[0108] Fig. 9 is a schematic diagram of method of making a dielectric swelled cellular electret film-based transducer in accordance with one or more embodiments of the presently claimed invention.

[0109] Figs. 10A, 10b, and 10c shows a device where the shape and design fits the sensors of Figs 4a, 4b, and 4c, respectively.

[0110] Figs. 11 A and 11 B are isometric views an enclosure that includes two internal threaded inserts designed for optional attachments.

[0111] Fig, 12 is an exploded view of the device of Figs. 11A and 11 B.

[0112] Fig. 13 is a cross-sectional view of the device of Figs. 11A and 11 B.

[0113] Fig. 14 is a perspective view of a wearable device on a user in accordance with one or more embodiments of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0114] The present invention describes a compact, multi-functional device for continuous physiological monitoring, i.e. a physiological monitoring device. The device is small enough to be comfortably worn on the body, for example using a chest or wrist strap, or just put on a pocket, and is capable of measuring one or more physiological parameters such as heart rate, heart rate variability, breathing rate, optionally also step count, general physical activity, body temperature and posture.

[0115] Uniquely versatile, the device incorporates a swelled cellular electret sensor that also enables accurate physiological monitoring when placed under a pillow, mattress, or mattress topper. This dual-use (not referring to tactical use here) capability ensures seamless 24-hour health tracking without compromising comfort or convenience.

[0116] Thanks to its high-sensitivity, permanently charged swelled cellular electret transducer — either arranged directly at the outer surface of the housing or positioned just beneath a soft, flexible interface layer — the device can also function as a wearable stethoscope. This enables non-invasive acoustic monitoring of heart and lung sounds when the device is placed on the chest or upper torso.

[0117] In one or more embodiments, the device is further configured to detect and record extremely high-amplitude pressure events, such as those caused by nearby explosions or concussive blasts. Uniquely, the same ferroelectret transducer element is used for both purposes — capturing subtle physiological signals (e.g., heartbeat, respiration) and intense pressure waves — thanks to its exceptionally wide dynamic range. This integration avoids the need for separate sensors, enabling a compact,lightweight, and power-efficient solution suitable for both health monitoring and tactical applications.

[0118]

[0119] DEFINITIONS

[0120] All definitions are given in the singular but are similarly applicable in the plural unless otherwise stated.

[0121] “Transducer” refers to a physical electromechanical sensor element that converts pressure changes, sound waves, and mechanical vibrations into electrical signals. In preferred embodiments of the invention, the transducer comprises a swelled cellular electret or ferroelectret film, optimized for use as a contact sensor and microphone to detect dynamic mechanical forces, including heartbeat, respiration, and acoustic vibrations. Alternative implementations may use piezoelectric PVDF film or printed piezoelectric materials, though these generally provide narrower dynamic range or reduced conformity compared to the swelled cellular electret approach.

[0122] “Electret,” “cellular electret,” or “ferroelectret” refers to a dielectric material with an essentially permanent electrical polarization. The term ferroelectret (also spelled ferro-electret) specifically denotes cellular or foam-like electret films that contain internal voids or air cavities. These voids act as elastic elements and play a critical role in enabling the electromechanical conversion of pressure waves to voltage signals. In preferred embodiments, the ferroelectret film is swelled (via pressure inflation) to enhance sensitivity and lower mechanical stiffness, resulting in improved impedance matching with soft tissue or bedding environments.

[0123] “Dielectric swelled cellular electret film” and “pressure-inflated pre-foamed cellular electret film” refer to a highly foamed, biaxial ly oriented plastic film that has been expanded (swelled) under pressure, then permanently charged by high-voltage DC injection. These structures are described in WO publication 96 / 06718 and its equivalent U.S. Patent No. 5,955,014 A, which is hereby incorporated by reference in its entirety. Such swelled films provide enhanced mechanical compliance and electromechanical responsiveness compared to unswelled films.

[0124] “Dielectric cellular electret film” without swelling refers to a foamed electret material possessing a permanent electric charge but manufactured without the pressure expansion step. These films have lower void height and typically lower sensitivity.

[0125] “Contact transducer” refers to a sensor element designed to operate without an air gap, directly coupled to the environment or body through mechanical contact orcompression. It may be surface-mounted externally or integrated within the device enclosure under a soft elastomeric interface.

[0126] “Ballistocardiographic signal” (BCG) refers to the mechanical response of the body to the cardiac ejection of blood, typically sensed as subtle micro-movements in the chest, back, or torso. “Phonocardiogram” (PCG) refers to the acoustic representation of heart sounds, such as S1 and S2, sensed via contact microphone.

[0127] “Wearable” refers to a configuration in which the device is carried on the body, for example, worn in a waistband, pocket, or chest strap, typically during daytime use.

[0128] “Under-mattress” or “contactless” mode refers to a configuration in which the device is placed beneath a mattress, cushion, or pillow, enabling nocturnal monitoring without being worn on the body.

[0129]

[0130] ADDITIONAL DISTINCTIONS OVER PRIOR ART

[0131] In addition to the issues discussed above, the present invention introduces multiple technical improvements and a broader application scope over both conventional electromechanical sensors and the applicant’s own prior disclosures, including U.S. Patent No. 11 ,908,576 and application publication US20240177852A1. Specifically, the invention differs in the following key aspects:

[0132] • Improved Mechanical Architectures in Two Embodiments:The invention includes two distinct structural approaches. In the first embodiment, the device has a sealed rigid housing (e.g., glued or ultrasonically welded) with integrated “arms” forming part of the PCB. These allow ECG and / or EDA connections via a chest band while maintaining comfort by routing connectors into recessed cavities, avoiding pressure on the user’s skin.In the second embodiment, a modular rigid-soft housing uses a removable elastomeric interface that enables disassembly, battery and sensor replacement, and mechanical robustness without adhesives. This design supports environmentally conscious servicing and durable integration of the sensor film, while maintaining water and dust resistance.

[0133] • Dual-Mode Operation:Unlike prior art focused solely on wearable operation (e.g., chest band), the present invention enables both wearable and non-contact use — such as placement under a mattress or cushion — supporting seamless 24-hour physiological monitoring with a single device.

[0134] • Simplified and Scalable Manufacturing:The invention minimizes the number of parts and avoids traditional lamination or complex electrode routing. The sensor and its reference electrode are clamped by mechanical compression, eliminating the need for adhesives, soldering, or precision- printed electrode layouts. This simplifies assembly and enhances manufacturability.

[0135] • High Dynamic Range Sensing:The permanently charged ferroelectret film is capable of capturing both low-amplitude signals (e.g., heartbeat, respiration) and high-intensity mechanical shocks or blast waves. This dual-use capability is not disclosed or suggested in earlier publications.

[0136] • Flexible Body Placement:The device operates effectively when worn in locations beyond the chest, such as on the waist, hip, or thigh, or even carried inside a trouser pocket. It does not require direct skin contact, enhancing comfort and flexibility in real-world scenarios.

[0137] • Effective Use Through Clothing:In contrast to ECG and PPG sensors, the invention maintains signal fidelity through multiple layers of clothing. This enables reliable use in cold climates and under layered garments, improving practical usability without sacrificing measurement quality.

[0138] • Improved Signal Quality and EMI Shielding:The structural design allows for a mechanically held reference electrode that also serves as an EMI shield. This reduces noise and improves reliability without relying on tightly aligned printed dual electrodes, which are fragile and error-prone in prior art.

[0139] These advancements collectively provide a novel and inventive platform for both civilian and tactical applications, combining health tracking, physiological monitoring, and high-intensity event detection in a compact, durable, and manufacturable device.

[0140]

[0141] LIMITATIONS OF EXISTING HEALTH MONITORING DEVICES AND ADVANTAGES OF THE PRESENT INVENTION

[0142] Beyond materials and manufacturing, current wearable or contactless health monitoring systems often face functional and usability constraints:

[0143] • Devices are typically specialized: one for heart rate (e.g., chest strap), one for activity (e.g., wristband), and another for respiratory or acoustic sensing.

[0144] • Users may be required to wear multiple devices simultaneously, or switch between devices for day vs. night use.

[0145] • Battery life is often limited, requiring frequent recharging, sometimes daily.

[0146] • Under-mattress systems (e.g., radar or pressure mats) are often bulky, have limited sensitivity through bedding, and are not portable.

[0147] • Piezoelectric sensors, although rugged, couple poorly with low-force signals like respiration or subtle heart vibrations and typically require rigid mounting or adhesives.

[0148] In contrast, the present invention:

[0149] • Enables multi-parameter sensing (heart rate, HRV, respiration, sound, motion, temperature) using a single, thin, and low-cost sensor element.

[0150] • Functions both as a wearable and as a contactless under-mattress solution, increasing usability and comfort.

[0151] • Avoids adhesives, cables, and complex assembly through a unified structure using integrated ferroelectret film and optimized enclosure mechanics.

[0152] • Delivers robust signals across both low and high pressure ranges, from faint heartbeat to explosive blast waves in military use scenarios.

[0153] These capabilities make the present invention a uniquely versatile, manufacturable, and user-friendly platform for continuous physiological monitoring — offering a level of integration and ease-of-use not seen in current systems such as chest-strap heart rate monitors (e.g., Polar®, Garmin®), smart rings (e.g., Oura®), or under-mattress sensors (e.g., Beddit®). Such prior systems are typically single-purpose, require direct skin contact, or lack portability — limitations which the present invention overcomes through its multifunctional, dual-mode design.

[0154]

[0155] INTEGRATED BALLISTO- AND PHOCARDIOGRAM TECHNOLOGY

[0156] Conventional electronic stethoscopes typically rely on air-gap electret microphones with applied bias voltage, which increases design complexity and limits their multifunctionality. Such configurations are not well-suited for applications requiring the simultaneous measurement of heart rate, heart rate variability (HRV), respiratory rate, and acoustic monitoring of heart and lung sounds.

[0157] The present invention overcomes these limitations by employing a permanently charged, swelled cellular ferroelectret film as the transducer element. This film provides dual functionality: it senses fine mechanical forces for physiological rhythm analysis and captures audio-frequency signals for auscultation.

[0158] Operating effectively from frequencies as low as 0.05 Hz — suitable for analyzing respiratory cycles — and extending to several kilohertz (e.g., 2 kHz or more), the filmenables stethoscope-like functionality. Technically, the sensor can respond to even higher frequencies, up to several tens of kilohertz, allowing detection of a wide range of physiological and environmental signals.

[0159] This single, cost-effective transducer element allows the device to function both as a ballistocardiogram (BCG) sensor and a high-fidelity acoustic microphone capable of producing a phonocardiogram (PCG) — an audio-based representation of cardiac activity. It is especially well-suited for capturing clear heart sounds such as S1 and S2, as well as discrete mechanical events like coughs.

[0160] While the dynamic, permanently charged, swelled electret sensor is capable of detecting frequencies up to several tens of kilohertz, in practice, the dominance of low- frequency response may reduce sensitivity to certain high-frequency lung sounds. Nonetheless, the device remains suitable for basic auscultation purposes and provides meaningful acoustic monitoring when placed in contact with the body — directly or through layers of clothing — or under a mattress or cushion.

[0161] The innovative integration of the swelled ferroelectret film sensor on a rigid-rigid enclosure embodiment, or soft-rigid enclosure embodiment structure ensures both mechanical compliance and durability. This makes the invention suitable for wearable configurations and non-contact setups, including tactical environments where blast wave detection may be required. The result is a compact, versatile system for sleep tracking, vital signs monitoring, and situational awareness, with applications ranging from consumer wellness to clinical and military use.

[0162]

[0163] ALTERNATIVE USE CASE: BLAST PRESSURE MONITORING AND EXPOSURE TRACKING

[0164] In certain embodiments, the device is configured to detect and record extremely high-amplitude pressure events, such as those caused by nearby explosions or concussive blasts, and / or when a weapon is fired and the explosion creates an invisible high-pressure shock wave as reported in www.abc.net.au / news / 2025-02-12 / sniper-blast- brain-injury-defence-personnel / 104847586.

[0165] The permanently charged swelled ferroelectret film used as a sensor element provides a uniquely wide dynamic range, allowing the same sensor to capture both low- amplitude mechanical signals (e.g., heartbeat, respiration) and very high-intensity pressure waves.

[0166] To support such dual-functionality, the device may include at least one analog input channel with signal attenuation, such as a resistive voltage divider or a multi-stage gain selection circuit. This ensures that the sensor signal is not saturated when exposed to intense pressure waves (e.g., from artillery fire or explosive devices). The system may be configured to automatically detect such blast events based on waveform thresholds or signal derivatives and log the occurrence for later review.

[0167] In military or high-risk environments, the device may be worn continuously by personnel, allowing long-term tracking of exposure to blast events. The system may also calculate an accumulated exposure dose over time, based on intensity, frequency, and duration of each detected blast wave. When a predefined cumulative threshold is exceeded, the device can flag the individual for medical evaluation or temporary rest, supporting operational health and safety protocols.

[0168] This use case is made possible by the inherent robustness and sensitivity of the ferroelectret sensor element, and by the device's ability to switch between physiological monitoring and environmental sensing without hardware modification.

[0169]

[0170] FERROELECTRET SENSOR STRUCTURE AND MANUFACTURING APPROACH

[0171] This invention leverages the exceptional properties of a novel material known as swelled cellular electret film, also referred to as ferroelectret film. This material is uniquely suited for physiological signal detection due to its high sensitivity and ability to convert mechanical vibrations into electrical signals across a wide dynamic and frequency range. The film consists of layered micro-scale air cavities which amplify sensitivity to subtle forces, such as heartbeat or respiration-induced motion, while also withstanding extremely high sound pressure levels.

[0172] Unlike conventional electret microphones, the transducer in this invention does not rely on an air gap. The absence of an air gap enables direct transmission of pressure variations from body movements, breathing, and heartbeats into the active sensing layer. This structural difference allows the transducer to detect a wide range of physiological signals with superior fidelity and resilience, especially under compressive loading conditions such as when placed under a mattress or pillow.

[0173] In one embodiment, the ferroelectret film is positioned directly on the outer face of the housing, covered by a protective thin membrane, for example a label layer, forming a contact surface with the environment or body. In another embodiment, thetransducer assembly is integrated within the device housing, underneath a soft elastomeric cover (802), and mechanically compressed between a reference electrode (805) and a signal electrode on the PCB (803). This internal placement provides enhanced durability, shielding, and long-term serviceability, while maintaining high sensitivity.

[0174] The invention also introduces a cost-efficient manufacturing method for producing these high-performance transducers. The process involves high-pressure gas expansion of biaxially stretched films such as cellular polypropylene (PP), cyclic olefin copolymer (COC), or their combination (PP / COC). After film expansion, the layers are permanently polarized via DC charging and laminated with dielectric layers (e.g., polyester, polyimide). In one embodiment, electrodes are applied to opposite surfaces using screen-printing of conductive silver, technically could also be etching from laminated metal lamination, and perforations may be introduced to support folding for integration. The resulting transducer is a shielded, flexible, and durable sensor capable of operation across both infrasound and audio ranges for use as ballisto- and phonocardiogram.

[0175] At least one electromechanical film, preferably ferroelectret transducer film, is integrated into the device. Whether mounted externally on the case surface, or internally beneath a soft cover, in the other explained embodiment, the film operates under controlled compression, enabling the capture of minute mechanical forces and acoustic vibrations. Its robustness allows it to detect extremely subtle heart signals even through thick bedding materials, while also tolerating mechanical shock from accidental drops or user abuse, or even explosions in user proximity.

[0176] This multifunctional transducer is a core enabler of the invention’s dual-purpose use: under-mattress operation for contactless nighttime monitoring, and wearable use during the day. Together with integrated wireless transmission, battery operation, motion sensing, and optional temperature and bioimpedance electrodes, the system forms a comprehensive, compact, and manufacturable solution for round-the-clock physiological tracking.

[0177]

[0178] DETAILED DESCRIPTION - CHEST BAND DESIGN AND FUNCTIONALITY

[0179] With reference to Fig. 14, chest band 900 is designed to securely hold the previously described in physiological monitoring device 100 against a user's chest. It ismade from a stretchable, elastic material and is adjustable in length for user comfort. Electrodes are integrated the band, on both left and right side of the body center line.

[0180] These electrodes are strategically aligned to interface with the device's "arms" or handles protruding from the PCB, to outside of the case. Only the sections of the electrodes intended to contact the skin remain exposed; the rest are covered by non- conductive fabric to maximize comfort and ensure correct positioning.

[0181] Each end of the chest band is formed by folding the fabric back on itself (approximately 180 degrees) and sewing it in place. The conductive fabric electrode passes between the folded layers and becomes visible again at the ends. This forms a "channel" that can be slipped over the device’s arms, creating a direct electrical interface between the band’s electrode and a matching contact on the device's circuit board.

[0182] This structure ensures a reliable electrical connection while maintaining a comfortable and secure fit. In configurations where both ECG and EDA signals are to be measured, the chest band may include multiple electrode layers. These are arranged so that ECG and EDA electrodes lie side-by-side within the same channel at one end of the band, aligning with corresponding electrodes on the device. This enables accurate, cost- effective acquisition of both ECG and EDA data.

[0183] Compared to the applicant’s patent application publication US20240177852A1 , which provides more details about a chest band suitable for use with an embodiment of the present invention, the innovative step here lies in the reduced number of parts (conductive arms) and assembly labor (potting), while still enabling connection to ECG and / or EDA electrodes on the chest band.

[0184]

[0185] BALLISTOCARDIOGRAM WITH INTEGRATED MICROPHONE

[0186] Referring to Figs. 1 and 11 , in accordance with two or more embodiments of the presently claimed invention, a ballistocardiogram device 100 is presented. Both figures show axonometric views of the wearable and under-mattress versions of the device.

[0187] Referring to Fig. 2, the ballistocardiogram device features a two-part enclosure (205a, 205b) made of biocompatible ABS or other suitable plastic. The transducer element 204 is mounted on the outer surface of the top half (205a), beneath a decorative and informative label 217, which may be made of biocompatible Lexan®. The transducer's flexible connector 207 passes through an opening 206 in the enclosure and is routed inside to connect with a pin header 208 on the circuit board (PCBA 209). The pin header may be a standard 2.54 mm type, a narrower 2.0 mm pitch, or a zero-insertion-force (ZIF) connector. In the ZIF option, the sensor 204 includes conductive areas aligned with the connector region 207.

[0188] Also mounted on the same side of the PCB is a rechargeable battery 210, with a nominal capacity of approximately 400 mAh. The opposite side of the PCBA (201) hosts the remaining electronics, including key analog components such as band-pass filters and amplification stages.

[0189] The enclosure includes small openings (215, 216) for two protruding arms (211 , 212), which are extensions of the PCB. A soft, elastic chest band (see Fig. 13) attaches to these arms, which may have electrodes arranged on them for ECG or EDA measurement. The arms extend slightly outside the case (205) but are recessed within protective contours (213, 214), so that only their outermost edges contact the skin, ensuring comfort during wear.

[0190] The arms are touch-accessible, enabling a quick ECG measurement by touching each arm with the corresponding hand (left hand finger to left arm, right to right). If ECG or EDA is not needed, the arms may be left without electrodes, relying solely on the BCG transducer.

[0191] Their shape also facilitates easy detachment of the chest band, allowing the device to be repositioned under a mattress, topper, or pillow for nighttime use. Alternatively, ECG / EDA connections can be implemented using metal snap connectors, as commonly seen in products by Polar or Garmin.

[0192] The circuit board hosts a module with an analog-to-digital (AD) converter, central processing unit (CPU), and Bluetooth radio, such as the Fanstel BT840F. Optionally, a Nordic nRF52840 chip supporting Bluetooth 5, and an ESP32-Wroom module for occasional WiFi-based data uploads can be included to conserve battery power. Alternatively, a cellular radio module such as the nRF9160 may be integrated. The specific radio configuration depends on the intended use case. All components are preferably arranged on one side of the circuit board for manufacturing efficiency.

[0193] Fig. 1A is an isometric top view, and Fig. 1 B is an isometric bottom view of a microphone in accordance with one or more embodiments of the presently claimed invention.

[0194] Fig. 2 is an exploded view of a ballistocardiogram with an integrated microphone in accordance with one or more embodiments of the presently claimed invention.

[0195] Referring to Figs. 1A and 1 B:

[0196] Referring to Fig. 1 B, it is possible to have a display 218 as well. For example, Sharp's memory display uses very low power, is thin, and can be integrated into the device. One or a few switches can be used for the user to interact with the device. A tiny speaker can be integrated for speaking remotely to a patient, and a tiny microphone can be integrated for speaking back to someone like a nurse.

[0197] Fig. 3A is a planar view of a ballistiocardiogram device 100 and Fig. 3B is a cross-sectional view itaken at section A-A. The microphone's transducer element 204 — preferably made of permanently charged, swelled cellular electret film — is mounted on the outer surface of case part 205a, where it responds directly to mechanical forces. By placing the transducer externally and protecting it only with a thin label sticker (e.g., made of polyester), the sensing element, despite its small area, generates a sufficiently strong charge signal for reliable acquisition even through a mattress.

[0198] This construction allows for a compact, comfortable, and unobtrusive device design, enabling continuous 24 / 7 use. During the day, the device does not need to be worn directly on the chest — it can be placed in a trouser pocket or clipped under the waistband, where it can still accurately detect heart rate and breathing rate, particularly in seated or low-movement conditions. Unlike wrist-worn devices or rings with optical PPG sensors, this device operates without any visible light emission, providing greater comfort and discretion.

[0199] When worn on the chest, the transducer is positioned close to the skin, enabling high-fidelity ballistocardiographic (BCG) and phonocardiographic (PCG) sensing. This is particularly beneficial for applications requiring precise signal quality, such as calculating heart rate (HR), respiratory rate (RR), and heart rate variability (HRV). The mechanical and electrical construction of the sensor offers excellent coupling to the body, resulting in a clean signal with minimal noise — making it ideal for advanced signal processing task.

[0200] Referring to Fig. 4A, 4B, and 4C.

[0201] Fig. 4C is an isometric view of a transducer 204, quite similar to that one of Figs. 1A, 1 B, 2, and 3, in completely folded status, in accordance with one or more embodiments of the presently claimed invention. It is to be noted that this transducer form factor does not fit the case design, but the methodology is the same, and the device 100 technically could be designed to fit that shape as well. Instead, Figs. 10A, 10b, and 10c shows a device 100 where the shape and design to fit to sensor in Figs 4a, 4b, 4c, respectively.

[0202] Fig. 4B is the same but in a partly folded status.

[0203] Fig. 4A is a top view, from the signal electrode side, of the transducer of Fig. 4C (before any folding step, release paper still attached) in accordance with one or more embodiments of the presently claimed invention.

[0204] In that order, Fig. 4A - 4B - 4C shows the transducer before and after various folding stages, from beginning to completion. To begin, begin being a cut form. Fig. 4A is a transducer after a prior manufacturing step, that being laser or die-cutting. Fig. 4C is a folded transducer after a prior manufacturing step 4B. Fig. 4C is completely folded, ready for crimping contacts, or if prepared for ZIF connector on the PCB, having contacts on the area 407. In Fig. 4B, the protective paper 410 from the adhesive 409 has already been removed.

[0205] The transducer signals are preferably transmitted via transmission traces 405 to a preamplifier on the PCBA 209. Two connectors, such as a 2,54 mm version Crimpflex™ from Nicomatic, are to be crimped to the traces' ends 407. One connector is for signal trace, and one is for ground electrodes on the opposite sides of the signal electrodes (403a, 403b, 403c).

[0206] Transducer 204 may have any suitable shape, form, or form factor, but preferably, it is designed to be rectangular or round. As round, suitable diameter is 50 mm, but it can be less or more, depending on the final application and characteristic preferences. It consists of the shape of transducer 204 and the shape of connector 406. However, other shapes may also be suitable for various reasons, not least for commercial purposes.

[0207] The transducer is attached to case 205a, preferably using a 10 to 50 micron thin acrylic adhesive. 50 micron thin adhesive is made, for example, by 3M®, 10 and 30 micron types are available for example from Nitto®.

[0208] Herein, a transducer 204 i. e. converts force changes and vibrations, such as breathing movements and heart beats, even heart sounds when placed on it on the chest, and in case of tactical use case, even explosions into electrical signals. Due to its cellular nature, sensitivity to thickness changes, and very good impedance matching with a human body, the swelled cellular ferroelectret material-based transducer is very good for the application.

[0209]

[0210] Continuing refers to Fig. 4A, 4B, 4C, and in addition to Fig. 5. Fig. 5 is an exploded view of the innovation’s transducer (sensor) in accordance with one or more embodiments of the presently claimed invention.

[0211] Transducer element 204 comprises a unitary ferroelectret film 504 for its entire area. Thus, advantageously, transducer 204 is realized as a unitary, flexible, and laminated structure that extends seamlessly from forces, sounds and vibrations picking areas 403a, 403b, and 403c, through a connector area 406, including contact area 407.

[0212] Transducer 204 is advantageously formed as a dual structure with a first side 403a and a second side formed of portions 403b and 403c. There are two perforations, 402a and 402b, to fold portions 403b and 403c against 403a. Portions 403a, 403b, 403c, and traces 405a and 405b of each of transducer 204, are disposed on same each side 403a, 403b and joined by the manufacturing process to form the respective transducer 204, connector 406, and contact area 407.

[0213] Advantageously, transducer 204 does not require a mechanically separate transducer and distinct wiring between the transducer and one or more connectors for connecting to a preamplifier since it will be formed by printing electrodes on substrate 151a, formed by laminating thin dielectric films, for example polyester, on a preferably swelled, voided ferro-electret film.

[0214] Transducer 204 comprises signal pickup (transducer) areas 403a, 403b, and 403c, divided along fold lines 402a and 402b. The first signal pickup area 403a, a second signal pickup area 403b, and a third signal pickup area 403c are connected via narrow traces 404 crossing (passing) fold lines. Sensing areas 403b and 403c continue to trace 405a and 405b to connect to the connector 407 preamplifier on circuit board 209. Transducer 204's final shape may be any suitable for its final purpose, but it preferably rectangular or almost round.

[0215] In accordance with one or more embodiments of the presently claimed invention, as shown in Fig. 4B, one or more margins 411 are disposed between an edge of a transducer 204 and signal electrode area 401. Therein, one or more margins 411 are preferably at least 0,5 but rather 1 mm to prevent 50 Hz / 60 Hz electromagnetic noise (hum) from entering the picked signal for amplification and preventing signal pickup at high enough frequencies for listening heart sounds.

[0216] Referring now to Fig. 5, it is an exploded view of a transducer during manufacturing in accordance with one or more embodiments of the presently claimed invention.

[0217] T ransducer 204 comprises a plurality of layers. Outer layer 501 , which comprises a protective paper layer 501a (to be removed before folding) and an adhesive 501b, more specifically, an adhesive layer 501b on the first side 501 and adhesive layer 503bon the opposite side 503 with protective paper layer 503a are applied in step 665 (Fig. 9).

[0218] Transducer 204 is disposed of two electrodes, signal (505) and ground (506), printed on opposite sides of the cellular electret film 504. Cellular, preferably swelled electret film 504, for example, made of PP, is made printable by laminating very thin PET layers, preferably 23 microns, due to their good availability and still being thin enough not to reduce much signal strength, on both sides of it.

[0219] A ground also can be called reference electrode 506 is disposed on the bottom side of the electret film 504, and a graphite layer 507 is disposed facing ground electrode 506.

[0220] Adhesive layers 501 b and 503b are preferably between 20 and 100 microns thick. However, in accordance with one or more embodiments of the presently claimed invention, the thickness of the adhesive 50 microns is a very good choice because of its good availability.

[0221] Since the electrodes are printed directly onto the PET layers, the adhesive thickness does not reduce signal strength and increase noise, as has been the case with prior art ferroelectret pickups, as explained in patents such as U.S. Pat. No. 6,242,683 and U.S. Pat. No. 6,336,367.

[0222]

[0223] METHOD OF MANUFACTURING DIELECTRIC SWELLED CELLULAR ELECTRET FILM-BASED TRANDSDUCER

[0224] Fig. 9 is a schematic diagram of method 600 of making a dielectric swelled cellular electret film-based transducer 204 in accordance with one or more embodiments of the presently claimed invention. This transducer is particularly suited for use as a microphone's transducer.

[0225] In the first step 605, a biaxially oriented polypropylene ("PP") film is manufactured for this purpose and used as a PP electret film for transducer 204.

[0226] The method of manufacturing of PP electret film is disclosed, for example, in U.S. Patent No. 4,654,546, which is hereby incorporated by reference in its entirety for all purposes. Alternately, PP electret film for transducer 104 is purchased, acquired, or provided as necessary by a user or other person associated with method 600. Therein, PP electret film will first be in roll form.

[0227] In a subsequent step 610a, the PP film is subjected to AC corona treatment. The AC corona treatment is necessary to make one or more PP film surfaces beneficial forlamination with PET layers in a subsequent step. The AC corona treatment improves the adhesive bonding of the PET layers and the PP film, i.e., the PP film surface.

[0228] In step 610b, which, while preferably performed at the same time as step 610a, is not required to be performed at the same time as step 610b, the PET layers are also subjected to an AC corona treatment on one or more sides of the PET layers, or preferably on both sides of the PET layer, for improved adhesion both with the swelled PP film and printing the silver paste, or other highly conductive electrode material.

[0229] In subsequent step 615, directed broadly to swelling, the material’s later (after step 625) sensitivity (pC / N) is enhanced by undergoing swelling after AC charging and before DC charging. This is explained in WO publication 96 / 06718 or its equivalent U.S. Patent No. 5,955,014. U.S. Patent No. 5,955,014 is hereby incorporated by reference in its entirety for all purposes.

[0230] During the swelling of step 615, the PP film's thickness is increased by increasing the height of cavities. Advantageously, the weight remains the same, but the thickness increases. This gives more sensitivity when charged for having a permanent electric charge.

[0231] As previously taught, as the thickness changes, the opposite charges on the opposite sides of the voids either draw closer together or move farther apart, generating so-called mirror charges across the electrodes positioned above the cellular electret film. Consequently, this produces a measurable electrical output voltage proportional to the force change.

[0232] The charged material PP electret film holds positive and negative charges on opposite sides. Thus, signal electrodes are usually printed on the positive side and ground on the negative side, but these can also be arranged in opposite manners.

[0233] Due to the elastic swelled cellular core, Young's modulus of cellular electret film transducer 204 is significantly reduced. This leads to improved impedance matching, particularly with air, as opposed to hard piezoelectric materials.

[0234] In a subsequent step, 620 is directed broadly to lamination, following the swelling, to prevent shrinkage during subsequent silver paste curing, preferably a 23- micron-thin polyester (PET) layer, but can be thinner or slightly thicker, is laminated onto both sides of the electret film in a reel-to-reel process preferably using the wet gluing method. The PET is preferred to be heat treated to prevent its shrinking during silver paste curing.

[0235] Advantageously, the thin PET film on both sides of the core’s cellular PP film enables the direct printing of transducer signal and ground electrodes, resulting in a laminate where the cellular, swelled ferroelectret film forms the core. Herein, the core is the material in the laminate that gets charged in a high DC field where discharges occur in the core’s lens like gas bubbles (cavities) during DC charging.

[0236] Advantageously, a thin PET layer of 10-20 microns does not significantly increase thickness. The excessive thickness of PET layers in the laminate would decrease the sensitivity of the achieved electromechanical films, i.e., the charge output from sound and vibrations. Herein, in accordance with one or more embodiments of the invention, an excessive thickness of a PET layer is defined as 23 microns. In accordance with one or more embodiments of the invention, an excessive thickness of a PET layer is defined as 30 microns or more. That is, advantageously, in accordance with one or more embodiments of the presently claimed invention, the thickness is kept at a minimum.

[0237] In step 620, instead of polyester (PET) many other plastics can be used. Therein, polyamide is a one good substitute. However, PET is the most cost-effective and much more cost-effective than polyamide; it is easily available and has excellent purpose- directed properties. Purpose-directed properties are defined herein as being the property of being heat treatable for becoming non-shrinking and the property of having, after corona treatment, good adhesion with silver paste.

[0238] Utilizing a very thin wet adhesive in a reel-to-reel lamination process, with an end thickness of 10-20 microns after curing, helps minimize overall thickness and weight and achieve the best properties for a force and vibrations and sound sending contact microphone transducer. Advantageously, the thinner PET with adhesive layers between later explained electrodes and the core’s cellular PP film yields higher output, as the thicker the entire structure between signal and ground electrodes, the lower the output of such ferroelectrics.

[0239] The laminated (PET-PP-PET) structure, with the PET being heat treated beforehand, does not shrink during the approximately 80°C curing required for the silver paste and graphite layers needed for electrodes, as explained later. Preferably, such a laminated structure facilitates creating a structure where electrodes printed on both side surfaces can be perfectly aligned before cutting into individual pickups.

[0240] Following the lamination process of step 620, in step 625, the obtained PET-PP- PET material, i.e., laminate 504, is charged at a very high DC voltage, typically in the range of 20-25 kV, against resistive material.

[0241] In accordance with one or more embodiments of the presently claimed invention, the cellular ferroelectret film is charged in step 625 after it is laminated with PET films. Technically electret film can be charged before lamination. The sequence of step 620, followed by step 625, helps prevent discharges when a charged material is rolled into an end-roll in the final phase of reel-to-reel charging. Charging this laminated material in sheets is also possible, but it is slower, resulting in increased manufacturing costs. Step 625 of charging must be completed before printing the electrodes in step 650.

[0242] After the laminated (PET-PP-PET) ferroelectret material is charged, it is preferably cut into smaller sheets 151a in step 630 of broadly cutting. In accordance with one or more embodiments of the presently claimed invention, five transducers 204 will be available for cutting from one sheet after screen printing the electrodes in step 650.

[0243] Referring to Fig. 7. After cutting onto smaller sheet 151a in step 630 to obtain the preferred quantity of transducers, the sheet is prepared for high-precision printing in step 640 by making one or more alignment holes 153 in sheet 151a. Hole cutting in the sheets can be done by easiest by laser cutting or die cutting.

[0244] After obtaining sheet 151a, alignment holes 153 are made through sheet 151a to prevent unintended displacement of sheet 151a during printing of signal electrodes 158 or ground electrodes 154 and to enable or proper alignment.

[0245] After sheets 151a are obtained and alignment holes 153 are made, signal electrodes 505 are arranged, preferably screen-printing with silver paste in step 650 (Fig. 6). Inkjet printing could be possible as well, but screen printing is a well-tested method. One embodiment's film for printing screen is shown in Fig. 7. Five individual transducers are obtained using it.

[0246] Referring to Fig. 7 and 8, after step 650 (Fig 6), ground electrodes 506 are screen-printed, preferably with silver paste in step 655 (Fig. 6) on the opposite side of sheet 151a. In one embodiment of the invention, a screenprinting film is shown in Fig. 7. Then, after curing the silver paste 506, in step 655, the same design is printed with graphite as a graphite layer 507. Since graphite serves as the outer face of the final product, this protection is preferred for durability. Silver could also be protected from oxidation and silver migration by using printed or cast lacquer or a very thin plastic filmwith adhesive. Graphite possesses excellent resistance to handling and abrasion, and unlike silver, it does not oxidize or migrate.

[0247] Fig. 6 is a plane view of a plurality of transducers' 204 signal electrodes 505 and a plurality of connector traces 405 having respective contact areas 701 printed on one side of a sheet 151a in accordance with one or more embodiments of the presently claimed invention.

[0248] Fig. 8 is a plane view of a plurality of transducers' 204 ground electrodes 506, and connector traces 508 having respective contact areas 509 printed on one side of a sheet 151 a in accordance with one or more embodiments of the presently claimed invention.

[0249] In step 650, signal electrodes 505 comprising transducers 104 and a plurality of connector traces 405 having respective contact areas 509 are directly printed on sheet 151a using sheet printing utilizing alignment holes 153 for precise alignment of sheet 151a.

[0250] Instead of sheet printing, signal electrodes can be screen-printed reel-to-reel on laminated PET-PP-PET electret film. However, sheet printing has a higher accuracy than reel-to-reel printing where accuracy is more difficult to obtain.

[0251] Both printed layers are printed exactly in the correct place using alignment holes 153.

[0252] After printing signal and ground electrodes, adhesive sheets with protective papers are applied. The signal side is completely covered with adhesive, and later, in step 670, the transducer is folded so that signal electrodes remain inside. In practice, only half of the whole area needs adhesive. The adhesive is also added on the ground electrode side. There, it is needed on the final folded transducer only in area 408 (Ref Fig. 4C) for attaching to case.

[0253] In step 665, sheet 151a is cut to individual transducers 204. This can be achieved through die-cutting or laser cutting. Alignment holes 153 are utilized to more accurately make the cuts.

[0254] Referring to Fig. 4B and Fig. 4C, an innovative new method is to use perforations (402a, 402b) that enable folding the transducer like origami in the final state before crimping contacts. In the described embodiment of the innovation, trying to achieve a rectangular or round shape, two perforations (402a, 402b) are crosswise. Depending on preferences, it is possible to have only longitudinal or only crosswise perforation, or both kinds, to enable folding and form a shield against EMI (electromagnetic interference, the50 or 60 Hz hum). In this method, the transducer area always has two layers of electroactive material and a complete shield in which signal strength and shielding are optimized for highly efficient production.

[0255] Fig. 4A represents a transducer to become like in Fig. 4C. Fig. 4B shows it during folding. At this point, the protective paper (409) covering the adhesive layer has already been removed. In the innovation's pickup production method, the perforations obtained during cutting facilitate the final folding process to create completed transducers ready for attaching connectors.

[0256]

[0257] DETAILED DESCRIPTION - EMBODIMENT WITH INTEGRATED SENSOR STACK

[0258] Referring now to Figs. 11 A, 11b, 12, and 13, in the second embodiment, the device includes, comprises or consists of three main structural components:

[0259] 1. Two rigid housing elements (800, 801), preferably made of hard plastic such as ABS. In other embodiments, these may be made partially or entirely of metal, for example die-cast aluminum or CNC-machined light alloy, with antenna transparency ensured by plastic or ceramic sections, or fully ceramic housings.

[0260] 2. A third component, the soft interface part (802), is made of a flexible elastomer such as silicone, polyurethane, or thermoplastic polyurethane (TPU).

[0261] The hard parts (800, 801) are joined together with screws (806), forming a sealed mechanical enclosure. During molding, the soft part (802) is shaped to include an internal flange or collar (807), which is elastically stretched to allow the larger-diameter PCB (803) to pass through during assembly and then becomes locked in a corresponding groove formed between the two hard parts. This ensures a mechanically fixed yet removable interface, providing both water and dust resistance without adhesives.

[0262] This flexible part (802) allows outer surface deformation when subjected to pressure or vibration, such as when the device is placed under a mattress or cushion or worn on the body — even through multiple layers of clothing. The soft elastomeric part (802) enables an electromechanical sensing film — such as a swelled and permanently charged ferroelectret film, a piezoelectric PVDF film, or a printed piezoelectric material — to detect vibrations and forces, allowing it to function as a ballistocardiogram and / or phonocardiogram sensor. Suitable body locations include the chest — enabling use as aphonocardiogram, not just a ballistocardiogram — as well as the waist, hip, or thigh region, for example under a trouser waistband or belt, or simply inside a pocket.

[0263] Beneath the soft part (802) lies a laminated sensor structure consisting of:

[0264] • A thin conductive reference film (805), preferably consisting of aluminum(~10 pm) on a PET substrate (~75 pm), or alternatively a silver-ink printed electrode on the outer surface of a PET layer laminated to the ferroelectret film.

[0265] • A permanently charged, swelled ferroelectret film (804), placed beneath 805, with its bottom surface facing the PCB (803), where the signal electrode is located.

[0266] The reference electrode (805), which also acts as an EMI shield, is not glued to the ferroelectret film but is held in place by mechanical compression from the enclosure. A narrow extension or tab on 805 wraps around the PCB and connects to a ZIF or equivalent connector to establish ground potential. This non-permanent stacking method enables cost-effective production, servicing, and eventual replacement of the sensor assembly.

[0267] In another configuration, the film stack may use a PET-PP-PET laminated ferroelectret structure, as described earlier in this application. In that case, a ground electrode may be printed with silver paste on the top PET layer, facing outward, and a signal electrode printed on the bottom side facing the PCB. The PCB may additionally include an external EMI shield, separated by an insulating PET layer, either printed or mechanically interleaved.

[0268] The printed circuit board (803) is positioned in a recess within housing part 801 to prevent lateral displacement. It includes:

[0269] • Analog filtering,

[0270] • Analog-to-digital conversion,

[0271] • A wireless communication module (e.g., Fanstel BT840F or ESP32),

[0272] • Optionally an Al coprocessor (e.g., Ambient Scientific GPX10),

[0273] • A temperature sensor 812 positioned near the center, with a dedicated aperture in the housing for accurate ambient or skin-adjacent thermal sensing near the films 804 and 805. Films 804 - 805 can have openings 813, 813b, for temperature sensor 812.

[0274] • Two AAA size NiMH rechargeable or could be primary cell batteries 811.

[0275] Other optional components include:

[0276] • A motion sensor (accelerometer and gyroscope) for tracking activity, posture, and falls,

[0277] • One or more mechanical buttons or slide switches for power control, activity marking, or battery level checks,

[0278] • One or more indicator LEDs, or optionally a small integrated display,

[0279] • Rechargeable AAA NiMH batteries or optionally other battery chemistries(e.g., LiPo), accessible by removing screws (806),

[0280] • A USB-C charging port with environmental sealing 810, preferably integrated into the soft part (802). As an alternative, inductive charging can be supported by placing a receiver coil between elements 802 and 805.

[0281] The sensor stack is capable of detecting fine mechanical impulses, enabling realtime estimation of heart rate, heart rate variability (HRV), and respiration rate. The device is suitable for continuous use under bedding during sleep, or worn in a pocket, at the waist, or on the chest during the day. The rigid-soft-rigid enclosure ensures mechanical robustness, signal clarity, and user safety, especially when avoiding LiPo batteries in bedding applications.

[0282] Referring to Figs. 11 A and 11 B, the enclosure includes two internal threaded inserts 809 designed for optional attachments — such as a clip for securing the device under a trouser belt or inside a jacket’s chest pocket. A flexible plug 810 to prevent dust entering the USB-C port is integrated into soft and flexible part 802.

[0283]

[0284] BLAST EXPOSURE MONITORING

[0285] The claims of this invention cover a multifunctional physiological monitoring device comprising a deformable elastomeric outer interface and a high-sensitivity electromechanical sensing film — preferably a swelled and permanently charged ferroelectret, but also optionally piezoelectric PVDF or printed piezoelectric materials. The invention enables detection of cardiac and respiratory signals such as ballistocardiograms and phonocardiograms without requiring direct skin contact, including when worn under clothing or placed beneath cushions or mattresses. Claimed usage locations include the chest, waist, hip, thigh, or inside pockets, allowing flexible and unobtrusive monitoring across a wide range of use scenarios. The invention also defines a cost-effective and mechanically durable structure, distinguishing it from prior art ECG or PPG-based solutions.

[0286] In addition to enabling unobtrusive physiological monitoring through clothing and bedding, the invention also claims a capability for detecting high-intensity mechanical events, such as shockwaves from blasts or explosions. This is achieved through the useof a wide-dynamic-range electromechanical film transducer — preferably a swelled, permanently charged ferroelectret, but optionally a piezoelectric PVDF film or printed piezoelectric material — integrated into a deformable elastomeric interface.

[0287] The device includes provisions for a dual-channel or signal-limited analog path to preserve data integrity during high-force events, allowing detection and classification of blast exposures without saturating the signal chain. These features make the invention suitable for use in military or law enforcement contexts, where tracking daily cumulative blast exposure and post-event physiological state (e g., HRV changes) is essential for health surveillance.

[0288] This enables real-time or retrospective detection of physiological impact from blast events, aiding in early intervention and injury prevention in high-risk occupational environments.

[0289]

[0290] It is evident to those skilled in the art that various embodiments of the invention are not limited to the examples outlined above, but rather can be modified within the scope of the claims provided below. The form (shape) can be selected based on the requirements of each specific case; there can be multiple transducer areas, and the shape of the area can vary beyond a rectangular form in the top view. These transducers have versatile applications, including their use as transducers in musical instruments.

[0291] While the invention has been described in conjunction with specific embodiments, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description.

Claims

Claims1 . A physiological monitoring device, the device comprising: a housing formed by two rigid structural elements (800, 801), a soft elastomeric part (802) mechanically locked between the two rigid elements, a electromechanical film sensor assembly (804) positioned beneath the soft part (802), wherein the assembly comprises a conductive electrode (805) arranged above the electromechanical film, wherein the electrode (805) includes electrical connection routed to the printed circuit board (PCB), and wherein the device further comprises electronics for signal processing, wireless communication, and power management.

2. The device of claim 1 , wherein the rigid housing parts are made of ABS plastic.

3. The device of claim 1 , wherein at least one of the rigid parts is made of metal or ceramic.

4. The device of claim 1 , wherein the soft elastomeric part (802) is made of silicone or thermoplastic polyurethane (TPU).

5. The device of claim 1 , wherein the reference electrode (805) is formed of aluminum on PET or printed silver ink.

6. The device of claim 1 , further comprising a USB-C charging port integrated into the soft part.

7. The device of claim 1 , further comprising a temperature sensor, an accelerometer, and a gyroscope.

8. A method of manufacturing a transducer assembly for use in a physiological monitoring device of claim 1 , comprising: providing electromechanical film, applying a conductive layer to at least one side of the electromechanical film to form one electrode, arranging the electromechanical film within a mechanical housing such that it is compressed between a soft elastomeric layer and a PCB-mounted another electrode, establishing electrical contact on the said electrodes, and enclosing the assembly using mechanically joined rigid housing parts.

9. The method of claim 8, wherein the ferroelectret laminate comprises a PET-PP-PET structure with silver paste printed electrodes.

10. The method of claim 8, wherein no adhesive is used between the ferroelectret film and the reference electrode.

11. A method of monitoring physiological or environmental signals, comprising: positioning the physiological monitoring device claim 1 on a user’s chest, hip or thigh, detecting ballistocardiographic and respiratory signals through one or more layers of 'clothing, and detecting a high-amplitude pressure event using the sensor assembly.

12. The method of claim 11 , wherein the high-amplitude pressure event is an explosive blast wave.

13. The device of claim 1 , further comprising a system is configured to detect and log blast wave events and calculate cumulative exposure over time.

14. The method of claim 11 , wherein the physiological monitoring device comprises a system configured to detect and log blast wave events and calculate cumulative exposure over time.

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