Devices and methods

Abstract

To provide an erbium doped glass for optical amplification for use in photoplethysmography.SOLUTION: A user device for monitoring body condition of a user such as a cardiac rate or blood oxygen level includes an erbium doped glass component and a light source. The light source is configured to generate light equal to an excitation frequency of an erbium doped glass. The erbium doped glass component is configured to generate one or more peaks of high-intensity light corresponding to wavelength that can be used for monitoring the user's condition via photoluminescence. Amplified light is transmitted to the user and returned and is received by a photodetector. Thus, it is possible to determine the user's condition with an algorithm.SELECTED DRAWING: Figure 4A

Description

[Background technology]

[0001] background Photoplethysmography (PPG) is a technique used to measure changes in tissue volume. PPG is an optical measurement method that measures blood flow, requiring a light source and a photodetector. Typically, a photodetector placed at or near the surface of the skin detects light transmitted or reflected from vascular tissue to the photodetector. This light corresponds to measuring the variations in blood circulating volume used to monitor heart rate. The changes in volume caused by the pulse or cardiac cycle are measurable as peaks or troughs in light intensity. This technique can also be used to measure other aspects related to blood flow, such as blood oxygen saturation. PPG technology is used to measure a consumer's heart rate, for example in personal consumer devices such as smartphones or smartwatches.

[0002] The reliability and effectiveness of PPG technology relies on using wavelengths of light suitable for penetrating skin and vascular tissue. Not all wavelengths of light are absorbed equally by blood. For example, wavelengths corresponding to green light show the strongest absorption in blood, giving the highest pulsatile signal strength corresponding to heartbeat. In practical implementations of PPG, LEDs corresponding to various wavelengths of light are used. Green LEDs are used to detect heartbeat. Infrared (IR) LEDs are used to detect heartbeat during sleep, and red LEDs are used to detect oxygen saturation. In terms of power consumption, each LED has a different efficiency. Green LEDs consume a higher amount of power to output light of a certain luminous intensity, while infrared LEDs consume a fraction of that power to output the same luminous intensity. Summary of the Invention

[0003] overview [Problem to be solved by the invention]

[0004] The present disclosure provides erbium-doped glasses for light amplification for use in photoplethysmography. [Means for solving the problem]

[0005] One aspect of the present disclosure provides a device comprising a first light source configured to generate light having a first wavelength and a first intensity, an amplification layer having a first side and a second side and further including a doped rare earth metal, configured to receive the light of the first wavelength and the first intensity and transmit light of a second wavelength having a second intensity, a photodetector receiving the light of the second wavelength from a user, and a processor configured to determine a physical condition of the user based on at least a signal received from the photodetector. The first wavelength may be an excitation frequency of the amplification layer, and the second intensity may be higher than the first intensity.

[0006] An additional aspect of the present disclosure provides a device comprising a first light source configured to generate light having a first wavelength and a first intensity; an amplification layer having a first side and a second side and further comprising a doped rare earth metal, configured to receive light at the first wavelength and the first intensity and transmit light at a second wavelength having a second intensity; a photodetector to receive light at the second wavelength from a user; and a processor configured to determine a physical condition of the user based on at least a signal received from the photodetector. The first wavelength may be an excitation frequency of the amplification layer, and the second intensity may be higher than the first intensity. The amplification layer may also transmit light at a third wavelength, and the photodetector may receive light at the third wavelength. The processor may determine a physical condition of the user based on a signal received from the light at the second wavelength. The device may be configured to monitor a blood oxygen level based on the received photons of the second wavelength, and / or the processor may also be configured to monitor a cardiac condition based on the light of the third wavelength. The photodetector may generate an electrical signal in response to the received light. The device may include a processor electrically coupled to the photodetector. The processor may be configured to assess a health status of the user based on the received photons of the second wavelength. The device may also further include a paint that blocks the visible light spectrum. The paint may be on either the first side or the second side of the amplification layer. The first wavelength may be in the infrared spectrum. The first amplification layer may be made of erbium doped phosphate glass. The first amplification layer may be erbium doped phosphate glass having between 0.4 mole percent and 0.6 mole percent erbium. The second wavelength may range from 550 nm to 750 nm wavelengths.

[0007] An additional aspect of the present disclosure provides for monitoring physical parameters of a user, comprising providing an amplification layer having a first excitation wavelength and configured to generate a second excitation wavelength; generating light of a first wavelength corresponding to the first excitation wavelength by a light source; receiving light of the first wavelength at the amplification layer; generating light of the second wavelength at the amplification layer in response to the received light of the first wavelength; transmitting light of the second wavelength from the amplification layer to a user; receiving light of the second wavelength from the user at a photodetector; and assessing, by a processor, a health status of the first user based on at least the light of the second wavelength received at the photodetector.

[0008] An additional aspect of the present disclosure provides for monitoring a physical parameter of a user, comprising providing an amplification layer having a first excitation wavelength and configured to generate a second excitation wavelength, generating light of a first wavelength corresponding to the first excitation wavelength by a light source, receiving the light of the first wavelength at the amplification layer, generating light of a second wavelength at the amplification layer in response to the received light of the first wavelength, transmitting the light of the second wavelength from the amplification layer to a user, receiving the light of the second wavelength from the user at a photodetector, and evaluating, by a processor, a health condition of the first user based on at least the light of the second wavelength received at the photodetector. The physical parameter may be a heart rate of the user. The physical parameter may be a blood oxygen level of the user. The amplification layer may be configured to generate light of a third wavelength. The second wavelength may correspond to red light and the third wavelength may correspond to green light. The evaluation by the processor may include execution of a machine learning algorithm to evaluate an additional underlying health condition of the user.

[0009] An additional aspect of the present disclosure provides a device including a housing, a first light source, an amplification layer, a photodetector, and a processor. The housing can include a rear portion adapted to be placed adjacent to the skin of a user, and the rear portion can be at least partially composed of glass doped with a rare earth metal. The first light source can be configured to generate light having a first wavelength and a first intensity. The amplification layer can be doped with a rare earth metal. The amplification layer can have a first side and a second side and can be configured to receive light at the first wavelength and the first intensity and transmit light at a second wavelength having a second intensity. The photodetector can receive light at the second wavelength from the user. The processor can be configured to determine a physical condition of the user based on at least a signal received from the photodetector. The first wavelength is an excitation frequency of the amplification layer, and the second intensity can be higher than the first intensity. The rare earth metal can be erbium. The glass can be at least partially painted with ink to block the visible light spectrum.

[0010] The accompanying drawings are not intended to be drawn to scale. Like reference numbers and designations in the various drawings indicate like elements. For purposes of clarity, not every component is labeled in every drawing. [Brief description of the drawings]

[0011] [Figure 1] 1 is a graph of wavelength and intensity for an exemplary erbium-doped glass plate according to an aspect of the present disclosure. [Diagram 2] 1 is a graph of wavelength and intensity for an exemplary erbium-doped glass plate according to an aspect of the present disclosure. [Figure 3A] FIG. 1 is a diagram of a user device according to an aspect of the disclosure. [Figure 3B] 1 is a diagram of a user interface according to an aspect of the present disclosure. [Figure 3C] 1 is a diagram of a user interface according to an aspect of the present disclosure. [Figure 4A] FIG. 2 is a diagram of a device having an erbium-doped glass plate according to an embodiment of the present disclosure. [Figure 4B] FIG. 2 is a diagram of a device having an erbium-doped glass plate according to an embodiment of the present disclosure. [Diagram 5] 1 is a flowchart of an exemplary method according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Detailed Description The present disclosure generally relates to methods, systems, and devices that use erbium-doped glass as optical amplifiers and wavelength shifters. In particular, rare earth metals exhibit photoluminescence. Photoluminescence is a phenomenon in which light is absorbed by a material at one wavelength and re-emitted at another wavelength. In particular, doped materials can be used to down-convert and amplify wavelengths of light suitable for a particular optimal purpose, such as photoplethysmography (PPG). Doped materials, such as erbium-doped glass, can be used to amplify light and improve the power consumption efficiency or performance of a device. In erbium-doped glass, there can be various doping levels, which can be measured by weight, weight percentage, volume percentage, or mole percentage of the material. Mole percentage is the percentage of the total moles of a particular component and can be annotated as "mol %". It is to be understood that erbium, as used in this disclosure, refers to both erbium and erbium compounds, such as erbium oxide Er2O3.

[0013] Photoluminescence is the re-emission of light from any form of matter after absorbing photons, light or electromagnetic radiation. In certain materials, such as rare earth ions and rare earth ion doped glasses, the intensity or lumens of light emitted by the photoluminescent material is higher than the intensity absorbed.

[0014] Erbium doped glasses may be of the class of sodium sulfophosphate glasses. Doped glasses and other materials have been found that exhibit strong photoluminescence effects. Spectral analysis of such materials reveals that, in particular, at 977 nm excitation, NPbPEr-0.5 glass emits enhanced green emission. Other doped glasses may also exhibit similar behavior.

[0015] Figure 1 shows the exc1 shows a graph 100 of the wavelength and intensity or luminosity of light emitted from erbium doped glass when exposed to light of a particular wavelength labeled 100. The excitation wavelength can be a wavelength of light such as ultraviolet, visible, or infrared. The physical phenomenon in which a material is exposed to such wavelengths of light and re-emits light of a different wavelength is known as photoluminescence. The erbium doped glass absorbs the exposed light and emits light of various wavelengths and intensities. The horizontal axis 105 shows the wavelength of the light emitted and is measured in nanometers (nm). The vertical axis 110 shows the intensity of the light emitted in arbitrary units. Also shown in graph 100 are several peaks 121-123. These are peaks of intensity at various wavelengths such as peak 121 near approximately 400 nm, peak 122 near 475 nm, and peak 123 near approximately 540 nm. Other smaller peaks are seen in graph 100 that are not labeled. Through the process of photoluminescence, Thus, the amplitude of the emitted light has a greater amplitude or intensity than the amplitude of light exciting the erbium-doped glass at a particular wavelength. The peaks correspond to the particular excitation and emission that occurs when an electron is excited by a photon of a particular wavelength, jumps between two electronic orbital states, and then jumps back to another orbital state, thereby emitting a photon of a different wavelength.

[0016] Erbium-doped glasses can be formed or synthesized by melt quenching (rapid cooling) methods. After choosing a specific molar composition of the glass, such as the composition (20-x)Na2SO4-20PbO-60P2O5-xEr2O3 (x=0.1, 0.3, 0.5, 0.7, 1.0 mol%), the material can be melted, poured into a mold, annealed, and gradually cooled to room temperature. x is a variable that can be adjusted in conventional compositions depending on the molar concentration of Er2O3.

[0017] Figure 2 shows the specific wavelength λ exc2 shows a graph 200 of wavelength and intensity for two erbium doped glasses when exposed to light of 1000 nm. As with the example of FIG. 1 above, the excitation wavelength can be any wavelength of light, such as ultraviolet, visible, or infrared. Two excitation curves, curve 220 and curve 230, are shown. Curve 220 corresponds to an erbium doped glass where the erbium constitutes 0.5 mole % of the glass. Curve 230 corresponds to an erbium doped glass where the erbium constitutes 0.1 mole % of the glass. Curves 220 and 230 generally share characteristics such as the location of the peaks, but the graphs reflect different amplitudes of light produced by the photoluminescence effect. The "doping ratio" or amount of erbium or other doping material used will result in different curves at different levels of doped material. In some instances, the glass may be doped to a degree that optimizes the height of the various excitation peaks shown in graph 200. In other instances, the glass may be doped such that the light produced by the photoluminescence effect is of a particular wavelength. While two graphs are shown for specific mole percentages, it is understood that other curves may be empirically derived for other mole percentages and the curve most suitable for a particular application may be selected. As can be seen from Figure 2, "Er-0.5" produces the strongest effect in the range of approximately 550 nm, which corresponds to green light, and approximately 640-680 nm, which corresponds to red light. As can be seen from Figure 2, the doped glass produces green light that is 100-1000 times as large as the amplitude of the infrared signal used to excite the doped glass.

[0018] FIG. 3 illustrates a user device 300 that may be used by a user, such as user 399. The user device may include a housing 301 and a strap 302. The housing 301 may have components such as a back portion that contacts the skin of the user 399. The back portion may include a glass portion that allows light to pass through the back portion. Light may be generated from other components contained within the housing 301, such as, for example, a light source. The user device 300 and the housing 301 may also have a user interface that allows the user 399 to interact and view information from the user device 300. The user interface may be a touch screen or part of another device. Additional components that may be included in the user device 300 or the housing 301 are further described below with reference to FIGS. 4A and 4B. The housing may further be of a suitable thickness to include the components described in FIGS. 4A and 4B. The strap 302 may be a strap for a user to hold the user device, such as one made of metal, leather, cloth, or other material. For example, the user device 300 may be a smart watch, a health sensor, earplugs, earbuds, over-ear headphones, in-ear headphones, or other wearables, a ring, anklet, necklace, or other jewelry.

[0019] 3B and 3C show various exemplary formats for displaying information about a user's physical condition on a display 303. The display 303 may be similar to the display 495 described below. For example, FIG. 3A illustrates a display 495 that may be used in accordance with aspects of the disclosure, such as the method 500. FIG. 3B shows a graph of a user's current heart rate of a device such as device 400. This graphical display may be updated in real time to display the trailing seconds of the user's heart beat. In some examples, information may be conveyed to the user through visual or audible methods. FIG. 3C shows a display in text form of information about the user's physical condition. For example, FIG. 3B shows the current heart rate in beats-per-minute (BPM), the current blood oxygen saturation, and other information about arrhythmias. Other conditions that may be of value to any user are shown. The example shown is of a cardiovascular condition, but other aspects of the heart may be monitored. Figure 3C also shows other options, such as the ability to sync the information to another user device, such as a smartphone, or to store the information on the Internet or in another storage unit, such as the cloud.

[0020] FIG. 4A illustrates a device, device 400, that may be used to perform PPG. Device 400 may include a light source, such as light source 410, one or more light sensors, such as photodetectors 420A and 420B, capable of detecting light, an ink layer that may be transparent to infrared light, such as layer 433, a glass layer, such as amplification layer 432 that amplifies the light received from light source 410, and a glass protective layer, such as back glass 431, and electronics 499. Electronics 499 may include some or all of the features of electronics 499 described below with reference to FIG. 4B. In FIG. 4, light is illustrated with unlabeled solid arrows, the arrows indicating the direction of light travel. Light may enter the dermis, such as skin 450. Although skin 450 is illustrated, the device may be applied to other parts of the human body, such as, for example, nails or soft tissue. Layers 431-433 may each have a first side and a second side and may be arranged in different permutations relative to the light source.

[0021] FIG. 4A shows a light source 410. One example of a light source is a light emitting diode (LED). An LED is a semiconductor light source that emits light when an electric current is passed through it. Electrons in the semiconductor recombine with holes and release energy in the form of photons. The LED may be designed or selected to emit light at a particular wavelength or range of wavelengths. In other examples, the light source 410 may be made of specially designed semiconductors, commercially available light sources such as incandescent lamps, electrodeless lamps, or halogen lamps. In other examples, the light source 310 may further be made of one or more light sources configured to generate different wavelengths of light, such as an LED configured to generate red light close to a wavelength of 660 nm, an LED configured to generate green light close to a wavelength of 530 nm, and so on. These different light sources may be selected to measure different aspects of the cardiovascular system when performing PPG. For example, red light may provide information about blood oxygen saturation while green light provides information about heart rate due to the relative absorption and reflection of these colors within the cardiovascular system. The light source 410 may be configured or selected to generate light corresponding to the excitation wavelength of the amplification layer 432. For example, 977 nm infrared light may be selected. The use of infrared light is more energy efficient compared to other high frequency / low wavelength light generation because infrared light is generated using less power and is generated from a single light source while still producing more than one wavelength of light through photoluminescence. As will be further explained below, the light source may be amplified by an amplification layer 432 before reaching the skin 450.

[0022] A photodetector, such as photodetector 420A or 420B, can be a semiconductor device that converts light into electrical current. A photodetector can generate an electrical current proportional to the number of photons that strike the surface. Because electricity is generated when a photon is absorbed by the photodetector, the photodetector can function as a sensor of light. A photodetector can be any device that can sense the intensity and / or wavelength of light. Photodetectors 420A and 420B can be photodiodes or photosensors. In some examples, photodetector 420A and photodetector 420B can be selected to be more sensitive to certain wavelengths of light. In some examples, photodetector 420A can be selected to be more sensitive to green light or to only have sensitivity to green light. While photodetector 420A may be selected or configured to be more sensitive to red light, photodetector 420B may be configured to be more sensitive to red light or to be sensitive only to red light. Photodetector 420A and photodetector 420B may also be made of an array of photodetectors. Additional circuitry, calibration, or electronics may be incorporated into photodetector or electronics 499 to ensure a better signal-to-noise ratio and to reduce the effects of ambient light.

[0023] Also shown in FIG. 4A is skin 450 having subcutaneous layer 451, dermis layer 452, and epidermis layer 453. Epidermis layer 453 is a thinner layer of skin and allows light to pass through. Skin includes veins and arteries, such as vein 460 and artery 470. Light generated from light source 410 may be emitted from device 400 to skin 450. The emitted light may pass through epidermis layer 453, dermis layer 452, and be reflected by veins and arteries in the skin, such as vein 460 or artery 470, back to photodetector 420A or 420B. Light that strikes skin 450 reflects off various layers in the skin depending on the angle of incidence of the light. Light that strikes the skin at a shallow angle reflects off the top or epidermis layer 453. This reflected light contains little or no heartbeat information because it does not interact with arteries. Light that strikes the skin at a steeper angle penetrates the top layer of the skin and enters other layers, such as the subcutaneous layer 451 or the dermal layer 452, which are home to a concentration of blood-carrying veins and arteries, such as vein 460 and artery 470. Light that reflects off these layers carries the heartbeat signal and serves the purpose of PPG. Various components, such as the amplification layers described herein, can be formed to improve the angle at which the light enters the skin 450 to improve the received information or signal. Changes in the light transmitted to the photodetectors can be used to determine various aspects of the cardiovascular system, such as heart rate, pulse, oxygen saturation in the blood, or other health-related information. In some examples, a waveform can be derived from continuous or near-continuous monitoring of the light received by the photodetector 420A. The light source 410 and the photodetectors 420A and 420B can be connected to electronics 499 to control the emission of light and to monitor and analyze the light received from the skin 450.

[0024] Glass layer 431 may be a layer of glass that transmits light and covers other components of device 400. Glass layer 431 may be formed from a silicate glass, such as soda-lime glass, lead glass, aluminosilicate, or a silica-free glass, such as an amorphous metal or polymer glass. Molecular liquids or molten salts may also be used to construct glass layer 431. Glass layer 431 may be hardened or tempered to provide additional durability and resistance to scratching, cracking, or shattering. In other examples, chemically strengthened commercially available glasses, such as alkali aluminosilicates, may be used.

[0025] The amplification layer 432 may be made of rare earth metal doped glass. In some examples, the rare earth metal may be erbium. The amplification layer 432 receives light of a particular excitation wavelength and intensity and re-emits light of higher intensity at other wavelengths through the process of photoluminescence. For example, referring back to FIG. 2, a doped glass may be selected to construct the amplification layer 432 to maximize the amplitude of the emitted light. In other examples, the amplification layer 432 may be made of one or more optical glass fibers that are doped. In still other examples, the amplification layer 432 may be made of more than one type of doped glass, which would allow for more flexible design of the device or applications requiring more than one strong emission peak. Since the erbium doped glass can be formed into any shape or configuration, the amplification layer may also be shaped for any use case. In some examples, the glass may be more curved to ensure better incidence of the light into the skin 450. In some examples, the erbium doped glass may be formed as an optical fiber. In some examples, the amplification layer may be coated with reflective surfaces on some sides to further direct the light so that it is emitted only from a portion of the surface. In other examples, the optical fiber may be coated with reflective surfaces on some sides to direct the light to the skin 450. It may be embedded in the amplification layer 432. In another example, the shape of the amplification layer 432 may ensure that the amplified light is more spread out with a uniform flux at the surface of the amplification layer.

[0026] Layer 433 may be a layer that selectively passes certain wavelengths of light and blocks other wavelengths of light. In some examples, layer 433 passes infrared light but blocks other wavelengths of light from passing through. For example, layer 433 may be made of glass painted with infrared-transparent ink. Layer 433 may extend along the length of amplification layer 432 or glass layer 431. In other examples, layer 433 may extend only to the portion of glass layer 431 where light source 410 or photodetector 420A may be visible. Thus, when incorporated into a user device, the internal components are hidden from the user without affecting the ease of use of device 400. The infrared-transparent ink may be selected from commercially available paints or may be specially crafted from a material that blocks light other than infrared light.

[0027] While layers 431-433 are shown as continuous rectangular adjacent layers, it should be understood that the arrangement, size, shape, and continuity of the layers may vary. For example, the layers may be curved to conform to other devices such as a smartwatch, such as device 300. In some examples, the layers may follow the curvature of a human wrist or other body part to better incorporate the layers into a device or housing that mimics the wrist. In other examples, the layers may be formed to fit around a molding, such as a smartphone camera lens. In some examples, additional layers may be inserted within or between layers to provide additional structural rigidity, amplification, heat dissipation, or toughness. In other examples, a vacuum may exist between layers to increase the bonding force between layers or allow additional space for thermal expansion and contraction. In some examples, multiple layers may be used that may be arranged in different permutations from one end of device 400 to the other end of the device. Additionally, other components, such as optical filters, may be included around or between the layers. In some examples, the optical filters may accommodate light that is not used to monitor the user's physical condition.

[0028] Although device 400 is shown in a particular configuration, it should be understood that other arrangements of these components are within the scope of this disclosure. For example, in some examples, these components may be disposed on a user device such as a mechanical watch, a smart watch, a smart ring, a mobile phone, earphones, headphones, an armband, or a laptop computer. In other examples, device 400 may be integrated into jewelry such as a pendant, necklace, bangle, earring, armband, ring, anklet, or other jewelry. In yet other examples, device 400 and / or its components may be integrated into a medical device such as a pump-based blood pressure monitor.

[0029] FIG. 4B illustrates additional aspects of electronic device 499. Electronic device 499 may include power source 490, processor 491, memory 492, data 493, user interface 494, display 495, communication interface 497, and indicator 498. The power source may be any suitable source of electricity generating power, such as a battery, chemical cell, capacitor, solar panel, or inductive charger. Processor 491 may be a conventional processor, such as a commercially available microprocessor or application specific integrated circuit (ASIC). Memory may store information accessible by the processor, including instructions and data executed by the processor. Memory 492 may be any type of memory that operates to store information accessible by the processor, and may include non-transitory computer readable media or other media that store data that can be read with the aid of an electronic device, such as hard drives, memory cards, read only memory (ROM), random access memory (RAM), optical disks, and other writable and read only memories. The subject matter disclosed herein may include different combinations of the foregoing, whereby different portions of the instructions and data are stored in different types of memory. The data 493 of the electronic device 499 may be retrieved, stored, or modified by a processor according to the instructions 498. For example, although the disclosure is not limited by a particular data structure, the data 493 may be stored in a computer register in a relational database, as a table with multiple different fields and records, an XML document, or a flat file. The data 493 may also be formatted in a computer readable format, such as, but not limited to, binary values, ASCII, or Unicode. Additionally, the data 493 may comprise sufficient information to identify related information, such as numbers, descriptive text, proprietary codes, pointers, references to data stored in other memory (including other network locations), or information used by a function to calculate related data.

[0030] The indicators 498 may control various configurations and functions of the device 400. For example, the indicators 498 may be executed to selectively activate the light source 410 or process information obtained by the photodetector 420. In some examples, algorithms may be included as a subset or as part of the indicators 498 included in the electronics 499. The indicators 498 may include algorithms to interpret or process received information, such as information received through or generated by analyzing the light beam received at the photodetector, or information stored in memory. For example, physical parameters of the user may be extracted or analyzed via the algorithm. The algorithm may use any or all information regarding the waveform, such as, without limitation, the shape of the wave, frequency, period, Fourier analysis of the signal, harmonic analysis, pulse width, pulse area, peak-peak interval, pulse interval, intensity or amount of light received by the photodetector, wavelength shift, first or second optical guidance of the signal generated or received by the photodetector 420A or 420B. Other algorithms may be included to calculate oxygen absorption in oxyhemoglobin and deoxyhemoglobin, cardiac arrhythmias, heart rate, premature ventricular contractions, missing beats, systolic and diastolic peaks, and aortic stiffness index. In yet another example, an artificial learning or machine learning algorithm may be included to calculate information related to the user's physical condition, such as blood pressure and stress level (such as heart rate, PPG may be used in both deterministic and non-deterministic ways to extract information about the heart rate (from fluctuations in the number of heart beats). PPG may also be used to measure blood pressure by calculating the pulse wave velocity between two points on the skin a fixed distance apart. Pulse wave velocity is proportional to blood pressure, and the relationship may be used to calculate blood pressure. In some examples, the algorithm may be modified or may use information entered into the memory of the electronic device 499 by the user, such as the user's weight, height, age, cholesterol, genetic information, body fat percentage, or other physical parameters. In other examples, machine learning algorithms may be used to detect and monitor known or undetected health conditions, such as arrhythmias, based on information generated by the photodetector and / or processor.

[0031] The user interface 494 may be a screen that allows a user to interact with the device 400, such as a touch screen or buttons. The display 495 may be an LCD, LED, cell phone display, electronic ink, or other display that displays information about the device 400. The user interface 494 allows both input from and output to the user. The communication interface 497 may include hardware and software that allows data communication via standards such as Wi-Fi, Bluetooth, infrared, radio waves, and / or other analog and digital communication standards. The communication interface 497 may update the electronics 499 and share information generated by the device 400 with other devices. In some examples, the communication interface 497 may transmit historical information stored in the memory 492 to another user device for display, storage, or further analysis. In other examples, the communication interface 497 may transmit the signal generated by the photodetector to another user device, either in real time or at a later time, for display on that device. The information can be sent to the device.

[0032] FIG. 5 illustrates a flow chart of an example method 500 for monitoring a physical parameter of a user.

[0033] In block 505, a light source can generate light, such as a light beam or photons. For example, the light source can be light source 410. The generated light can have a first excitation wavelength, which can correspond to a known excitation wavelength of a rare earth metal. The generated light can be incident on one surface of an amplification layer, such as amplification layer 432. The process of generating light is energy intensive, so generating high intensity light requires more energy, which can cause devices, such as device 400, to be bulky to accommodate larger power sources or to function for a shorter time before needing to be recharged. Furthermore, the wavelength of light cannot be tightly controlled in a single light source, so a larger wavelength spectrum of light may be generated or dedicated light sources that accommodate red and green light may be required. As described further below, the use of doped glass plates designed with specific responses to excitation wavelengths can generate green and red light and can be used to monitor a user's physical parameters.

[0034] In block 510, the light generated in block 505 may be absorbed by the amplification layer 432 or a photoluminescent material, such as an erbium-doped glass plate as referenced in Figures 1 and 2. The light received by the photoluminescent material may be amplified by the amplification layer 432. During this process, light having a spectrum of intensities and wavelengths may be generated by the amplification layer 432. The amplification may occur several times.

[0035] At block 515, the light generated by the amplification layer 432 may be emitted. The light may be transmitted through one or more faces of the amplification layer. In some examples, the amplification layer may be formed such that light passes through only one surface of the amplification layer.

[0036] In block 520, the light may be transmitted to the dermis, such as dermis 450. In block 520, the light may be further reflected from systems and organs within the epidermis, such as veins 460, arteries 470, or other capillaries. The amplified light enters the dermis and a portion of the light may be reflected back from or through the dermis.

[0037] In block 525, the light may be detected by a photodetector, such as photodetectors 420A and 420B. The received light may be converted by the photodetector into a digital or analog electrical signal and transmitted to electronics, such as electronics 499.

[0038] At block 530, the received signal and the light received from the photodetector may be analyzed by electronics, such as electronics 499. Referring to FIG. 4B above, electronics 499 may include algorithms that can analyze aspects of the user's physical parameters from the information gathered through the light received at block 525.

[0039] Although the method 500 is described below in a particular order, it should be understood that operations may be performed in a different order or simultaneously. Additionally, operations may be added or omitted.

[0040] As explained with reference to the disclosure above, the use of doped photoluminescent materials can increase the signal received from a user and reduce the energy requirements of the device to monitor the user's physical condition. As used within this disclosure, the particle / wave duality of light, beam of light, ray, photon, or light are intended to convey quanta of light having a wavelength and amplitude and may be used interchangeably.

[0041] Although the present disclosure includes many specific implementation details, these should not be construed as limitations on the scope of the claims, but rather as descriptions of features specific to particular implementations. Certain features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable subcombination. Furthermore, although features may be described above as functioning in a particular combination and initially claimed as such, one or more features from a claimed combination may in some cases be deleted from the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0042] Similarly, although operations are shown in the figures in a particular order, this should not be understood as requiring that such operations be performed in the particular order or sequential order shown, or that all of the operations shown be performed, to achieve desirable results. In certain situations, multitasking and parallel processing may be advantageous.

[0043] References to "or" may be construed as inclusive such that any term described using "or" may refer to either the single, the plural, and all of the described terms. Labels such as "first," "second," "third," etc. are not necessarily meant to denote an order, but may simply be used generally to distinguish between like or similar items or elements.

[0044] Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of the present disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and novel features disclosed herein.

Claims

1. an amplification layer including a doped rare earth metal and configured to receive light at a first wavelength and a first intensity and transmit light at a second wavelength having a second intensity to a user, the first wavelength being an excitation frequency of the amplification layer; a photodetector configured to receive light at the second wavelength from the user; a processor configured to determine a physical condition of the user based on at least the signal received from the optical detector, and to provide for output information related to the determined physical condition of the user; The second wavelength is different from the first wavelength and the second intensity is greater than the first intensity.

2. The device of claim 1 , wherein the processor is further configured to execute one or more machine learning algorithms to assess a health status of the user.

3. The device of claim 1 or claim 2, wherein when determining the physical condition of the user, the processor is further configured to execute one or more machine learning algorithms to extract information related to the physical condition of the user.

4. the amplification layer further transmits light at a third wavelength; the photodetector receives light at the third wavelength; The device of claim 1 , wherein the third wavelength is different from the first wavelength and the second wavelength.

5. the processor is configured to monitor blood oxygen levels based on the second wavelength of light; The device of claim 4 , wherein the processor is configured to monitor a cardiac condition based on light at the third wavelength.

6. 6. The device of claim 1, wherein the optical detector generates an electrical signal in response to receiving light at the second wavelength.

7. The device of claim 6 , further comprising a processor electrically coupled to the photodetector.

8. The device of claim 7 , wherein the processor is configured to assess a health status of the user based on the received photons at the second wavelength.

9. 9. The device of claim 1, further comprising a coating on the amplification layer that blocks visible light.

10. The device of claim 1 , wherein the first wavelength is an infrared wavelength.

11. 11. The device of claim 1, wherein the amplification layer is an erbium doped phosphate glass.

12. 12. The device of claim 11, wherein the amplification layer is an erbium doped phosphate glass having between 0.4 mole percent and 0.6 mole percent erbium.

13. 13. The device of claim 1, wherein the second wavelength is in the wavelength range of 550 nm to 750 nm.

14. 1. A method for monitoring a physical parameter of a user, comprising: receiving light of a first wavelength and a first intensity in an amplification layer having an excitation wavelength corresponding to the first wavelength, the first wavelength being an excitation frequency of the amplification layer, the amplification layer including a doped rare earth metal; generating light at a second wavelength having a second intensity in the amplification layer in response to receiving light at the first wavelength; transmitting light at the second wavelength from the amplification layer to the user; receiving light at the second wavelength from the user at a photodetector; and determining, by a processor, based on at least the light of the second wavelength received by the photodetector. assessing a health condition of the user based on the providing, by the processor, information related to a physical condition of the user for output; The method of claim 1, wherein the second wavelength is different from the first wavelength and the second intensity is greater than the first intensity.

15. The method of claim 14 , wherein the physical parameter is at least one of the user's heart rate or blood oxygen level.

16. The method of claim 14 or claim 15, further comprising running, by the processor, one or more machine learning algorithms to assess a health status of the user.

17. 17. The method of claim 14, further comprising, when determining the physical condition of the user, executing, by the processor, one or more machine learning algorithms to extract information related to the physical condition of the user.

18. generating light at a third wavelength in the amplification layer; 18. The method of any one of claims 14 to 17, wherein the third wavelength is different from the first wavelength and the second wavelength.

19. the second wavelength corresponds to red light; The method of claim 18 , wherein the third wavelength corresponds to green light.

20. a housing including a rear portion adapted to be placed adjacent to the skin of a user, the rear portion being constructed at least in part from an amplification layer, the amplification layer including a doped rare earth metal, the amplification layer being configured to receive light at a first wavelength and a first intensity and to transmit light at a second wavelength having a second intensity towards the user, the first wavelength being an excitation frequency of the amplification layer; a photodetector configured to receive light at the second wavelength from the user; a processor configured to determine a physical condition of the user based on at least the signal received from the optical detector, and to provide for output information related to the determined physical condition of the user; The second wavelength is different from the first wavelength and the second intensity is greater than the first intensity.

21. 21. The device of claim 20, wherein the processor is further configured to execute one or more machine learning algorithms to assess a health status of the user.

22. 22. The device of claim 20 or 21, wherein when determining the physical condition of the user, the processor is further configured to execute one or more machine learning algorithms to extract information related to the physical condition of the user.

23. 23. A device according to any one of claims 20 to 22, wherein the rare earth metal is erbium.

24. 24. The device of any one of claims 20 to 23, wherein the amplification layer is at least partially coated with ink to block visible light.

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