WO2024173585A1

WO2024173585A1 - System, method, and apparatus for performance of reflectance mode laser speckle imaging

Info

Publication number: WO2024173585A1
Application number: PCT/US2024/015841
Authority: WO
Inventors: Samir Shreim
Original assignee: Graftworx Inc
Current assignee: Alio Inc
Priority date: 2023-02-15
Filing date: 2024-02-14
Publication date: 2024-08-22
Anticipated expiration: 2025-08-15

Abstract

A wearable biosensing device features a laser diode and a camera module. The camera module is positioned in a reflectance geometry with the laser diode to detect photon waves reflecting from a diffused target.

Description

SYSTEM, METHOD, AND APPARATUS FOR PERFORMANCE OF REFLECTANCE MODE LASER SPECKLE IMAGING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 63/445,853, filed February 15, 2023, which is incorporated by reference in its entirety into this application.

FIELD

[0002] Embodiments of the disclosure relate to the field of wearable biosensing devices, and more specifically, wearable biosensing devices utilizing speckle technology.

GENERAL BACKGROUND

[0003] Currently, there exists a form of laser speckle imaging (LSI) referred to as affixed transmission speckle analysis (ATSA), which was disclosed by a publication entitled “Wearable speckle plethysmography (SPG) for characterizing microvascular flow and resistance,” published 1 Aug. 2018 in Vol. 9, No. 8 of the Biomedical Optics Express 3927 (hereinafter, “Ghijsen”).

[0004] As discussed in the Ghij sen, ATSA uses a single coherent light source to probe two physiological signals: a first physiological signal related to pulsatile vascular expansion (referred to as a “photoplethysmographic (PPG) waveform”) and a second physiological signal related to pulsatile vascular blood flow (referred to as a “speckle plethysmographic (SPG) waveform”). Additionally, Ghij sen states that the PPG signal is determined by recording intensity fluctuations, and the SPG signal is determined via an LSI-based dynamic light scattering technique, where these two co-registered signals are obtained by transilluminating a finger which produces quasi-periodic waveforms derived from the cardiac cycle. Because PPG and SPG waveforms probe vascular expansion and flow, respectively, in centimeter-thick tissue, these complementary phenomena are offset in time and have rich dynamic features.

[0005] As is further explained in Ghijsen, LSI is a non-contact imaging modality capable of measuring relative perfusion by utilizing a coherent light source and a light detector such as a complementary metal-oxide-semiconductor (CMOS) array or a charge coupled device (CCD). Scattered coherent light generates a speckle interference pattern on the light detector, where the pattern can be analyzed computationally to measure the speed of the light-scattering particles. Relative blood flow can be determined with this image by measuring the fluctuations in the speckle pattern and the overall blurring of the individual speckles.

[0006] Conventional LSI systems suffers from a number of disadvantages. One disadvantage is that conventional LSI systems are typically cumbersome, sizeable optical systems, which are susceptible to motion artifacts and deploy components that are not suitable for integration into a wearable device due to size, cost, and complexity. For instance, most conventional LSI systems feature a high-end laser with a Gaussian mode and a sophisticated camera system including one or more lenses and imaging optics.

[0007] ATSA is intended to address some of the shortcomings of LSI by utilizing transmission geometry with the light source and the light detector positioned on different sides of a monitored portion of the body such as a digit of a human hand. In fact, ATSA (a modified version of LSI) has been utilized in compact finger-clip monitors operating in accordance with the transmission geometry, where the finger-clip monitors detect highly diffuse speckle signals that have penetrated the skin at least several millimeters. For this type of finger-clip monitor architecture, operating in accordance with the transmission geometry (i.e., in transmission mode) to gather transmission mode optical measurements, the light source and light detector are placed opposite sides of the finger in a form factor practically identical to a commercially available pulse-oximeter.

[0008] As described above, the conventional usage of LSI and ATSA are directed to various solutions with technical limitations as such usage involves transmission mode optical measurement in which the measurement sites occurs on a different side of a narrow body part than the light source. Transmission mode optical measurements may be reasonable for certain body parts, such as digits, ear lobes, ear concha, or nasal ala. However, these solutions are not applicable to the measurement of body appendages having thicker planar geometry such as areas on the wrist, neck, torso, arm, forearm, or forehead for example, because these sites (based on the absorption and scattering properties of human tissue) are too thick and attenuate transmitted light to such an extent that achieving reasonable signal to noise ratios is not feasible using hardware amenable to a wearable device. [0009] Also, within these areas, sites with large vasculatures including, but not limited to native arteries or veins (e.g., radial, brachial, femoral, supraorbital, or carotid arteries) or surgically created vessels, in particular an arteriovenous (AV) access or dialysis fistula, contain a high concentration of hemoglobin and attenuate light at a particularly high rate. As a result, ATSA-based monitoring devices operating in transmission mode are incapable of accurately monitoring these large vasculature sites, which preclude the monitoring device from gathering important physiologic information pertaining to vascular tone, blood pressure, and blood flow in which continuous or highly frequent monitoring is needed for some patients.

[0010] A new deployment of a wearable biosensing device that is configured in accordance with reflectance geometry in which the light source and the light detector on the same side of the body appendage is needed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:

[0012] FIG. 1 is an illustrative embodiment of a reflectance mode, lens-free, wearable biosensing device that utilize speckle technology.

[0013] FIG. 2A is a first illustrative diagram of components of the wearable device of FIG. 1 implemented in accordance with a first exemplary configuration of a lensless, laser speckle imaging (LSI) system.

[0014] FIG. 2B is a second illustrative diagram of components of the wearable device of FIG. 1 implemented with an alternative or additional light shield to block ambient light from the laser diode of the first exemplary configuration of a lensless, laser speckle imaging (LSI) system.

[0015] FIG. 3 is an illustrative diagram of the first exemplary configuration of the lensless LSI system of FIG. 2A or FIG. 2B including a speckle imaging control unit and a laser orientation unit.

[0016] FIG. 4A is a perspective view of the speckle imaging control unit of FIG. 3. [0017] FTG. 4B is a bottom view of the speckle imaging control unit of FIG. 3.

[0018] FIG. 5A is an interior view of the laser orientation unit of FIG. 3.

[0019] FIG. 5B is a perspective view of the laser orientation unit of FIG. 3.

[0020] FIG. 6A is an illustrative result of light detected by a light detector deployed within the speckle imaging control unit of FIGS. 4A-4B.

[0021] FIG. 6B is an illustrative flow of data in determining an SPG waveform produced by the LSI system and an optional PPG waveform.

[0022] FIG. 6C is an illustrative diagram of SPG signal arrays generated by the speckle imaging control unit of FIGS. 4A-4B.

[0023] FIG. 6D is an illustrative graphical representation of a PPG signal and a SPG signal derived from processing the speckle data of FIG. 6A.

[0024] FIG. 6E illustrates a subset of the graphical representation of FIG. 6D.

[0025] FIG. 7A is an illustrative diagram of a second exemplary configuration of the lensless LSI system including a light shield integrated as part of the speckle imaging control unit and/or the laser orientation unit of FIG. 3.

[0026] FIG. 7B is an illustrative diagram of a third exemplary configuration of the lensless LSI system including a light shield deployed as a component attached to the speckle imaging control unit and/or the laser orientation unit of FIG. 3.

[0027] FIG. 8A is an illustrative diagram of a fourth exemplary configuration of the lensless LSI system including a light diffuser positioned to diffuse light provided to a light detector deployed as part of the speckle imaging control unit.

[0028] FIG. 8B is an illustrative diagram of a fifth exemplary configuration of the lensless LSI system including a partially covered light diffuser positioned to diffuse a portion of the light provided to a light detector deployed as part of the speckle imaging control unit. DETAILED DESCRIPTION

[0029] Embodiments of the disclosure generally relate to a wearable biosensing device deployed as part of a health monitoring system that enables replication of certain aspects of the standard of care experienced by a physical examination. Herein, the wearable biosensing device features a lensless, laser speckle imaging (LSI) system operating in accordance with a reflectance geometry (i.e., in reflectance mode). Herein, the LSI system may provide a single speckle plethysmography (SPG) waveform output or multiple waveform output such as a SPG waveform and a photopl ethysmographic (PPG) waveform. For clarity, the disclosure will focus on speckle technology and the generation of SPG waveforms, but it is contemplated that PPG waveforms also may be computed as these waveforms may be generated from data gathered by a light detector from photon waves produced by reflection of laser light emitted from a laser diode being part of the wearable biosensing device. PPG waveforms are based on average light intensity measured from the gathered reflective light data while the SPG waveforms are based on light intensity variance from the gathered reflective light data.

[0030] Unlike conventional optical systems that utilize speckle technology, the LSI system of the wearable biosensing device operates in reflectance mode, and thus, is able to effectively monitor vascular tone, blood pressure, and/or blood flow for large vasculatures within a body appendage such as an arteriovenous (AV) access for example. An AV access is a surgical connection made between an artery and a vein, normally for use during a dialysis session. The AV access is typically located in an arm, however, if necessary, it can be placed in the leg or another part of the human anatomy.

[0031] Herein, according to one embodiment of the disclosure, the wearable biosensing device features an LSI system and is physically attached to a patient (wearer) by a connection mechanism such as one or more straps. According to one embodiment of the disclosure, the LSI system includes a speckle imaging control unit and a laser orientation unit. The speckle imaging control unit features a first housing, which includes at least a component retention element and a first coupling element. According to one embodiment of the disclosure, the first coupling element may be configured as a cylindrical member with a first opening of a prescribed diameter. [0032] The component retention element is configured to maintain a circuit board, which includes a light detecting component (hereinafter, “light detector”), a processing component, a control component, a storage component, and/or a data transmission component. These components may be mounted on the circuit board. For example, the light detector may be mounted on a first (bottom) surface of the circuit board and positioned facing the first opening created by the first coupling member in order to receive reflected light from tissue visually exposed to the light detector and defined the first opening of the cylindrical member. Herein, the reflected light features SPG and/or PPG signal (waveforms) as light that has substantially interacted with tissue and not a first surface reflection from skin of the patient (wearer). Some or all of the remaining components, such as the processing component, the control component, the storage component, and/or the data transmission component, may be mounted on a second (top) surface of the component retention element.

[0033] The laser orientation unit features a second housing, which including a light source retention component and a second coupling element. The light source retention component may be integrated as part of the second coupling element or may be a separate element physically attached to the second coupling element. The light source retention component is configured to house a light source such as a laser diode and/or laser diode driver.

[0034] The second coupling element is sized to engage with the first coupling element of the first housing in order to secure the laser orientation unit to the speckle imaging control unit. As an illustrative example, the second coupling element may be configured with a fastening platform having a raised projection (boss), where both the fastening platform and the raised projection feature an adjustable diameter. This adjustable diameter allows the cylindrical member of the first coupling element within the first housing to be inserted into an opening formed by an interior surface of the fastening platform and the raised projection of the second housing and subsequently tightened to apply fastening pressure against the cylindrical member when inserted.

[0035] The laser diode is angularly positioned within the light source retention component between zero (aligned with a detector array of the light detector) and 90 degrees (perpendicular to the detector array) within the light source retention component to emit a light beam into an interior area formed by the second coupling element (i.e., opening) towards tissue upon which a bottom surface of the second coupling element rests. Photon waves associated with the light beam are reflected by different layers of the body appendage, inclusive of photon wave reflection from tissue of the body appendage under the skin, from a vasculature wall, and cell layers forming a fluid flowing within the vasculature for example.

[0036] As another illustrative embodiment of the disclosure, the wearable biosensing device features additional configurations of the LSI system, which include the above-described speckle imaging control unit and the laser orientation unit. However, for these configurations, a light shield is interposed between the light detector and the laser diode. With respect to a second configuration of the LSI system, the light shield may be integrated as part of the first housing of the speckle imaging control unit and/or the second housing of the laser orientation unit. According to a third configuration of the LSI system, the light shield may be a separate component coupled to the first housing and/or the second housing. The light shield is established to reduce or eliminate first surface reflection from the laser diode and ambient light received by the light detector, which may adversely impact the SPG signal arrays produced by the LSI system.

[0037] As yet another illustrative embodiment of the disclosure, the wearable biosensing device features other configurations for the LSI system, which includes the above-described speckle imaging control unit and the laser orientation unit. A fundamental challenge exists in assessing light that has substantially interacted with tissue scattering elements arises from the exponential decay of brightness versus distance in reflectance mode optical interrogation of tissue, which leads to pixels nearest to the light source to be substantially brighter than those located at the center or other end of the light detector such as a CMOS array or CCD array. CMOS and CCD-based systems can apply pixel binning and analog gain functions to somewhat address brightness challenges, however these approaches are limited to operate on the entire array and cannot be tuned spatially for a single acquisition.

[0038] For these configurations, a light diffuser is interposed between the light detector situated in the speckle imaging control unit and the laser diode situated in the laser orientation unit. The light diffuser is adapted to spread captured light (i.e., reflected photon waves resulting from the application of a laser light beam on a body appendage on which the wearable device is placed) across a greater number of photosensitive elements forming the light detector to produce a series of images associated with a selected frame rate for data gathering, where each image may constitute a speckle (SPG) pattern. Additionally, as other LSI system configurations, a portion of the specific diffusers or specific areas of the CMOS or CCD array may be covered to generate a dark reference to remove results of electrical noise measured by the photosensitive devices of the light detector (referred to as “dark current”). This is of particular importance for reflectance speckle applications because (1) comparatively high frame rates for image sequence acquisition coupled with low light levels in reflectance as compared to transmission mode speckle leads to situations where image acquisition hardware is running high analog gain, which leads to increased dark noise and (2) because speckle relies on assessing spatial variability in the optical signal, increased frame-to-frame variability due to electronic noise is a particular problem.

[0039] Also, some types of diffusers may be deployed that features geometries that both diffuse light, but also preserve spatial information, for example micro-lens arrays, or transparent structures that smoothly vary on the millimeter to micron scale. Absent these specific types of diffusing elements, each photoactive element of the CMOS or CCD array is exposed to light from all areas of the scene as defined by the numerical aperture of the optical system as dictated by physical pixel geometries. By reducing the apparent numerical aperture for each pixel or group of pixels, these specific types of diffusing elements preserve spatial information, and thus the frame-to-frame variance that comprises the speckle signal. The resulting interference pattern can be inverted to create the speckle images or pattem(s).

[0040] More specifically, with respect to a fourth configuration of the LSI system, the light diffuser may be positioned adjacent to the light detector to diffuse light onto photosensitive elements (e.g., pixel elements, etc.) of a CMOS array or onto photosensitive elements (e.g., linked capacitors, etc.) of the CCD. With respect to a fifth configuration, a portion of the light diffuser (e.g., a region of the light diffuser furthest away from the laser diode) is masked for usage of a reference signal for dark current subtraction. With respect to a sixth configuration of the LSI system, a certain type of light diffuser may be installed that creates an interference pattern, which can be inverted to create an image. [0041] As another embodiment of the disclosure, the wearable biosensing device may be configured with a lens-based LSI system with a short focal length (e.g., 2-3 millimeters) with or without an automated image focusing mechanism.

[0042] As described below, the LSI system is configured to compute a waveform of collected light-sourced data set to compute a first waveform, namely a SPG waveform. Additionally, the wearable device may be further configured to compute a PPG waveform from the collected light-sourced data as well. A PPG waveform may be related to volume changes in the vasculature that result from a beating heart and pressure differences. As a result, a PPG waveform may also be related to blood flow, vascular tone, and blood pressure. Blood vessels may be referred to as having an active system, where the vasculatures modulate their stiffness and resistance due to changes in their diameter, which are a result of local cell signaling, and also as a result of inputs from the nervous system. With pulse-oximetry for example, obtaining a PPG waveform tends to work well, because the components comprising the complicated nature of vasculatures tend to cancel each other out. Additionally, a PPG waveform provides a ratio of two different hemoglobin species in the same volume.

[0043] However, attempting to assess blood flow or blood pressure from a PPG waveform is complicated and tends to be inaccurate. SPG is a similar waveform, but one that is derived from the direct motion of the red blood cells within a monitored vasculature, not from volume changes within that vasculature. Also, the type of emitted light may vary as light emitted from a light emitting diode (LED) compared to light that is emitted from a laser diode (or “laser light beam”) is that in a laser, all of the reflected photon waves are oscillating in sync (e.g., the photon waves are in phase or coherent). The coherent nature of laser light leads to an interference pattern of constructive (light spots) and destructive (darker spots) interference when reflected off a diffuse target (e.g., skin, tissue, blood, etc.). As the target changes, for example by moving red blood cells, the interference pattern changes and this variance comprises the speckle signal. In contrast, the photon waves in light emitted from an LED are not in phase and cannot be used for speckle.

[0044] Specifically with light emitted from a laser diode, there exist two components: spatial coherence and temporal coherence. Spatial coherence refers to the photon waves maintaining a substantially a linear path, e.g., a photon on the left side of the beam remains on the left side and does not drift to the right (and vice versa). Temporal coherence refers to maintaining the same phase or coherence over time, e.g., a photon wave that was emitted at time A will have substantially the same coherence a time B.

[0045] Generally, when a coherent source (e.g., a laser light beam) scatters off a diffused target or within tissue of a body appendage (e.g., blood flow) because all of those photon waves were in sync, when they scatter, now the phases are different and the photon waves constructively and/or destructively interfere with each other. The constructive and/or destructive interference creates light and dark spots in reflected light, which may be referred to as a speckle (or SPG) pattern, and which may be captured (e.g., detected by photosensitive elements of a light detector). Importantly, reflected light in this case has interacted with tissues below the surface of the skin and has been scattered back towards the light detector and captured as an image. In particular, at least one scattering event with a red blood cell generates a dynamic speckle pattern correlated with blood flow parameters. Following detection of the speckle pattern, a series of image processing steps may be performed on multiple speckle patterns to convert them into the SPG waveform.

[0046] In contrast with convention optical systems utilizing speckle technology, the wearable device is configured with an architecture to leverage speckle technology in reflectance mode to monitor patient health conditions in a real-time and/or in a continuous or highly repetitive time frame (e.g., sample every few seconds, minute, hour, etc.).

I. TERMINOLOGY

[0047] In the following description, certain terminology is used to describe aspects of the invention. The terms “unit,” “component,” “element,” and “module” are representative of hardware, firmware, and/or software that is configured to perform one or more functions. As hardware, the unit (or component, element, or module) may include circuitry associated with data processing, data storage, and/or data communications. Examples of such circuitry may include, but are not limited or restricted to a processing component (e.g., a programmable logic device such as a programmable gate array, a controller, microcontroller, an application specific integrated circuit, etc.), a transmission component such as a wired or wireless receiver, transmitter and/or transceiver circuitry, an interface (e.g., Universal Serial Bus connector, port, etc ), a storage component (e.g., non-transitory storage medium), sensor, and/or combinatorial logic.

[0048] Alternatively, or in combination with the hardware circuitry described above, the unit (or component, element, or module) may include software in the form of one or more software modules (hereinafter, “software module(s)”), which may be configured to support certain functionality upon execution by data processing circuitry. For instance, a software module may constitute an executable application, a daemon application, an application programming interface (API), a machine-learning (ML) model or other artificial intelligence-based software, a routine or subroutine, a function, a procedure, an applet, a servlet, source or object code, shared library/dynamic load library, or even one or more instructions. The “software module(s)” may be stored in any type of a suitable non-transitory storage medium, or transitory storage medium (e.g., electrical, optical, acoustical, or other form of propagated signals such as carrier waves, infrared signals, or digital signals). Examples of non-transitory storage medium may include, but are not limited or restricted to a programmable circuit; a semiconductor memory; non-persistent storage such as volatile memory (e.g., any type of random access memory “RAM”); persistent storage such as non-volatile memory (e.g., readonly memory “ROM”, power-backed RAM, flash memory, phase-change memory, etc.), a solid-state drive, a hard disk drive, an optical disc drive, a portable memory device, or cloudbased storage (e.g., AWS™ S3 storage, etc.). As firmware, the logic (or component or assembly) may be stored in persistent storage.

[0049] The term “attach” and other tenses of the term (e.g., attached, attaching, etc.) may be construed as physically connecting a first unit (or component, element, or module) to a second unit (or component, element, or module).

[0050] The term “speckle data” may be generally construed as an inherent fluctuation in diffuse reflections, namely a result of the interference of numerous photon waves of the same frequency having different phases and amplitudes, which are formed from one or more images to generate a SPG waveform whose amplitude, and therefore intensity, varies in a systematic way. The speckle data include individual image frames, which are used to generate discrete SPG timepoints forming the SPG waveform, with the sampling frequency is determined by the frame rate. [0051] The term “computing device” should be generally construed as physical or virtualized device with data processing capability and/or a capability of connecting to a network, such as a public cloud network (e.g., Amazon Web Service (AWS®), Microsoft Azure®, Google Cloud®, etc.), a private cloud network, or any other network type. Examples of a computing device may include, but are not limited or restricted to, the following: a server, a router, modem or other intermediary communication device, an endpoint (e.g., a laptop, a smartphone, a tablet, a desktop computer, a netbook, etc.) or virtualized devices being software with the functionality of the computing device.

[0052] The term “interconnect” may be construed as a physical or logical communication path between two or more units (or components or elements). For instance, as a physical communication path, wired interconnects may be provided as electrical wiring, optical fiber, cable, and/or bus trace. As a logical communication path, the interconnect may be a wireless channel using short range signaling (e.g., Bluetooth™) or longer range signaling (e.g., infrared, radio frequency “RF” or the like), a communication pathway between two software-based interfaces, or the like.

[0053] Finally, the terms “or” and “and/or” as used herein are to be interpreted as inclusive or meaning any one or any combination. As an example, “A, B or C” or “A, B and/or C” mean “any of the following: A; B; C; A and B; A and C; B and C; A, B and C ” An exception to this definition will occur only when a combination of elements, functions, steps, or acts are in some way inherently mutually exclusive.

[0054] As this invention is susceptible to embodiments of many different forms, it is intended that the present disclosure is to be considered as an example of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described.

II. FIRST EXEMPLARY EMBODIMENT - WEARABLE BIOSENSING DEVICE

[0055] Referring to FIG. 1, an illustrative embodiment of a reflectance mode, lens-free, wearable biosensing device 100 (hereinafter, “wearable device”) utilizing speckle technology is shown. For the illustrated embodiment, the wearable device 100 includes a laser speckle imaging (LSI) system 105, which is configured to perform lensless laser speckle imaging of a measurement site 160, namely tissue 162 (of a wearer of the wearable device 100) having a vasculature 164 such as a radial artery for example. The wearable device 100 generally includes a laser diode driver 110 with a laser diode 120, a lensless camera module 130 (e.g., light detecting component), and a connection mechanism 140 (e.g., a strap that may be attached or coupled with a human body). The lensless camera module 130 is configured to collect speckle data or locally perform analytics results on the speckle data. In some configuration, the lensless camera module 130 may be further configured to provide the speckle data (or speckle analytic results) 172 to a computing device 170, such as a computer or tablet for example.

[0056] As shown, the wearable device 100 may be communicatively coupled to the computing device 170, which is configured to capture speckled data 172 at a prescribed frame rate (frames per second). It should be understood that other frame rates may be used, e.g., 50 frames per second, 200 frames per second, etc. Speckle data 172 comprises individual image frames, which are post processed to generate an instantaneous estimate of discrete SPG timepoints. These images are used to generate discrete SPG timepoints, where the sampling frequency is determined by the frame rate and collectively form a SPG waveform. In some embodiments, the speckle data 172 may be stored and processing locally, such as by an on-board processing component which generates speckle analytic results that may be provided to the computing device 170 in lieu of or in addition to the speckle data 172. In other embodiments, the speckle data 172 may be transmitted to the computing device 170 for analysis and/or storage. The capturing of the speckle data 172 may be controlled manually from the computing device 170 that provides signaling to the laser diode driver 110 to cause a speckle data cycle to commence or the capturing of the speckle data 172 may be automated at prescribed periods of time.

[0057] The laser diode driver 110 operates to place the laser diode 120 in an illumination mode during which a laser light beam 150 is emitted with a wavelength ranging from 680 nanometers (nm) to 850nm (e.g., 780nm). In the embodiment illustrated in FIGS. 1, 3-5B, 7A-7B & 8A- 8B, the laser diode 120 is positioned in a non-contact configuration, namely the laser diode 120 is in close proximity (e.g., less than 2 inches away), but it is not in direct contact with the tissue 162 at the measurement site 160. However, other configurations may include the laser diode 120 being situated in contact with the tissue 162. Thus, the wearable device 100 may be defined as including an air gap being the distance between the laser and skin (“laser air gap”), where the air gap may be greater than or equal to zero. As one embodiment of the disclosure, the laser air gap may range from four (4) millimeters to twenty (20) millimeters.

[0058] Additionally, as shown in FIG. 1, the laser diode 120 is positioned such that a long axis 152 of the laser light beam 150, emitted as a cone-shaped light with unequal axes, projects along the tissue 162 of a body appendage 166 of the wearer. The long axis 152 of the laser light beam 150 is aligned with the radial artery 164. Specifically, embodiments of the disclosure take particular advantage of the highly divergent light that comes out of the laser diode 120. The laser diode 120 emits the laser light beam 150 in a highly divergent pattern, which is atypical of lasers, and the divergence angle is actually asymmetric, namely it is wider (longer) in one axis (i.e., the long axis 152) than the other. While laser diodes are typically used on conjunction with converging optics (e.g., a converging lens) to collimate or focus the laser light, according to embodiments of the disclosure, the highly divergent and asymmetric output of the laser diode 120 enables reflectance mode speckle by emitting the laser light beam 150 from the laser diode 120 at an angular offset from both vertical and horizontal axes (i.e., downward angularly directed). As a result, the photon waves produced from reflection of the laser light beam 150 from the tissue 162 and/or vasculature 164 (and blood cells flowing therein) are more likely to scatter toward a light detector of the lensless camera module 130. This reflectance scattering is utilized for large vasculature measurement sites as hemoglobin in blood has a strong attenuation effect. Using the laser diode 120 in accordance with this mode of operation enables reflectance mode geometry for speckle contrast measurements on large vasculatures (vessels).

[0059] The lensless camera module 130 may be communicatively coupled to an interface 180 such as a universal serial bus (USB) interface. Information may be exported from or imported into components of the lensless camera module 130 to control its operability. As described below, the lensless camera module 130 is part of the LSI system 105 and may represent the speckle imaging control unit 300 of FIG. 3, where the lensless camera module 130 may include camera modules with a global shutter, camera modules with a rolling shutter, or a combination of a light detector and a processing component. In some embodiments, the local components may include one or more storage components (e.g., non-transitory, computer-readable medium) to store images (speckle data) locally and/or transmission components to transmit the images to the computing devices, via a wired or wireless interconnect. [0060] Referring still to FIG. 1, the wearable device 100 includes one or more connection mechanisms 140, which may be configured as a strap including hook-and-loop fasteners. Other connection mechanisms 140 may include, but are not limited or restricted to, a strap with snaps or a patch having an adhesive for adhering to human skin.

[0061] Referring now to FIG. 2A, an illustrative diagram of components of the wearable device 100 of FIG. 1 implemented in accordance with a first exemplary configuration of the LSI system 105 is shown. Herein, the LSI system 105, operating in reflectance mode, comprises at least one laser source (e.g., laser diode 120) and at the lensless camera module 130, which includes a light detector 405 (see FIG. 4B) such as a CMOS sensor array or a CCD for example. Given the varying surface of the tissue 162 pertaining to a body appendage, the laser diode 120 and lensless camera module 130 are offset from a top surface (skin) 200 of the tissue 162 by a first distance a 210 and a second distance /? 215, respectively. In some embodiments distances a and/or ft are zero implying that either the laser diode 120, lensless camera module 130, or both are in contact with the top surface 200 of the tissue 162.

[0062] As further shown in FIG. 2A, a first optical axis 220 of the laser diode 120 and a second optical axis 225 of the lensless camera module 130 are separated laterally by a distance y 230, and offset by an angle 0 240. Both the lateral offset (y ) 230 and angle (0) 240 may be adjusted to interrogate different depths within the tissue 162 and to optimize the signal to noise ratio (SNR). According to one embodiment of the disclosure, y 230 corresponds to a distance greater than zero (e.g., y< 15 centimeters) and 0 240 corresponds to an angular offset greater than zero and less than or equal to 90 degrees (e.g., 15°< 0 < 45 from the first optical axis 220).

[0063] As an optional feature, a light shield 250 may be deployed to preclude the light detector 405 from having a direct line-of-sight with the laser diode 120 and/or substantially reduce or eliminate reflected from the top surface 200 of the of the tissue 162. Additionally, or in the alternative, a diffuser 260 may be positioned in front of and proximate (or in contact) with the light detector 405 to spread photon waves received upon reflection from the tissue 162.

[0064] Although not shown, it is contemplated that some embodiments of the LSI system 105 of the wearable device may be implemented with multiple laser sources, which may be arranged linearly or radially with respect to the lensless camera module 130. In some cases, the multiple laser sources have a common wavelength characteristic and are arranged to optimize the mode of detected light. In other cases, the multiple laser sources comprise different wavelengths to interrogate specific aspects of the tissue light characteristic and/or interrogate tissue at specific depths. In other cases, multiple laser sources may be configured with different lateral offsets to interrogate the tissue at specific depths. Other embodiments multiple lensless camera modules may be arranged linearly or radially with one or more laser sources associated with these modules.

[0065] Referring to FIG. 2B, second illustrative diagram of components of the wearable device 100 of FIG. 1 implemented with an alternative or additional light shield 270 to block ambient light 275 from the laser diode 120 of the LSI system 105 is shown. As shown in FIG. 2A, the LSI system 105, operating in reflectance mode, comprises the laser diode 120 and the lensless camera module 130. The light shield 270 is interposed between the laser diode 120 and detection area of the lensless camera module 130 (e.g., illustrated as a nearest edge 280 of the lensless camera module 130) to block a first portion of the laser light beam 150 (i.e., ambient light) produced by the laser diode 120. For this embodiment, the reflected light 285 detected by the lensless camera module 130 includes a second portion 290 of the laser light beam 150 directed to the tissue 162 on a first side 272 of the light shield 270, which is reflected by portions of the tissue 162 and escapes towards the lensless camera module 130 from the tissue 162 on a second side 274 of the light shield 270.

[0066] Referring now to FIG. 3, a detailed illustration of the first exemplary configuration of the lensless LSI system 105 implemented within the wearable device 100 of FIGS. 1-2 is shown, where the lensless LSI system 105 is implemented as a speckle imaging control unit 300 and a laser orientation unit 350. The speckle imaging control unit 300 features a first housing 310, which includes a component retention element 320 and a first coupling element 340. The laser orientation unit 350 features a second housing 360, which includes a light source retention element 370 and a second coupling element 380.

[0067] According to this embodiment of the disclosure, the first coupling element 340 of the first housing 310 is configured to securely attach to the second coupling element 380 of the second housing 360. As shown in FIGS. 3-5B, the first coupling element 340 may be configured as a cylindrical member 342 having an opening 344 with a first diameter while the second coupling element 380 may be configured with a fastening platform 382 having a raised projection (boss) 384, both of which having an adjustable second diameter. The diameter adjustability of the fastening platform 382 enables the cylindrical member 342 to be inserted into an opening 386 formed by an interior surface of the fastening platform 382 and the raised projection 384. The fastening platform 382 and the raised projection 384 may be adjusted to reduce the diameter of the opening 386 to apply fastening pressure against the cylindrical member 342 when inserted into the opening 386. As a result, the first coupling element 340 is secured to the second coupling element 380.

[0068] Herein, the openings 344/386 allow the laser diode 120 to emit that a light beam into an interior area defined by the second opening 386 and for a light detector 405 of the lensless camera module 130 (see FIG. 4B) to receive reflected light (photon waves) from tissue of a body appendage upon which a bottom surface 390 of the fastening platform 382 rests. The photon waves associated with the light beam are reflected at different layers of the body appendage, such as a surface (skin) of the body appendage, a vasculature under the skin, and/or propagating cell layers forming a fluid flowing within the vasculature for example. The light detector 405 is oriented to receive the reflected photon waves propagating through an interior area 345/395 of the coupling elements 340/380.

[0069] Referring back to FIG. 3, the laser orientation unit 350 features the light source retention element 370 that is adapted to receive the laser diode 120, which is placed within a chamber 372 formed along an outer side surface of the fastening platform 382 and the raised projection 384. The interior surface of the raised projection 384 features an opening 500 in the chamber 372 to allow the laser diode 120 to emit laser light beams into the interior area 395 formed by the second coupling element 380 (see FIG. 5A). The fastening platform 382 of the laser orientation unit 350 further includes slots 398 that are adapted to receive the connection mechanism 140 such as a strap as illustrated in FIG. 1.

[0070] Referring to FIG. 4A, a perspective view of the speckle imaging control unit 300 of FIG. 3 is shown. Herein, the component retention element 320 is configured to maintain the lensless camera module 130. More specifically, the lensless camera module 130 includes a circuit board 400 upon which a plurality of components are mounted. These components may include, but are not limited or restricted to, a light detector 405 (see FIG. 4B), one or more processing components 410 (e.g., processor component, control component, etc.), a storage component 415, and a data transmission component 420. These components 405-420 may be maintained on the circuit board 400 with the light detector 405 mounted on a first (bottom) surface 402 of the circuit board 400 and some or all of the remaining components 410-420 may be mounted on a second (top) surface 404 of the circuit board 400.

[0071] According to one embodiment of the disclosure, the processing component(s) 410 may include an on-board processor that is adapted to receive speckle data from the light detector 405 and perform analytics on the speckle data to generate a SPG signal array as shown in FIG. 6C for each of a plurality of frames associated with the light beam 150 reflecting from monitored tissue. The processor component(s) 410 may further include an on-board controller that is adapted to control operability of the light detector 405 for capture of reflected photon waves from the monitored tissue to generate the speckle data and/or manage overhead in the storage of the speckle data into the storage component 415.

[0072] The storage component 415 is configured to include logic utilized by the processing component(s) 410 to control operability of the LSI system 105 to gather and/or conduct analytics on the speckle data in order to generate a speckle pattern (image) for further analytics. The storage component 415 is also configured to temporarily store the speckle data 172 prior to transmission to the computing device 170 as shown in FIG. 1.

[0073] The data transmission component 420 is adapted to transmit the speckle data captured by the light detector 405 and/or to transmit the speckle analytic results computed by the processing component 410 to the computing device remotely located from the wearable device 100. The computing device 170 may be configured to perform analytics on the speckle data (or further analytics of the speckle analytic results) or storage of the speckle data (and/or speckle analytic results) for generation of display information 174 (see FIG. 1) viewable by the wearer or a health professional.

[0074] Referring to FIG. 4B, a bottom view of the speckle imaging control unit 300 of FIG. 3 is shown. Herein, the light detector 405 is mounted on the bottom surface 402 of the circuit board 400 and positioned to be exposed to the interior area 345 of the first coupling element 340. Stated differently, the light detector 405 is enclosed within a chamber formed by the interior area 345 of the second coupling element 340 and an interior area 440 within the component retention element 320. Hence, this chamber establishes an area clear of obstruction to enable photon waves reflecting from the tissue (e g., skin, vessel, blood flowing in the vessel) to be captured by the light detector 405. As shown, the light detector 405 may be implemented as a CMOS sensor array, a CCD, or a type of photodiode array.

[0075] Referring now to FIG. 5A, an interior view of the laser orientation unit 350 of FIG. 3 is shown. Herein, as part of the second housing 360, the light source retention element 370 is configured with the chamber 372 and formed as part of the raised projection 384. The chamber 372 includes the opening 500 to allow the laser diode 120 to emit laser light beams into the interior area 395 formed by the second coupling element 380. As shown, the laser diode 120 is oriented with an angular offset downward from a horizontal reference to direct the long axis 152 of the laser light beam 150 towards a body appendage positioned under the interior area 395. Stated differently, the laser diode 120 is situated in a downward angular orientation so that the long axis 152 of laser light beam 150 emitted by the laser diode 120 is positioned lengthwise along a pathway of a vasculature being monitored. This angular offset (o), shown in FIG. 2A, identifies that the laser light beam 150 is composed of an elliptical light representative of a cone-shaped light with unequal axes and can be emitted in front of the light detector 405 of the lensless camera module 130 shown in FIG. 4B.

[0076] Referring to FIG. 5B, a perspective view of the laser orientation unit 350 of FIG. 3 is shown. Herein, the second coupling element 380 features a fastener 510 that is adapted to adjust the diameter of the second coupling element 380, namely both the fastening platform 382 and the raised projection 384, to securely apply pressure forces against the first coupling element 340 when inserted into the interior area 395. The laser diode is partially sealed by a wall 530 formed on a backend of the chamber 372 with leads 540 extending from the laser diode for coupling to the laser diode driver that may be positioned adjacent to the laser orientation unit 350.

[0077] Referring now to FIG. 6A, an illustrative result of light detected by the light detector 405 of the lensless camera module 130 of FIGS. 1-5B is shown and may be applicable to other embodiments of the LSI system. Herein, the detected light includes variations that correspond to the speckle data 600. The speckle data is represented with a bright side 610 (right hand side) and a dim side 620 (left hand side), where the bright side 610 represents positions of photosensitive elements of the light detector 405 that are closer to the laser diode 120 than those light capturing elements pertaining to the dim side 620. For example, the photosensitive elements may constitute an array of pixels (e.g., photodiodes) when the light detector 405 is a CMOS sensor or may constitute an array of linked, capacitors when the light detector 405 is a CCD. A horizontally center line 630 is intended to illustrate the light-dark contrast of the two sides of the captured speckle data and is not actually part of the captured speckle data.

[0078] Referring to FIG. 6B, an illustrative flow of data in determining an SPG waveform 640 and optionally a PPG waveform 650 is shown. The flow of data includes the capturing of speckle data 600 over time (e.g., in frames 660) and an analysis procedure where each captured frame 665 is analyzed using a sliding window 670, e g., 7x7 window (pixels). This procedure utilizes multiple nested loops to calculate parameters within the sliding window 670, where optimization is achieved by considering the image frame as a matrix. At a high-level, the analysis procedure includes calculating the expected value (which may be the average light intensity over the sliding window 670) to produce a first set of images 680 and calculating the standard deviation over that window, which results in a second set of images 690. The first set of images 680 is the average light intensity, which is used to generate PPG signal arrays 682 and these PPG signal arrays 682 (operating as discrete PPG waveform sections) are converted into the PPG waveform (or signal) 650. The second set of images 690 are light variance images, where the second set of images 690 are used to generate SPG signal arrays 692 that are converted into the SPG waveform (or signal) 650.

[0079] FIG. 6C illustrates exemplary PPG signal arrays 682 and SPG signal arrays 692 according to some embodiments. For instance, the exemplary SPG signal arrays 692 may be resultant from the processing the speckle data of FIG. 6A (captured light variances) using the analysis procedure set forth in FIG. 6B.

[0080] Referring now to FIG. 6D, an illustrative graphical representation of the PPG waveform 640 and the SPG waveform 650 derived from processing the speckle data 600 of FIG. 6A with the analysis procedure set forth in FIG. 6B is shown. A dashed-line representation of the PPG waveform 650 is illustrated in combination with a dotted-line representation of the SPG waveform 640. FIG. 6E illustrates a subset of the graphical representation of FIG. 6D in accordance with some embodiments. For each, the subset illustrated in FIG. 6E may the PPG and SPG signals at 11 -14.25 seconds (see dotted box 685 of FIG. 6D)

[0081] Referring to FIG. 6E, a few observations become apparent about the collected data following analysis with the analysis procedure of FIG. 6B. First, there is the fact that two distinct waveforms 640/650 are able to be calculated using the novel approach disclosed herein with the reflectance mode and a lensless camera module. A second important observation is that the SPG and PPG waveforms 640 and 650 are slightly out of phase. Thus, there is a peak- to-peak delay between the two signals, which related to vascular tone, where vascular tone is an important confounder in trying to take a non-invasive, cuffless blood pressure measurement.

[0082] A third important observation is that the SPG signal height may be determined, which is linear to blood flow. Thus, combining the second and third observations, the wearable device may enable determination of blood pressure. SPG has a particular advantage in non-invasive, cuffless assessment of blood pressure vs. other optical and non-optical measures because the amplitude of the SPG waveform 640 is linearly proportional to flow. Volumetric flow and pressure are directly proportional as described in fluid dynamics, which by extension implies SPG amplitude to be linearly related to blood pressure. Importantly, vascular tone modulates vascular resistance, which has long been established as a confounding factor in non-invasive, cuffless assessment of blood pressure. Vascular tone is related to the phase delay between the SPG waveform 640 and the PPG waveform 650, which are acquired simultaneously and time synchronized in the disclosed invention.

[0083] Referring to actual test data and, specifically, the phase delay detected between the SPG waveform 640 and the PPG waveform 650, a cross correlation analysis was run on those two waveforms to calculate an average peak to peak delay. The cross-correlation analysis resulted in approximately 5 hundredths of a second, which is substantially corroborated for a transmission mode measurements.

II. SECOND EXEMPLARY EMBODIMENT - WEARABLE DEVICE WITH LIGHT SHIELD

[0084] Referring now to FIG. 7A, an illustrative diagram of a second exemplary configuration of a lensless LSI system 1105 implemented within the wearable device 100 of FIG. 1 is shown. Herein, the lensless LSI system 1105 features a speckle imaging control unit 1300 and a laser orientation unit 1350, which include components deployed by the speckle imaging control unit 300 and the laser orientation unit 350 of FIGS. 3-5B. Similar components will be represented by similar reference numbers as a light detector J_405 of the lensless LSI system J_105 features a similar reference numeral as the light detector 405 of the lensless LSI system 105 of FIGS. 3-5B (“Yxxx”). A notable differences between these LSI system 105 and 1105 is that the lensless LSI system 1105 further includes a light shield 700 integrated as part of a first coupling element 1340 and/or a second coupling element 1380.

[0085] For instance, the light shield 700 may be integrated as part of the first coupling element

1340 in order to substantially reduce or preclude ambient light directly from a laser diode 1120. For this illustrative example, the light shield 700 may be positioned as a flange extending from an inner edge 1341 towards a first portion 1343 of a cylindrical member 1342 of the first coupling element 1340. The light shield (flange) 700 may be extended from the inner edge

1341 less than a centimeter (e.g., 1-5 millimeters) to preclude the light detector 1405 from having a direct line-of-sight with the laser diode 1120. Additionally, or in the alternative, the light shield 700 may be positioned as a flange (represented by dashed lines) extending from an interior surface 710 of a raised projection 1384 of the second coupling element 1380.

[0086] Although these configurations illustrate the light shield 700 being positioned on the edge 1341 of the cylindrical member 1342 and/or on the interior surface 710 above the laser diode 1 120, it is contemplated that other positions may be selected for the light shield 700. The selected position is chosen to preclude the light detector 1405 from having a direct line-of- sight with the laser diode 1120 and to substantially reduce or preclude the detection of photon waves reflected from a top surface of a body appendage oriented to receive the long axis of the laser light beam emitted from the laser diode 1120.

[0087] Referring to FIG. 7B, an illustrative diagram of a third exemplary configuration of the lensless LSI system 1105 implemented within the wearable device 100 of FIG. 1 is shown. Herein, a light shield 750 is deployed as a separate component that may be attached to the speckle imaging control unit 1300 and/or the laser orientation unit 1350. As shown, the light shield 750 is inserted into the area 1345 formed by an interior perimeter of the first coupling element 1340. Alternatively, the light shield 750 may be attached to the second coupling element 1380 to reside within the interior area 1345 formed by the first coupling element 1340 in order to substantially reduce or preclude the light detector 1405 from receiving ambient light directly from the laser diode 1120.

III. THIRD EXEMPLARY EMBODIMENT - WEARABLE DEVICE WITH DIFFUSER

[0088] Referring now to FIG. 8A, an illustrative diagram of a fourth exemplary configuration of a lensless LSI system 2105 implemented within the wearable device 100 of FIG. 1 is shown. Herein, the lensless LSI system 2105 features a speckle imaging control unit 2300 and a laser orientation unit 2350, which also include components deployed by the speckle imaging control unit 300 and the laser orientation unit 350 of FIGS. 3-5B. However, the lensless LSI system 2105 further includes a light diffuser 800 positioned to diffuse light provided to a light detector 2405.

[0089] Herein, the light diffuser 800 is adapted to spread the light signals in a more uniform basis to photosensitive elements forming a detector 2405 operating as a CMOS sensor array or a CCD. The distance between the light diffuser 800 and the detector 2405 may be less than one inch and the diffusion angle may range from 0.50 degree to 95 degrees. With this configuration, the light diffuser 800 is positioned proximate to and interposed between the light detector 2405 and the body appendage illuminated by a laser light beam 2150 emitted from the laser diode 2120, where an air gap 810 remains between the light diffuser 800 and the light detector 2405. The light diffuser 800 may be mounted to the circuit board 2400 or may be coupled to an interior surface 820 within a component retention element 2320 or first coupling element 2340.

[0090] It is contemplated that the diffuser 800 may be a specific type of diffuser positioned a prescribed distance from the light detector 2405 and operating similar to optical lenses. Herein, the diffuser 800 conducts light intensity smoothing operations to alter the diffused image into a focused image. SPG computations may be conducted on the focused image in which spatial information associated with specific areas of the “scene” (i.e., resultant reflected light from the diffused target) are directed to specific pixels (i.e., photosensitive elements) of the light detector 2405. This improves SNR given the improved recovery of spatial information that is correlated to improved light variance across the speckle image.

[0091] Referring to FIG. 8B, an illustrative diagram of a fifth exemplary configuration of the lensless LSI system 2105 including a partially covered light diffuser 830 positioned to diffuse a portion of the light provided to a light detector 2405 deployed as part of the speckle imaging control unit 2300 is shown. Herein, a region of the light diffuser 830 namely a first region 835 furthest away from a side of the laser orientation unit 2350 including the laser diode 2120 is covered. As a result, photosensitive elements 840 of the light detector 2405 positioned under the first region 835 of the light diffuser 830 are configured to not receive photon waves reflected from the body appendage being monitored, but are minimally illuminated due to dark current (e.g., electrical noise measured by the photosensitive elements 840). As a result, signaling produced from the photosensitive elements 840 operates as a reference signal to eliminate the dark current from the remaining portions of the speckled data gathered by photosensitive elements 845 unblocked by the covered first region 835 of the diffuser 830. This dark current subtraction provides more accurate SPG waveforms to provide better accuracy in determining vascular tone, blood pressure, and/or blood flow for vasculatures within a body appendage being monitored, including an AV access.

IV. FOURTH EXEMPLARY EMBODIMENT - WEARABLE DEVICE WITH OPTICS

[0092] Although not shown, the LSI system may substitute the diffuser 800 of FIG. 8A with one or more optical lens. The optical lens may be configured with a focal length (FL) approximately (e.g., 10% error range) equal to (A) the distance between the diffused target (top surface of tissue of a monitored body appendage) and the light detector divided by (B) 2 or 4 (i.e., FL=A/B) For this configuration, an image acquisition rate of the diffuser 800 to be a multiple of the sample rate of the pulse waveform (photon waves) reflected from the diffused target (body appendage). As an example, where the sample rate of the pulse waveform is thirty hertz (30 HZ), the image acquisition rate would be set to at least 30 Hz and perhaps in the range of 50-90 Hz (i.e., a multiple of the sample rate such as at least 2X the sample rate).

[0093] In the foregoing description, the invention is described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims.

Claims

CLAIMS What is claimed is:

1. A wearable biosensing device, comprising: a laser diode; and a camera module positioned in a reflectance geometry with the laser diode to detect photon waves reflecting from a diffused target.

2. The wearable biosensing device of claim 1, wherein the camera module is a lensless camera module.

3. The wearable biosensing device of claim 2, wherein the laser diode is situated in a downward angular orientation so that a long axis of laser light beam emitted by the laser diode is positioned lengthwise along a pathway of a vasculature being monitored.

4. The wearable biosensing device of claim 3, wherein the lensless camera module operates as and includes a light detector including a plurality of photosensitive elements to capture speckle data associated with the photon waves.

5. The wearable biosensing device of claim 4, wherein the lensless camera module further includes a plurality of components to process the speckle data and generate one or more speckle plethysmography (SPG) waveforms, the plurality of components include a processing component, a storage component and a transmission component mounted on a first surface of a circuit board placed within the lensless camera module while the light detector is mounted on a second surface of the circuit board situated on an opposite side of the circuit board than the first surface.

6. The wearable biosensing device of claim 4 further comprising a light shield interposed between the light detector and the diffused target toward which the laser light beam is emitted, the light shield to substantially reduce or preclude ambient light directly from the laser diode being detected by the light detector of the lensless camera module.

7. The wearable biosensing device of claim 6, wherein the light shield is integrated as part of a speckle imaging control unit housing the light detector and a circuit board including at least a processing component to process the speckle data.

8. The wearable biosensing device of claim 7, wherein the laser diode is maintained within a laser orientation unit removably coupled to the speckle imaging control unit.

9. The wearable biosensing device of claim 4 further comprising a light diffuser interposed between the light detector and the diffused target toward which the laser light beam is emitted, the light diffuser is configured to spread light associated with the photon waves to an increased number of photosensitive elements forming the light detector.

10. The wearable biosensing device of claim 9, wherein the light diffuser is covered at a first region furthest from the laser diode to diffuse a portion of the light provided to the light detector so that a group of photosensitive elements of the light detector are precluded from receiving a portion of the light from the photon waves and are minimally illuminated due to dark current.

11. The wearable biosensing device of claim 9, wherein the light diffuser corresponds to a specific type of diffuser positioned a prescribed distance from the light detector and operating similar to optical lenses by conducting light intensity smoothing operations to alter a diffused image into a focused image and SPG computations are conducted on a calculated focused image in which spatial information associated with specific areas of a scene are directed to specific photosensitive elements of the light detector.

12. The wearable biosensing device of claim 3, wherein the laser light beam is composed of an elliptical light representative of a cone-shaped light with unequal axes and can be emitted in front of the lensless camera module.

13. A method for generating speckle plethysmography (SPG) waveforms representing a vascular tone, blood pressure, or blood flow for vasculature within a body appendage being monitored by a wearable biosensing device, comprising: positioning a laser diode and a camera module in a reflectance geometry positioned on a same side of the body appendage; and detecting photon waves reflecting from a diffused target by a light detector of the wearable biosensing device in response to a laser light beam being emitted from the laser diode, the light detector including a plurality of photosensitive elements to capture speckle data associated with the photon waves that are used to generate the SPG waveforms.

14. The method of claim 13, wherein the camera module is a lensless camera module.

15. The method of claim 14, wherein the positioning of the laser diode involves placing the laser diode in a downward angular orientation so that a long axis of laser light beam is positioned lengthwise along a pathway of the vasculature being monitored.

16. The method of claim 15 further comprising: processing, by a plurality of components mounted on a circuit board maintained as part of the lensless camera module, the speckle data by a plurality of components to generate the SPG waveforms, the plurality of components include a processing component, a storage component and a transmission component mounted on a first surface of the circuit board while the light detector is mounted on a second surface of the circuit board situated on an opposite side of the circuit board than the first surface.

17. The method of claim 16 further comprising: interposing a light shield between the light detector and the diffused target toward which the laser light beam is emitted, the light shield to substantially reduce or preclude ambient light directly from the laser diode being detected by the light detector of the lensless camera module.

18. The method of claim 17, wherein the positioning the laser diode and the lensless camera module in the reflectance geometry comprises positioning laser diode within a laser orientation unit and placing the lensless camera module with a speckle imaging control unit, wherein the laser orientation unit is removably coupled to the speckle imaging control unit.

19. The method of claim 15 further comprising: interposing a light diffuser between the light detector and the diffused target toward which the laser light beam is emitted, the light diffuser is configured to spread light associated with the photon waves.

20. The method of claim 19, wherein the light diffuser is covered at a first region furthest from the laser diode to diffuse a portion of the light provided to the light detector so that a group of photosensitive elements of the light detector are precluded from receiving a portion of the light from the photon waves and are minimally illuminated due to dark current.

21. The method of claim 19, wherein the light diffuser corresponds to a specific type of diffuser positioned a prescribed distance from the light detector and operating similar to optical lenses by conducting light intensity smoothing operations to alter a diffused image into a focused image and SPG computations are conducted on the focused image in which spatial information associated with specific areas of a scene are directed to specific photosensitive elements of the light detector.