Device with microneedles for communicating signals through skin

Abstract

Devices and methods for communicating signals through the skin of a patient are disclosed. The devices include a transmitter that can transmit an optical signal into a dermal layer of skin of a patient and a receiver that can detect at least part of the optical signal reflected back from the dermal layer. At least part of the detected optical signal is associated with a physiological characteristic of the patient. The devices also include and a microneedle that defines a distal opening. The distal opening can be inserted into the skin through an epidermal layer of the skin and into the dermal layer. The microneedle is operatively connected to at least one of the transmitter or the receiver.

Description

DEVICE WITH MICRONEEDLES FOR COMMUNICATINGSIGNALS THROUGH SKINCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 675,276, filed July 25, 2024, the entirety of which is incorporated herein for any and all purposes.BACKGROUND

[0002] Photoplethysmography (PPG) sensors are non-invasive, low-cost sensors that can be used to measure signals associated with physiological characteristics. PPG sensors can be optical contact sensors that emit light (e g., infrared, green LED, etc.) at skin and that detect the light after the light interacts with the skin and other bodily fluids / structures. Physiological characteristics can be inferred from detected light after the interaction with the skin and other bodily fluids / structures. For example, heart rate can be inferred as the detected light signals interact with different volumes of blood passing through the skin. PPG sensors can be wearable and can be used outside of clinical settings. PPG sensors can monitor biofeedback to help user track physiological functions.BRIEF SUMMARY

[0003] The accuracy of some current PPG sensors can be compromised by various interfering factors on or in the skin (e.g., the stratum comeum layer of skin, melanin, hair, sweat, movement, wrinkles, etc.). There therefore exists a need to improve the accuracy of sensors, including of PPG sensors, by eliminating or reducing the impact of such interfering factors. This need is addressed, to a great extent, by devices and methods according to some aspects of this disclosure. In one aspect, a device includes a transmitter configured to transmit an optical signal into a dermal layer of skin of a patient, a receiver configured to detect at least part of the optical signal reflected back from the dermal layer, the detected at least part of the optical signal being associated with a physiological characteristic of the patient, and a microneedle defining a distal opening. The distal opening is configured to be inserted into the skin through an epidermal layer of the skin and into the dermal layer. The microneedle is operatively connected to at least one of the transmitter or the receiver.

[0004] Implementations may include one or more of the following features. The microneedle is operatively connected to the transmitter such that the transmitter is configured to transmit the optical signal, via the distal opening, within the dermal layer. The microneedle is a firstmicroneedle and the distal opening is a first distal opening, the device further includes a second microneedle defining a second distal opening, the second distal opening being configured to be inserted into the skin through the epidermal layer and into the dermal layer, and the second microneedle is operatively connected to the receiver such that the receiver is configured to receive the at least part of the optical signal within the dermal layer via the second distal opening of the second microneedle. The microneedle is operatively connected to the receiver such that the receiver is configured to receive the at least part of the optical signal, via the distal opening, within the dermal layer. The transmitter is configured to be positioned outside of the skin such that the optical signal is transmitted, within the microneedle through the epidermal layer into the dermal layer.

[0005] In another aspect, a device includes a base configured to be held against an outer surface a skin of a patient, a transmitter configured to transmit a signal through the skin, a receiver configured to detect at least part of the signal after the signal is transmitted through the skin, the detected signal being associated with a physiological characteristic of the patient, and a microneedle extending in a direction away from the base. The microneedle includes a distal opening at a distance, along the direction away from the base, of at least 200 pm from the base, where the microneedle is operatively connected to one of the transmitter or the receiver.

[0006] Implementations may include one or more of the following features. The microneedle is operatively connected to the transmitter such that, when the base is held against the outer surface of the skin, the transmitter is configured to transmit the signal, via the distal opening, at a depth of at least 200 pm within the skin. The microneedle is configured to direct the at least part of the signal out of the distal opening at an angle. The microneedle is a first microneedle and the distal opening is a first distal opening, the device further includes a second microneedle extending in the direction away from the base, the second microneedle defining an second distal opening at a distance, along the direction away from the base, of at least 200 pm from the base, and the second microneedle is operatively connected to the receiver such that, when the base is held against the outer surface of the skin, the receiver is configured to receive the signal, via the second distal opening of the second microneedle, at the depth within the skin. The transmitter is within a hollow' interior of the microneedle. The microneedle is filled with a material that is configured to guide the signal to the distal opening. The microneedle comprises a hollow7interior that is lined with a reflective material. The microneedle is operatively connected to the transmitter at a proximal opening of the microneedle. The microneedle is operatively connected to the receiver such that, when the base is held against the outer surface of the skin, the receiver is configured to receive the at least part of the signal, via the distal opening, at a depth of at least200 pm within the skin. The signal is an optical signal. The transmitter is an LED, and the receiver is a photodiode.

[0007] In yet another aspect, a method of measuring a physiological characteristic includes inserting a microneedle, which is operatively connected to a transmitter, into a dermal layer of skin, emitting an optical signal, using the transmitter, through the microneedle and into the dermal layer of skin, detecting, using a receiver, at least part of the optical signal from within the dermal layer, and determining the physiological characteristic based on the detected optical signal.

[0008] Implementations may include one or more of the following features. The method further includes inserting the microneedle comprises inserting at least part of a distal opening of the microneedle through an epidermal layer of the skin and into the dermal layer, and emitting the optical signal into the dermal layer comprises emitting the optical signal, via the distal opening of the microneedle, into the dermal layer. The microneedle is a first microneedle and the distal opening is a first distal opening, the method further includes, before detecting the at least part of the optical signal, inserting a second microneedle, which is operatively connected to the receiver, into the dermal layer. The method further includes inserting the second microneedle comprises inserting at least part of a second distal opening of the second microneedle through an epidermal layer of the skin and into the dermal layer, and detecting the optical signal comprises detecting the optical signal, via the distal opening of the second microneedle, from the dermal layer.

[0009] Various additional features and advantages of this invention will become apparent to those of ordinary' skill in the art upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0010] The following detailed description is better understood when read in conjunction with the appended drawings. For the purposes of illustration, examples are shown in the drawings; however, the subject matter is not limited to the specific elements and instrumentalities disclosed. In the drawings:

[0011] FIG. 1A illustrates a schematic view of an example device.

[0012] FIG. IB illustrates a magnified view' of the device of FIG. 1 A within region A.

[0013] FIG. 2 illustrates a schematic view of an example microneedle and transmitter.

[0014] FIG. 3 illustrates a schematic view' of another example microneedle and transmitter.

[0015] FIG. 4 illustrates a schematic view of another example microneedle.

[0016] FIG. 5 illustrates a schematic view of another example microneedle.

[0017] FIG. 6 illustrates a schematic view of another example device.

[0018] FIG. 7 illustrates a schematic view of another example device.

[0019] FIG. 8 illustrates a process of measuring a physiological characteristic.DETAILED DESCRIPTION

[0020] Sensors can be placed on top of an outer surface of the skin of a patient. Such sensors can detect signals associated with physiological characteristics of the patient. The physiological characteristics can include, for example, blood oxygen saturation (SpO2), respiration rate, heart rate, blood pressure, among other possibilities. For some such sensors, light can be emitted from a transmitter of the sensor incident to the skin, and the light can be absorbed by the skin and other bodily fluids / structures (e.g., blood, tissues, blood vessels, etc.). A receiver can detect some of the light that is not absorbed by the skin and other bodily fluids / structures. Information regarding physiological characteristics of the patient can be inferred from the detected light.

[0021] Photoplethysmography (PPG) sensors are one example type of a sensor that can be placed on top of the outer surface of the skin of the patient to detect signals associated with physiological characteristics of the patient. PPG is an emerging optical technology and is non- invasive in nature. PPG sensors can be inexpensive to implement. A PPG sensor can include a transmitter (e.g., a light source such as LEDs) and a receiver (e.g., a photo detector). The optical signals detected from PPG sensors can be used to detect signals associated with, for example, volumetric changes in blood. PPG sensors can be implemented in at least two types: transmittance or reflectance. For some transmittance type PPG sensors, the transmitter can oppose the receiver. For some reflectance type PPG sensors, the transmitter and the receiver can be arranged at the same location. PPG sensors can be used in clinical applications, like obstructive sleep apnea detection and respiration influence on arterial pressure, among other applications. PPG sensors can also be used in non-clinical applications, like chewing rate, personal authentication, driver drowsiness, among other applications.

[0022] One problem associated with some existing sensors that are placed on top of the skin for detecting signals associated with physiological characteristics of the patient, such as PPG sensors, is variation in detected signals caused from differences in the thickness of skin layers that the sensors are placed on top of. The stratum comeum, or outermost layer of skin, includes dead skin cells, lipids, and proteins. Limited information regarding physiological characteristics of the patient can be gleaned from detected signals associated with the stratum comeum. Accordingly, some sensors aim to probe deeper into the skin, such as further into the epidermal layer or into the dermal layer, which can offer more information regarding physiologicalcharacteristics of the patient than the stratum comeum. But characteristics of the stratum comeum (e.g., opacity, density, thickness, etc.) can interfere with the emission or detection of some signals. Such interference can result in less accurate physiological characteristic inferences drawn from the detected signals. For example, the thickness of the stratum comeum can vary depending on where the skin is on the patient, the age of the patient, skin health, and other factors. The stratum comeum for an adult human forearm can be, for example, about one third the thickness of the stratum comeum for an adult human abdomen. Because the sensors aim to probe into the skin bey ond the stratum comeum, a comparatively thicker stratum comeum layer can cause more interference with the detected signal than a thinner stratum comeum layer. This can compromise the accuracy of sensors placed on top of certain regions of the body (e.g., the abdomen) or of certain persons with relatively7thick stratum comeum layers. This can also require calibrating the sensor based on the anticipated location of use on the body and knowing the expected thickness of the stratum comeum in that specific location.

[0023] Another problem associated with some existing sensors that are placed on top of the skin for detecting signals associated with physiological characteristics of the patient, such as PPG sensors, is variation in detected signals caused from differences in melanin levels of the skin. Melanin can interfere with the emission or detection of some signals traveling through skin layers containing melanin, such as portions of the epidermal layer. Higher melanin levels in the skin can cause more interference with the detected signal than similar skin layers with lower melanin levels.

[0024] Yet another problem associated with some existing sensors that are placed on top of the skin for detecting signals associated with physiological characteristics of the patient, such as PPG sensors, is detected signal noise resulting from movement of the sensor and / or the patient. This noise can appear as unruly signals of large amplitudes in the detected signals. The noise can also be reflected in the frequency domain and can overlap with other frequency ranges, such as for detected signals associated with breathing or heart rates.

[0025] Hair, sweat, wrinkles, skin growths, skin hydration levels, etc., can also interfere with emission or detection of some signals for some existing sensors that are placed on top of the skin.

[0026] Aspects of this invention are directed to devices and methods that include and / or utilize microneedles to direct signals (e.g., light) directly from the device to portions of the skin that are deeper / below a predetermined layer of the skin (e.g., the stratum comeum or other portions of the epidermis) and / or directly from skin below the epidermal layer to the device. The term “directly” as used in this context can mean that the signal does not travel through the interveninglayers of skin, such as the stratum comeum and / or other portions of the epidermal layer) and instead bypasses these intervening layers by traveling through the microneedles. Microneedles can be micron-scale needles with one or more dimensions (e.g., diameter, width, length, etc.) of less than about 1 mm (1000 pm). Though the microneedles of this disclosure can be micron-scale needles, it is to be understood that the term “microneedle” as used herein is not strictly limited to micron-scale needles. For example, the term “microneedle” as user herein can, in embodiments, encompass needles with one or more dimensions (e.g., diameter, width, length, etc.) greater than 1000 pm such as dimensions between 1000 pm and 1500 pm, inclusive (i.e., including both endpoints of the range), greater than 1500 pm. among other possibilities. Using microneedles to direct signals directly to and / or from skin below the epidermal layer can reduce or eliminate the impact of the previously described interfering factors (e.g., the stratum comeum layer of skin, melanin, hair, sweat, movement, wrinkles, etc.) and can improve the accuracy of the device and associated methods. The microneedles can direct the signals directly to and / or from the desired layer of skin (e.g., the dermis), which contains, for example, neurons and blood capillaries that can reveal important information regarding certain physiological characteristics of the patient. The length of the microneedles of the devices and methods according to some aspects can be tuned to limit microneedle interaction with neurons and blood vessels and thereby avoid or minimize bleeding or pain. These and other aspects are described further below and shown in FIGS. 1A-8.

[0027] FIG. 1 A discloses a schematic view of a device 100 according to some aspects of the disclosure. The device 100 can be a medical device, such as an injector. The device 100 can be a wearable medical device. The device 100 can include a transmitter 102 and a receiver 104. The transmitter 102 can transmit a signal (e.g., an optical signal) at a skin S of the patient when the device 100 is placed on and / or attached to the skin S. It is to be understood that the term “signal” as used herein can be used interchangeably with “optical signal" and that any description of the “signal” can at least include an optical signal. However, it is also to be understood that the disclosure is not limited to optical signals and in embodiments can include other signal types, such as sound signals. In embodiments, when the device 100 is placed on and / or attached to the skin S, the transmitter 102 can transmit the signal directly into a dermal layer D of the skin S via one or more microneedles 106, as described further later. In embodiments, the transmitter 102 can include one or more light source (e.g., LED). The transmitter 102 can transmit light at any wavelength including infrared, visible light (e.g., green, red, etc.), among other possibilities. The device 100 can include a single transmitter 102 or multiple transmitters 102 (e.g., two, three, four, or more). Although this disclosure refers to transmitting the signal to the dermal layer D, it should be understood that the signal can be transmitted to other portions of the skin S accordingto other embodiments, for example, into portions of the epidermis deeper than the stratum comeum.

[0028] The receiver 104 can detect at least part of the signal that reflects back from and / or travels through the dermal layer D. In embodiments, when the device 100 is placed on and / or attached to the skin S, the receiver 104 can receive at least part of the signal directly from the dermal layer D of the skin S via one or more of the microneedles 106, as described further later. In embodiments, the receiver 104 can include one or more photodetectors (e.g.. photodiodes). The photodiodes can detect at least part of light signals emitted, for example, from the transmitter 102. The device 100 can include a single receiver 104 or multiple receivers 104 (e.g., two, three, four, or more). The detected at least part of the signal can be associated with one or more physiological characteristics of the patient since physiological characteristics of the patient can cause changes to the signal emitted by the transmitter 102 that can be detected by the receiver 104. Example physiological characteristics that can be associated with the signal include heart rate, heart rate variability, blood pressure, SpO2, sleep quality, respiration rate, other cardiovascular information, other nervous system information, among other possibilities.

[0029] The device 100 includes the one or more microneedles 106. Each microneedle 106 can define a distal opening 108. The device 100 can be configured and arranged such that, when the device 100 is placed on and / or attached to the surface of the skin S, the microneedles 106 can be inserted into the skin S with some or an entirety of the distal opening 108 inserted through a stratum comeum St and an epidermal layer E and into a dermal layer D, as described further later. Each microneedle 106 can include a proximal opening 110 operatively connected to the distal opening 108. It is to be understood that the term “operatively connected” as used herein can include its plain and ordinary meaning and can include connected in a manner so as to be able to communicate (e.g., optically or otherwise) the signal between respective structures (e.g., the proximal opening 110 and the distal opening 108). Each microneedle 106 can include a tip 112 at a distal-most end of the microneedle 106.

[0030] Each microneedle 106 can be operatively connected to the transmitter 102 and / or the receiver 104. In embodiments, the device 100 can include connections 105 that can operatively connect the microneedle 106 to the transmitter 102 and / or the receiver 104. In embodiments, the connections 105 can include light fibers (e.g., multi-mode, single-mode, etc.), waveguides (planar, rectangular, etc.), among other possibilities. One or more of the dimensions of the connections 105 can correspond to one or more dimensions of the microneedle 106 that the respective one of the connections 105 is operatively connected to. For example, in embodiments, a core size of the connections 105 can correspond to (e.g., equal or approximately equal) a sizeof the proximal opening 110. For example, a diameter of a core of one or more of the connections 105 can be 62.5 pm (+ / - 5%) and a diameter of the proximal opening 110 operatively connected to the core of the respective one of the connections 105 can also be 62.5 pm (+ / - 5%). It is to be understood that other diameters for the core of the connections 105 and / or for the proximal opening 110 are possible.

[0031] Because each microneedle 106 can be operatively connected to the transmitter 102 and / or the receiver 104 when the microneedles 106 are inserted into the skin S, the microneedles 106 can communicate the signals, via the distal openings 108. directly to and / or from within the skin S. Put differently, the microneedle 106 can create a pathway for the signals emitted from the transmitter 102 and / or for signals returning from the skin S to the receiver 104. The pathways created by the microneedles 106 can bypasses layers of the skin S (e.g., the stratum comeum St and / or other portions of the epidermal layer E) and can reduce or eliminate the impact of one or more of the previously described interfering factors (e.g., melanin, hair, sweat, movement, wrinkles, etc.).

[0032] The device 100 can include any number of microneedles 106 arranged in any number of different groups or configurations. In embodiments such as shown in FIG. 1A, the device 100 can include a first microneedle 106a and a second microneedle 106b arranged in a pair. The device 100 can include any number of pairs of first microneedles 106a and the second microneedles 106b and the pairs can be arranged in arrays of varying sizes and shapes. The first microneedle 106a and second microneedle 106b can include each of the features, structures, relationships, etc. described in reference to the microneedle 106, and vice versa. For example, the first microneedles 106a can include a first distal opening 108a, a first proximal opening 110a, and a first tip 112a. and the second microneedle 106b can include a second distal opening 108b, a second proximal opening 110b, and second tip 112b. It is to be understood that the numerical terms “first,” “second,” “third,” “fourth,” etc., as used herein can be used as a naming convention without limiting the device 100 to any particular numerical value. For example, the term “first” in first distal opening 108a does not limit the first microneedle 106a to only one distal opening and the term “second” in second distal opening 108b does not limit the second microneedle 106b to more than one distal opening. The first microneedle 106a can include only one first distal opening 108a, two first distal openings 108a, or more, and the second microneedle 106b can include only one second distal opening 108b, two second distal opening 108b, or more.

[0033] The first proximal opening 110a of the first microneedle 106a can. in embodiments, be operatively connected to the transmitter 102 with one of the connections 105 and the second proximal opening 110b of the second microneedle 106b can be operatively connected to thereceiver 104 with another one of the connections 105. The first distal opening 108a and the second distal opening 108b can, in embodiments, be structured and arranged to face each other. According to this configuration, when the first microneedle 106a and the second microneedle 106b are inserted into the skin S the signal can be transmitted from the transmitter 102. through the first microneedle 106a and out the first distal opening 108a directly into the skin S thereby bypassing layers of the skin S associated with the one or more of the previously described interfering factors. Moreover, at least some of the signal can be communicated out of the skin S and to the receiver 104 via the second distal opening 108b and the second microneedle 106b thereby bypassing layers of the skin S associated with the one or more of the previously described interfering factors, such as the stratum comeum St and other parts of the epidermal layer E.

[0034] The device 100 can include a housing 120. The housing 120 can house at least one of the transmitter 102, the receiver 104, the connections 105, or the microneedles 106. The housing 120 can include a base 122. An outer-most surface of the base 122 can be structured and arranged to be placed directly on and / or attached directly to the surface of the skin S. For example, in embodiments, the outer-most surface of the base 122 can include an adhesive for adhering to the surface of skin S. The longitudinal axis of each of the microneedles 106 can extend normal to the outer-most surface of the base 122.

[0035] FIG. IB discloses a magnified view of a region A of the device 100 of FIG. 1 A. The device 100 can be structured and arranged to optimize signal transmission to and / or reception from the dermal layer D while minimizing patient discomfort or pain when the device 100 is placed on and / or attached to the skin S. For example, one or more of the microneedles 106 can be structured and arranged such that, when the device 100 is placed on and / or attached to the surface of the skin S. the tips 112 extend entirely through the stratum comeum St into the desired location within the skin. In some aspects, the tips 112 can extend entirely through the epidermal layer E and into the dermal layer D. According to this configuration, the microneedles 106 can provide a pathway for the signal that bypasses the interfering factors associated with the surface of the skin S and / or with the stratum comeum St and / or other portions of the epidermal layer E. In embodiments, one or more of the microneedles 106 can be structured and arranged such that, when the device 100 is placed on and / or attached to the surface of the skin S, the tips 112 extend entirely through the stratum comeum St and the rest of the epidermal layer E and into, but not entirely through, the dermal layer D. According to this configuration, the microneedles 106 can provide the pathway for the signal that bypasses the interfering factors associated with the stratum comeum St and / or with other portions of the epidermal layer E while minimizing oravoiding contact with nerves located within the skin S inwards relative to the dermal layer D. For example, one or more of the microneedles 106 can have a length such that the tip 112 extends a first distance dl from the base 122. The first distance dl can extend normal to the outer-most surface of the base 122. Since the base 122 can be placed directly on and / or attached directly to the surface of the skin S. the first distance dl can correspond to a depth that the tip 112 of the microneedle 106 extends into the skin S when the device 100 is placed directly on and / or attached directly to the skin S. In embodiments, the first distance dl can be at least 200 pm, though it is to be understood that other distances are possible depending for example on the thicknesses of the skin layers that the device 100 is to be attached to. In embodiments, the device 100 can include multiple microneedles 106 and each can have the same length and / or can extend the same first distance dl from the base 122 to the respective tip 112. In alternative embodiments, the device 100 can include multiple microneedles 106 and one or more of the microneedles 106 can have different lengths and / or can extend different first distances dl from the base 122 to the respective tip 112.

[0036] In embodiments, one or more of the microneedles 106 can be structured and arranged such that, when the device 100 is placed on and / or attached to the surface of the skin S, the distal openings 108 extend entirely through the epidermal layer E and into the dermal layer D. According to this configuration, the microneedles 106 can provide a pathway for the signal that bypasses the interfering factors associated with the stratum comeum St and / or with other portions of the epidermal layer E. In embodiments, one or more of the microneedles 106 can be structured and arranged such that, when the device 100 is placed on and / or attached to the surface of the skin S, the distal openings 108 extend entirely through bot the stratum comeum St and the rest of the epidermal layer E and into, but not entirely through, the dermal layer D. According to this configuration, the microneedles 106 can provide the pathway for the signal that bypasses the interfering factors associated with the stratum comeum St and / or with other portions of the epidermal layer E while minimizing or avoiding contact with nerves located within the skin S inwards relative to the dermal layer D. For example, one or more of the microneedles 106 can a distal opening 108 adjacent to the tip 112 and extending a second distance d2 from the base 122. The second distance d2 can extend normal to the outer-most surface of the base 122. In embodiments, the second distance d2 can be measured from the base 122 to a center of the distal opening 108. Since the base 122 can be placed directly on and / or attached directly to the surface of the skin S, the second distance d2 can correspond to a depth that distal opening 108 of the microneedle 106 extends into the skin S when the device 100 is placed directly on and / or attached directly to the skin S. In embodiments, the second distance d2can be at least 200 pm. though it is to be understood that other distances are possible depending for example on the thicknesses of the skin layers that the device 100 is to be attached to.

[0037] In embodiments, one or more of the microneedles 106 can be structured and arranged to direct the signal at a target region within the skin S and / or to receive the signal from the target region. The target region can be a region within the skin S beyond (i.e., deeper into) the stratum comeum St to minimize or eliminate the impact of the interfering factors associated therewith. In some aspects, the target region can be a region within the skin S beyond the entire epidermal layer E. In embodiments, the target region can be within the dermal layer D. In embodiments, the target region can be a third distance d3 beyond the second distance d2. That is, the target region can extend distally beyond the base 122 by an amount equal to the sum of the second distance d2 and the third distance d3. The third distance d3 can extend normal to the outer-most surface of the base 122. The microneedles 106 can be structured and arranged to direct the signal at and / or receive at least part of the signal from the target region in a number of different ways. For example, in embodiments such as shown in FIG. IB the geometry of the first distal opening 108a, the geometry' of the second distal opening 108b, and a lateral spacing (i.e., a fourth distance d4) between the first distal opening 108a and the second distal opening 108b can direct the signal at and / or receive the signal from the target region of the skin S. In embodiments, the geometries of the first distal opening 108a and the second distal opening 108b can direct and / or receive the signals at an angle 9 relative to a virtual line VL that extends normal to the outermost surface of the base 122 and through the target region. The angle 0 can be 0° (i.e., the signal can be directed to and / or received from a direction normal to the outer-most surface of the base 122), between 0° and 30°, 30°, between 30° and 60°, 60°, between 60° and 90°, 90°, among other possibilities. It is to be understood that a number of different combinations of the geometry' of the first distal opening 108a (e.g., the angle 0 that the first distal opening 108a directs the signal relative to the virtual line VL), the geometry of the second distal opening 108b (e.g.. the angle that the second distal opening 108b receives the signal relative to the virtual line VL), and the lateral spacing (i.e., a fourth distance d4) between the first distal opening 108a and the second distal opening 108b can direct the signal to and / or receive the signal from the same the target region of the skin S.

[0038] FIG. 2 shows a schematic cross-section view of a microneedle 206 with a transmitter 202 within the microneedle 206. The microneedle 206 and / or transmitter 202 can be aspects of the device 100. Except where clearly mutually exclusive, the microneedle 206 can include each of the features, structures, relationships, etc. of any of the microneedles described herein and vice versa. Except where clearly mutually exclusive, the transmitter 202 can include each of thefeatures, structures, relationships, etc. of any of the transmitters described herein and vice versa. As shown in FIG. 2, the transmitter 202 can be arranged within an interior 214 of the microneedle 206. For example, the transmitter 202 can be arranged within the interior 214 at the distal opening 208. The transmitter 202 can be electrically connected to the device 100 via a connection 205 such that the device 100 can control operation of the transmitter 202. In embodiments of the device not shown, a receiver can be arranged within an interior of a microneedle as in any of the manners described here with respect to the transmitter 202.

[0039] FIG. 3 shows a schematic cross-section view of a microneedle 306 with a transmitter 302 at the proximal opening 310 of the microneedle 306. The microneedle 306 and / or transmitter 302 can be aspects of the device 100. Except where clearly mutually exclusive, the microneedle 306 can include each of the features, structures, relationships, etc. of any of the microneedles described herein and vice versa, including the distal opening 308. Except where clearly mutually exclusive, the transmitter 302 can include each of the features, structures, relationships, etc. of any of the transmitters described herein and vice versa. As shown in FIG. 3, the transmitter 302 can be arranged at the proximal opening 310. For example, the transmitter 302 can be arranged over and / or abut against the proximal opening 310. In embodiments of the device not show n, a receiver can be arranged at a proximal opening of a microneedle as in any of the manners described here with respect to the transmitter 302.

[0040] FIG. 4 shows a schematic cross-section view of a microneedle 406 with the interior 414 filled with a light guide 416. The microneedle 406 can be an aspect of the device 100. Except w here clearly mutually exclusive, the microneedle 406 can include each of the features, structures, relationships, etc. of any of the microneedles described herein and vice versa. The light guide 416 can be a material that can guide the light through the interior 414.

[0041] FIG. 5 shows a schematic cross-section view of a microneedle 506 with the interior 514 filled with a reflector 516. The microneedle 506 can be an aspect of the device 100. Except where clearly mutually exclusive, the microneedle 506 can include each of the features, structures, relationships, etc. of any of the microneedles described herein and vice versa. The reflector 516 can be a material that can guide the light through the interior 514.

[0042] FIG. 6 shows a schematic cross-section view of a device 600. Except where clearly mutually exclusive, the device 600 can include any of the features, structures, relationships, etc. of any of the devices described herein and vice versa. The transmitter 602 can be operatively connected to the microneedles 606 in any of the previously described manners, including via connections 605. The receiver 604 or receivers 604 of the device 600 are not operatively connected to the microneedles 606. The receiver 604 or receivers 604 thus receive at least part ofthe signal emitted from the transmitter 602 and through microneedles 606 operatively connected to the transmitter 602 at the surface of the skin after the at least part of the signal travels directly through the epidermal layer and the stratum comeum.

[0043] FIG. 7 shows a schematic cross-section view of a device 700. Except where clearly mutually exclusive, the device 700 can include any of the features, structures, relationships, etc. of any of the devices described herein and vice versa. The transmitter 702 or transmitters 702 of the device 700 are not operatively connected to the microneedles 706. The transmitter 702 or transmitters 702 thus transmit the signal at the surface of the skin and directly through the stratum comeum and the epidermal layer. The receiver 704 can be operatively connected to the microneedles 706 in any of the previously described manners, including via connections 705.

[0044] FIG. 8 shows an example process 800 for measuring a physiological characteristic. The process 800 can be implemented with any of the devices described herein including at least the device 100.

[0045] The process 800 can include, at step 802, inserting a microneedle, which is operatively connected to a transmitter, into a dermal layer of skin. In embodiments, inserting the microneedle can include inserting at least part of a distal opening of the microneedle through an epidermal layer of the skin and into the dermal layer. In embodiments, the microneedle is a first microneedle and the distal opening is a first distal opening,

[0046] The process 800 can include, at step 804, emitting a signal (e.g., an optical signal), using the transmitter, through the microneedle and into the dermal layer of skin. In embodiments, emitting the signal into the dermal layer can include emitting the signal, via the distal opening of the microneedle, into the dermal layer.

[0047] The process 800 can include, at step 806, detecting, using a receiver, at least part of the signal (e.g., the optical signal) from within the dermal layer. The process 800 can also include, before detecting the at least part of the signal, inserting a second microneedle, which is operatively connected to the receiver, into the dermal layer. The second microneedle can be inserted concurrently with the first microneedle at step 802. In embodiments, inserting the second microneedle can include inserting at least part of a distal opening of the second microneedle through an epidermal layer of the skin and into the dermal layer. Detecting the signal can include detecting the signal, via the distal opening of the second microneedle, from the dermal layer.

[0048] The process 800 can include, at step 808, determining the physiological characteristic based on the detected optical signal. The physiological characteristic can include any of the previously described physiological characteristics.

[0049] It will be appreciated that the foregoing description provides examples of the invention. However, it is contemplated that other implementations of the invention may differ in detail from the foregoing examples. All references to the invention or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the invention more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the invention entirely unless otherwise indicated.

Claims

CLAIMSWhat is claimed is:

1. A device comprising: a transmiter configured to transmit an optical signal into a dermal layer of skin of a patient; a receiver configured to detect at least part of the optical signal reflected back from the dermal layer, the detected at least part of the optical signal being associated with a physiological characteristic of the patient; and a microneedle defining a distal opening, the distal opening being configured to be inserted into the skin through an epidermal layer of the skin and into the dermal layer, wherein the microneedle is operatively connected to at least one of the transmitter or the receiver.

2. The device of claim 1, wherein the microneedle is operatively connected to the transmitter such that the transmitter is configured to transmit the optical signal, via the distal opening, within the dermal layer.

3. The device of claim 1 or claim 2, wherein: the microneedle is a first microneedle and the distal opening is a first distal opening, the device further comprises a second microneedle defining a second distal opening, the second distal opening being configured to be inserted into the skin through the epidermal layer and into the dermal layer, and the second microneedle is operatively connected to the receiver such that the receiver is configured to receive the at least part of the optical signal within the dermal layer via the second distal opening of the second microneedle.

4. The device of any one of the preceding claims, wherein the microneedle is operatively connected to the receiver such that the receiver is configured to receive the at least part of the optical signal, via the distal opening, within the dermal layer.

5. The device of claim 4, wherein the transmitter is configured to be positioned outside of the skin such that the optical signal is transmitted, within the microneedle through the epidermal layer into the dermal layer.

6. A device comprising: a base configured to be held against an outer surface a skin of a patient;a transmiter configured to transmit a signal through the skin; a receiver configured to detect at least part of the signal after the signal is transmitted through the skin, the detected signal being associated with a physiological characteristic of the patient; and a microneedle extending in a direction away from the base, the microneedle comprising a distal opening at a distance, along the direction away from the base, of at least 200 pm from the base, wherein the microneedle is operatively connected to one of the transmitter or the receiver.

7. The device of claim 6, wherein the microneedle is operatively connected to the transmitter such that, when the base is held against the outer surface of the skin, the transmitter is configured to transmit the signal, via the distal opening, at a depth of at least 200 pm within the skin.

8. The device of claim 6 or claim 7, wherein the microneedle is configured to direct the at least part of the signal out of the distal opening at an angle.

9. The device of any one of claims 6-8, wfierein: the microneedle is a first microneedle and the distal opening is a first distal opening, the device further comprises a second microneedle extending in the direction away from the base, the second microneedle defining a second distal opening at a distance, along the direction away from the base, of at least 200 pm from the base, and the second microneedle is operatively connected to the receiver such that, when the base is held against the outer surface of the skin, the receiver is configured to receive the signal, via the second distal opening of the second microneedle, at the depth within the skin.

10. The device of any one of claims 6-9, wherein the transmitter is within a hollow interior of the microneedle.

11. The device of any one of claims 6-10, wherein the microneedle is filled with a material that is configured to guide the signal to the distal opening.

12. The device of any one of claims 6-11, wherein the microneedle comprises a hollow interior that is lined with a reflective material.

13. The device of any one of claims 6-9, 11, or 12, wherein the microneedle is operatively connected to the transmitter at a proximal opening of the microneedle.

14. The device of any one of claims 6-13. wherein the microneedle is operatively connected to the receiver such that, when the base is held against the outer surface of the skin, the receiver is configured to receive the at least part of the signal, via the distal opening, at a depth of at least 200 pm within the skin.

15. The device of any one of claims 6-14, wherein the signal is an optical signal.

16. The device of any one of claims 6-15, wherein: the transmitter is an LED. and the receiver is a photodiode.

17. A method of measuring a physiological characteristic, the method comprising: inserting a microneedle, which is operatively connected to a transmitter, into a dermal layer of skin; emitting an optical signal, using the transmitter, through the microneedle and into the dermal layer of skin; detecting, using a receiver, at least part of the optical signal from within the dermal layer; and determining the physiological characteristic based on the detected optical signal.

18. The method of claim 17, wherein: inserting the microneedle comprises inserting at least part of a distal opening of the microneedle through an epidermal layer of the skin and into the dermal layer; and emitting the optical signal into the dermal layer comprises emitting the optical signal, via the distal opening of the microneedle, into the dermal layer.

19. The method of claim 17 or claim 18, wherein: the microneedle is a first microneedle and the distal opening is a first distal opening, the method further comprises, before detecting the at least part of the optical signal, inserting a second microneedle, which is operatively connected to the receiver, into the dermal layer.

20. The method of any one of claims 17-19. wherein: inserting the second microneedle comprises inserting at least part of a second distal opening of the second microneedle through an epidermal layer of the skin and into the dermal layer; anddetecting the optical signal comprises detecting the optical signal, via the distal opening of the second microneedle, from the dermal layer.

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