Patent Description:
Cardiovascular disease (CVD) accounts for approximately a significant number of deaths on a world-wide basis. CVD includes coronary heart disease (CHD), which accounts for the majority of CVD deaths, as well as stroke and heart failure. Many more individuals carry a diagnosis of CVD and live with the diagnosis. Those living with CVD are at risk of acute heart attack, strokes and other chronic conditions that can adversely affect the individual's quality of live over a long term long-term. Ultimately, CVD increases the risks of mortality in the patient. Therefore, there is a keen interest by governments, healthcare providers, as well as the general population to prevent CVD.

The rise of portable smart-devices, such as smart phones, smart watches, fitness monitors, etc. has given individuals a useful tool to monitor health parameters to address CVD symptoms, where such health parameters include blood pressure and heart rate. Such devices are also of interest to healthy individuals so that who can monitor such data to avoid the onset or progression of CVD. In addition, a number of drugs or therapeutic strategies treat or manipulate the cardiovascular diseases. As a result, predicting short-term and long-term risk of cardiovascular diseases for people plays an important role in treatment. To this end, although pathogenesis of different cardiovascular diseases might be distinct from each other, most of them can be monitored and precautionary assessed through specific physical signs. Since most cardiovascular diseases including hypertension diseases and hypotension diseases are significantly related to blood pressures and such monitoring techniques thereof are not well-developed and implemented universal, there is a need to establish or develop a monitoring device or a monitoring method for monitoring blood pressures in households or hospitals in a simpler manner.

Non-invasive blood pressure measuring devices including sphygmomanometers and photoplethysmography are used in monitoring patient' s blood pressures to prevent various cardiovascular diseases or provide doctors with early diagnosis. However, most of them are bulky and heavy which are inconvenient for outdoor applications and long-time monitoring.

Furthermore, a need remains for a device to monitor blood pressure but avoids discomfort for patients.

Previously, wearable blood-pressure monitoring devices that allowed for real-time monitoring and portable capability are described in <CIT> and <CIT>, the entirety of each of which is incorporated by reference. However, there remains a need to more accurately measure blood pressure using a portable, non-obtrusive device. Further devices are known from <CIT> and <CIT>, wherein <CIT> suggests deforming an optical thin film layer by means of applying a shear force via a fingertip, thereby creating a portion with increased thickness that can be determined by reflected light differing in the power spectrum.

The present disclosure includes a force detecting device that uses elastomeric polymers to determine application of a force applied to the device. In one variation, the present disclosure includes devices for detecting a force in a surface region of tissue. For example, the device includes a transparent backing material comprising a planar shape, the transparent backing material comprising a first surface and a second surface on an opposite side of the planar shape; a first elastomer on the first surface of the transparent backing material, where a light transmission property of the first elastomer changes upon application of force to the first elastomer; and wherein when positioned on the surface region of tissue the force in the surface region causes a deformation of the first elastomer resulting in a change in the light transmission property of the first elastomer.

The configuration described herein using polymers and optical devices allows for the optical devices to be monolithically integrated into a chip, allowing further miniaturization of the device. The configuration of the device allows for the optical devices could to be a camera module of a smart phone, allowing the user to measure their own blood pressure on demand. The configuration also allows this measurement method to be applied on other portions of a body rather than just on a digit.

The device further includes a second elastomer on the first surface of the transparent backing material, where a light transmission property of the second elastomer changes upon application of force to the first elastomer; an opaque divider between the first elastomer and the second elastomer to block propagation of light therebetween; a stiffening layer on the second elastomer on a side opposite to the transparent backing material; and wherein when positioned on the surface region the stiffening layer prevents the force from changing the light transmission property of the second elastomer such that the second elastomer provides a reference to determine a deformation of the first elastomer.

A variation of the device further includes an opaque cover on the first elastomer and the second elastomer located on the side opposite to the transparent backing material, where the stiffening layer is located on the opaque layer and adjacent to the second elastomer.

Another variation of the invention includes an opaque cover on the first elastomer and the second elastomer located on the side opposite to the transparent backing material, where the stiffening layer is located on the second elastomer and opaque layer and adjacent to the opaque cover. Variations of the device can include a stiffening layer, additive, or reinforcement on any portion of the elastomers.

The device further includes a light emitting source and a light detecting element both located adjacent to the first elastomer and possibly to the second elastomer, where the light emitting source is configured to illuminate the first elastomer and possibly the second elastomer and where the light detecting element is configured to determine an absorption of light in the first elastomer and possibly in the second elastomer.

Another variation of the device includes the light detecting element being configured to transmit a signal to a controller, where the signal comprises data of the absorption of light in the first elastomer and possibly in the second elastomer to determine the force in the surface region.

The present disclosure also includes method of measuring a blood pressure in an artery within a region of tissue. The measurements can be continuous over a period of time or on demand. The method includes positioning a device as described above on the region of tissue, where deformation of the region of tissue causes deformation of the first elastomer; illuminating the first elastomer; observing an emission of light from the first elastomer during application of a force on the first elastomer where the force is produced by the artery; and determining a change in the emission of light caused by application of the force to calculate a blood pressure in the artery.

A variation of the method can include a second elastomer, where the second elastomer is configured such that deformation of the region of tissue does not cause deformation of the second elastomer. The method can include illuminating the second elastomer during illuminating of the first elastomer.

A variation of the method further includes observing an emission of light from the second elastomer during application of the force on the first elastomer.

The methods can include comparing the emission of light of the first elastomer to the emission of light from the second elastomer.

The methods described herein can be performed on a region of tissue such as a digit, an arm, a leg, or any body part where measurement of tissue displaced by blood flow in an artery occurs.

The methods and device discussed herein can transmit the blood pressure information via a wired or wireless connection to any personal electronic device including but not limited to a smart phone, a smart watch, a fitness tracker, a tablet, a computer, and/or a network.

The methods and devices can also continuously illuminate the first elastomer for a period of time to continuously calculate the blood pressure in the artery over the period of time.

Another variation of the devices described herein include a patch that converts external forces into change of light absorption, comprising: a transparent backing; a light-absorptive sensing elastomer on one surface of the transparent backing, wherein: the light absorption of the light-absorptive sensing elastomer is indicative of the elastomer deformation subjected to static and fluctuating external forces.

The patch can further include an opaque cover on the surface, opposite to the interface between the transparent backing and the light-absorptive sensing elastomer, of the light-absorptive sensing elastomer.

A variation of the patch further includes a light-absorptive reference elastomer on the surface of the transparent backing and by one side of the light-absorptive sensing elastomer, wherein: the light absorption of the light-absorptive reference elastomer is indicative of the elastomer deformation subjected to static external forces.

The patch can also include an opaque divider that prohibits light propagation between the light-absorptive reference elastomer and the light-absorptive sensing elastomer.

Additional variations of the patch include an opaque cover on the surface, opposite to the interface between the transparent backing and the light-absorptive sensing elastomer, of the light-absorptive sensing elastomer and the light-absorptive reference elastomer.

The present disclosure also includes methods to measure blood pressure. For example, such a method can include attaching a patch, that converts external forces into change of light absorption, on the skin under which an artery passes through; emitting at least a light into the patch; measuring the lights propagating out from the patch; and converting the measurement of the lights, propagating out from the patch, into blood pressure.

The disclosure also includes variations of continuous blood pressure monitoring systems. For example, such systems include a patch that converts external forces into change of light absorption; a light emitter that emits at least a light into the patch; a light detector that measures the lights propagating out from the patch; and an algorithm that converts the measurement of the lights, propagating out from the patch, into blood pressure.

A variation of the continuous blood pressure monitoring system includes a transparent backing; and a light-absorptive sensing elastomer on one surface of the transparent backing, wherein: the light absorption of the light-absorptive sensing elastomer is indicative of the elastomer deformation subjected to static and fluctuating external forces.

The present disclosure also includes wearable devices that continuously monitor blood pressure. Such devices include a ring body; a light emitter disposed on a monitoring surface at the inner side of the ring body; a light detector disposed on a monitoring surface at the inner side of the ring body and by a side of the light emitter; and a light-absorptive sensing elastomer covering the light emitter and the detector, wherein: the light absorption, which is measured by the light detector, of the light-absorptive sensing elastomer is indicative of the blood pressure of a wearer.

Another example of a wearable device that continuously monitors blood pressure, includes a ring body; a light emitter disposed on a monitoring surface at the inner side of the ring body; a light detector disposed on a monitoring surface at the inner side of the ring body and by a side of the light emitter; a light-absorptive sensing elastomer covering a portion of the light emitter and a portion of the detector; and a light absorptive reference elastomer covering the remaining portion of the light emitter and the remaining portion of the detector; wherein: the comparative light absorption, which is measured by the light detector, of the light-absorptive sensing elastomer and the light-absorptive reference elastomer is indicative of the blood pressure of a wearer.

Methods and devices are described herein that relate to monitoring blood pressure in a vessel of a region of tissue. The methods and devices described herein can monitor blood pressure in a digit of a hand or in other areas of the body where the pulsatile flow of blood in a vessel displaces adjacent tissue that can be detected from a surface of the tissue. In addition, the methods and devices disclosed herein include improvements for detecting movement in a tissue of a region of the body, where the movement in the tissue arises from blood pressure changes within a vessel in that tissue. Optionally, the devices and methods described herein can be used wearable devices and non-invasive monitoring blood-pressure in real-time.

<FIG> illustrate respective front and oblique views of an example of a monitoring device <NUM> configured to monitor blood pressure using movement in tissue that is driven by the blood flow within a vessel located in that tissue. In the examples illustrated in <FIG>, the variation of the monitoring device <NUM> is configured with a ring-shaped body <NUM> that houses a device for detecting a force in a region of tissue <NUM> where a portion of the force detecting device <NUM> protrudes from an inner surface <NUM> of the ring shaped body <NUM>. This variation is suited for placement about a digit of an individual's hand such that it can detect movement of tissue in the digit that is caused by pulsatile flow of a vessel within the digit/tissue. However, additional variations of a blood pressure monitoring apparatus under the present disclosure are not limited to ring-type devices. The movement detecting apparatus <NUM> monitors movement of tissue in the digit, where the tissue movement can be caused by the oscillation of the blood vessel due to pressure changes therein. As shown, the device <NUM> can communicate <NUM> (either via a wire, wireless connection, cloud-based transmission, etc.) to a user interface <NUM>. The user interface <NUM> can comprise a body wearable apparatus or can comprise a computer, smart-phone, smart-watch, tablet, or other electronic apparatus. Variations of the user interface <NUM> can include a feedback portion <NUM> (either visual, audible, etc.) and/or controls <NUM>.

<FIG> illustrate additional variations of tissue displacement assemblies <NUM> for use with additional variations of blood pressure measuring devices <NUM>. The variation shown in <FIG> illustrates a finger cuff or cradle <NUM> that houses one or more force detecting devices <NUM>. As shown, a finger <NUM> of a hand <NUM> is positioned within or on the device <NUM> such that one or more force detecting assemblies <NUM> can detect movement of tissue and transmit information (via a wired or wireless connection <NUM>) to a user interface device <NUM> (as described above) such that blood pressure can be monitored. <FIG> illustrates a traditional blood pressure cuff <NUM> having a pump or bladder <NUM> that is used to secure the cuff <NUM> about a leg or arm of a patient. The cuff <NUM> includes any number of force detecting devices <NUM> that can measure displacement of tissue due to pulsatile flow of blood in a vessel within the tissue that is adjacent to the cuff <NUM>.

<FIG> illustrates components of a force detecting device <NUM> used to detect movement. Variations of the device <NUM> can be used as described herein to monitor movement of tissue arising from flow of blood in an artery within the tissue. The force detecting device <NUM> includes a first elastomer <NUM> a first surface <NUM> of a transparent backing material <NUM>, where a light transmission property of the first elastomer <NUM> changes upon application of force to the first elastomer <NUM>. The first elastomer <NUM> and the second elastomer <NUM> can comprise the same or different materials. However, as noted below, the operation of the first and second elastomers <NUM><NUM> will vary in the device <NUM>.

In this variation of the device <NUM>, the first surface <NUM> of the transparent backing material <NUM> is positioned facing tissue while the second surface <NUM> is opposite to the first surface <NUM> and faces away from tissue. The transparent backing material <NUM> can also be malleable or shaped to conform to a surface for measuring deflection of that surface.

Variations of the transparent backing materials include, but are not limited to: silicone rubber, polycarbonate, PDMS, polyethylene terephthalate, polyethylene, PMMA, gelatin, hydrogel, polymer-dispersed liquid crystal, amorphous copolyester, polyvinyl chloride, cyclic olefin copolymers, ionomer resin, polypropylene, fluorinated ethylene propylene, styrene methyl methacrylate. The first/second polymer materials: same as above and their composites or nanocomposites by adding nanomaterials made of titanium oxides, silicon oxides, cavities, or others.

<FIG> shows components of another variation of a force detecting device <NUM> where a second or reference elastomer <NUM> is positioned adjacent to a first elastomer <NUM>. The second elastomer <NUM> can be spaced from the first elastomer <NUM> or positioned in contact with the first elastomer <NUM>. Optionally, an opaque barrier (e.g., a film, coating, layer, etc.) <NUM> is positioned between the first elastomer <NUM> and second elastomer <NUM> to enable separate measurement of the light transmission properties of each elastomer.

<FIG> illustrates another variation of components of a variation of a force detecting device <NUM> showing a first elastomer <NUM> and a second elastomer <NUM> on a transparent backing material <NUM> where the elastomers are separated by an opaque divider <NUM>. This variation also includes an opaque cover <NUM> that prevents undesirable illumination from the tissue surface of the device <NUM>. As discussed above, the second elastomer <NUM> includes a stiffening reinforcement or layer <NUM> to prevent deformation of the second elastomer <NUM>.

<FIG> illustrates a cross sectional view of the components shown in <FIG> taken along the line 4B-4B to demonstrate an operation of a variation of a force detecting device <NUM>. As discussed herein, a surface of the device <NUM> opposite to the transparent backing material <NUM> is positioned adjacent to a surface to be monitored. In one example, the surface being monitored is a tissue region having an artery, where the tissue region experiences displacement arising from the pressure differential caused by flow of blood in the artery. The displacement creates a force <NUM> that acts on a surface of the device <NUM>. The first elastomeric material <NUM> experiences deformation (along with any opaque layer <NUM>) depicted by deformed lines <NUM>. In contrast, the second elastomer <NUM> is configured to resist deformation typically by the use of a stiffening layer <NUM> (alternative means of stiffening the polymer without affecting the light transmission properties of the elastomer are within the scope of this disclosure.

<FIG> depicts a force <NUM> acting on the second elastomer <NUM> but failing to cause displacement of the second elastomer <NUM>. <FIG> also shows a representation of an emitting device <NUM> (e.g. laser, LED, or other illumination source) that directs electromagnetic radiation (e.g., visible light or other electromagnetic radiation) through the transparent backing material <NUM> to the first and second elastomers <NUM><NUM>. Although the figure illustrates a single emitter <NUM> any number of emitters can be used. The device <NUM> also includes one or more detectors <NUM> (e.g., detectors configured to measure reflected light and/or radiation). The deformation of the first elastomer <NUM> changes the optical properties of the elastomer <NUM> such that an absorption of the light (or other radiation) changes. Therefore, the reflected illumination <NUM> from the first elastomer <NUM> will be different than a reflected illumination <NUM> from the second non-deformed elastomer <NUM>. This change in reflected illumination is used to determine the force <NUM> applied to the device <NUM>, which is then used to determine a blood pressure of the artery causing the displacement <NUM>. As shown, the elastomers <NUM><NUM> can be optically separated by an opaque divider <NUM> or via any other structural configuration that optically separates the elastomers.

Although the above example illustrates a second elastomer or reference elastomer, variations of the device <NUM> can omit this reference elastomer and determine an applied force by monitoring changes in a single elastomer.

<FIG> illustrates a variation of a force detecting device <NUM> positioned on a finger <NUM> to detect a blood pressure of a vessel <NUM> within the finger <NUM> using displacement of tissue adjacent to the blood vessel. The illustrated variation of the device <NUM> includes one or more light emitters <NUM> and one or more light detectors <NUM>. <FIG> shows a cross sectional view of the device of <FIG> taken along line 5B-5B. This cross sectional view illustrates a variation of a device for detecting movement <NUM> as the transparent backing layer <NUM> is shaped or shapeable to conform to a finger <NUM>. Accordingly, the elastomeric polymer <NUM> and opaque barrier layer <NUM> conform to tissue <NUM> that is adjacent to an artery <NUM> within the finger <NUM>. In this variation, the two vessels <NUM> run along a bone <NUM> within the finger. Pulsatile flow of blood within the vessel <NUM> causes displacement of tissue <NUM>, which produces deflection of the barrier layer <NUM> and first elastomer <NUM>. As discussed herein, the optical properties of the elastomer <NUM> change upon deflection of the elastomer <NUM>. Therefore, light <NUM> emitted from an illumination component <NUM> is absorbed by the compressed/displaced elastomer <NUM> and is reflected <NUM> to a light detector <NUM>. The detector <NUM> can produce a signal that is then used to determine a force applied to the device <NUM> for calculation of blood pressure within the artery <NUM>.

<FIG> is a cross sectional illustration taken along lines 5C-5C from <FIG>. As shown, the second elastomeric polymer <NUM>, opaque barrier layer <NUM>, and stiffening layer <NUM> conform to tissue <NUM> that is adjacent to the artery <NUM> within the finger <NUM>. The pulsatile flow of blood within the vessel <NUM> causes displacement of tissue <NUM> but fails to produce deflection of the barrier layer <NUM> and second elastomer <NUM> because of the reinforcement or stiffening layer <NUM>. Therefore, the optical properties of the second elastomer <NUM> do not change because there is no deflection of the elastomer <NUM> (alternatively, the deflection of the second elastomer <NUM> is insignificant). Therefore, light <NUM> emitted from the illumination component <NUM> is absorbed by the second elastomer <NUM> and is reflected <NUM> to a light detector <NUM> for use as a reference for comparison for the light reflected <NUM> from the first elastomer. Again, the detector <NUM> can produce a signal that is then used to determine a force applied to the device <NUM> for calculation of blood pressure within the artery <NUM>.

<FIG> illustrate another variation of a device <NUM> having a force detecting apparatus positioned on a ring body <NUM>. As shown in <FIG>, the device <NUM> includes a body structure <NUM> that houses the force detecting apparatus as well as an emitting component <NUM> and a detecting component <NUM>.

<FIG> illustrates a cross sectional view of the device <NUM> and finger <NUM> taken along the line 6B-6B of <FIG>. This sectional view illustrates the finger <NUM> having a bone <NUM> adjacent to two vessels where the ring body <NUM> is positioned such that the force detecting apparatus <NUM> is positioned adjacent to an artery <NUM> and where flow of blood in the artery <NUM> displaces adjacent tissue <NUM> causing movement at the tissue surface interface of the force detecting device <NUM>. Similar to the variations discussed above, the force detecting device <NUM> includes an opaque cover <NUM> that is placed adjacent to a skin <NUM> of the finger <NUM>. A first elastomer <NUM> is positioned adjacent to the cover <NUM> with an emitter <NUM> of electromagnetic radiation positioned adjacent to the elastomer <NUM> to provide electromagnetic radiation (e.g., light) to the first elastomer <NUM>. As noted above, deformation of the first elastomer <NUM> occurs as a result of tissue <NUM> movement caused by blood flow in artery <NUM>. The deformation of the first elastomer <NUM> alters optical properties of the elastomer <NUM> causing the elastomer <NUM> to change absorption of the electromagnetic radiation. This reflected illumination <NUM> is then used to determine a pressure acting upon the device <NUM> to determine a blood pressure within the artery <NUM>.

As shown in <FIG>, the force detecting device <NUM> does not require an optically transparent backing material. Optionally, an optically transparent backing material can be used adjacent to the elastomer <NUM> and within the body <NUM> of the device.

<FIG> illustrates a cross sectional view of the device <NUM> and finger <NUM> taken along the line 6C-6C of <FIG>. This sectional view also illustrates the finger <NUM> with a bone <NUM> adjacent to two vessels where the ring body <NUM> is positioned such that the force detecting apparatus <NUM> is positioned adjacent to an artery <NUM> and where flow of blood in the artery <NUM> displaces adjacent tissue <NUM> causing movement at the tissue surface interface of the force detecting device <NUM>. Again, as noted herein, the second elastomer <NUM> comprises a stiffening layer <NUM> (or is otherwise reinforced to prevent deformation). As a result, the displacement of tissue <NUM> and skin <NUM> does not affect the second elastomer (or only compresses the second elastomer an insignificant amount). The emitter <NUM> of electromagnetic radiation is positioned adjacent to the elastomer <NUM> to provide electromagnetic radiation <NUM> (e.g., light). Since the second elastomer <NUM> does not deform there is no change in any optical properties of the elastomer <NUM>. Therefore, the reflected radiation or light <NUM> can be used as a reference relative to light reflected from the first elastomer. The reflected radiation <NUM> is then used to determine a pressure acting upon the device <NUM> to determine a blood pressure within the artery <NUM>.

<FIG> illustrates a variation of a force detecting device <NUM> used in <FIG>. As shown, the device <NUM> does not require the use of a transparent backing material. Instead, the first elastomer <NUM> and the second elastomer <NUM> can be positioned adjacent to electromagnetic radiation emitters <NUM> and detectors <NUM>. Therefore, the reflected radiation <NUM> from the first elastomer <NUM> and the reflected radiation <NUM> from the second elastomer <NUM> can be detected by the detector element <NUM> and used to ultimately determine a blood pressure of a vessel (or other force applied on the device <NUM>).

Well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the described devices. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the scope of the present invention.

Claim 1:
A device for detecting a force in a surface region of tissue, the device comprising:
a transparent backing material (<NUM>) comprising a planar shape, the transparent backing material (<NUM>) comprising a first surface (<NUM>) and a second surface (<NUM>) on an opposite side of the planar shape;
a first elastomer (<NUM>) on the first surface (<NUM>) of the transparent backing material (<NUM>), where a light transmission property of the first elastomer (<NUM>) changes upon application of force to the first elastomer (<NUM>);
a second elastomer (<NUM>) on the first surface (<NUM>) of the transparent backing material (<NUM>), where a light transmission property of the second elastomer (<NUM>) changes upon application of force to the first elastomer (<NUM>); and
a stiffening layer (<NUM>) on the second elastomer (<NUM>) on a side opposite to the transparent backing material (<NUM>),
wherein when positioned on the surface region of tissue, the force in the surface region causes a deformation of the first elastomer (<NUM>) resulting in a change in the light transmission property of the first elastomer (<NUM>) and wherein when positioned on the surface region, the stiffening layer (<NUM>) prevents at least a portion of the force from changing the light transmission property of the second elastomer (<NUM>) such that the second elastomer (<NUM>) provides a reference to determine a deformation of the first elastomer (<NUM>).