WO2018141705A1

WO2018141705A1 - Pulsation visibility

Info

Publication number: WO2018141705A1
Application number: PCT/EP2018/052195
Authority: WO
Inventors: Kiran Hamilton J. DELLIMORE; Jens Muehlsteff
Original assignee: Koninklijke Philips N.V.
Priority date: 2017-02-03
Filing date: 2018-01-30
Publication date: 2018-08-09

Abstract

There is provided an apparatus. The apparatus comprises a first patterned element for being positioned on or adjacent to a surface of a subject's body, the first patterned element having a first pattern formed thereon; and a second patterned element positioned above the first patterned element, the second patterned element having a second pattern formed thereon. At least part of the first patterned element is moveable relative to the second patterned element in response to a pulsation of an underlying body part within the subject's body. The first and second patterns are such that, when the first patterned element moves relative to the second patterned element, an optical effect resulting from a superposition of the first and second patterns is visible.

Description

Pulsation Visibility

Technical Field of the Invention

The invention relates to an apparatus for visualising a pattern resulting from a pulsation, particularly a pulsation of a body part. The invention also relates to a method and a system for visualising such a pattern.

Background to the Invention The ability to detect a pulse in a subject, such as a person or an animal, is important, particularly in a situation where the subject may require immediate medical treatment. For example, a person who suffers a sudden cardiac arrest is likely to require treatment to restart their heart. Cardio pulmonary resuscitation (CPR) is a recommended intervention which can be delivered by medically-trained professionals or by individuals with relatively little medical training to a subject whose heart has stopped. Performing CPR on humans involves the delivery of chest compressions in combination with artificial ventilation (for example, rescue breaths) to maintain (or restart) circulatory flow and oxygen supply to vital organs in the subject's body until spontaneous circulation resumes.

During the application of CPR, regular pulse checks are performed in order to determine whether spontaneous circulation has resumed. After suffering a sudden cardiac arrest, a subject's pulse may resume more slowly and/or more faintly than is expected in a healthy subject and, therefore, their pulse may be difficult to detect, particularly for a medically-untrained person.

A subject's pulse may be detected in a number of ways. One commonly-used method is manual palpation, in which two fingers are used to feel for a subject's pulse through the tissue above their carotid artery in their neck. In some cases, a relatively strong pulse may be visible through the user's skin due to pulsations in the underlying artery causing rhythmic or periodic vibrations in the overlying skin. More reliable pulse detection/measurement techniques rely on the use of medical equipment. For example, a known defibrillation device includes a photoplethysmography (PPG) based pulse detection sensor designed to be attached to a person's finger. The person's pulse can be represented graphically on a display on the defibrillation device for viewing and interpretation by a user. However, such defibrillation devices are typically complicated to use, and are generally capable of being used only by medically-trained professionals.

Therefore, there exists a need for a device that can be used by users who are not medically trained, or who are not trained to use medical apparatus such as defibrillation devices.

Summary of the Invention

One way in which a medically-untrained person can detect a pulse in a subject is to look for movement in the skin close to a major artery. Vibrations in the skin caused by pulsations in an underlying artery may be optically enhanced or amplified to make it easier for the skin movement to be seen. The invention uses an effect caused by the superposition of two patterns. The effect can be likened to the generation of an interference pattern between two patterns. This effect is used to create a clearly visible effect representative of the pulsation in the underlying artery.

According to a first aspect, there is provided an apparatus comprising: a first patterned element for being positioned on or adjacent to a surface of a subject's body, the first patterned element having a first pattern formed thereon; and a second patterned element positioned above the first patterned element, the second patterned element having a second pattern formed thereon; wherein at least part of the first patterned element is moveable relative to the second patterned element in response to a pulsation of an underlying body part within the subject's body; and wherein the first and second patterns are such that, when the first patterned element moves relative to the second patterned element, an optical effect resulting from a superposition of the first pattern and the second pattern is visible.

The optical effect resulting from a superposition of the first and second patterns can be considered to be an optical interference pattern. Thus, the term "interference pattern" used herein is intended to refer to an optical pattern or effect resulting from the superposition of two or more patterns. It is intended that the interference pattern (and any movement thereof) is easier to see than movement of the skin resulting from the pulsation. Thus, a medically-untrained person should be able to determine relatively easily whether or not the pattern is moving. Moreover, the user should be able to determine whether the subject to whom the apparatus is attached has a pulse. The apparatus can be interpreted easily using the naked eye. Thus, additional specialist equipment is not required. Moreover, the apparatus can be constructed, maintained and used easily, and includes no electronic components. Therefore, the apparatus can be used in a location where power (mains power or batteries) is not available.

The optical effect may comprise an interference pattern, such as a moire pattern.

In some embodiments, the apparatus may further comprise a frame coupled to the first patterned element and to the second patterned element, the frame configured to support the second patterned element in a stationary position relative to the first patterned element.

In some embodiments, the first patterned element may comprise a flexible membrane having a periphery, the flexible membrane being coupled to the frame at a plurality of points around the periphery. The flexible membrane may be capable of flexing in response to the pulsation.

In other embodiments, the first patterned element may comprise a rigid element having a periphery, the rigid element being pivotally coupled to the frame at a point on the periphery. The rigid element may be capable of pivoting about the point on the periphery in response to the pulsation.

The second patterned element may, in some embodiments, be at least one of: offset from the first patterned element, (ii) inclined with respect to the first patterned element, and (iii) rotated with respect to the first patterned element.

At least one of the first patterned element and the second patterned element may be at least partially transparent. In some embodiments, at least one of the first pattern and the second pattern may comprise at least one of: a series of parallel lines, a series of concentric circles, a grid, a series of non-parallel lines, a series of curved lines and a series of dots. In some embodiments, the pattern formed on the first patterned element may be different to the pattern formed on the second patterned element. In other embodiments, the patterns may be the same. The apparatus may further comprise a reflective element for being positioned between the first patterned element and the subject's body. The reflective patterned element may be configured to reflect light through the first patterned element towards the second patterned element. A reflective element may assist the user in distinguishing the pattern from the background (i.e. the skin).

According to a second aspect, there is provided a method comprising: positioning a first patterned element on or adjacent to a surface of a subject's body, the first patterned element having a first pattern formed thereon and being movable in response to a pulsation of an underlying body part within the subject's body; and positioning a second patterned element above the first patterned element, the second patterned element having a second pattern formed thereon. At least part of the first patterned element may be moveable relative to the second patterned element in response to said pulsation. The first and second patterns may be such that, when the first patterned element moves relative to the second patterned element, an optical effect resulting from a superposition of the first pattern and the second pattern is visible.

In some embodiments, positioning the first patterned element may comprise positioning the first patterned element over an artery of the subject.

According to a third aspect, there is provided a system comprising a patterned element for being positioned on or adjacent to a surface of a subject's body, the patterned element having a first pattern formed thereon and being movable in response to a pulsation of an underlying body part within the subject's body; and a computing device. The computing device may comprise: an image capture module; a processor for processing an image captured by the image capture module; and a display screen for displaying the captured image to a user. At least a portion of the patterned element may be movable relative to the computing device. The processor may be configured to generate a second pattern for display to the user. When the patterned element moves relative to the computing device, an optical effect resulting from a superposition of the first pattern and the second pattern may be visible to the user.

An advantage of the system is that a user can position the patterned element on the body of the subject, then use a device such as a smart phone, a smart watch or smart glasses to create or function as the second pattern. The computing device may execute instructions, for example an application, to generate the second pattern. In some embodiments, the second pattern may be displayed on the display screen with the captured image. The optical effect resulting from a superposition of the first and second patterns may be visible to the user on the display screen.

The second pattern may, in some embodiments, be projected onto the surface of the subject's body. The optical effect resulting from a superposition of the first and second patterns may be visible to the user on the subject's body. In some embodiments, the computing device may comprise a device selected from a group comprising: a smart phone, a tablet computer, a smart watch, a laptop computer, a pair of smart glasses and a wearable computing device.

Other advantageous features will become apparent from the following description.

Brief Description of the Drawings

For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

Figure 1 is an illustration, in side view, of an example of an apparatus according to embodiments of the invention;

Figure 2 is an illustration, in perspective view, of the apparatus of Figure 1 ;

Figure 3 is an illustration of an example of the apparatus of Figures 1 and 2 positioned on a person;

Figure 4 is a schematic illustration of a further example of an apparatus according to embodiments of the invention;

Figure 5 is a schematic illustration of a further example of an apparatus according to embodiments of the invention; Figure 6 is an illustration of an example of a pattern formed by a combination of two line patterns; Figure 7 is an illustration of a further example of a pattern formed by a combination of two line patterns; Figure 8 is an illustration of a further example of a pattern formed by a combination of two line patterns;

Figure 9 is a flowchart of an example of method according to embodiments of the invention; and

Figure 10 is a schematic illustration of an example of a system according to embodiments of the invention.

Detailed Description of the Preferred Embodiments

It can be desirable to visualise a pulsation in a subject's artery, and to enhance an effect of the pulsation such that a pulsation caused by a weak or faint pulse can more easily be detected by a person. The present invention makes use of the moire effect. The effect is caused when an opaque pattern with transparent gaps is overlaid on another similar pattern. If the two patterns are slightly displaced, rotated or inclined with respect to one another, then a moire interference pattern may appear. The interference pattern includes a series of moire fringes whose appearance change as the two patterns are moved relative to one another. Example patterns suitable for use in the invention are discussed below with reference to Figures 6, 7 and 8. It is noted that, while examples are discussed herein in the context of detecting and visualising a pulse in a human, the invention may also be used to detect and visualise a pulse in an animal. Referring to the drawings, Figure 1 shows an illustration of an apparatus 100 for visualising pulsations. The apparatus 100 includes a first patterned element 102 and a second patterned element 104 which, in some embodiments, are secured to one another by a frame 106. In the embodiment shown in Figures 1 and 2, the frame 106 comprises four supports 108 positioned around the edges of the patterned elements 102, 104 while, in other embodiments, the frame may take a different form, such as a wall extending around the edges of the patterned elements, such that the apparatus 100 resembles a cylinder having ends formed by the patterned elements. In general, the frame may be coupled to the first patterned element 102 and to the second patterned element 104, and may be configured to support the second patterned element in a stationary position relative to the first patterned element.

The first patterned element 102 and the second patterned element 104 may comprise a relatively thin, transparent or semi-transparent, material. In some embodiments, each patterned element 102, 104 may have a respective support structure 1 10, 1 12 formed around its periphery. As discussed below, one or more of the first and second patterned elements 102, 104 may be formed from a rigid material, such as a polymer, or from a flexible material, such as a silicone rubber membrane, polyurethane foam, flexible glass, or flexible ceramics. In embodiments where the patterned elements 102, 104 are formed from a flexible material, then the flexible patterned elements may be stretched and held taut by the support structures 1 10 and 1 12 respectively.

Figure 2 shows the apparatus 100 in perspective view so that patterns formed on the patterned elements 102, 104 can be seen. Referring to Figure 2, the first patterned element 102 includes a pattern formed thereon comprising a series of parallel lines. The second patterned element 104 includes a second pattern formed thereon which, in this embodiment, also comprises a series of parallel lines. As noted below, however, the patterns formed on the patterned elements 102, 104 need not be the same. In some embodiments, such as the embodiment shown in Figure 2, the pattern formed on the first patterned element 102 may be rotated slightly with respect to the pattern formed on the second patterned element 104. Thus, in this embodiment, the parallel lines of the pattern on the first patterned element 102 are not parallel to the parallel lines of the pattern formed on the second patterned element 104.

The first patterned element 102 is moveable relative to the second patterned element 104. Movement of the first patterned element 102 may be caused by a pulsation that causes a force to be applied to the first patterned element 102 but not to the second patterned element 104. Thus, in use, the apparatus 100 may be positioned on or adjacent to (i.e. not directly on) a surface (i.e. skin) of the body of a subject whose pulse is to be detected. Specifically, the device is positioned on the body above a major artery, such as the carotid artery, which supplies blood to the brain, neck and face. Figure 3 shows an example of the apparatus 100 positioned on the neck of a person 300. The apparatus 100 may be positioned such that the first patterned element 102 is in contact with the subject's skin. In some embodiments, the first patterned element 102 may further include an adhesive layer to adhere the patterned element to the subject's skin and to improve coupling of the first patterned element with the skin. If blood pumps through an artery 1 14 beneath the surface of skin 1 16 on which the apparatus 100 is placed, then contraction and dilation of the artery 1 14 will cause arterial dilatation, which, in most cases, will cause movement of the skin 1 16. As the artery 1 14 pulsates, a corresponding pulsation or vibration may occur in the skin 1 16 above the artery, thereby causing a corresponding pulsation to occur in the first patterned element 102. In the embodiment shown in Figures 1 and 2, the first patterned element 102 is formed from a flexible material or membrane having a periphery. The flexible membrane is coupled to the frame 106 at a plurality of points around the periphery. In some examples, the flexible membrane may be stretched within the rigid support structure 1 10. Thus, the flexible membrane is capable of flexing in response to the pulsation such that, as the skin 1 16 pulsates, the flexible membrane is caused to move. The first patterned element 102 may, for example, flex upwards into a position shown in Figure 1 by a dashed line 1 18.

Although the first patterned element 102 may be caused to move as a result of the pulsation within the artery 1 14, the effect is not experienced by the second patterned element 104. Thus, the pattern formed on the first patterned element 102 may be caused to move relative to the pattern formed on the second patterned element 104 for the duration of each pulsation. A user viewing the device 100 from above may see an effect resulting from the superposition of the two patterns. For example, the effect may include an interference pattern (e.g. a moire pattern) in the form of a series of moire interference fringes resulting from the interference between the patterns of the first and second patterned elements 102, 104. A consequence of the moire effect is that a relatively small movement of the first patterned element 102 (e.g. caused by a relatively weak pulsation) may cause a significant interference pattern which moves as the patterns move relative to one another. In this way, the moire interference effect can be considered to amplify or enhance the visibility of any movement of the skin caused by the pulsation in the artery 1 14. As such, a medically untrained person may easily be able to determine if a subject to which the device 100 is attached has a pulse.

As noted above, in the embodiment shown in Figures 1 and 2, the first patterned element 102 is formed from a flexible material. However, in the embodiment shown in Figure 4, the first patterned element 102 may be formed from a rigid material, for example a plastics material such as acrylic. Figure 4 shows a device 400 which is similar to the device 100 of Figures 1 and 2. However, in the device 400, the first patterned element 102 comprises a rigid element having a periphery, the rigid element being pivotally coupled to the frame 106 at a point on the periphery. In the embodiment shown in Figure 4, the first patterned element 102 is formed from a rigid material and is connected to the second patterned element 104 by a support member 402. During a pulsation in the artery 1 14, a surface of the skin 1 16 may move into the position shown by dotted line 1 16a. The first patterned element 102 is pivotally attached to the support member 402 such that the pulsation in the artery 1 14 located under the skin 1 16 underlying the device 400 may cause the first patterned element to pivot upwards into a position shown by dashed lines 404. Thus, the rigid element 104 is capable of pivoting about the point on the periphery in response to the pulsation. Pivotal movement of the first patterned element 102 relative to the second patterned element 104 will result in relative movement of the patterns formed on the patterned elements. Therefore, a user viewing the device 400 from above may see a moire interference pattern resulting from the patterns on the patterned elements 102, 104.

In the embodiments shown in Figures 1 , 2 and 4, the first and second patterned elements 102, 104 are arranged substantially parallel to one another, and are configured such that, when no pulsation is causing the first patterned element to move, both patterned elements are substantially parallel to the surface (i.e. the skin 1 16) on which they are positioned. Figure 5 shows an alternative embodiment of the invention in which the device 500 has first and second patterned elements 102, 104 that are inclined with respect to one another. In the device 500, the first and second patterned elements 102, 104 are connected to a frame 502, similar to the frame 106 in Figure 1. The frame 502 includes at least a first support member 504 and a second support member 506. In the device 500, however, the second patterned element 104 is inclined relative to the first patterned element 102. The first patterned element 102 is pivotally attached to the first support member 504, but is not connected to the second support member 506. Thus, a pulsation in the artery 1 14 under the skin 1 16 underlying the device 500 may cause the surface of the skin 1 16 to move into the position shown by the dotted line 1 16a which, consequently, may cause the first patterned element 102 to pivot upwards into a position shown by dashed lines 508. The movement of the pattern formed on the first patterned element 102 relative to the pattern formed on the second patterned element 104 will cause moire interference patterns which may be visible to a user viewing the device 500 from above. Forming the first and second patterned elements 102, 104 such that they are not parallel to one another may further amplify the optical effect caused by the pulsation, thereby enhancing the visibility of a relatively small movement in the skin 1 16. As noted above, while the patterns formed on the first and second patterned elements 102, 104 of the device 100 in Figures 1 and 2 comprise a series of parallel lines, other patterns may alternatively be used, which are capable of causing a visible moire interference pattern when used as described herein. Figures 6, 7 and 8 show examples of various patterns that might be formed on one or both of the first and second patterned elements 102, 104. Figures 6a, 7a and 8a show patterns to be formed on the first patterned element 102, and Figures 6b, 7b and 8b show patterns to be formed on the second patterned element 104.

In Figure 6, a pattern to be formed on each of the patterned elements 102, 104 is in the form of a series of parallel lines. The pattern of Figure 6b is rotated slightly with respect with to the pattern of Figure 6a. Figure 6c shows an interference pattern resulting from a superposition of the patterns of Figures 6a and 6b. In Figure 7, the pattern to be formed on both the first patterned element 102 (shown in Figure 7a) and on the second patterned element 104 (shown in Figure 5b) comprises a series of concentric circles. The pattern on the second patterned element 104 is offset slightly from the pattern on the first patterned element 102, such that they are not perfectly aligned with one another. Figure 7c shows a resulting interference pattern caused by a superposition of the patterns of Figures 7a and 7b. The pattern shown in Figures 8a and 8b is a grid. The grid pattern of Figure 8b is rotated slightly with respect to the grid pattern of Figure 8a. Figure 8c shows a resulting interference pattern when the patterns of Figures 8a and 8b are superposed.

As noted above, to achieve a moire interference pattern, the two patterns cannot be exactly aligned with one another and in the same plane. Thus, the second patterned element 104 may be offset with respect to, inclined with the respect to, and/or rotated with respect to the first patterned element. With the patterned elements 102, 104 arranged in this way the interference patterns between the patterns should be visible, and any movement of one of the patterns relative to the other should cause a clear movement of the interference pattern. A rotation of the first patterned element relative to the second patterned element is considered to include a rotation about a central axis (denoted by dotted/dashed line A in Figure 1 ) through the first patterned element. An inclination of the first patterned element relative to the second patterned element is considered to include an arrangement in which the first and second patterned elements do not lie in planes that are parallel to one another, as shown for example in Figures 4 and 5.

It will be appreciated that the patterns shown in Figures 6, 7 and 8 are merely examples of a large number of possible patterns that could be used. Thus, at least one of the patterns of the first patterned element 102 and the second patterned element 104 may comprise a series of parallel lines (as shown in Figure 6), a series of concentric circles (as shown in Figure 7), a grid (as shown in Figure 8), a series of non- parallel lines, a series of curved lines, and/or a series of dots or dashes. In some embodiments, the pattern formed on the first patterned element 102 may be different to the pattern formed on the second patterned element 104. The visibility of the pulsation in the artery 1 14 may be improved by enhancing the moire interference effect. The interference pattern may be enhanced by forming patterns having varying degrees of spacing between the lines. The interference effect may also vary based on an angle of rotation of the first pattern relative to the second pattern, a pitch (i.e. inclination) of the first pattern relative to the second pattern, and/or an offset distance between the first pattern and the second pattern. In some embodiments, one or more of these variants may be used to enhance the interference pattern.

In some embodiments, a combination of two or more patterns may be formed on at least one of the first or second patterned elements 102, 104.

In some embodiments, a contrast between the pattern formed on the first patterned element 102 and the underlying skin 1 16 may be improved or enhanced by a reflective layer (not shown) positioned between the first patterned element and the skin. The reflective layer may, for example, comprise a sheet of mirrored material. The reflective material may serve to reflect light through the first patterned element 102 towards to the second patterned element 104.

A further aspect of the invention relates to a method for visualising a pulsation, such as a pulsation occurring in an artery. Figure 9 is a flowchart showing an example of such a method. In Figure 9, a method 900 comprises, at step 902, positioning a first patterned element on or adjacent to a surface of a subject's body, the first patterned element having a first pattern formed thereon and being moveable in response to a pulsation of an underlying body part within the subject's body. The method 900 further comprises, at step 904, positioning a second patterned element above the first patterned element, the second patterned element having a second pattern formed thereon. The first patterned element and the second patterned element may, in some embodiments, be coupled to one another by a frame, as shown in Figures 1 , 2, 4 and 5. At least part of the patterned element may be moveable relative to the second patterned element in response to the pulsation. The first and second patterns may be such that, when the first patterned element moves relative to the second patterned element, an optical interference pattern between the first pattern and the second pattern is visible. In some embodiments, the positioning (step 902) of the first patterned element may comprise positioning the first patterned element over an artery of the subject. A further aspect of the invention relates to a system for visualising a pulsation, such as a pulsation caused by a pulse in an artery of a subject. Figure 10 shows an example of such a system 1000. The system 1000 functions in a manner similar to the device described with reference to Figures 1 to 5 above, in that visualisation of a pulsation is achieved from moire interference patterns caused by relative movement of two patterns. However, in the system 1000, the second pattern (i.e. the pattern of the second patterned element 104) may be generated virtually, for example in a computing device, rather than being formed on a patterned element.

As shown in Figure 10, the system 1000 comprises a patterned element 1002 for being positioned on or adjacent to a surface of a subject's body, the patterned element having a first pattern formed thereon and being moveable in response to a pulsation of an underlying body part within the subject's body. The patterned element 1002 may be similar to the first patterned element 102 discussed above. The system 1000 further comprises a computing device 1004. The computing device 1004 includes an image capture module 1006, a processor 1008 for processing an image captured by the image capture module, and a display screen 1010 for displaying the captured image to a user. At least a portion of the patterned element 1002 is movable relative to the computing device 1004. The processer 1008 is configured to generate a second pattern for display to the user. When the patterned element moves relative to the computing device, an optical interference pattern between the first pattern and the second pattern is visible to the user. In the system 1000, therefore, the second pattern may be displayed to the user on the display screen 1010. In some embodiments, the second pattern may be displayed along with the captured image. Any optical interference pattern (e.g. a moire interference pattern) resulting from interference between the first pattern and the second pattern may be visible to the user on the display screen. In other embodiments, the second pattern may be projected onto the patterned element 1002, or onto the subject's skin, such that an interference pattern may be visible to the user on the subject's skin or on the patterned element positioned on the subject's skin. For example, the second pattern may be projected using an LED laser projector.

In some embodiments, the computing device 1004 may comprise a smart phone. In other embodiments, the computing device may comprise a tablet computer, a smart watch, a laptop computer, a pair of smart glasses, or a wearable computing device. A benefit of the system 1000 is that a user need only position a single patterned element over an artery of a subject whose pulse is to be detected and, by holding the computing device still relative to the patterned element 1002, a moire interference pattern resulting from a pulsation in the artery should be visible.

Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1 . An apparatus comprising:

a first patterned element for being positioned on or adjacent to a surface of a subject's body, the first patterned element having a first pattern formed thereon; and

a second patterned element positioned above the first patterned element, the second patterned element having a second pattern formed thereon;

wherein at least part of the first patterned element is moveable relative to the second patterned element in response to a pulsation of an underlying body part within the subject's body; and

wherein the first and second patterns are such that, when the first patterned element moves relative to the second patterned element, an optical effect resulting from a superposition of the first pattern and the second pattern is visible.

2. An apparatus according to claim 1 , wherein the optical effect comprises a moire pattern.

3. An apparatus according to claim 1 , further comprising:

a frame coupled to the first patterned element and to the second patterned element, the frame configured to support the second patterned element in a stationary position relative to the first patterned element.

4. An apparatus according to claim 3, wherein the first patterned element comprises a flexible membrane having a periphery, the flexible membrane being coupled to the frame at a plurality of points around the periphery;

wherein the flexible membrane is capable of flexing in response to the pulsation.

5. An apparatus according to claim 3, wherein the first patterned element comprises a rigid element having a periphery, the rigid element being pivotally coupled to the frame at a point on the periphery;

wherein the rigid element is capable of pivoting about the point on the periphery in response to the pulsation.

6. An apparatus according to claim 1 , wherein the second patterned element is at least one of: (i) offset from the first patterned element, (ii) inclined with respect to the first patterned element, and (iii) rotated with respect to the first patterned element.

7. An apparatus according to claim 1 , wherein at least one of the first patterned element and the second patterned element is at least partially transparent.

8. An apparatus according to claim 1 , wherein at least one of the first pattern and the second pattern comprises at least one of: a series of parallel lines, a series of concentric circles, a grid, a series of non-parallel lines, a series of curved lines and a series of dots.

9. An apparatus according to claim 1 , further comprising:

a reflective element for being positioned between the first patterned element and the subject's body, the reflective element configured to reflect light through the first patterned element towards the second patterned element.

10. A method comprising:

positioning a first patterned element on or adjacent to a surface of a subject's body, the first patterned element having a first pattern formed thereon and being movable in response to a pulsation of an underlying body part within the subject's body; and

positioning a second patterned element above the first patterned element, the second patterned element having a second pattern formed thereon;

wherein at least part of the first patterned element is moveable relative to the second patterned element in response to said pulsation; and

1 1 . A method according to claim 10, wherein positioning the first patterned element comprises positioning the first patterned element over an artery of the subject.

12. A system comprising:

a patterned element for being positioned on or adjacent to a surface of a subject's body, the patterned element having a first pattern formed thereon and being movable in response to a pulsation of an underlying body part within the subject's body; and

a computing device comprising:

an image capture module; a processor for processing an image captured by the image capture module; and

a display screen for displaying the captured image to a user;

wherein at least a portion of the patterned element is movable relative to the computing device;

wherein the processor is configured to generate a second pattern for display to the user; and

wherein, when the patterned element moves relative to the computing device, an optical effect resulting from a superposition of the first pattern and the second pattern is visible to the user.

13. A system according to claim 12, wherein the second pattern is displayed on the display screen with the captured image, and wherein the optical effect resulting from a superposition of the first and second patterns is visible to the user on the display screen.

14. A system according to claim 12, wherein the second pattern is projected onto the surface of the subject's body, and wherein the optical effect resulting from a superposition of the first and second patterns is visible to the user on the subject's body.

15. A system according to claim 12, wherein the computing device comprises a device selected from a group comprising: a smart phone, a tablet computer, a smart watch, a laptop computer, a pair of smart glasses and a wearable computing device.