DESC:
TECHNICAL FIELD
[1] The present disclosure generally relates to the field of finger plethysmography. In particular, the present disclosure relates to a non-invasive device for finger plethysmography.

BACKGROUND
[2] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[3] Arterial pulse pressure waveforms are indicators for the cardiovascular health of a person. The most preferred mode of recording he pulse pressure waveform is by using an intra-arterial probe. However, this method is invasive.
[4] To overcome this limitation, non-invasive techniques have been developed. Plethysmography is one such technique which involves determining change in blood flow in an artery by measuring the volumetric change of the tissue surrounding the artery.
[5] Several plethysmography techniques have been developed to with specific transduction techniques to measure volumetric change in the tissues surrounding the artery.
[6] Chamber Plethysmography uses volumetric displacement of a water or air filled tube to measure volumetric displacement of the tissue. However, the set-up is heavy and difficult to implement. The sensitivity to motion is poor and inaccurate as the water or air in the tube can be affected by temperature.
[7] Strain Gauge Plethysmography uses a volumetric change in a rubber tube filled with mercury (Hg) tube to measure volumetric displacement of the tissue. However, an occlusion cuff is required to enable measurement, and further, measurement can be done only one a section of a limb.
[8] Impedance Plethysmography measures the volume change in tissues by measuring resistivity changes as shunting impedance of blood. The drawback for this method is very poor accuracy.
[9] Among the plethysmography methods, Photoelectric Plethysmography on the finger, which further employs pulse oximetry, is the most preferred technique due to its accuracy, rapid detection and ease of implementation. Finger plethysmography is a well-known technique for the acquisition of pulse pressure waveforms in the field of cardiology. The technique involves the analysis of the volumetric variation of the finger due to pulsatile flow of blood in ulnar artery, in order to obtain the pulse pressure waveform of the subject.
[10] However, one of the major drawbacks of Photoelectric Plethysmography is inaccuracies arising from disturbance due to motion, optical shunting, excess ambient light, electromagnetic interference, difficulty with poor peripheral perfusion and interference of skin pigmentation etc.
[11] There is, therefore a need in the art, to develop a finger plethysmograph means to measure arterial pulse that is accurate, reliable and can be easily implemented.
[12] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[13] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about”. Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[14] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[15] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[16] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

OBJECTS
[17] A general object of the present disclosure is to provide a finger plethysmograph arterial pulse detector.
[18] Another object of the present disclosure is to provide an accurate, non-invasive means of detecting arterial pulse.
[19] Another object of the present disclosure is to provide a pulse detector that detects pulse on a beat-to-beat basis.
[20] Another object of the present disclosure is to provide a pulse detector with high sensitivity and quick response.
[21] Another object of the present disclosure is to provide a pulse detector that is easy to implement in a clinical environment.

SUMMARY
[22] The present disclosure generally relates to the field of finger plethysmography. In particular, the present disclosure relates to a non-invasive device for finger plethysmography.
[23] The present disclosure presents a pulse detector, which comprises: a hollow tube with an open slit along its length; a diaphragm stretched over the slit of the hollow tube; one or more sensors bonded over the diaphragm; and an interrogator.
[24] In an aspect, the hollow tube is a mount through which an appendage passes, where pulse of the appendage is to be detected. In an embodiment, the appendage is a finger. In a further embodiment, the hollow tube is tapered to more closely fit the finger profile.
[25] In another aspect, a diaphragm is stretched over the open slit on the hollow tube. The hollow tube along with the diaphragm form part of the device which detects the pulse. In an embodiment, the device is a finger plethysmograph pulse detector.
[26] In another aspect, the device works by detecting maximum variation in the tissue volume due to the pulse.
[27] In another aspect, the diaphragm stretched over the appendage, particularly over the area which experiences maximum variation in tissues volume due to the pulse. As volumetric change occurs of the tissue volume due to pulse, the diaphragm expands and contracts. In an embodiment, the diaphragm is made of silicone rubber.
[28] In another aspect, one or more sensors are bonded over the diaphragm to sense the pulse. The sensing occurs by sensing the expansion and contraction of the diaphragm due to pulse. As the sensors detect an expansion or contraction, one or more signals associated with the pulse are generated by the sensors.
[29] In an embodiment, the one or more sensors are Fibre Bragg Grating sensors. The sensors work when an external perturbation alters the periodicity of the grating or effective refractive index, causing a shift in reflected Bragg wavelength.
[30] In another aspect, an interrogator is configured to receive the one or more signals generated by the sensors. The interrogator senses the shifts in reflected Bragg wavelengths and appropriately converts it to a pulse waveform. In an embodiment, the interrogator is an optical interrogator.
[31] In another aspect, the pulse detector detects the pulse on a beat-to-beat basis, that is, the sensors generate the one or more signals associated with the pulse, with every expansion of the diaphragm due to said pulse.
[32] In an embodiment, the pulse detector detects arterial pulse and generates an arterial pulse waveform.
[33] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.

BRIEF DESCRIPTION OF DRAWINGS
[34] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[35] FIG.1 illustrates an exemplary finger plethysmography device, along with a schematic representation of the FBG based arterial pulse plethysmograph device, in accordance with an embodiment, of the present invention.
[36] FIG. 2 illustrates an exemplary experimental set-up to measure arterial pulse of the subject using the device.
[37] FIG. 3A illustrates a typical arterial pulse waveform recorded by a plethysmography known in the art.
[38] FIG. 3B illustrates an exemplary arterial pulse waveform acquired by the FBGPPR using the plethysmograph technique, in accordance with an embodiment of the present disclosure.
[39] FIG. 4 illustrates a plurality of waveforms obtained from the plethysmography technique based FBGPPR being superimposed over one another.
[40] FIG. 5A illustrates the comparison of the arterial pulse waveforms obtained from the FBGPPR and FBGPR devices, when recorded simultaneously.
[41] FIG. 5B illustrates the comparison of the total pulse duration of the waveforms obtained by the FBGPPR and FBGPR devices for the same cardiac cycle, when recorded simultaneously.

DETAILED DESCRIPTION
[42] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
[43] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[44] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[45] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. These exemplary embodiments are provided only for illustrative purposes and so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. The invention disclosed may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
[46] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[47] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[48] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[49] In an aspect, a Fibre Bragg Grating (FBG) is periodic modulation of refractive indices in the core of a single-mode photosensitive optical fibre. When a broadband light is introduced in the FBG, a single wavelength which satisfies the Bragg condition is reflected, while the rest is transmitted through. The reflected Bragg wavelength (?B) is given by:

? – periodicity of the FBG
n¬eff – effective refractive index of the fibre core.

[50] In another aspect, an external perturbation such as strain or temperature variation at the site of FBG can alter the periodicity of the grating or effective refractive index, which causes a shift in the reflected Bragg wavelength. The external perturbation can be quantified by interrogating the shift in Bragg wavelength.
[51] In an instance, the effect of external strain on an FBG can be expressed as follows:

P11, P12 – components of strain-optic tensor
? – Poisson’s ratio
e – axial strain change.

[52] In another aspect, the temperature effect on the FBG sensor can be neglected, if said FBG is used in a temperature-controlled environment.
[53] FIG.1 illustrates an exemplary finger plethysmography device, along with a schematic representation of the FBG based arterial pulse plethysmograph device, in accordance with an embodiment, of the present invention. In an embodiment, said device 102 comprises a hollow tapered tube 108, made of a light, flexible but strong material selected from any of plastic, high density polymers such as polyurethane, polyvinyl chloride, and metal and metal alloys.
[54] In another embodiment, the hollow tube is a mount through which a finger of a subject passes and is tapered to better fit the contour of the finger. Additionally, the tapered tube has an open slit along its length, upon which a diaphragm 104 is adhered. In an exemplary instance the length and width of the tube 108 can be about 25mm and 1.5mm respectively. Further, width of the slit can be about 16mm.
[55] In another embodiment, the diaphragm 104 is made of a silicone rubber and is mounted on the hollow tapered tube 108, over the slit, along the length of the tube 108. The dimensions of the diaphragm 104 are such that the entire slit area is covered. In an exemplary instance, the silicone diaphragm 104 can be 0.3mm thick.
[56] In another embodiment, an FBG sensor 106 is bonded over the silicone diaphragm so that said sensor can acquire variations of strain due to pulsating variations in the volume of the finger, through the silicone diaphragm. In an exemplary instance, the FBG sensor 106 can have a gauge length of 3mm is fabricated in a photo sensitive Germania doped silica fibre, using a phase mask inscription method. The strain sensitivity of the FBG sensor 106 is approximately 1.20 pm/µE.
[57] In another embodiment, the FBG sensor 106 is coupled to an optics interrogator 110 which can appropriately and suitably sense shifts in Bragg wavelength at a high sampling rate and resolution. In an exemplary instance, the interrogator 110 can be an SM 130-700 FBG Micron Optics Interrogator capable of acquiring Bragg wavelength shifts at a sampling rate of 1kHz and a resolution of 1pm. This converts to 0.81µe strain variation.
[58] In a further embodiment, the hollow tube 108 with the diaphragm 104 and the interrogator 110 coupled to it constitute a Fibre Bragg Grating Plethysmograph Pulse Recorder (FBGPPR) (hereinafter also referred to as “device”).
[59] In another embodiment, the device 102 is mounted on the finger of the subject such that the silicone diaphragm 104 stretches over the area of the finger that shows maximum volumetric variations due to pulse, that is, the diaphragm 104 experiences maximum volumetric changes on the finger. The hollow tube 108 is rigid, and therefore resists expansion thereby reducing loss of signal due to volumetric change available to the silicone diaphragm 104.
[60] In another embodiment the volumetric change of the finger due to the beat-to-beat pulsation is recorded by the diaphragm as strain variations, which are, in turn, acquired by the FBG sensor106 to generate a waveform representing the arterial pulse of the subject.
[61] In an aspect, it can be appreciated that the studies undertaken to demonstrate the capability of the device has been approved by the Institutional Human Ethics Committee (IHEC), Indian Institute of Science, and the experiments carried out in the present study are within the guidelines of the IHEC for human studies.
[62] In an exemplary embodiment, the subjects for said study are requested to relax for a period of about 10 minutes prior to the conduction of the experiment.
[63] FIG. 2 illustrates an exemplary experimental set-up to measure arterial pulse of the subject using the device. The device 102 is mounted on the finger of the subject. As a control, a device known in the art for the measurement of arterial pulse is used and mounted on the same arm on which the device of the present disclosure is mounted. In an exemplary instance, the control device is a Fibre Bragg Grating Pulse Recorder (FBGPR) 202 mounted on the wrist of the subject. The FBGPR 202 measures the arterial pulse waveform using a tonometry technique.
[64] In another embodiment, the arterial pulse waveforms are acquired through the PBGPPR 102 and the FBGPR 202 for a period of about 3 minutes. The acquired arterial pulse waveforms from both devices are compared to gauge the accuracy of the device of the present disclosure. The results of the comparison and inferences drawn thereon are discussed in the following sections.
[65] FIG. 3A illustrates a typical arterial pulse waveform recorded by a plethysmography known in the art. In an aspect, the pulse waveform comprises a forward wave travelling from the heart to the peripheral sites, and a reflected wave travelling from the peripheral sites to the heart.
[66] In another aspect, the waveform comprises a notch known as the dicrotic notch which indicates when the aortic valve closes and the onset of filling of the left ventricle of the heart.
[67] In another aspect, the time duration from the onset of the pulse to the dicrotic notch is referred to as the systolic time (T1) and the duration of time from the dicrotic notch to the end of the pulse is referred to as diastolic time (T2). The total pulse time is denoted by T3.
[68] In another aspect, the time duration between systolic peak P1 and the diastolic peak P2 is referred to as ?T. Further, the morphology of the arterial pulse waveform acquired varies with arterial sites picked for recording said waveform.
[69] In another aspect, together, the values of T1, T2, T3, P1, P2 and ?T are known indicators of cardiovascular status of a person and their variation with age and cardiovascular ailments of a person are valuable parameters to judge the health of the cardiovascular system of the person.
[70] FIG. 3B illustrates an exemplary arterial pulse waveform acquired by the FBGPPR 102 using the plethysmograph technique, in accordance with an embodiment of the present disclosure. In an embodiment, the strain variations over the silicone diaphragm 104 is acquired by the interrogator 110 in the form of shifts in Bragg wavelength, and is indicated in the figure as such. It is noted that the beat-to-beat signal obtained is repetitive and continuous.
[71] It can be appreciated by one skilled in the art that the shift in Bragg wavelength can be configured to display pressure of the arterial waveform, in accordance with measurements performed in the art.
[72] FIG. 4 illustrates a plurality of waveforms obtained from the plethysmography technique based FBGPPR 102 being superimposed over one another. In an embodiment, the superimposition indicates the reproducibility and repeatability of the technique.
[73] In another embodiment, it is observed that the morphologies of the plurality of waveforms superimposed on one another is similar. The cardiovascular parameters as described before are obtained for each of the plurality of waveforms considered and analysed to obtains standard deviation of these parameters, as displayed in Table 1 below.

Mean Standard Deviation
Systolic Time T1 (s) 0.336 0.0154
Diastolic Time T2 (s) 0.35 0.0196
Total Pulse Duration T3 (s) 0.686 0.0168
?T (s) 0.261 0.009
Systolic Peak Pressure P1 (nm) 0.013 0.0005
Diastolic Peak Pressure P2 (nm) 0.008 0.0008

Table 1: Statistical analysis of plurality of waveforms recorder using FBGPPR.

[74] In another embodiment, it can be seen that the low values of standard deviation for the cardiovascular parameters shows the repeatability and reproducibility of the plethysmograph technique based FBGPPR 102 to record arterial pulse waveform.
[75] In an aspect, the validity of the arterial pulse waveform obtained through the device is compared with the waveform obtained from the control FBGPR 202 to evaluate accuracy of the device of the present disclosure.
[76] FIG. 5A illustrates the comparison of the arterial pulse waveforms obtained from the FBGPPR 102 (504) and FBGPR 202 (502) devices, when recorded simultaneously. It is observed that the morphology of the waveforms is very similar. This can be attributed to the proximity of arterial sites for the two devices, namely, the finger and the wrist respectively.
[77] FIG. 5B illustrates the comparison of the total pulse duration (T3) of the waveforms obtained by the FBGPPR and FBGPR devices for the same cardiac cycle, when recorded simultaneously. In an embodiment, the plot shows a Pearson correlation coefficient of almost 1 and a slope of almost 1 shows the high degree of linear agreement between the waveforms recorded by the two devices.
[78] Thus, the present disclosure discloses a Fibre Bragg grating based arterial pulse plethysmograph recorder which senses volumetric changes in a finger due to pulse using a diaphragm and converts it into shifts in Bragg wavelength to generate an arterial pulse waveform.
[79] Without departing from the spirit and concept of the present invention, any variations and modifications to the embodiments should be within the apprehension of those with ordinary knowledge and skills in the art, and therefore fall in the scope of the present invention which is defined by the accompanied claims. Though the present invention has been described on the basis of some preferred embodiments, those skilled in the art should appreciate that those embodiments should by no means limit the scope of the present invention. Without departing from the spirit and concept of the present invention, any variations and modifications to the embodiments should be within the apprehension of those with ordinary knowledge and skills in the art, and therefore fall in the scope of the present invention which is defined by the accompanied claims.
[80] The present invention provides an FBG based plethysmograph device for measuring arterial pulse, that is susceptible of modifications or variations all within the scope of the inventive concept as defined by the appended claims; any details may be replaced with technically equivalent elements. One or more of the elements above described may be differently shaped and/or positioned, can be differently coupled or positioned, etcetera. The materials, so long as they are compatible with the specific use, as well as the individual components, may be any according to the requirements and the state of the art.
[81] Only certain features of the invention have been specifically illustrated and described herein, and many modifications and changes will occur to those skilled in the art. The invention is not restricted by the preferred embodiment described herein in the description. It is to be noted that the invention is explained by way of exemplary embodiment and is neither exhaustive nor limiting. Certain aspects of the invention that have not been elaborated herein in the description are well understood by one skilled in the art. Also, the terms relating to singular form used herein in the description also include its plurality and vice versa, wherever applicable. Any relevant modification or variation, which is not described specifically in the specification are in fact to be construed of being well within the scope of the invention. The appended claims are intended to cover all such modifications and changes which fall within the spirit of the invention.
[82] The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.
[83] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the appended claims.
[84] While embodiments of the present disclosure have been illustrated and described, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the scope of the disclosure, as described in the claims.
[85] In the description of the present specification, reference to the term "one embodiment," "an embodiments", "an example", "an instance", or "some examples" and the description is meant in connection with the embodiment or example described, the particular feature, structure, material, or characteristic included in the present invention, at least one embodiment or example. In the present specification, the term of the above schematic representation is not necessarily for the same embodiment or example. Furthermore, the particular features structures, materials, or characteristics described in any one or more embodiments or examples in proper manner. Moreover, those skilled in the art can be described in the specification of different embodiments or examples are joined and combinations thereof.
[86] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
[87] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
[88] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
[89] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES
[90] The present disclosure provides a finger plethysmograph arterial pulse detector.
[91] The present disclosure provides an accurate, non-invasive means of detecting arterial pulse.
[92] The present disclosure provides a pulse detector that detects pulse on a beat-to-beat basis.
[93] The present disclosure provides a pulse detector with high sensitivity and quick response.
[94] The present disclosure provides a pulse detector that is easy to implement in a clinical environment.

,CLAIMS:
1. A pulse detector comprising:
a hollow tube with an open slit across its length, wherein said hollow tube is a mount through which an appendage passes, where pulse associated with said appendage is to be detected;
a diaphragm mounted over the slit of said hollow tube to sense pulse, wherein the diaphragm covers an area of said appendage which experiences maximum volumetric variation due to the pulse;
one or more sensors bonded over the diaphragm, wherein, on expansion of diaphragm due to volumetric variation caused by the pulse, one or more signals associated with the pulse are generated by said one or more sensors; and
an interrogator configured to receive said one or more signals from said one or more sensors, wherein said interrogator converts said one or more signals into a pulse waveform,
wherein said sensor generates said one or more signals associated with pulse on a beat-to-beat basis.

2. The pulse detector as claimed in claim 1, wherein said pulse detector is a plethysmograph pulse detector.

3. The pulse detector as claimed in claim 1, wherein said one or more sensors are Fibre Bragg Grating sensors.

4. The pulse detector as claimed in claim 1, wherein said interrogator is an optical interrogator.

5. The pulse detector as claimed in claim 1, wherein said pulse detected is an arterial pulse.

6. The pulse detector as claimed in claim 1, wherein said appendage is selected from any of finger, wrist and arm.

7. The pulse detector as claimed in claim 1, wherein the hollow tube is tapered to more closely fit appendage profile.

8. The pulse detector as claimed in claim 1, wherein the diaphragm is made of silicone rubber.