Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed:
[0001] Field of the invention:
The invention is related to a control unit for calculating blood pressure using at least one signal and a method thereof.

[0002] Background of the invention:
The conventional methods of blood pressure (BP) measurement involve the use of arm cuff that is inflated to obstruct the blood flow and measure BP from mercury column (Sphygmomanometer) or algorithmic mapping of cuff pressure (automated BP monitors). The latter method that is employed in ICUs and in home monitors requires periodic calibration and creates utmost inconveniences to users due to prolonged cuff usage. Though techniques such as estimating blood pressure from pulse arrival time has been proposed for being continuous and non-invasive, pulse arrival time and similar parameters demands the analysis of both ECG and PPG resulting in restricted measuring environment (clinical setting). The need for the recording of ECG is completely eliminated and the features extracted from the PPG signals are utilized for the blood pressure estimation.

[0003] A US patent application 20170112395 discloses a method of estimating a blood pressure is provided. The method of estimating blood pressure includes inputting physical characteristic information and blood pressure information of a subject, determining, among a plurality of groups classified according to hemodynamic characteristics, a group to which the subject belongs based on the physical characteristic information and the blood pressure information, detecting a bio-signal of the subject, extracting a plurality of features from the detected the bio-signal, and estimating a blood pressure corresponding to the extracted plurality of features and the determined group based on a learned blood pressure estimation algorithm.

[0004] Brief description of the accompanying drawings:
An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0005] Figure 1 illustrates a control unit for calculating blood pressure using at least one signal according to one embodiment of the invention: and
[0005] Figure 2 illustrates a flow chart of a method of operating the control unit according to the present invention.
Detailed description of the embodiments:
[0006] Figure 1 illustrates a control unit for calculating blood pressure using at least one signal in a device according to one embodiment of the present invention. The device 12 comprises plurality of light sources 14(a, b, c, d) and slot 16 for inserting of a body appendage of a person. According to one embodiment of the invention, the device 12 comprises four light sources 14(a, b, c, d) and the type of light source is a Light emitting diode (LED). Each of the light source (14 (a/b/c/d)) has a specific wavelength which it is operated in. For example, a first light source 14(a) has a wavelength of 590nm. The control unit 10 generates at least one signal corresponding to each of the plurality of the light sources 14(a/b/c/d) when a body appendage of a person is inserted in the slot 16. The control unit 10 considers a first generated signal from a first light source 14(a) out of the plurality of light sources (14(b, c, d) as a reference signal.
[0007] The control unit 10 then modifies an amplitude of the generated signals of the corresponding plurality of light sources 14(b, c, d) with a first correction module 18 and with the reference signal. The control unit 10 reduces a switching time between the first light source 14(a) and a next light source of the plurality of light sources (14(b, c, d)) using a second correction module 20. The control unit 10 transmits the modified signals of the plurality of light sources 14(b, c, d) for calculating the blood pressure of the person.
[0008] Further the components of the control unit 10 and the function of the components of the control unit is explained further. The control unit 10 according to the present invention is chosen from a group of control units comprising a microprocessor, a microcontroller, a digital circuit, an integrated chip and the like. The device12 as mentioned above comprises four light sources.14(a, b, c, d) I.e.., L1, L2, L3 and L4. According to one embodiment of the invention, the light sources 14(a, b, c, d) have wavelengths 590nm, 660nm, 810nm,940nm respectively. However, a different wavelength light sources can also be used as per the requirement.
[0009] As the L1 light source 14(a) has low wavelength, it can’t penetrate deeper into the body and will reach up to the skin tissues. Wherein the other light sources 14(b, c, d) L2, L3 and L4 having higher wavelengths than L1, reaches deeper into the body, where it touches an artery nerve through which the blood pressure of a person is calculated. The reflected light of the first light source 14(a) L1 when operated gives only the value of the skin tissue, not the artery nerve. Hence, it is eliminated from other reflected light values of other light sources while calculating the blood pressure of a person.
[0010] According to one embodiment of the invention, the signal is a photoplethysmogram (PPG) signal. The reflected light from each of the light source 14(a, b, c, d) produces a signal, wherein according to this present invention, the device 10 produces four PPG signals of different values based on the corresponding wavelength of the light source 14(a, b, c, d). i.e., each light source 14(a, b, c, d) generates a corresponding PPG signal when travelled into the body of the person. As the first PPG signal generated from the first light source .14(a)
[0011] The control unit 10 as mentioned above comprises the first correction module 18, wherein the first correction module 18 is adapted to correct the amplitude of the signals generated from the light sources by taking the first PPG signal as reference. The first correction module 18 adapted to eliminate the generated first signal values from other the generated signals. The first correction module 18 uses an amplitude correction factor for the other generated signals after the first signal value is removed.
[0012] The second correction module 20 is a switching time correction module. The second correction module 20 reduces the switching time based on a time correction factor. After the correction of the amplitude and the time in the signals taking first signal as reference, the modified signals of the other light sources 14(b, c, d) (apart from the first light source 14(a)) are transmitted to an intelligence module 22 for calculating the blood pressure.
[0013] A method of calculating blood pressure using multiple signals in a device 12. The device 12 comprises plurality of light sources 14(a, b, c, d) and a slot 16. The method involves the following steps. In step S1, at least one signal is generated corresponding to each of the plurality of light sources 14(a, b, c, d) when a body appendage of a person is inserted in the slot 16. In step S2, a first generated signal from a first light source 14(a) is generated and considered as a reference signal out of said plurality of light sources 14(b, c, d).
[0014] In step S3, an amplitude of the generated signals of the corresponding plurality of light sources14(b, c, d) is generated with a first correction module 18 and with the reference signal. In step S4, a switching time between the first light source 14(a) and a next light source 14(b) or 14(c) or 14(d) of the plurality of light sources (14(bcc’d)) using a second correction module 20 is reduced. In step S5, the modified signals of the plurality of light sources 14(b, c, d) are used for calculating the blood pressure of the person.
[0015] The above disclosed method is explained in detail. According to one embodiment of the invention, the device 12 is any body parameter sensing device, wherein in this present invention, the body parameter being the blood pressure. As mentioned above, the device comprises plurality of light sources 14(a, b, c, d), i.e.., L1, L2, L3, L4 and each has a different wavelength. When the person inserts his/her body appendage in the slot 16 of the device 12, the device 12 is operated, and a light is made to pass through the body appendage. According to one embodiment of the invention, one light source 14(a, b, c, d) is switched ON at a time when the device 12 is operated. All the four light sources 14(a, b, c, d) are operated simultaneously one after the other. Each light source 14(a, b, c, d) generates one signal respectively. I.e., S1, S2, S3, S4.
[0016] When the first light source 14(a) L1 is made pass through the body appendage of the person present in the slot 16, a first PPG signal S1 is generated. This first PPG signal S1 is taken as a reference signal by the control unit 10. The light from the first light source 14(a) L1 will not be able to penetrate deeper into the body of the person due to its small wavelength. The S1 generated from L1 will have only the values that are related to the skin tissues rather than the arteries. The control unit 10 upon receiving the value due to the penetration of light from the first light source 14(a) L1, the S1 is generated according to the received value and the taken that as a reference signal.
[0017] After a predefined amount of time, the second light source 14(b) is switched ON and the light is generated from the second light source 14(b). When the light is made to pass on the body appendage of the person, a value is generated and the second signal S2 is made by the control unit 10. Since, the second light source 14(b) has a wavelength more than the first light source 14(a), the light from the second light source 14(b) reaches the artery nerve. The value generated from the second light source 14(b) comprises the value of the skin tissues and the artery nerve.
[0018] In order to obtain, the value that is related to the artery nerve, the skin tissue value has to be removed from the generated signal S2. The control unit 10 eliminates/removes the skin tissue value from the signal S2.ie., the amplitude of the signal S1 is removed from the signal S2. In addition to this, the control unit 10 reduces the switching times between the light sources 14(a, b) L1 and L2. The first correction module 18 modifies the signal S2 by eliminating the signal S1 value from signal S2, as signal S2 comprises the values related to both skin tissues and the artery nerve. The modified PPG signal (S2) is given to the control unit 10 for calculating the blood pressure.
[0019] The control unit 10 in this process uses an intelligence module 22 that is loaded with any one of the intelligence neural networks comprising an artificial intelligence module, a machine learning module, a deep learning module. Using any one of these learning modules and the modified signals, the control unit 10 calculates the blood pressure of the person. The same process is adapted to the other light sources 14(c, d) L3 and L4 and the signals S3 and S4. Thus, all the three modified signals S2, S3, S4 are transmitted to the control unit 10 for calculating the blood pressure of the person using the device 12.
[0020] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims , Claims:We claim: -
1. A control unit (10) for calculating blood pressure using multiple signals in a device, said device (12) comprises plurality of light sources (14) and a slot (16), said control unit (10) adapted to:
- generate at least one signal corresponding to each of said plurality of light sources (14) when a body appendage of a person is inserted in said slot (16);
- consider a first generated signals from a first light source (14(a)) out of said plurality of light sources (14(b, c, d) as a reference signal;
- modify an amplitude of said generated signals of said corresponding plurality of light sources (14(b, c, d)) with a first correction module (18) and with said reference signal generated from said first light source (14(a));
- reduce a switching time between first light source (14(a)) and a next light source (14(b) or 14(c) or 14(d)) of said plurality of light sources (14(b, c, d)) using a second correction module (20);
- transmit said modified signals of said plurality of light sources (14(b, c, d)) for calculating said blood pressure of said person.
2. The control unit (10) as claimed in claim 1, wherein said at least one signal is a photoplethysmogram (PPG) signal and said device (12) comprises four light sources (14(a, b, c, d)) having four different wavelengths, wherein each said of light source (14(a/b/c/d)) generate a respective signal.
3. The control unit (10) as claimed in claim 1, wherein said first correction module (18) adapted to eliminate said generated first signal value from other said generated signals.
4. The control unit (10) as claimed in claim 3, wherein said first correction module (18) uses an amplitude correction factor for said other generated signals after said first signal value is removed.
5. The control unit (10) as claimed in claim 1, wherein said first correction module (18) is an amplitude correction module and said second correct (20) ion module is a switching time correction module.
6. The control unit (10) as claimed in claim 1, wherein said second correction module (20) reduces said switching time based on a time correction factor.
7. The control unit (10) as claimed in claim 1, wherein modified signals of said other light sources (14(b/c/d)) are transmitted to an intelligence module (22) for calculating said blood pressure.
8. A method of calculating blood pressure using multiple signals in a device, (12), said device comprises plurality of light sources (14(a, b, c, d)) and a slot (16) and a control unit (10), said method comprising:
- generating at least one signal corresponding to each of said plurality of light sources (14(a, b, c, d)) when a body appendage of a person is inserted in said slot (16);
- considering a first generated signal from a first light source (14(a)) out of said plurality of light sources (14(b, c, d)) as a reference signal;
- modifying an amplitude of said generated signals of said corresponding plurality of light sources (14(b, c, d)) with a first correction module (20) and with said reference signal generated from said first light source(14(a));
- reducing a switching time between the first light source (14(a)) and a next light source of said plurality of light sources (14(b, c, d)) using a second correction module (22);
- transmitting said modified signals of said plurality of light sources (14(b, c, d)) for calculating said blood pressure of said person.