Methods of and apparatus for measuring physiological parameters

1 . Apparatus for measuring physiological parameters in a blood vessel of a subject, the apparatus comprising:

a means for attachment of the apparatus on a part of the subject's body;

at least one acoustic sensor positionable on the part of the subject's body and configured to receive an acoustic signal from the blood vessel, the at least one acoustic sensor comprising:

a first microphone positioned to measure an acoustic signal from the blood vessel,

a second microphone positioned to measure ambient background noise, and

a processor for receiving signals from the first microphone and the second microphone, the processor being configured to generate a noise-reduced acoustic signal by subtracting the background noise measured by the second microphone from the acoustic signal measured by the first microphone;

an optical sensor comprising a light source, and comprising a photosensor configured to measure one or more properties of the light source through absorption, refraction, or reflection of the light source from the blood vessel; and

a motion sensor for determining whether the apparatus is being worn by a subject;

wherein the apparatus is configured to activate the optical sensor only when the motion sensor determines motion representative of the apparatus being worn by the subject; and

wherein the apparatus is configured to activate the first microphone and the second microphone only when the optical sensor determines light absorption, refraction, or reflection representative of the apparatus being located in close proximity to the blood vessel.

2 . The apparatus according to claim 1 , wherein each of the first microphone and optical sensor are mounted on a common surface and facing a portion of the subject's body surface.

3 . The apparatus according to claim 1 , wherein the means for attachment of the apparatus on a part of the subject's body comprises means for attachment of the apparatus on a limb of the subject.

4 . The apparatus according to claim 1 , wherein the means for attachment of the apparatus on a part of the subject's body comprises a sensor housing and an attachment interface, the attachment interface having a first attachment configuration and a second attachment configuration such that, in the first attachment configuration, the sensor housing can be moved in three degrees of freedom relative to the attachment interface, and in the second attachment configuration, the sensor housing is positionally fixed relative to the attachment interface.

5 . The apparatus according to claim 4 , wherein the sensor housing further comprises sealing means configured to provide an air tight seal between the sensor housing and the subject's body surface.

6 . The apparatus according to claim 4 , wherein the sensor housing comprises a sidewall having at least one opening and open upper and lower surfaces to permit insertion of the acoustic sensor into the sensor housing when the attachment interface is in the first attachment configuration.

7 . The apparatus according to claim 6 , wherein at least one of the at least one openings in the sidewall is fitted with a lens.

8 . The apparatus according to claim 1 , further comprising a transmitter for sending acoustic signals measured by the acoustic sensor to an external electronic device.

9 . The apparatus according claim 1 , wherein the apparatus is configured to activate one or more additional electronic components when the photosensor determines one or more properties of light representative of the apparatus being located in close proximity to an artery or vein.

10 . The apparatus according to claim 1 , wherein the acoustic sensor is configured to measure acoustic signals in the range of 10 Hz to 10 KHz.

11 . The apparatus according to claim 1 , wherein the apparatus is configured to be worn on the subject's forearm.

12 . A system for measuring physiological parameters in a blood vessel comprising the apparatus according to claim 1 and an electronic device configured to receive signals from the apparatus and display one or more data field representative of physiological parameters measured by the apparatus.

13 . A method of measuring physiological parameters in a blood vessel using the apparatus according to claim 1 , the method comprising:

using the motion sensor to determine whether the apparatus is being worn;

activating the optical sensor only in response to determining that the apparatus is being worn;

using the optical sensor to determine a position of the apparatus relative to the blood vessel;

activating the first microphone and the second microphone only when the optical sensor determines light absorption, refraction, or reflection representative of the apparatus being located in close proximity to the blood vessel;

using the first microphone to measure the acoustic signal from the blood vessel;

using the second microphone to measure ambient background noise; and

subtracting the ambient background noise measured by the second microphone from the acoustic signal measured by the first microphone to generate the noise-reduced acoustic signal.