Component concentration measuring device
A first holding member and a second holding member are arranged so as to sandwich a measurement site of a measurement subject, and are capable of clamping the measurement site. A light beam emitted from a light emitting unit is guided to the first holding member by an optical fiber, passes through an optical system, is reflected by a reflection unit, and is then incident on the measurement site. A detection unit housed in the second holding member detects a photoacoustic signal generated in the measurement site irradiated with the light beam emitted from the light emitting unit. A matching member is arranged between the second holding member and the measurement site, and is in contact with the measurement site.
1 . A component concentration measuring device comprising:
a pair of holding members including a first holding member and a second holding member that are configured to clamp a measurement site of a measurement subject;
a light emitting device configured to emit a light beam having a wavelength absorbed by a measurement target substance from the first holding member toward the measurement site;
a detector housed in the second holding member and configured to detect a photoacoustic signal generated by the measurement site when irradiated with the light beam;
a matching member configured to be arranged between the second holding member and the measurement site, and is configured to perform acoustic matching between the detector and the measurement site by undergoing elastic deformation with a constant elastic modulus while in contact with the measurement site; and
a resonator configured to cause the photoacoustic signal to resonate, the resonator being constituted by a first reflector that is arranged between the first holding member and the measurement site and has a first reflection surface configured to reflect the photoacoustic signal while allowing the light beam to pass therethrough, and a second reflector that is arranged between the second holding member and the measurement site and has a second reflection surface configured to reflect the photoacoustic signal, wherein the matching member fills a gap between the second reflector and the measurement site when the measurement site is clamped between the pair of holding members, and wherein a distance between the first reflection surface and the second reflection surface is a distance at which the photoacoustic signal resonates;
wherein:
the first reflection surface and the second reflection surface are parallel with each other,
the second reflection surface faces the measurement site, and
the second reflector includes a second contact surface that faces the second holding member and is in contact with a detection surface of the detector housed in the second holding member, wherein the detection surface faces the measurement site, and a void is disposed between the second reflection surface and the second contact surface.
2 . The component concentration measuring device according to claim 1 , wherein:
the first reflection surface faces the measurement site, and
the first reflector further includes a first contact surface that faces the first holding member and is in contact with a light emitting end of the light emitting device, and a void is disposed between the first reflection surface and the first contact surface.
3 . The component concentration measuring device according to claim 1 , wherein:
the matching member is constituted by a sponge made of a synthetic resin.
4 . The component concentration measuring device according to claim 1 , wherein:
the measurement target substance is glucose, and the light emitting device is configured to emit a light beam having a wavelength absorbed by glucose.
5 . A method comprising:
clamping, by a pair of holding members including a first holding member and a second holding member, a measurement site of a measurement subject;
emitting, by a light emitting device, a light beam having a wavelength absorbed by a measurement target substance from the first holding member toward the measurement site;
detecting, by a detector, a photoacoustic signal generated by the measurement site when irradiated with the light beam;
performing, by a matching member, acoustic matching between the detector and the measurement site by undergoing elastic deformation with a constant elastic modulus while in contact with the measurement site; and
causing, by a resonator, the photoacoustic signal to resonate, the resonator being constituted by a first reflector that is arranged between the first holding member and the measurement site and has a first reflection surface configured to reflect the photoacoustic signal while allowing the light beam to pass therethrough, and a second reflector that is arranged between the second holding member and the measurement site and has a second reflection surface configured to reflect the photoacoustic signal, wherein the matching member fills a gap between the second reflector and the measurement site when the measurement site is clamped between the pair of holding members, and wherein a distance between the first reflection surface and the second reflection surface is a distance at which the photoacoustic signal resonates;
wherein:
the first reflection surface and the second reflection surface are parallel with each other,
the second reflection surface faces the measurement site, and
the second reflector includes a second contact surface that faces the second holding member and is in contact with a detection surface of the detector housed in the second holding member, wherein the detection surface faces the measurement site, and a void is disposed between the second reflection surface and the second contact surface.
6 . The method according to claim 5 , wherein the detector is housed in the second holding member.
7 . The method according to claim 5 , wherein the matching member is disposed between the second holding member and the measurement site while the matching member is performing the acoustic matching between the detector and the measurement site.
8 . The method according to claim 5 , wherein:
the first reflection surface faces the measurement site, and
the first reflector further includes a first contact surface that faces the first holding member and is in contact with a light emitting end of the light emitting device, and a void is disposed between the first reflection surface and the first contact surface.
9 . The method according to claim 5 , wherein:
the matching member is constituted by a sponge made of a synthetic resin.
10 . The method according to claim 5 further comprising:
obtaining a concentration of the measurement target substance using the photoacoustic signal.
11 . The method according to claim 5 , wherein:
the measurement target substance is glucose, and the light emitting device emits a light beam having a wavelength absorbed by glucose.