Photoacoustic measuring apparatus
Provided is a photoacoustic measuring apparatus. The apparatus comprises a light source configured to emit laser of a predetermined wavelength to a measurement target, a photoacoustic detector configured to detect a photoacoustic signal generated from the measurement target receiving the laser light emitted from the light source, a contact sensor including a first bioimpedance electrode, a second bioimpedance electrode, and a third bioimpedance electrode and configured to obtain a bioimpedance value when the electrodes come into contact with the measurement target and an operator during use of the photoacoustic measuring apparatus, and a controller configured to decide whether the apparatus is in proper contact with the measurement target and whether the operator and the measurement target are the same individual based on a bioimpedance value measured using the contact sensor.
1 . A photoacoustic measuring apparatus comprising: a light source configured to emit laser of a predetermined wavelength to a measurement target; a photoacoustic detector configured to detect a photoacoustic signal generated from the measurement target receiving the laser light emitted from the light source; a contact sensor including a first bioimpedance electrode, a second bioimpedance electrode, and a third bioimpedance electrode, the contact sensor being configured to obtain a bioimpedance value when the first, second, and third bioimpedance electrodes come into contact with the measurement target and an operator during use of the photoacoustic measuring apparatus; and a controller configured to decide whether the apparatus is in proper contact with the measurement target and whether the operator and the measurement target are the same individual, based on the bioimpedance value measured using the contact sensor.
2 . The photoacoustic measuring apparatus of claim 1 , further comprising: a proximity sensor for outputting a proximity decision of the light source to the measurement target as one of proximity state and non-proximity state; and a light source driver configured to drive the light source according to a predetermined operation setting, wherein a proximity determination result of the proximity sensor is changed from the non-proximity state to the proximity state in response to the configuration of the light source driver, the controller is configured to initiate an operation of each of the light source driver and the photoacoustic detector.
3 . The photoacoustic measuring apparatus of claim 2 , further comprising a memory module having a plurality of memory areas,
wherein the controller is configured to:
store photoacoustic wave detection data of a current cycle in a first memory area among the plurality of memory areas;
verify validity of unverified photoacoustic wave detection data of a previous cycle stored in a second memory area different from the first memory area in the current cycle; and
determine to stop the operation of the light source based on a first event in which the photoacoustic wave detection data of the previous cycle is determined invalid.
4 . The photoacoustic measuring apparatus of claim 3 , wherein the validity of the unverified photoacoustic wave detection data is determined based on at least one of a peak magnitude, a peak-to-peak difference, a zero-crossing timing, a zero-crossing AUC (area under the curve), or an envelope shape as time domain features.
5 . The photoacoustic measuring apparatus of claim 3 , wherein the validity of the unverified photoacoustic wave detection data is determined based on at least one of a peak magnitude, a relative peak ratio, energy, or power of specific peak frequencies as frequency domain features.
6 . The photoacoustic measuring apparatus of claim 3 , wherein the validity of the unverified photoacoustic wave detection data is determined based on a relative variation of the photoacoustic wave detection data of the current cycle relative to the photoacoustic wave detection data in at least one previous cycle.
7 . The photoacoustic measuring apparatus of claim 3 , wherein after the respective operations of the light source driver and the photoacoustic detector have started with the proximity decision of the proximity sensor being changed from the non-proximity state to the proximity state,
the controller is configured to determine to stop the operation of the light source based on a combination of (i) a first event in which the photoacoustic wave detection data is determined to be invalid and (ii) a second event in which the proximity decision of the proximity sensor is changed from the proximity state to the non-proximity state.
8 . The photoacoustic measuring apparatus of claim 3 , wherein after determining to stop the operation of the light source, the controller is configured to control the light source driver to prevent the light source from further generating the laser light before a corresponding cycle is terminated.
9 . The photoacoustic measuring apparatus of claim 8 , wherein the controller is configured to set a time duration between an initial timing at which the stop of the operation of the light source is determined and a time point at which the oscillation of the laser light is actually stopped to be shorter than or equal to a safety-stop time duration.
10 . The photoacoustic measuring apparatus of claim 3 , wherein after determining to stop the operation of the light source, the controller is configured to control the light source driver to not proceed to a next cycle at an end of the current cycle.
11 . The photoacoustic measuring apparatus of claim 10 , wherein the controller is configured to set a sum of a length of the current cycle and a length of the next cycle not to exceed a safety-stop time duration.
12 . The photoacoustic measuring apparatus of claim 3 , wherein the first memory area and the second memory area are respectively allocated to different memory devices connected to a bus through different memory ports,
wherein one of the first and second memory areas is connected to a DMA channel to store photoacoustic wave detection data therein while the other thereof is connected to a MPU to verify the validity of the photoacoustic wave detection data.
13 . The photoacoustic measuring apparatus of claim 1 , further comprising: a proximity sensor for outputting a proximity decision of the light source to the measurement target as one of proximity state and non-proximity state; a light source driving unit configured to drive the light source according to a predetermined operation setting; and a memory module having at least two memory areas, wherein the controller is configured to: determine to start an operation of each of a light source driver and the photoacoustic detector according to the proximity decision of the proximity sensor; and determine to stop the operation of the light source based on a validity determination of the photoacoustic wave detection data of a previous cycle among the photoacoustic wave detection data detected for divided cycles.
14 . The photoacoustic measuring apparatus of claim 1 , further comprising:
a proximity sensor for outputting a proximity decision of the light source to the measurement target as one of proximity state and non-proximity state; and
a light source driver configured to drive the light source according to a predetermined operation setting,
wherein the controller is configured to:
determine to start an operation of each of the light source driver and the photoacoustic detector according to the proximity decision of the proximity sensor; and
determine to stop the operation of the light source based on a change in the proximity decision of the proximity sensor.