Photoacoustic sensor with light-steering system
Some disclosed examples involve controlling a light-steering system to direct light emitted by at least a first light source of a light source system to a first plurality of areas of a target object, wherein controlling the light-steering system involves controlling one or more adjustable micromirrors, one or more adjustable lenses, one or more adjustable diffraction gratings, or combinations thereof. Some examples involve receiving ultrasonic receiver signals from an ultrasonic receiver system corresponding to photoacoustic responses of the target object to light provided the light source system to each area of the first plurality of areas and determining a selected area of the target object from which additional ultrasonic receiver signals will be obtained, wherein determining the selected area involves detecting a blood vessel within the target object. Some examples involve controlling the light source system to obtain additional ultrasonic receiver signals from the selected area.
1 . An apparatus, comprising:
a light source system configured for providing light to a target object on an outer surface of the apparatus, the light source system including a light-steering system comprising at least a first light-steering device including one or more moveable components, the first light-steering device being configured to direct light emitted by at least a first light source of the light source system to a first plurality of areas of the target object, the first plurality of areas corresponding to a first plurality of positions of the one or more moveable components of the first light-steering device;
an ultrasonic receiver system configured to receive ultrasonic waves generated by the target object responsive to the light from the light source system and to generate ultrasonic receiver signals based, at least in part, on the ultrasonic waves generated by the target object; and
a control system including one or more general purpose single- or multi-chip processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or combinations thereof, the control system being configured to:
receive the ultrasonic receiver signals from the ultrasonic receiver system, the ultrasonic receiver signals corresponding to each area of the first plurality of areas of the target object;
determine a selected area of the target object corresponding to an area from which additional ultrasonic receiver signals will be obtained, wherein determining the selected area involves detecting a blood vessel within the target object and estimating a signal-to-noise ratio (SNR) of ultrasonic receiver signals corresponding to at least a portion of the blood vessel; and
control the light source system to obtain the additional ultrasonic receiver signals from the selected area by positioning the one or more moveable components of the first light-steering device by selecting an area corresponding to a highest estimated SNR of the ultrasonic receiver signals corresponding to at least the portion of the blood vessel.
2 . The apparatus of claim 1 , wherein the light-steering system includes one or more adjustable micromirrors, one or more adjustable lenses, one or more adjustable diffraction gratings, or combinations thereof.
3 . The apparatus of claim 1 , wherein determining the selected area involves selecting an area corresponding to a greatest estimated distance between a first blood vessel wall and a second blood vessel wall of the blood vessel.
4 . The apparatus of claim 1 , wherein the light-steering system includes a second light-steering device configured to direct light emitted by a second light source of the light source system to a second plurality of areas of the target object.
5 . The apparatus of claim 1 , wherein the first light-steering device is configured to direct light emitted by a second light source of the light source system to a second plurality of areas of the target object.
6 . The apparatus of claim 1 , wherein the light source system includes a plurality of light guides.
7 . The apparatus of claim 6 , wherein the light-steering system is configured to direct light emitted by at least the first light source to each light guide of the plurality of light guides.
8 . The apparatus of claim 6 , wherein the ultrasonic receiver system includes a plurality of receiver portions, each receiver portion corresponding to one light guide of the plurality of light guides.
9 . The apparatus of claim 6 , each light guide of the plurality of light guides is configured to direct a first portion of received light along an axis of the light guide and to direct a second portion of the received light towards the target object.
10 . The apparatus of claim 1 , wherein the ultrasonic receiver system includes transparent material and wherein the light source system is configured for providing light through the transparent material to the target object.
11 . The apparatus of claim 1 , wherein the control system is further configured to:
estimate one or more blood vessel features based, at least in part, on the additional ultrasonic receiver signals; and
estimate blood pressure based, at least in part, on the one or more blood vessel features.
12 . The apparatus of claim 11 , wherein the one or more blood vessel features include blood vessel diameter, blood vessel distention, volumetric flow, pulse wave velocity, blood vessel wall thickness, or combinations thereof.
13 . The apparatus of claim 1 , further comprising an inertial sensor system including one or more motion detectors, wherein the control system is further configured to:
receive inertial sensor data from the inertial sensor system;
determine whether the inertial sensor data indicates apparatus motion that exceeds a threshold; and
control the light-steering system according to whether the apparatus motion exceeds the threshold.
14 . The apparatus of claim 13 , wherein the control system is further configured to control the light-steering system to compensate for the apparatus motion.
15 . The apparatus of claim 13 , wherein the one or more motion detectors include one or more accelerometers.
16 . The apparatus of claim 1 , wherein the ultrasonic receiver system includes an array of ultrasonic receiver elements and wherein the control system is configured to receive ultrasonic receiver signals from each of a plurality of ultrasonic receiver elements in the array.
17 . The apparatus of claim 16 , wherein the array of ultrasonic receiver elements comprises a two-dimensional array of ultrasonic receiver elements.
18 . The apparatus of claim 16 , wherein the array of ultrasonic receiver elements comprises an array of electrodes arranged on a piezoelectric layer.
19 . The apparatus of claim 18 , wherein the piezoelectric layer comprises lead zirconate titanate (PZT) or a piezoelectric composite.
20 . The apparatus of claim 16 , wherein the control system is configured to apply a receiver-side beamforming process to the ultrasonic receiver signals, to produce a beamformed ultrasonic receiver image.
21 . The apparatus of claim 20 , wherein the receiver-side beamforming process comprises a delay-and-sum beamforming process.
22 . The apparatus of claim 1 , wherein the apparatus is configured to be worn by, or attached to, a person.
23 . An apparatus, comprising:
a light source system configured for providing light to a target object on an outer surface of the apparatus, the light source system including a light-steering system comprising at least a first light-steering device including one or more moveable components, the first light-steering device being configured to direct light emitted by at least a first light source of the light source system to a first plurality of areas of the target object, the first plurality of areas corresponding to a first plurality of positions of the one or more moveable components of the first light-steering device;
an ultrasonic receiver system configured to receive ultrasonic waves generated by the target object responsive to the light from the light source system and to generate ultrasonic receiver signals based, at least in part, on the ultrasonic waves generated by the target object; and
a control system including one or more general purpose single- or multi-chip processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or combinations thereof, the control system being configured for:
receiving the ultrasonic receiver signals from the ultrasonic receiver system, the ultrasonic receiver signals corresponding to each area of the first plurality of areas of the target object;
determining a selected area of the target object corresponding to an area from which additional ultrasonic receiver signals will be obtained, wherein determining the selected area involves detecting a blood vessel within the target object and selecting an area corresponding to a greatest estimated distance between a first blood vessel wall and a second blood vessel wall of the blood vessel; and
controlling the light source system to obtain the additional ultrasonic receiver signals from the selected area by positioning the one or more moveable components of the first light-steering device to direct light to the area corresponding to the greatest estimated distance between the first blood vessel wall and the second blood vessel wall.
24 . The apparatus of claim 23 , wherein the light-steering system includes one or more adjustable micromirrors, one or more adjustable lenses, one or more adjustable diffraction gratings, or combinations thereof.