Multimodal wearable measurement systems and methods

1. A multimodal measurement system comprising:

a wearable assembly configured to be worn by a user and comprising:

a plurality of light sources each configured to emit light directed at a target within the user,

a plurality of detectors configured to detect arrival times for photons of the light after the light is scattered by the target,

a plurality of electrodes configured to be external to the user and detect electrical activity of the target,

a first slot surrounded by a first wall,

a second slot surrounded by a second wall,

a third slot surrounded by a third wall,

a first module configured to be removably inserted into the first slot, the first module comprising a first light source included in the plurality of light sources and a first set of detectors included in the plurality of detectors,

a second module configured to be removably inserted into the second slot, the second module physically distinct from the first module and comprising a second light source included in the plurality of light sources and a second set of detectors included in the plurality of detectors, and

a third module configured to be removably inserted into the third slot, the third module physically distinct from the first and second modules and comprising a third light source included in the plurality of light sources and a third set of detectors included in the plurality of detectors,

wherein the first module comprises:

a housing,

a printed circuit board (PCB) housed within the housing, and

a light guide assembly that implements the first light source, the light guide assembly comprising:

a lower light guide portion housed within the housing and having a proximal end attached to the PCB,

a conductive spring member housed within the housing and comprising a coil positioned around an external surface of the lower light guide portion, and

a conductive upper light guide portion connected to the lower light guide portion and configured to protrude from an upper surface of the housing and be in contact with a surface of a body of the user, the conductive upper light guide portion conductively coupled to circuitry on the PCB by way of the conductive spring member;

wherein the conductive upper light guide portion functions as an electrode included in the plurality of electrodes.

2. The multimodal measurement of claim 1 , wherein the first and second sets of detectors each include at least two detectors.

3. The multimodal measurement system of claim 1 , wherein:

the first and second light sources are both configured to emit light having a first wavelength;

the first module further comprises a fourth light source configured to emit light having a second wavelength different than the first wavelength; and

the second module further comprises a fifth light source configured to emit light having the second wavelength.

4. The multimodal measurement system of claim 1 , wherein the plurality of electrodes further comprises an electrode on a surface of the first module and an electrode on a surface of the second module.

5. The multimodal measurement system of claim 1 , wherein the conductive spring member is further configured to bias a distal end of the conductive upper light guide portion towards the surface of the body of the user.

6. The multimodal measurement system of claim 1 , wherein the plurality of electrodes are conductively coupled to one another to create a single channel.

7. The multimodal measurement system of claim 1 , wherein at least one electrode of the plurality of electrodes is conductively isolated from a remaining number of electrodes of the plurality of electrodes to create at least two channels.

8. The multimodal measurement system of claim 1 , wherein the electrical activity comprises electroencephalogram (EEG) activity.

9. The multimodal measurement system of claim 1 , further comprising a processing unit configured to generate optical measurement data based on the arrival times detected by the plurality of detectors and electrical measurement data based on the electrical activity detected by the plurality of electrodes.

10. The multimodal measurement system of claim 9 , wherein the optical measurement data comprises time-domain functional near infrared spectroscopy (fNIRS) data and the electrical measurement data comprises electroencephalogram (EEG) data.

11. The multimodal measurement system of claim 9 , wherein the processing unit is further configured to process the optical measurement data and the electrical measurement data in accordance with a data fusion heuristic to generate an estimate of cortical source activity.

12. The multimodal measurement system of claim 11 , wherein the generating of the estimate of the cortical source activity is performed in real-time while the plurality of detectors are detecting the arrival times and the plurality of electrodes are detecting the electrical activity.

13. The multimodal measurement system of claim 9 , wherein the processing unit is included in the wearable assembly.

14. The multimodal measurement system of claim 9 , wherein the processing unit is not included in the wearable assembly.

15. The multimodal measurement system of claim 1 , wherein each detector in the plurality of detectors comprises:

a photodetector configured to generate a photodetector output pulse in response to detecting a photon of the light; and

a time-to-digital converter configured to record a timestamp symbol in response to an occurrence of the photodetector output pulse, the timestamp symbol representative of an arrival time for the photon.

16. The multimodal measurement system of claim 1 , wherein the target is a brain of the user.

17. The multimodal measurement system of claim 1 , wherein the plurality of electrodes are configured to be in contact with the surface of the body of the user while the wearable assembly is worn by the user.

18. The multimodal measurement system of claim 1 , wherein the wearable assembly comprises headgear configured to be worn on a head of the user.