Multimodal wearable measurement systems and methods

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.