Non-invasive Wearable Brain Interface Systems Including a Headgear and a Plurality of Self-contained Photodetector Units

A non-invasive wearable brain interface system comprising:

• a headgear configured to be worn on a head of a user;
• a plurality of self-contained photodetector units configured to removably attach to the headgear, the photodetector units each comprising a plurality of photodetectors;
• wherein a photodetector included in the plurality of photodetectors comprises:
• a single photon avalanche diode (SPAD);
• and
• a capacitor configured to
• be charged, while the SPAD is in a disarmed state, with a bias voltage by a voltage source, and
• supply, when the SPAD is put in an armed state, the bias voltage to an output node of the SPAD such that a voltage across the SPAD is greater than a breakdown voltage of the SPAD.

A non-invasive wearable brain interface system comprising:

• a headgear configured to be worn on a head of a user, the headgear comprising a plurality of cutouts;
• a plurality of self-contained photodetector units configured to removably attach to the headgear and fit within the cutouts, the photodetector units each comprising:
• a light source configured to generate light, and
• a plurality of photodetectors configured to detect photons of the light after the photons reflect from a target within a brain of the user;
• and
• a master control unit coupled to each of the photodetector units and configured to control the photodetector units.