Thin-film high-density sensing array, sub-scalp implantation tool and implant method

A method comprising:

• positioning an implant device to collect neural recordings from a person, wherein the implant device includes:
• a set of branch portions, wherein, for each branch portion of the set of branch portions:
• a first end of the branch portion is connected to a central section;
• the branch portion includes a subset of a set of electrodes, wherein each electrode in the subset is disposed on a bottom surface of the branch portion, wherein the subset of the set of electrodes includes three or more electrodes;
• the branch portion includes multiple vias that extend from the bottom surface of the branch portion to a top surface of the branch portion;
• and
• at least one electrical trace is disposed on the top surface of the branch portion, wherein the multiple vias electrically connect each of the subset of the set of electrodes to the at least one electrical trace;
• and
• separation spaces configured to maintain separations between adjacent branch portions of the set of branch portions along a length of the adjacent branch portions, wherein the separation spaces increase a distance between the subset of the set of electrodes disposed on the adjacent branch portions along the length of the adjacent branch portions from the first end of each adjacent branch portion to a second end of each adjacent branch portion disposed distally from the first end, two adjacent branch portions of the adjacent branch portions are separated by a groove, and the groove is a part of a separation space among the separation spaces, the separation space being between the two adjacent branch portions;
• activating the implant device so as to trigger collecting voltage signals at the set of electrodes and outputting neural-recording signals that correspond to the voltage signals;
• and
• accessing the neural-recording signals at an electronic device.