Fabrication, methods, apparatuses, and systems for ultra-compliant probes for neural and other tissues

A method of fabricating a top mold of a neural probe mold comprising the steps of:

• proving a master mold with a needle array shape with a depth equal to a target top mold thickness;
• applying a first molding material to the master mold to fill the depth of the needle array shape;
• curing the first molding material;
• separating the cured first molding material from the master mold;
• sandwiching the cured first molding material between two glass slides;
• applying force to the two glass slides to hold them together;
• pouring a top mold material to fill a gap between the glass slides and the cured first molding material;
• curing the top mold material between the glass slides to obtain the cured top mold with the target top mold thickness;
• and
• separating the cured top mold from the glass slides and the cured first molding material.

A method of spin coating fabrication of needle for a neural probe comprising the steps of:

• providing an assembled top-bottom mold with wires;
• dispensing a dissolvable material in a hydrogel form onto the assembled top-bottom mold with wires;
• centrifuging the dissolvable material to spin-cast the dissolvable material by evaporating the solvent to form a dried dissolvable polymer;
• and
• using a wiping device with intermittent applications of water to remove excess dissolvable material to obtain needle shape only in the assembled top-bottom mold with wires to form a final dissolvable needle with embedded wires.

A method to fabricate a neural probe needle comprises the steps of:

• applying a bottom insulator layer to a substrate;
• depositing a conducting material that forms an electrode and associated wiring;
• patterning of a first photoresist with an electrode pattern and an associated wiring pattern;
• selectively removing the conducting material to transfer the electrode pattern and the wire pattern from the photoresist;
• removing the first photoresist and cleaning of exposed surfaces for preparation of subsequent depositions of material;
• forming an upper insulator layer;
• depositing a hard mask layer on the upper insulator layer and the exposed surfaces;
• patterning of a second photoresist with a bottom mold pattern onto a portion of the hard mask layer;
• selectively removing other portions of the hard mask layer to transfer the bottom mold pattern from the second photoresist;
• removing the second photoresist and cleaning of exposed surfaces;
• selective vertical directionally removing of the substrate;
• selective isotropically removing of the substrate;
• selectively removing of the hard mask layer;
• placing a top mold patterned with the bottom mold pattern on top of a bottom mold to form an assembled mold;
• applying a polymer gel to the assembled mold;
• drying the polymer gel to form an encased electrode and wires;
• and
• demolding the encased electrode and wires.