Implantable all diamond microelectrode and fabrication method

An electrode comprising:

• at least one individual electrode comprising:
• a contact pad comprising boron-doped polycrystalline diamond (BDD);
• a fiber core comprising BDD extending longitudinally from the contact pad from a proximal end that is in direct contact with the contact pad to an opposing distal end;
• and
• a polycrystalline diamond (PCD) cladding that coats and hermetically seals the entire individual electrode except for at least a first portion of the contact pad and a single second portion at the distal end of the fiber core, the single second portion being pristine BDD,
• wherein
• the distal end of the fiber core having the PCD cladding is configured to be inserted between neurons in a brain or within a single neuron in a brain,
• the fiber core and the PCD cladding collectively define a longitudinal shank,
• BDD of the first portion is exposed at the distal end of the longitudinal shank, is pristine BDD, and defines a sensing region,
• BDD of the single second portion is exposed at an outermost surface of the contact pad and defines an electrode lead region.

A method for fabricating an electrode, the method comprising:

• depositing a first layer of polycrystalline diamond (PCD) onto a substrate;
• depositing a layer of boron-doped polycrystalline diamond (BDD) on the first layer of PCD;
• forming the first layer of PCD and the layer of BDD into a pattern, the pattern comprising a first section defining a contact pad and a second section extending longitudinally from the first section from a proximal end to an opposing distal end that defines a fiber core;
• depositing a second layer of PCD over the entire layer of BDD, wherein the second layer of PCD contacts the first layer of PCD to coat and hermetically seal a first portion of the contact pad and a second portion of the fiber core, wherein a third portion of the contact pad and a fourth portion of the fiber core are not coated and hermetically sealed by the PCD, to form the electrode;
• and
• removing the electrode from the substrate, wherein
• BDD of the fourth portion is exposed at the distal end of a longitudinal shank is pristine BDD, and defines a sensing region of the electrode,
• BDD of the third portion is exposed at an outermost surface of the contact pad and defines an electrode lead region, and
• the fiber core and the PCD layer collectively define the longitudinal shank.