Microfabricated neurostimulation device
Described herein are microelectrode array devices, and methods of fabrication and use of the same, to provide highly localized and efficient electrical stimulation of a neurological target. The device includes multiple microelectrode elements arranged along an elongated probe shaft. The microelectrode elements are dimensioned and shaped so as to target individual neurons, groups of neurons, and neural tissue as may be located in an animal nervous system, such as deep within a human brain. Beneficially, the neurological probe can be used to facilitate location of the neurological target and remain implanted for long-term monitoring and/or stimulation.
1. An implantable neurological probe comprising:
a cylindrical member having a distal end, a proximal end, and an internal lumen;
a flexible planar substrate comprising:
a first insulative layer,
a microelectrode film,
an extension including a plurality of wire lead contacts,
a plurality of microelectrode elements disposed on an outer surface of the microelectrode film,
a plurality of conductive traces to selectively couple the plurality of microelectrode elements to the plurality of wire lead contacts, and
a plurality of wires to electrically couple the plurality of wire lead contacts to a proximal end of the probe;
wherein the microelectrode film of the flexible planar substrate is coupled to an outer surface of the cylindrical member with the extension of the flexible planar substrate extending in the internal lumen toward the proximal end of the cylindrical member, and
wherein the plurality of wire lead contacts are disposed within the internal lumen such that at least a portion of the extension of the flexible planar substrate is disposed in the internal lumen.
2. The implantable neurological probe of claim 1 , wherein the extension of the flexible planar substrate is wrapped along a most distal portion of the cylindrical member.
3. The implantable neurological probe of claim 1 , wherein the extension of the flexible planar substrate is wrapped radially into a most distal portion of the cylindrical member.
4. The implantable neurological probe of claim 1 , wherein an electronic component is electrically coupled between the plurality of microelectrode elements and the plurality of wire lead contacts.
5. The implantable neurological probe of claim 4 , wherein the electronic component comprises a router that is programmable to selectively couple the plurality of microelectrode elements to the plurality of wire lead contacts.
6. The implantable neurological probe of claim 1 , wherein the cylindrical member is configured for insertion into a human body using an accepted procedure for insertion of deep brain stimulation leads.
7. The implantable neurological probe of claim 1 , wherein the outside diameter of the cylindrical member is about 1.27 mm.
8. The implantable neurological probe of claim 1 , wherein at least one of the plurality of microelectrode elements is shaped substantially different from another microelectrode element of the plurality of microelectrode elements.
9. The implantable neurological probe of claim 1 , wherein at least one of the plurality of microelectrode elements is a stimulating electrode and at least one of the plurality of microelectrode elements is a detecting electrode; and/or optionally wherein the at least one stimulating electrode is shaped substantially different from the at least one detecting electrode; and/or optionally wherein the at least one of the stimulating electrode and the detecting electrode comprises a plurality of electrically conducting sub-elements; and/or optionally wherein the at least one of the stimulating electrode and the detecting electrode comprises a tetrode arrangement of electrically conducting sub-elements.
10. The implantable neurological probe of claim 1 , wherein the plurality of microelectrode elements are configured as a micro-electromechanical system (MEMS).
11. The implantable neurological probe of claim 1 , wherein each microelectrode element of the plurality of microelectrode elements is cylindrical.
12. The implantable neurological probe of claim 1 , wherein each microelectrode element of the plurality of microelectrode elements is rectangular.
13. The implantable neurological probe of claim 1 , wherein each microelectrode element of the plurality of microelectrode elements is rectangular with rounded corners.
14. The implantable neurological probe of claim 1 , further comprising at least one electronic circuit element coupled with the substrate; and/or optionally wherein the at least one electronic circuit element is selected from the group consisting of: a switch; a router; an amplifier; a controller; a microprocessor; memory; a multiplexer; a filter; an attenuator; a resistor; a capacitor; an inductor; a diode; a transistor; and combinations thereof.
15. The implantable neurological probe of claim 1 , wherein a height of at least one of the plurality of wire lead contacts is less than 1 mm.
16. The implantable neurological probe of claim 1 , wherein the cylindrical member is flexible; and/or optionally wherein the internal lumen is open at a proximal end; and/or optionally wherein at least one of the conductive traces extends along a substantial portion of the cylindrical member, without interfering with the open ended internal lumen.
17. The implantable neurological probe of claim 1 , wherein the plurality of wires are wrapped around a second cylindrical member disposed in the internal lumen of the cylindrical member.
18. A method for stimulating a neurological target comprising:
implanting the implantable neurological probe of claim 1 within a vicinity of a neurological target site; and
connecting at least one of the plurality of wire lead contacts to a neurological stimulation source supplying an electrical signal; and
energizing, by the supplied electrical signal, one or more of the microelectrode elements, wherein the one or more energized microelectrode elements produce an electric field adapted to stimulate the neurological target site.
19. The method of claim 18 , wherein implanting further comprises:
inserting a substantially rigid stylet into the internal lumen of the cylindrical member to provide temporary rigidity to the cylindrical member;
inserting the cylindrical member along a trajectory toward the neurological target site;
positioning a distal end of the neurological probe within the vicinity of the neurological target site;
removing the stylet; and
selectively stimulating the neurological target site using at least one of the plurality of microelectrode elements.
20. The method of claim 19 , wherein the act of positioning the distal end of the neurological probe comprises recording neurological activity detected by at least one of the plurality of microelectrode elements and repositioning the distal end of the neurological probe as required, until the recorded activity is indicative of the distal end of the elongated shaft being located sufficiently close to the neurological target site.
21. The method of claim 19 , wherein the act of selectively stimulating comprises applying a stimulation signal to at least one of the plurality of wire lead contacts; and/or optionally wherein the stimulation signal is obtained from an implanted pulse generator; and/or optionally further comprising selecting at least one of the plurality of microelectrode elements, the at least one selected microelectrode being energized by the supplied electrical signal.
22. An implantable neurological probe kit comprising:
the implantable neurological probe of claim 1 ; and
a stylet configured for removable insertion into the internal lumen of the cylindrical member, to keep the cylindrical member substantially rigid during insertion into biological tissue.