EP-4736935-A2 - DEVICE FOR INSERTION OF MICROFILAMENTS IN SOFT TISSUE

EP4736935A2EP 4736935 A2EP4736935 A2EP 4736935A2EP-4736935-A2

Abstract

The present invention relates to an implantable microfilament guiding structure comprising spatially arranged channels intended for the accommodation and movement of microfilaments such as electrically conductive microelectrodes. The channels of the microfilament guiding structure are spatially arranged such that the distances between at least some of said channels gradually increase in distal direction. The microfilament guiding structure comprising microfilaments forms part of a proto electrode also referred to as prior microfilament assembly. The invention also encompasses methods for manufacturing the microfilament guiding structure and proto microelectrode assemblies and further a method for implantation of microfilaments in soft tissue.

Inventors

SCHOUENBORG, JENS

Assignees

Neuronano AB

Dates

Publication Date: 20260506
Application Date: 20211210

Claims (18)

A proto microfilament assembly (7) for insertion of microfilaments within soft tissue such as nervous tissue, having a distal region and a proximal region comprising: - a microfilament guiding structure comprising channels (1, 101), - microfilaments, - an elongated hollow guiding member, - a pin; wherein microfilaments (6) are disposed in the channels (8) of the microfilament guiding structure (101), the channels (8) providing a continuous lumen through the microfilament guiding structure configured to allow accommodation, and axial movement of the microfilaments, the channels having a diameter and length of a size facilitating the precise guidance of the microfilaments within the channels, wherein the microfilament guiding structure is of materials which are transient or of materials essentially preserving the configuration over time; wherein at least in a distal section/part of the microfilament guiding structure the radial distances between at least some of the channels gradually increases in distal direction; wherein the microfilaments from the microfilament guiding structure (101) extend in proximal direction; wherein the microfilaments are attached to the pin (4); wherein the pin (4) is located proximally to the microfilament guiding structure (101) and is configured to be slidably disposed inside the elongated hollow guiding member (2); wherein the proto microfilament assembly is sufficiently stiff to be inserted into a targeted area of soft tissue; wherein the microfilament guiding structure (101) is essentially spatially fixated by the elongated hollow guiding member (103, 103a); wherein the microfilaments can be propelled outside of the channels in distal direction by moving the pin in distal direction without essentially moving the elongated hollow guiding member and the microfilament guiding structure.
The proto microfilament assembly according to claim 1, wherein the elongated hollow guiding member has an annular cross-section with a lateral opening along at least the distal section and that the microfilaments are removable attached to the pin.
The proto microfilament assembly of claim 1 or 2, wherein the rigidity of the microfilaments is enhanced by the addition of rigidity providing structural elements.
The proto microfilament assembly of any one of claims 1 to 3, wherein the microfilaments comprise a blunt distal bulge at the very distal end, the bulge preferably having a radial extension larger than the radial extension of the distal end of the microfilament.
The proto microfilament assembly according to claim any one of claims 1 to 4, wherein the microfilaments or a part of the microfilament or at least part of the microfilament adjacent and in direct contact with soft tissue, possess a level of internal tensions that prevents the microfilament to substantially deviate from the trajectory provided by the channels of the filament guiding structure during insertion into soft tissue, and having a flexibility sufficient for accommodating movement of soft tissue, such as neural tissue, without significantly affecting the soft tissue.
The proto filament assembly according to any one of claims 1 to 5, wherein the diameter of an individual microfilament is from about 5 µm up to about 120 µm, suitably from about 5 µm up to about 70 µm.
The proto microfilament assembly of claim 1 or 6, wherein the microfilaments are electrically conductive microelectrodes, the microelectrodes preferably comprising an electrode body, the body comprising noble metals such as gold, silver, platinum, iridium, but other biologically acceptable metals such as stainless steel, tantalum and gold plated copper, or the electrode body consists of or comprise an electrically conducting polymer, electrically conducting carbon, the metallic surface of the electrode body preferably modified by a layer of another metal or metal alloy or a layer comprising or consisting of an electrically conducting non-metallic material; or the body comprises a core of nonconductive polymer material coated with a metal.
The proto microfilament assembly of any one of claims 1 to 7, wherein the microfilaments are highly flexible and do not themselves possess sufficient rigidity to be implanted all the way to a target tissue without significantly bending away from their intended track lines.
The proto microfilament assembly of any one of claims 1 to 8, wherein the inner diameter of the channels are from about 105% up to about 200% of the diameter of the microfilaments, preferably from about 105% up to about 150%.
The proto microfilament assembly according to any one of claims 1 to 9, wherein the microfilament guiding structure comprises a distal part (101a) and a proximal part (101b), the distal part of the microfilament guiding structure disposed distally to the elongated hollow guiding member and the proximal part being disposed inside the elongated hollow guiding member.
The proto microfilament assembly according to any one of the preceding claims, wherein the microfilament guiding structure has a radial extension (diameter) from about 250 µm up to about 2 mm, preferably from about 300 µm up to about 2 mm, and preferably an axial extension from about 0.5 mm up to about 25 mm.
The proto microfilament assembly according to any one of the preceding claims, wherein the diameter of the channels of the microfilament guiding structure is from about 5 µm up to about 250 µm, suitably from about 10 to about 120 µm.
The proto microfilament assembly according to any one of the preceding claims, wherein the microfilament guiding structure gradually disintegrates and/or dissolves when contacted by tissue fluids, and that the microfilaments are removably attached to the pin.
The proto microfilament assembly according to claim 1, wherein the transient attachment of the microfilament guiding structure (1, 101) to the hollow guiding member is established by threads comprised in the microfilament guiding structure and attached at a proximal region to the elongated hollow guiding member.
The proto microfilament assembly according to claim 13 or 14, further comprising a hollow supporting guide (102) between the microfilament guiding structure (101) and the pin (4) and disposed within the elongated hollow guiding member, the hollow supporting guide comprising a central conduit (102a) accommodating the microfilaments, the pin being disposed inside the elongated hollow guiding member and proximal with respect to the hollow supporting guide to provide a gap (501a) between the hollow supporting guide and the pin, the structural rigidity of the microfilaments preferably enhanced along a section between the hollow supporting guide (102) and the distal end of the pin such as to prohibiting or essentially prohibiting individual microfilaments to bend or buckle when the pin is moved in distal direction.
The proto microfilament assembly according to claim 1, further comprising a pin guiding structure (3), wherein the pin is transiently attached to the pin guiding structure, and the pin guiding structure configured to be slidably disposed inside the elongated hollow guiding member.
The proto microfilament assembly according to any one of the preceding claims, wherein the pin comprises a recess laterally along at least a section of the pin, preferably from the distal end to a location between the distal and proximal end, optionally along the entire length of the pin, the recess configured for the accommodation of the microfilaments, the microfilament preferably bundled with a glue.
The proto microfilament assembly according to claim 17, wherein the microfilaments are not disposed inside the entire axial length of the pin, the microfilaments deviating laterally from the pin and the elongated hollow guiding member.

Description

FIELD OF INVENTION The present invention relates to an implantable microfilament guiding structure comprising spatially arranged channels intended for the accommodation and movement of microfilaments such as electrically conductive microelectrodes. The microfilament guiding structure comprises materials which disintegrates and/or dissolves when subjected to mammalian tissue fluids. The channels of the microfilament guiding structure are spatially arranged such that the distances between the majority of said channels gradually increase in distal direction. The microfilament guiding structure comprising microfilaments forms part of a proto electrode also referred to as prior microfilament assembly. The invention also encompasses methods for manufacturing the microfilament guiding structure and proto microelectrode assemblies and further a method for implantation of microfilaments in soft tissue BACKGROUND OF THE INVENTION Electrodes for implantation into the nervous system are widely used for recording neuronal electrical and chemo-electrical signals and may also be used for electrical stimulation of the nervous system at specific regions thereby ameliorating for example motor symptoms in Parkinson's disease or chronic pain. The functionality of implantable electrodes depends on the injury caused by the electrodes on insertion, the severity of the tissue responses triggered by the implant and the extent of the loss of neurons nearby the implanted electrode. The tissue responses comprise glial reactions (e.g. such as activation of microglia and proliferation of astrocytes) that after a while may encapsulate the implant, thereby isolating the electrode(s) from the rest of the brain. As a consequence, the ability of the electrode(s) to record neuron signals often deteriorate with time. While size of the electrodes will impact on the initial injuries caused by the insertion, one important trigger of the glial reactions is microforces between implanted electrode and nearby tissue occurring when electrodes are unable to follow movements of the tissue. Examples of movements that may cause the nervous tissue to move with respect to the implanted electrode are breathing movements, pulsations in blood pressure or body movements such as rotation of the head. To reduce the severity of the tissue reactions, the electrode needs to be as mechanically compliant with the target soft tissue as possible to be able to move with pulsative and other movements in the tissue thereby reducing the tearing forces between implanted electrode and tissue. For this reason, highly flexible microelectrodes (here defined as electrodes with a diameter less than about 100 µm) have been developed. To precisely implant highly flexible microelectrodes without substantial deviation from intended track lines, structural support during insertion is necessary. Several methods providing structural support during insertion to deep structures are known by the art such as transiently attaching the microelectrodes to a rigid support rod with a dissolvable glue or by embedding the microelectrodes in a hard but dissolvable material. WO 2017/095288 discloses a proto microelectrode comprising individual microelectrodes and a biocompatible solid support material. The solid support material sufficiently stabilizes the proto microelectrode to allow implantation into soft tissue. According to an embodiment the microelectrodes can be disposed to fan out in distal direction. The individual microelectrodes are firmly embedded into the solid support material. WO 2017/095288 fails to disclose a solid support material providing a continuous lumen trough the solid support material. The microelectrodes are further firmly embedded into the support material which prohibits the microelectrodes to move with respect to the solid support. US 2019/0298993 relates to a neural probe comprising an electrode assembly with simulation and recording electrodes positioned on a very specific carrier similar to a carpenter's tape spring. The tape spring-type carrier provides the electrode assembly with stiffness along a line of trajectory once deployed into body tissue, but with a degree of flexibility that allows the electrode assembly to move with the tissue. Each thin-film neural probe electrode assembly comprises multiple metal traces and sites. These electrode assemblies cannot be precisely introduced into tissue without a carrier. As further elaborated, the probe is not rigid but has a degree of stiffness provided by the tape spring-type carrier (inside the probe) that maintains a desired trajectory into the body but will subsequently allow the probe to flex and move unison with the movement of the body tissue. Further, the probe contains a guide tube which allows for the deployment of the carrier in a three-dimensional arrangement. As disclosed the guide tube is made of a rigid material that can be inserted into tissue without buckling and can maintain a generally straight trajecto