Implantable electrical device comprising a substrate, encapsulation layer and adhesion layer
Implantable devices require protection to protect a human or animal body from implant contamination and to protect implant electrical connections and electronics from corrosion. Although PDMS can be substantially biocompatible, it still has a relatively high permeability to moisture which can lead to degradation of the implant electronics. An implantable electric device is provided comprising: a flexible substrate having one or more electrical conductors and a first surface comprising a Liquid-Crystal Polymer (LCP); a first biocompatible encapsulation layer; a first adhesion layer disposed between the first surface and the first encapsulation layer; wherein: the first adhesion layer comprises a ceramic material; the first encapsulation layer comprises a silicone rubber such as a PDMS, and the first adhesion layer and the first encapsulation layer are configured and arranged to conform to the first surface and to resist the ingress of fluids into at least a portion of the first surface. By providing a bilayer having an encapsulant comprising a silicone rubber and a conformal adhesion layer comprising ceramic materials, the adhesion layer appears to show significantly higher stability in ionic media, thereby providing relatively longer protection in case of any delamination or water permeation through the encapsulant.
1 . An implantable electrical device comprising:
a flexible substrate having a first surface and one or more electrical conductors;
a first biocompatible encapsulation layer;
a first adhesion layer, disposed between the first surface and the first encapsulation layer; and
one or more interconnect layers,
wherein:
the first surface comprises a Liquid-Crystal Polymer (LCP);
the first adhesion layer is configured and arranged to conform to the first surface;
the first encapsulation layer comprises a silicone rubber, and
the first adhesion layer and the first encapsulation layer are configured and arranged to resist the ingress of fluids from a human or animal body into at least a portion of the first surface, and
the one or more electrical conductors are comprised in the one or more interconnect layers.
2 . An implantable electrical device comprising:
a flexible substrate having a first surface and one or more electrical conductors;
a first biocompatible encapsulation layer;
a first adhesion layer, disposed between the first surface and the first encapsulation layer;
wherein;
the first surface comprises a Liquid-Crystal Polymer (LCP);
the first adhesion layer is configured and arranged to conform to the first surface;
the first encapsulation layer comprises a silicone rubber, and
the first adhesion layer and the first encapsulation layer are configured and arranged to resist the ingress of fluids from a human or animal body into at least a portion of the first surface,
wherein the substrate further comprises a second surface, the electrical device further comprising:
a second biocompatible encapsulation layer that is physically separate from, and disconnected from, the first biocompatible encapsulation layer; and
a second adhesion layer, disposed between the second surface and the second encapsulation layer;
wherein:
the second surface comprises a Liquid-Crystal Polymer (LCP);
the second adhesion layer is configured and arranged to conform to the second surface;
the second encapsulation layer comprises a silicone rubber, and
the second adhesion layer and the second encapsulation layer are configured and arranged to resist the ingress of fluids from a human or animal body into at least a portion of the second surface.
3 . The implantable electrical device according to claim 1 , wherein the silicone rubber comprised in the first encapsulation layer is a polydimethylsiloxane (PDMS) rubber.
4 . The implantable electrical device according to claim 1 , wherein the first adhesion layer has an average thickness in the range of 50 nm to 100 nm.
5 . The implantable electrical device according to claim 1 , wherein the first adhesion layer is deposited using an Atomic Layer Deposition (ALD) process.
6 . The implantable electrical device according to claim 1 , wherein the first surface comprises a substance selected from the group comprising: a polyimide, Parylene-C, SU-8, a polyurethane, or any combination thereof.
7 . An implantable electrical device comprising:
a flexible substrate having a first surface and one or more electrical conductors;
a first biocompatible encapsulation layer; and
a first adhesion layer, disposed between the first surface and the first encapsulation layer;
wherein:
the first surface comprises a Liquid-Crystal Polymer (LCP);
the first adhesion layer is configured and arranged to conform to the first surface;
the first encapsulation layer comprises a silicone rubber,
the first adhesion layer and the first encapsulation layer are configured and arranged to resist the ingress of fluids from a human or animal body into at least a portion of the first surface, and
the first adhesion layer comprises a ceramic material selected from the group comprising: HfO 2 , Al 2 O 3 , Ta 2 O 3 , SiC, Si 3 N 4 , TiO 2 , and any combination thereof.
8 . An implantable electrical device comprising:
a flexible substrate having a first surface and one or more electrical conductors;
a first biocompatible encapsulation layer; and
a first adhesion layer, disposed between the first surface and the first encapsulation layer;
wherein:
the first surface comprises a Liquid-Crystal Polymer (LCP);
the first adhesion layer is configured and arranged to conform to the first surface;
the first encapsulation layer comprises a silicone rubber,
the first adhesion layer and the first encapsulation layer are configured and arranged to resist the ingress of fluids from a human or animal body into at least a portion of the first surface, and
the first adhesion layer comprises at least one layer comprising HfO 2 , adjacent to at least one further layer comprising Al 2 O 3 .
9 . An implantable electrical device comprising:
a flexible substrate having a first surface and one or more electrical conductors;
a first biocompatible encapsulation layer; and
a first adhesion layer, disposed between the first surface and the first encapsulation layer;
wherein:
the first surface comprises a Liquid-Crystal Polymer (LCP);
the first adhesion layer is configured and arranged to conform to the first surface;
the first encapsulation layer comprises a silicone rubber,
the first adhesion layer and the first encapsulation layer are configured and arranged to resist the ingress of fluids from a human or animal body into at least a portion of the first surface, and
the first adhesion layer comprises at least one layer comprising Ta 2 O 3 , adjacent to at least one further layer comprising Al 2 O 3 .
10 . The implantable electrical device according to claim 1 , wherein the first adhesion layer is substantially biocompatible.
11 . The implantable electrical device according to claim 1 , wherein:
the substrate has a Young's modulus in the range of 2500 to 3600 MPa.
12 . The implantable electrical device according to claim 1 , wherein the substrate has a maximum thickness of 1 millimeter or less.
13 . The implantable electrical device according to claim 1 , wherein the first encapsulation layer has a tensile strength in the range of 6 to 8 MPa.
14 . The implantable electrical device according to claim 1 , wherein the implantable electrical device is comprised in an implantable medical device.
15 . The implantable electrical device according to claim 14 , wherein the implantable medical device is configured and arranged to provide a degree of sensing, stimulation, data processing, detection or measurement, data storage, oscillation, logic performance, stimulation pulses generation, or any combination thereof.
16 . The implantable electrical device according to claim 14 , wherein the implantable medical device further comprises:
one or more stimulation electrodes, configured and arranged to transmit energy to human or animal tissue when electrical energy is applied to the one or more electrical conductors.
17 . The implantable electrical device according to claim 16 , wherein the one or more stimulation electrodes are located along a conformable portion of the substrate.
18 . The implantable medical device according to claim 14 , configured for stimulating: one or more nerves, one or more muscles, one or more organs, spinal cord tissue, brain tissue, one or more cortical surface regions, one or more sulci, and any combination thereof.
19 . The implantable medical device according to claim 14 , configured for treatment of: headaches, chronic headaches, primary headaches, incontinence, occipital neuralgia, sleep apnea, hypertension, gastro-esophageal reflux disease, an inflammatory disease, limb pain, leg pain, back pain, lower back pain, phantom pain, chronic pain, epilepsy, an overactive bladder, poststroke pain, obesity, an autoimmune disorder, rheumatoid arthritis, inflammatory bowel disease, Crohn's disease, and any combination thereof.
20 . The implantable electrical device according to claim 1 , wherein the one or more electrical conductors are completely embedded within the flexible substrate.
21 . The implantable electrical device according to claim 1 , wherein, in a cross-section of the implantable electrical device, an extent of the first adhesion layer is equal to, or larger than, an extent of the first encapsulation layer.
22 . The implantable electrical device according to claim 2 , wherein the second adhesion layer comprises a ceramic material.
23 . An implantable electrical device comprising:
a flexible substrate having a first surface and one or more electrical conductors;
a first biocompatible encapsulation layer; and
a first adhesion layer, disposed between the first surface and the first encapsulation layer;
wherein:
the first surface comprises a Liquid-Crystal Polymer (LCP);
the first adhesion layer is configured and arranged to conform to the first surface;
the first encapsulation layer comprises a silicone rubber,
the first adhesion layer and the first encapsulation layer are configured and arranged to resist the ingress of fluids from a human or animal body into at least a portion of the first surface, and
in a cross-section of the implantable electrical device, (i) an extent of the first adhesion layer is less than an extent of the first surface, and (ii) an extent of the first encapsulation layer is less than the extent of the first surface.