Ceramic-to-metal joint for implantable pulse generators

A method of assembling an implantable pulse generator configured to deliver one or more electrical pulses to a target region within a body of a patient via an implantable neurostimulation lead, the method comprising:

• forming a ceramic portion comprising a first ceramic material, the ceramic portion defining a first inner volume;
• aligning the ceramic portion adjacent to a first side of an intermediate metal ring, wherein the intermediate metal ring comprises a different material than Grade 5 Titanium, and joining the ceramic portion to the first side of the intermediate metal ring by brazing or diffusion bonding, wherein a braze material of the brazing or a diffusion bond of the diffusion bonding is substantially free of nickel and forms a first hermetic seal between the ceramic portion and the intermediate metal ring;
• depositing at least a portion of a charging-coil assembly within the first inner volume, wherein the charging-coil assembly comprises a charging coil, and wherein the charging-coil assembly is configured to receive wireless power through the ceramic material from an external charger to charge a battery at least partially housed within a second inner volume defined by a case portion, wherein the case portion comprises a second ceramic material, wherein the charging coil extends at least partially into the second inner volume;
• and
• joining a second side of the intermediate metal ring to the case portion to form a second hermetic seal,
• wherein the intermediate metal ring defines one or more first alignment guides on the first side configured to physically align the intermediate metal ring with the ceramic portion and one or more second alignment guides on the second side configured to physically align the intermediate metal ring with the case portion during assembly of the implantable pulse generator.

An implantable neurostimulator device configured for delivering one or more electrical pulses to a target region within a body of a patient via an implantable neurostimulation lead comprising a plurality of neurostimulation electrodes electrically coupleable to the implantable neurostimulator device, the implantable neurostimulator device comprising:

• a ceramic portion comprising a first ceramic material and forming a first part of a housing of the implantable neurostimulator device, wherein the ceramic portion defines a first inner volume;
• a case portion comprising a second ceramic material, the case portion forming a second part of the housing of the implantable neurostimulator device, wherein the case portion defines a second inner volume;
• an intermediate metal ring comprising a different material than Grade 5 Titanium, the intermediate metal ring being positioned between the ceramic portion and the case portion and forming a third part of the housing of the implantable neurostimulator device, wherein the intermediate metal ring comprises a first side joined to the ceramic portion by a first braze material or a first diffusion bond, wherein the first braze material or the first diffusion bond is substantially free of nickel, wherein the intermediate metal ring comprises a second side joined to the case portion by a laser-weld joint or by a second braze material or a second diffusion bond, wherein the second braze material or the second diffusion bond is substantially free of nickel, and wherein the ceramic portion, the case portion, and the intermediate metal ring collectively define a third inner volume of the housing, and wherein the intermediate metal ring defines one or more first alignment guides with the first part of the housing configured to physically align the intermediate metal ring with the ceramic portion and one or more second alignment guides with the second part of the housing configured to physically align the intermediate metal ring with the case portion during assembly of the implantable pulse generator;
• a header portion configured to electrically couple to the implantable neurostimulation lead, wherein the header portion comprises a multi-pin feed-through assembly comprising a metallic base plate, wherein the metallic base plate of the multi-pin feed-through assembly is laser-welded, brazed or diffusion bonded to the case portion to provide a hermetic seal between the header portion and the case portion, wherein the multi-pin feed-through assembly electrically couples components of the header portion and the implantable neurostimulation lead to electronic circuitry at least partially positioned within the second inner volume;
• and
• electronic circuitry disposed within the third inner volume of the housing, wherein the electronic circuitry is configured to generate the one or more electrical pulses delivered to the target region within the body of the patient via the implantable neurostimulation lead, wherein the electronic circuitry comprises:
• a printed circuit board at least partially housed within the second inner volume, the printed circuit board having a rechargeable battery and a temperature sensor electrically coupled thereto, wherein the temperature sensor is configured to detect a temperature of the implantable neurostimulator device during a recharge cycle of the implantable neurostimulator device or while delivering the one or more electrical pulses;
• and
• a charging-coil assembly comprising a charging coil defining a central coil axis, wherein the charging-coil assembly is housed within the first inner volume so that the central coil axis is substantially parallel to a normal defined by a major plane of the implantable neurostimulator device, and wherein the charging-coil assembly is configured to receive wireless power through the ceramic material from an external charging device to charge the rechargeable battery;
• wherein the implantable neurostimulator device is hermetically sealed and defines a total volume of less than 10 cubic centimeters, and
• wherein the charging coil extends at least partially around a perimeter of the printed circuit board positioned within the second inner volume.