Miniature Implantable Device enclosure having an optically transparent window bound to a metal housing with a micro-scale diffusion bond

An optical sensor, comprising:

• a) an open-ended container comprising a housing sidewall extending to an open perimeter edge;
• b) a lid secured to the open perimeter edge of the housing sidewall to form a device housing defining an enclosed space, wherein the housing sidewall is comprised of titanium and has at least one housing opening communicating with the enclosed space;
• c) a sapphire window comprising opposed planar window body fluid and device side surfaces, wherein a micro-scale diffusion bond having a diffusion bond thickness that is greater than 1 μm as measured along an x-axis aligned perpendicular to a planar contact interface between the sapphire window and the titanium washer connects the sapphire window body fluid side surface to a planar inner surface of the housing sidewall aligned with the at least one housing opening so that the sapphire window diffusion bonded to the housing sidewall hermetically closes the at least one housing opening, and wherein the diffusion bond thickness includes the combined depth of the diffusion bond extending from the planar contact interface along the x-axis into the sapphire window and the titanium washer, but the diffusion bond thickness does not include undisturbed portions of the sapphire window and the titanium washer;
• d) a printed circuit board (PCB) assembly housed inside the enclosed space of the device housing, the PCB assembly comprising a printed circuit board supporting at least an optical sensor, wherein the optical sensor is aligned with the sapphire window and the housing opening;
• and
• e) an electrical energy power source that is configured to power the PCB assembly including the optical sensor.

A diffusion bonded assembly, comprising:

• a) a titanium sidewall comprising opposed inner and outer sidewall surfaces, wherein at least one sidewall opening extends through the sidewall to the inner and outer sidewall surfaces;
• b) a titanium washer comprising opposed washer first and second side surfaces surrounding a washer opening, wherein at least the washer first side surface is planar;
• c) a sapphire window comprising opposed planar window first and second side surfaces, wherein a micro-scale diffusion bond having a diffusion bond thickness that is ≥4 μm as measured along an x-axis aligned perpendicular to a planar contact interface between the sapphire window and the titanium washer connects the sapphire window second side surface to the washer first side surface aligned with the washer opening, and wherein the diffusion bond thickness includes the combined depth of the diffusion bond extending from the planar contact interface along the x-axis into the sapphire window and the titanium washer, but the diffusion bond thickness does not include undisturbed portions of the sapphire window and the titanium washer;
• and
• d) a weld connecting the washer second side surface to the inner surface of the sidewall aligned with the at least one sidewall opening so that the sapphire window diffusion bonded to the titanium washer in turn connected to the housing sidewall hermetically closes the at least one sidewall opening.