Progress in materials science, and in the areas in which that field overlaps with biotechnology, are enabling many different lines of artificial organ development. The resulting machinery will be competitive with tissue engineering in the decades to come: everything from artificial blood through to artificial hearts and artificial kidneys are on the agenda - even artificial brain sections are under development.

Work on replacement electromechanical and bioartificial solutions for other organs are in earlier stages, and these include artificial lungs. Here, the first necessary step towards enabling lung devices as an implantable option is to make them small enough to fit into the chest cavity. Artificial lungs remain large devices in the popular imagination, but in fact have been shrinking just as rapidly as other medical technologies, as noted in a recent popular science article:

Scientists at Case Western Reserve University in Cleveland have designed an artificial lung that uses air instead of pure oxygen as a ventilating gas - an advance that could turn accompanying oxygen cylinders into relics of the past. What's more, the device for use in humans could come in at just 6x6x4 inches, which is roughly the volume of the real human lung, meaning it could conceivably pave the way for implantable artificial lungs. The team first built a miniature-feature mold, layered a liquid silicone rubber over it that hardened into artificial capillaries and alveoli, and then separated the air and blood channels with a gas diffusion membrane. By building a small unit, they were able to maximize the surface-area-to-volume ratio and shrink the distance for gas diffusion to improve efficiency.

This is a prototype technology, tested on blood but yet to be trialed over the long haul in animals. Yet it remains a good indicator of what lies ahead as researchers ever more effectively mimic or integrate biological functions in artificial devices. The mid-term future will feature a competitive race between tissue engineering and prosthetics technology, but in the long term the distinction between biological and non-biological replacement parts will begin to blur. Nanotechnology will lead to artificial cells, artificial immune systems, swarms of tiny machines to replace blood cells, and a range of other foreseeable machinery far better at their jobs than our evolved organs. It's a future worth trying to hang around for, as it will certainly include rejuvenation of one form or another: if you can make it another fifty years, there is a fair chance that you'll have the opportunity to live for centuries - or longer.