3D printing of nanomaterials and implanted prosthetic limbs.

Apr 02, 2016

Long-time readers of my site no doubt know of my fascination with the field of 3D printing and tracking the advances that are made almost weekly to this technology. From simple plastic tchotchkes to replacement parts to materials that few ever dreamed would be used, 3D fabbers are fast becoming an integral part of manufacturing at all levels of complexity. A few months ago researchers at Lawrence Livermore National Laboratory published the results for a revolutionary 3D printer called the Optomec Aerosol Jet 500, a fabber which uses a range of nanomaterials as its feedstock. To cut to the chase they've been using it to construct electronic components and integrated circuits at the molecular level, laying down conductive pathways in three dimensions, constructing semiconductor units material by material, and linking everything together into working circuitry in situ. Current semiconductor prototyping fabs are huge, on the order of thousands of square feet in size but the Optomec is just slightly over 250 square feet in size, well within the working space of your average science lab (and doesn't use any of the incredibly dangerous chemicals ordinarily involved in semiconductor manufacture). The new generation fabber prints at a resolution of 10 microns, which is about the size of a large grain of pollen or silt but far to small for the human eye to discern unaided. I don't know when this technology will leave the lab but you can bet that the semiconductor giants are going to be keeping a close eye indeed on them, if only because eliminating many of the chemicals they use would raise their bottom line significantly (by not needing to worry about licensing and disposal costs).

Several years ago, Dr. Max Ortiz Catalan of Chalmers Technological University in Sweden, who specializes in biomedical engineering began working on a prosthetic limb which is truly integrated with the human body. A titanium attachment point would be set directly into the bone of an amputee where osseointegration would take place as the body healed and fuse the implant permanently in place, while electrodes would be integrated with the remaining nerves and muscles of the patient's post-amputation limb. The electrodes would directly control the servomotors of the prosthesis, in effect integrating it with the patient's nervous system so that the limb could be controlled in the same fashion as an organic limb. In 2013.ev a patient referred to as Magnus (no last name given) received one of two such implanted prosthetic arms which he's used in his everyday life for the past three years as a heavy machinery operator. The prosthesis can be physically disconnected from Magnus' upper arm for maintenance and bathing, then reconnected for normal operation. There are a few subtle things implied by this advance: First, medical science seems to have licked the problem of having something inorganic protruding through the skin while not leaving the seam between organic and inorganic open to infection, which to date had been the biggest problem. Second, the problem of patching directly into nerves for long periods of time seems to have been solved. Prior to this, interfacing with living nerves was possible for varying periods of time but scarring, thickening of cell membranes, and inflammation would cause damage to the electrodes or cause them to lose contact with the nerve endings, effectively breaking the connection. Solving this second problem strongly implies that permanent interface with the peripheral nervous system is indeed possible and opens up an entire world of new medical techniques. Third, tactile sensors on the prosthetic arm that are patched into Magnus' nervous system give him direct tactile feedback, meaning that his prosthetic limb is capable of fine motor control - he's able to pick up an egg with his prosthetic arm without damaging or breaking it. That Magnus had this done roughly three years ago, and only now are we really hearing about it speaks volumes to how advanced this technology really is. It seems reasonable to state that we could be in the home stretch for (semi-)permanently integrated prosthetic limbs.