Many are familiar with brain machine interfaces abundantly popularized in the news media. These interfaces are particularly useful for immobilized people, for example patients with Amyotrophic Lateral Sclerosis or spinal injuries. They rely on the traditional electrode implant concept that shock neurons to produce action potentials. The procedures are very invasive since they require the surgical implantation and permanent insertion of electrodes near neurons, producing bleeding, scar and continuous stress in the surrounding nervous tissues. A solution to these problems is the generation of stand-alone autologous-induced-neurons that can be reimplanted without rejection in their initial donor and deliver action potentials remotely. Here, we propose a new concept of brain-machine interface that combines genetic engineering and nanotechnologies to generate neuron-machine hybrids that can synapse normally with other neurons. These neuron hybrids will contain gold nanoparticles acting as nano-antennas to trigger action potentials in response to external electromagnetic stimulation. In effect they could behave as implantable ‘bio-electrodes’ in brains or spinal cords. Beside constituting the base for new types of brain machine interfaces, nano devices present inside neurons offers untapped opportunities, for example in spinal cord injuries.
The image illustrates a microtubule, a cylinder-like subcellular structure abundant inside neurons. Here, gold nanorods (yellow), insulators and metal nanoparticles are randomly inserted inside a host microtubule. Some of these random arrangements may act like rectennas. Rectennas are a particular type of antennas which convert the terahertz oscillating electric field of an incoming near infrared light into DC currents. Such currents may induce action potentials in the host neuron through membrane depolarization, or supply energy to the neuron, depending on the rectenna location. Near Infrared wavelength can penetrate a few centimeters below the skull, therefore external and non-invasive devices such as laser diodes, located outside the head, could stimulate nano-rectennas hosted in these bioengineered neurons implanted deep inside the cortex. In effect, this would transform each nano-rectenna/neurons hybrid into a remotely activable electrode. An alternative solution is to introduce fully formed nano-rectennas inside neurons. Being autologous with their host, these neurons should interface normally within the host neural network via normal synapses. In spinal cord injuries where axonal tracts are interrupted by cysts and fibrotic tissues, the implantation of a small number of nano-rectennas-carrying neurons could produce significant improvement, due to the possibility to excite these neurons by an external light source remotely.