Newscientist follow up to previous nextbigfuture article on neurophotonics
Imagine a bionic arm that plugs directly into the nervous system, so that the brain can control its motion, and the owner can feel pressure and heat through their robotic hand. This prospect has come a step closer with the development of photonic sensors that could improve connections between nerves and prosthetic limbs.
Existing neural interfaces are electronic, using metal components that may be rejected by the body. Now Marc Christensen at Southern Methodist University in Dallas, Texas, and colleagues are building sensors to pick up nerve signals using light instead. They employ optical fibres and polymers that are less likely than metal to trigger an immune response, and which will not corrode.
The sensors are currently in the prototype stage and too big to put in the body, but smaller versions should work in biological tissue, according to the team.
The researchers plan to demonstrate a working prototype on a cat or dog within the next two years. Before then, the sensor will need to be shrunk from hundreds of micrometres to 50 micrometres. The project has $5.6 million of funding from the US military's Defense Advanced Research Projects Agency (DARPA).
Christensen says one day the sensors and optical fibre could acts as "jumper cord" to restore movement and sensation to patients with spinal cord damage, by routing nerves in the brain to the legs, circumventing the damaged area.
Ravi Bellamkonda, a bioengineer at the Georgia Institute of Technology in Atlanta, is impressed. "I would be excited to have them succeed – it is important to develop robust interfaces to the nervous system," he says.
But Marc Gasson of the University of Reading, UK, says the sensors may still be rejected by the body. "Certainly these are largely biocompatible materials. However, I doubt you can totally rule out some form of immune response," he says.
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