Within the body
These sensors can currently be placed within the peripheral nervous system, the nerves that work throughout our arms and legs. One day, scientists hope to use sensors in the central nervous system, including the brain and spinal cord.
The scientists had previously explored using radio waves to power and communicate with neural dust motes. However, radio waves are not good at reaching deep within the body, while decades of ultrasonic imaging has revealed that ultrasonic pulses are very good at penetrating soft tissues, says researcher Michel Maharbiz, an electrical engineer at the University of California at Berkeley.
“This is a breakthrough technology that really changes what’s possible in terms of sensing and stimulating nerve activity, especially nerves deep inside the body,” Weber says.
Ultimately, the researchers want to shrink neural dust motes down to just 50 microns wide, or roughly half the average width of a human hair. At that size, “the body should tolerate them much longer,” Maharbiz says.
The scientists are currently developing motes that can also electrically stimulate the body. If they are successful, this means that neural motes can not only monitor health, but actively serve as electroceutical therapies to treat brain disorders such as epilepsy.
Experiments so far with neural dust motes have only involved the peripheral nervous system, which serves the limbs and organs, and not the central nervous system consisting of the brain and spinal cord. Still, electroceutical therapies may still have many applications in the peripheral nervous system, such as bladder control or appetite suppression, says researcher Jose Carmena, a neuroscientist and electrical engineer at the University of California at Berkeley.
In the long run, the scientists want neural dust motes in the brain and spinal cord. One challenge that neural dust targeting the central nervous system faces is how ultrasound does not pass well through bone, Weber says. “That raises challenges if you want to create a brain-machine interface, but I’m not saying it’s impossible by any means,” Weber adds.
The researchers are now working on miniaturizing the motes further, discover more biocompatible materials to package them in so they can last in the body longer, and incorporate other sensors into them. Eventually motes could find use anywhere in the body, not just the nervous system, Maharbiz says.
“In the long term, we want to be able to send energy to and communicate with implants all over the body, to record data from a variety of organs in many different ways, maybe even report on the conditions of tumors or cancer therapies,” Maharbiz says.
The scientists detailed their findings online August 3 in the journal Neuron.
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