At Berkeley researchers started to play a few years ago with the idea of microscopic sensing and communication devices, motes, and envisioned a time when they could be dispersed in the environment to monitor what was going on. They called it Smart Dust.
Now in an evolution of those studies researchers at Berkeley have created a Neural Dust that can be implanted on nerves to monitor the neural activity and to send signals to the nerve.
What sets this innovation apart from other work on microscopic sensors is the possibility to power them via ultrasound, they are battery-less.
The first experiments have involved placing the neural dust on peripheral nerves of mice, as shown in the photo. The sensor is connected to a microscopic piezoelectrical "cube" that convert ultrasound waves into electricity, very low power but sufficient to power the sensor to detect nerve signals and to transmit signals to the nerve. In the experiment they have sent six 540 nanosecond ultrasound pulses every 100 µs providing sufficient power to run the sensor continuously.
Although the current version of the sensor is 1mm high, 3mm long and 5 mm thick the researchers are confident that the size, already minuscule, can be further decreased. In a paper published in 2013 they have discussed the creation of a fully functional sensor in the form of a cube 50µm on a side. At that size it could fit side by side to a neurone.
They are also working on using a bio-compatible thin film to embed the sensor so that it can be implanted and remain functional for a decade or more.
The breakthrough, as I mentioned, is the possibility to power the sensor wirelessly. This would make a brain implant possible with no need for wires going through the skull, which is what happens today opening the door to infection.
This neural dust could also be used to monitor other tissues in our body, not just neural tissue. It would provide a continuous black box monitoring of our metabolisms and a very precise map of our organs activity making proactive medicine a reality.