People have been studying neurons
for quite a bit of time actually
and two main features that are
really important: one, is that
device should be small so that
it doesn't cause very much damage.
And the other one is that it should
be bio-compatible so it doesn't
damage tissues. We're working
to use polymers which is a unique
approach and we're making polymer
fibers that are really flexible
so when they are put in the brain
they don't cause a lot of scarring.
So the fabrication method that
we use, makes use of a process
that is commonly used in the
telecommunication industry which
is the thermal drawing process.
In this process we start with a
large template of what we want
the geometry of our neuro-probe,
and then by heating it and applying
controlled stress we can reduce
its dimensions up to 200x.
So this allows us to design a
geometry in a scale that is easy
for us to fabricate and then
reduce its dimensions to a useful
So after we thermally draw the
fiber it looks like this and it's
super flexible but its still a
little too thick to be implanted
so we're going to selectively
etch the outer layer so we can
make it smaller and be implanted.
We started off with a diameter
similar to this one, which is
about the diameter of fishing
wire, and then this piece here
shows the transition from that
thicker, fishing wire, to the
diameter closer to the human hair.
And then it's this thinner piece
that we're going to start using
to connect to a board and prepare
So one of the advantages of this
fabrication method is that we can
incorporate many different
materials in the same process.
And by combining different
materials we can achieve different
functionalities in our devices.
So we can achieve not only re-
cording electrodes but also have
ways in which we can guide light
into the brain or also inject drugs.
In this work we show for the
first time that we can modulate
the activity in the brain via the
injection of drugs while we are
stimulating neurons in the brain
using light, with a method called
optogenetics. And through all
this process in which we are
stimulating and modulating the
response of the neurons we are
recording this activity in the
neurons. We hope that these
devices we have developed can be
useful for other people to do
further experiments in the brain
so people who are more interested
in discovering how the brain works
we hope that these tools will be
helpful for them in discovering
these relationships in the brain.