Hi, everyone, my name is Jas Brooks and today I'll be presenting work I could put my colleagues Shan-Yuan,
Jingxuan,
Romain, Jun, and my advisor Pedro Lopes at the University of Chicago. This work is about creating a sense of stereo smell
by electrically stimulating a special nerve in our body called the trigeminal nerve. So let me start with a teaser.
Here Shan-Yuan making breakfast, he turns the stove on, puts some toast -
sounds pretty good -
and, well,
But he did find the gas leak super fast. So how do you do that, he must have been wearing some kind of smell
interface. Let me show you how researchers tend to use and create smell interfaces. Most researchers approach smell by
well producing odors. That is by pushing odor molecules from reservoirs to the user's notice. In fact, last CHI I
presented such a display that used chemical smells from reservoirs to create temperatures. It's a very standard and
sensible approach to smell. But you can see that it has limitations like you need a large device, and you're limited
by reservoirs. So one of the most promising ways to break from this is to shift from analog to digital actuation, aka
electrical stimulation. How does it work? It's kind of tricky. You have to put these prongs all the way up until it
reaches the olfactory bulb, and then you need to initiate stimulation. And well, normally, you do this with an expert
on hand. Due to its precision and a lot of anatomical slash stimulation factors we have yet to understand, it still
doesn't produce reliable smells digitally. So we're kind of exploring the space between the positives of chemical and
electrical stimulation. And we want something easy to set up without the need of an expert, but that also alleviates the
messiness and the bulkiness of chemical displays. Following, we instead approached digital actuation from a new angle by
searching for a less invasive location to apply electrical stimulation. One that still works for electrical smell
sensations, but without deep implants. We do this by actuating the septum. Let me play the video again. As
Shan-Yuan inhales, he feels a tingle on his left nostril.
And our device essentially renders this via electrical trigeminal stimulation.
Our device gives him a sense of stereo smell, which it determines by pairing with external gas or odor sensors,
and that's how we found the gas leak to the left. But does this feel like smell? Well, not quite, but actually at the
same time yes. Let me show you why.
You're probably used to hearing that the olfactory bulb is what mediates smell. But it turns out there's a lesser known
nerve, the trigeminal nerve, that also has a stake.
In fact, both of them contribute to smell. For instance, when you take a whiff of vinegar, you smell that sharpness.
The olfactory bulb is reacting, but it's especially the trigeminal nerve that gives rise that distinctive,
recognizable sharp smell. Sensations evoked by these two systems are perceptually fused to be what we understand as
smell. Now these two systems also contribute to an interesting phenomenon. If I hold a flower to my left or my
right, its smell has little trigeminal stimulation. And my olfactory bulb might distinguish the direction of the
flower's smell in stereo, but it won't arise to my conscious perception. However, if I smell vinegar, I will consciously
smell in which nostril the trigeminal sensation is more intense and thereby have an idea of direction. We are trying
to take advantage of this ability of the trigeminal nerve to feel left or right intensities to make a device that creates
electrical stereo smell. That's why the device is at the user's nasal septum where it can already accesss the
trigeminal nerve with its small form factor and without the implantation or long prongs. We then validated our device in
two experiments. As the first exploration of electrical stereo smell, we found out which electrical waveforms create
stereo smell sensations, and found that people can navigate using electrical stereo smell in what seems to be a similar
manner to how they would search a chemical odor in the room.
So to conclude, we explored a new way of producing certain smell sensations, specifically trigeminal sensations, via
electrical stimulation, and we showed we could create a noticeable stereo smell! The main limitation is that we
found out how to create these sensations for direction and intensity, but not different trigeminal qualities like
tingling, refreshing, or sharp, and so on. Now, the reason why we're so excited about this is that it extends our
investigations on making the trigeminal nerve an interface for computing technologies, and follows up on our CHI 2020
chemical exploration of the trigeminal nerve. So thank you very much for listening!