North Paw and Heart Spark

Computers & Mobile Craft & Design


Sensebridge ( is a maker of electronic kits geared toward personal hacking. It was started by a group of friends at the San Francisco hackerspace Noisebridge. Jon Kalish spoke with Sensebridge’s Eric Boyd, who now lives in Toronto, about the company’s first two products.

Jon Kalish: How does North Paw work?

Eric Boyd: It’s a compass anklet. You strap it on and it basically vibrates to tell you which way is north. Inside the anklet are eight vibrating motors just like the one inside your cellphone. And they’re spaced equally around your ankle. One of those motors is on at all times — it’s a persistent stimulus.

No matter which way you’re facing, it tells you where north is. That persistent sense of north is the most important thing about North Paw. Because of the plasticity of your brain, after a while it will stop telling you, “I’m feeling a buzzing on my ankle,” and instead your brain will tell you, “North is that way.” And that’s the genius of the device, this idea that our brains can adapt over time to a persistent stimulus. It’s really amazing.

JK: What do you see as the market for North Paw?

EB: As soon as we could strap working prototypes on our friends, people started telling us that they wanted them. They were like, “Thisis so cool. I want to be able to buy it. Are you going to sell kits?” Our market is the geek market and people who are really into hacking themselves.

But in the wider market there are so many people who claim they have no sense of direction. And this can totally fix that problem. You know when you come up out of the subway station and have no idea which way to go? The North Paw solves that problem. I think there’s a market for it with outdoor enthusiasts, the military, firefighters — anybody who finds it kind of important to have situational awareness.

JK: So, tell me about Heart Spark.

EB: It’s a pendant that you wear, and it flashes little lights in time with your heartbeat. You have to wear the type of chest strap used by runners and people who want to optimize their exercise experience. It detects your heartbeat using electrocardiogram technology, and transmits it wirelessly to the pendant, which receives the signal and flashes the lights.

JK: Why did you come up with Heart Spark?

EB: I’m really interested in the implications of making that kind of personal biometric data totally visible. When you broadcast your heartbeat into a social situation, how does that change the way people behave? How does it make people feel about you?

I’ve had all kinds of very interesting social dynamics when I wear it, and that’s one very interesting reason to wear it. It’s a good way to start conversations. I can use the pendant to not only display the heartbeat data but to log it. Then I can go back later and look at the logs of my heartbeat to see what was happening over the course of the day. And that’s just fascinating stuff.

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