Simply Spiked: Lie Detector in a Can!

from the promo video

My career is strange. No doubt about it (say that in as Canadian a voice as you can). I get requests that sound like I’m being punked. “Hey can you make a lie detector in a can?” is up there. I was sent a single image with a bunch of labels of what they wanted and a can with a light on the bottom. Not pictured because I don’t think I can share it. The client in question was Molson. The agency, Citizen Relations.

I mean, the answer is “sure, I can” right?

After investigating lie detectors (polygraphs, etc) I figured I could make something that reacts to biometric input. Trick is, they wanted one in a week’s time! After working out the details, I set to work. First thing was to determine what I could actually accomplish a week. When I agreed to take on the project, I stipulated that V1 would be only using a heart rate sensor. I decided to add fries with that and offered to include haptic feedback in addition to the lighting. I had a vibration motor on hand and determined I could trigger it easily using a micro-controller.

What’s in the can?

So glad you asked. For the controller I used an ESP32 S3 Adafruit Feather. This has a lot of capabilities and, most importantly, on-board Wi-Fi.

For the heart rate, I found a great breakout from DFRobot.

The lighting on the bottom was a NeoPixel strip.

This first version was a little rough but it was a learning experience.

To communicate with the can, I had it launch its own web-server and server pages for an administrator to tell the can when a question was asked and then answered. Then I designed lighting effects for all portions of the experience. Golden orbit meant the can was waiting for commands. Blue pulse it found a heartbeat. Green flash was truth. Red flash and vibration meant false.

I designed the internal component structure in Fusion360 and 3D printed all the parts on my Eryone Thinker SE.

I joked in meetings that the components were held together with “hope and tape”. I was very happy with the locking mechanism I designed, everything but the sensor was integrated into a central post that was unscrewed to turn on and charge. It was not a good long-term solution.

Why a week?

I was told they were shipping the can to the set of Love Island Québec in the Dominican Republic to shoot with the contestants. I actually think this happened and when I have video of it or a post to link to, I will.

Version 2?

Yes! So they liked version 1 so much, they wanted more cans. This time it was explained that they wanted a second data point. Galvanic Skin Response (GSR). I needed to reconfigure the design and code to accommodate this. I found a breakout with two nickel pads from seeedStudio.

The modifications to the pads was to cut away the elastic covers and shorten the wires to the breakout. Then to remodel the component structure to include the pads to the external area.

In addition I lowered the height of the lighting by replacing the LED strip with a ring.

Version 3?

Finally with V3 (my internal V16) of the cans, I redesigned the internal structure again. This time, to enclose the components and make the entire system more secure. I also changed the surrounding cylinder into a two-part container. I also swapped the large vibration motor for a small cell-phone vibration motor that could sit on the sensor strip and made the haptic sensations work just as well with a smaller footprint. This allowed me to remove the main centre stem.

I wanted a repeatable system that I could quickly implement with a pre-determined set of components. The bottom now unlocks and reveals a power switch and USB-C charging port. No more “hope and tape”. I am confident in the construction and no longer worried if some random person decides to fiddle with the can.

Psst. Don’t stare at the LED ring when you turn it on. It’s pretty bright (read: blinding)

Anyway, the project launched and it’s very cool to see in the world. I hope you like it. Here’s the promo video they made.

Special thanks to Nicole St. Jean for being a kick-ass producer. And thank you to the team at Citizen Relations for their faith in the process. Not to mention their willingness to listen to my nutty ideas.

Yelp review: 10/10 would can with them all again.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.