Arduino Polygraph Shows How It’s Done

Sometimes, a project comes along that makes a good reference design for anyone doing similar work. In this particular case, it’s a DIY USB polygraph-like machine by [Juangg] using an Arduino and sensors on the hardware side, and a Python front end for data visualization. It’s even complete with 3D printed enclosure and sensor elements.

[Juangg] designed it to use three sensors: a pulse sensor, a breath sensor, and one to measure Galvanic Skin Response (GSR). The pulse sensor uses a piezo element pressed against a fingertip to detect changes in pressure resulting from blood flow. It can be picky about placement, but finding sweet spot can yield remarkably good readings. The breath sensor works on a similar principle but uses a 3D printed fixture to hold the sensor between a strap and the subject’s chest, so that breathing in and out can be detected. The GSR sensor is a voltage divider used to measure small changes in skin conductivity. How well does it all work? That depends on what one is looking to get out of it, but the documentation and design files are available from the project page and the GitHub repository if anyone wants a reference for similar work.

The polygraph may have a mixed reputation, but it makes a good project that demonstrates just how messy biometrics can be from an engineering perspective. And in case you missed it, here’s a reminder that Wonder Woman and the polygraph have much more in common than you might realize.

Arduino Based Biofeedback Unit

[Michael Gerstenmayer] has been very successful in developing a biofeedback system. He’s based the build around an Arduino and started adding different chunks to the project to develop a full-featured unit. It can take your temperature (with an IR sensor…. not the hard way), measure your galvanic skin response (conductance), and produce feedback based on this data. Interestingly enough, he built a peripheral vision feedback system based on the glasses frames seen above. They have an LED on each side which are illuminated based on the sensor data.

By using the Arduino’s USB connection the data can also be processed by a PC. [Michael] spent some time working with an open source program called BrainBay to gather and map the stream from the sensors.

We enjoyed reading about the build, but there’s no information about what he’s got planned for this project. That shouldn’t stop you from setting up your own rig and using it as a lie detector, or for the devilish purposes we’ve seen in the past.