Posts with «pulse sensor» label

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.

Theater Safety Glasses

Watch horror movies without the fear of having to cover your eyes when things get scary with these ingenious Theater Safety Glasses created by Aisen Caro Chacin in collaboration with Shawn Lauriat.

Read more on MAKE

Portable and cloud-based heart rate tracker

In his blog, Charalampos describes his experience with SeeedStudio’s Grove Ear-clip Heart Rate sensor and Cosm (former Pachube) cloud service. The employed sensor is quite cheap and can detect heart pulses from the ear lobe, by measuring the infra-red light reflected by the tissue and by checking for intensity variations.

By connecting this sensor with an ADK board and, in turn, with an Android smartphone, Charalampos implemented a portable heart-rate tracker, which is used to send the recorded data to Cosm cloud service.

For more information and sample code, see here.

[Via: Building Internet of Things]