An interesting new project on Kickstarter is raising money to support the creation of a small, cheap pulse sensor. The device is being developed on the open source Arduino platform so that it can be easily integrated into other projects.
From the Kickstarter project page:
After a few months of testing a gaggle of techniques, we developed what we think is an innovative pulse sensor. Our prototype (and accompanying code) plugs right into Arduino and easily clips onto a fingertip or earlobe. It’s super small too, button-sized with holes, so it can be sewn into a garment as well. We’d like to manufacturer the actual pulse sensor, making it low-cost, open source, and accessible for students, artists, and developers.
Our Arduino and Processing software graphs heart rate and pulse data instantly. We also made sure that exporting data to your software or web app of choice is simple.
Kickstarter project page: Pulse Sensor: an Open Source Heart-rate Sensor that Rocks