Thanks so much to Sam for sending in info about this awesome burning man project! It’s truly impressive. He writes:

Pulse & Bloom is a 2014 honorarium art installation at
Burning Man 2014. We built 20 interactive lotus flowers made out of steel
and rowlux. Each lotus flower ranges from 8 to 18 feet tall, each of which
lights up with your pulse. You and another person can put your hands on a
couple of Hamsa hands at the base of the lotus flower and your respective
heartbeats will light up the flower.

This blog post details how the electronics were made, from the board layout
and schematic of the pulse sensor to the custom circuit boards used to drive
the lighting and controls. Uses a few hundred dollars worth of Adafruit
parts, both for the installation itself and for the 3 months of prototyping.
Full Arduino source code included and explained.

View the blog post with all the detail here.