Straw Heart Monitor

This DIY 'heart rate monitor' will open your eyes to the amazing muscle that keeps you alive and kicking.

Suitable for kids aged 5+ with parental supervision.

You Need:
  • Drinking straw
  • Lump of putty, plasticine or blu-tac - that's it!
What to do:
  1. Poke the straw into the putty. Okay, so it looks nothing like an expensive ECG monitor but wait till you see what this thing can do!
  2. Lay on your back and find the pulse in your neck. Lay the putty on top of this spot so that the tip of the straw is just above your eye. Now watch what happens... it's a little freaky.

Why is it so?

The straw moves in time with your beating heart. Each contraction sends a pressure wave through your arteries which causes the straw to vibrate along like a metronome. The tip of the straw amplifies the small movements in the putty so you literally see your pulse, right before your eye!

You've probably noticed that there are actually two thuds in every heartbeat. It goes lub-DUP, lub-DUP, lub-DUP. These sounds are made by heart valves slamming shut, not the heart's muscular contractions. These valves prevent blood from flowing backwards in the wrong direction. How many times a minute does your heart beat? Start a stop watch, and count how many beats pass in a minute. Or count how the beats in 10 seconds and multiply that number by 6.

From here you can assess how healthy your heart is. On average, a healthy human heart will beat 70 to 80 times per minute. Slightly more during periods of exercise, excitement or stress. You'd hardly know it was happening while you're relaxed, which makes watching your straw heart monitor seem almost surreal.