DIY Ballistocardiogram Bed
Every time your heart beats, a column of blood is ejected primarily towards
your feet. Your body recoils a little (thanks Newton) and with a careful setup
we can actually witness that recoil. Dynamics are complex though so the recoil is actually more of an osscilation with a strong peak at the time your heart ejects the blood. This osscillation is called a Ballistocardiogram, and this page discusses an easy to make DIY system for viewing it with your own eyes in real time. Note that "we" here refers to myself, Brian Schiffer, Sima Mitra.
Using open CV on the video we were able to derive the actual signal. It is so smooth it almost looks fake, but this is real data!
It all started when our CTO brought in a TSA roller table and a board of plywood for the purpose of making a BCG bed. The roller bearing had too much rolling resistance so we took the thing apart and created a kind of railroad track. By putting the board right on top of a few rollers we got super-lower resistance.
The next step was to attach a small mirror to one of the rollers, the angle relative to the laser changes when it spins. With the setup a sufficient distance from the wall, very small changes in angle result in visible movements of the laser.
Here is Brian on the bed working hard to be as still as possible while jostling his blood around as vigirously as possible. Nothing needs to be tuned carefully for this to work. You can see we've propped up the laser with a wrench, the mirror is taped to the lid of something that we bolted to one of the original axels of the roller table.
Here is Brian's heart beats showing up on a wall. This is shamefully looped with just one period, so please view the unedited video above to see the beat-by-beat pattern.
Here is one last photo of Brian on the bed, with a few people watching his heart rate on the wall.
If you haven't yet, check out the video at the top, and let me know if you have any questions! Contact.
Using open CV on the video we were able to derive the actual signal. It is so smooth it almost looks fake, but this is real data!
It all started when our CTO brought in a TSA roller table and a board of plywood for the purpose of making a BCG bed. The roller bearing had too much rolling resistance so we took the thing apart and created a kind of railroad track. By putting the board right on top of a few rollers we got super-lower resistance.
The next step was to attach a small mirror to one of the rollers, the angle relative to the laser changes when it spins. With the setup a sufficient distance from the wall, very small changes in angle result in visible movements of the laser.
Here is Brian on the bed working hard to be as still as possible while jostling his blood around as vigirously as possible. Nothing needs to be tuned carefully for this to work. You can see we've propped up the laser with a wrench, the mirror is taped to the lid of something that we bolted to one of the original axels of the roller table.
Here is Brian's heart beats showing up on a wall. This is shamefully looped with just one period, so please view the unedited video above to see the beat-by-beat pattern.
Here is one last photo of Brian on the bed, with a few people watching his heart rate on the wall.
If you haven't yet, check out the video at the top, and let me know if you have any questions! Contact.