Each year the team at StarFish Medical takes part in the Festival of Trees, a community event that raises funds for B.C. Children’s Hospital. This year was no exception and the StarFish team (comprised of Steve, Christian, Ted, and Debbie, plus a host of StarFish advisors ;- ) went all out with their creative skills and created a ‘living tree’, complete with a heart at its centre and ‘blood’ pumping around its boughs. It even has an audible heartbeat! The entire effect was very cool and the judges seemed to think so as well since we won the Festival of Trees – “Best Decorated Tree” award.

As mentioned, this is a fundraising event and if you are so inclined, you can join us in our efforts by checking out our page on the Festival of Trees – BCCH website and casting your vote for us!

For those of you who are interested in the nitty gritty engineering/design details of how the tree was decorated, Steve and Christian have come through for you.

Notes from Steve

The idea was originally just based on the blood pumping around inside clear tubes concept. From there we thought of adding the heart and blood bags to make a more complete theme for the tree.

To create the visible pumping effect I knew that we needed to have a bright red liquid and a 50/50 ratio of air and liquid inside the tube so that you could easily see the movement. I started by using a steady flow pump but this did not work because the air bubbles all gathered to one spot and the pump only worked when it was primed with fluid. My next attempt was to use a voice coil to drive a 60ml syringe. I did not get the power or the displacement required out of the voice coil, and did not want to use a large expensive one to increase the power. I finally borrowed a gear motor from Allan and made a bracket which cycled the plunger of the cylinder in and out with the rotation of the motor shaft. This worked very well to pressurize the tube of air and liquid and create a visible motion of the fake blood.

The team combined this moving fluid tube with white gauze bandage on the tree to create a stunning effect. Christian rigged up a sub-woofer with the sound of his own beating heart which added an extra level of experience to the theme, while Cam provided a model heart center piece in the middle of the tree.

Notes from Christian

  • Heart beat that you hear is mine and is from work I did previously in developing my own electronic stethoscope
  • Heartbeat sound was taken at the third left intercostal space (Erb’s point), where the most pronounced heartbeat is usually heard (especially S2)
  • The sound was recorded using a prototype wireless electronic stethoscope
  • There is a subwoofer in a box that is playing the sound
  • Red and white lighting was chosen to best accentuate the plastic veins around the tree and the gauze

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