SierrOS - Cardiopulmonary Resuscitation Device

In US, 790.000 people have a heart attack every year. SierrOS is a self-service device which does a resuscitation while awaiting rescue.

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We are four classmates from Lyon in France. For our last year in high school we needed to create a project in Engineering Sciences. We decided to design a heart massage system which responds to a real need. Actually today 790.000 people have a heart attack each year in the US. And they are pretty low chances of survival, around 6%. In addition rescue usually takes around 15 minutes to come and most people do not follow first aid gestures or do it wrongly.
It is why our project, named SierrOS, may be a solution to save lives in the future if it is deployed in our daily.
SierrOs is an automated and portable cardiopulmonary resuscitation (CPR) device which can be used my everybody, even if they are not trained at.
Our project is divided in 4 main parts: the massage, the air insufflator, the power supply and electronics.
SierrOs has won the 2nd prize of a regional contest and is looking to participate to the nationals in May.

Thanks to JLCPCB, they provide us our PCB for free!

Firstly about the massage device. We needed to find a solution to create a system which could do a heart massage. After checking at systems such as cylinders, rack and pinion, we have chose to use a crank rod linked with a DC motor and a reduction gear. Our researches on the characteristics gave us each steps of the movement. The massage should be at a rythme of 100 compressions per minute and the piston should give at least 600N on the chest with penetration of 5,5cm. We the help of simulations on SolidWorks Méca3D we have found the characteristics of our motor. We actually have a 400W dc motors 24-48V, 6 000RPM-12 000RPM, with a reduction gear of 1:100. Here our motor would turn under 40V for a rotation speed of 1000RPM and a couple of 29,5Nm and a rotation speed of 100rpm at the exit of the reduction gear. We designed the whole system with different materials to limit friction and manufactured it in our school.

The insufflator system has been design to be able to insufflate de perfect amount of oxygen in the victim's lungs. We chose to compress a special medical balloon used in hospitals with a press and a rack and pinion. This device is connected to the massage with a special rythme directed by the microcontrolor. Actually the whole system should respect this special pace of 30 compressions-2 insufflations. To manufacture the rack you used laser cutting.

In terms of electronics we took the decision of designing our own card and manufacturing it in China , by JLCPCB, to limit use of wires everywhere. Our microcontrolor is a ESP32, it includes many functions such as: possibility of communication with rescue, communicate with a screen to explain users where to place SierrOs on the victim, drawing a Electro-cardiodiagram with electrodes, measurements of the quantity of oxygen in blood...

SierrOs is power supplied with 3 batteries LiPo which give us an autonomy of an hour.

  • 3 × LiPo 1500mAh 11,1V Batteries
  • 1 × 400W DC Motor, 24V-48V, 6 000rpm-12 000rpm Motor
  • 1 × Reduction gear 1:100 Reduction Gear
  • 3 × AD8232 + 3 heart electrodes Rescue material
  • 1 × ESP32 Microcontrolor

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  • Olympics of Engineering (Paris) review

    Mattis EYNARD06/04/2019 at 08:21 0 comments

    We went to Paris the 28th of May to defend our projet at the final of the Olympics of Engineering. It was really interesting to see various and original projects. We have met Jamy from "C'est pas sorcier", one of the most known TV program about science.

    Finally, we have been rated 20th of the contest, on a total of 1500 projects.

    We were a bit disappointed of our rank but it was really a learning and nice experience.

    PS: You can see the new version of our device, we will present you soon!

  • Electrical and logical circuit: tested and approved

    Mattis EYNARD05/21/2019 at 18:27 0 comments

    We have just tested our new electrical circuit, which is composed of batteries, big red button, fuse holder, PCB, 2 relay modules , limit switches and the motors.

    All the components are screwed on a Plexiglass board, we tried to make an evoluable and flexible circuit: it can be set and unset within 15 minutes, the only tool needed is a screw driver!

  • New printed board

    Mattis EYNARD05/19/2019 at 07:39 0 comments

    We have decided to minimize all the wires, breadboards or others electrical circuits on our system.

    To do that we have designed a new PCB, which contains all the pull-up/down resistors, power the other modules... Moreover it is way more simple to connect the circuit at the system and other components: we have chosen to replace the classic pin headers by JST connectors: it's really plug and play!

  • Positioning guide - Final visual aspect

    Lucas Sautier05/08/2019 at 07:47 0 comments

    Hi guys, we are finishing the conception of our new version of SierrOS. You can find above through a positioning guide, how our system would look like. We all keep you in touch !

  • Where is SierrOs going on ?

    Mattis EYNARD04/14/2019 at 20:44 0 comments

    04/04: SierrOs was presented at the Lyon regional engineering contest. It has done the 2nd price and has been qualified for the French national finals in Paris in May. We keep you up to date on the 28th of May.

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Thomas Leputsch wrote 05/06/2019 at 15:53 point

Nice project! 

I‘m working in med-tech industry. Feel free to ask if you have some questions, may I can help. 

Regards, Thomas

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Lucas Sautier wrote 05/07/2019 at 06:27 point

Thank you for your support and your help! We keep you in touch on this page. 

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Mike Szczys wrote 04/22/2019 at 17:02 point

Wow, excellent project! Really drives home the difficulty of interfacing hardware (or electronics) with the human body. Watching your experiments with the depth of the compressions was really neat. Looking forward to progress on this one!

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Mattis EYNARD wrote 04/23/2019 at 12:57 point

Thanks a lot for your comment!

We have had some troubles with the mechanical parts because of the important stress needed. We are developping the next version, with components in steel (rather than aluminium) and with a better finish. We keep you informed!

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dchambon007 wrote 04/20/2019 at 23:25 point

I'm a 67 years old emergency physician. Retired but still aware with improving resucitation techniques. Keep on going boys!

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Mattis EYNARD wrote 04/21/2019 at 17:32 point

Thank you for your support!

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t0mm4rx wrote 04/15/2019 at 11:50 point

This guys are awesome !

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MertenSa wrote 04/20/2019 at 22:04 point

i agree.

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Mattis EYNARD wrote 04/21/2019 at 17:32 point

Thank you!

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