CeNSE, IISc-KAS Tech. Ventilator-T1D2(We have also consulted with Manipal Hospitals, HydroPneo, VT Vacuum and VASMED)

This is an open source design. You are welcome to take it up.Stay tuned for a possible D3

Disclaimer• This is not a certified ventilator. We have put it together as a demonstration

of how a simple pressure controlled ventilator can be assembled inanticipation of a very large demand that India may not be able to cater to.Only time will tell. But then, as they say, hindsight is 20-20.

• We are not medical doctors. We are engineers and the informationcontained in the next few slides is based on our understanding on how aventilator works. We may not be academically speaking, 100% accurate.

• Remember a person’s life will be at stake.

Main differences between D1 and D2

• D1 can only do pressure pulses. D2 can do pressure pulse, volume pulse and pressure regulated volume flow. Other modes can be programmed in. The time profiles you see in the videos will change in our final design as system conductances change.

• D1 had a single solenoid controlled by a timer circuit for breathing rate. D2 has a proportional valve driven by an Arduino code.

• D1 has no alarms built in. D2 can have all the alarms required.

• D1 cannot communicate with a local or remote display. D2 can communicate with a remote or local display

• D1 cannot display profiles. D2 can display profiles.

Pneumatic and Electrical Circuits

• The only difference between D1 and D2 pneumatic circuits is thereplacement of the solenoid valve by the proportional valve and theremoval of the bypass with the orifice. Rest they remain the same.

• Pressure sensors and flow sensors have been introduced to providean input to the PID logic that controls the proportional valve.

• Control is through an Arduino board

• Updated PCBs for D1 and D2 will be posted shortly.

D2 Profiles

• The profiles you will see in D2, P, V and Flow rate with time are not the most ideal.

• We plan to resolve that issue in our final prototype in which the conductances will change due to design changes that will be implemented based on the current development.

• Our most significant challenge has been reliable flow measurement that does not cause a significant pressure drop, is simple to integrate electronically and does not need to be reused. Meeting these multiple requirements is not trivial.

Electrical BOM (final configuration to be updated)- Look up excel sheet for suppliers, - Medical grade electronics is recommended,

Sl No Equipment Equipment description Quantity Cost

1 Arduino board Mega 1 nos 27502 24 Power supply 24 V DC, 10 A 1 nos 18003 Proportional Valve FESTO 300 LPM flor rate valve 1 nos 95004

DisplayLCD display at terminal 1 nos 5000

5Raspberry Pi

For display communication 1 nos 50005 Pressure Sensors 0-100 mbar 2 nos 5000

6 Flow sensors 0-300 slpm flow rate 2 nos 20007 PCB 1 nos 10008 Oxygen 1 nos 5000

Total 37050

Pneumatic BOM:Sr No. Item Description Qty Potential Cost Amount

1 Regulator (Oxygen) Outlet pressure 10-100 mbar 1 2000 2000

2 Rotameter (Air)1/4'' FNPT With Inlet 175 PSI outlet 0.3 to 3.6 psi, 0-50 SLPM

2 2500 5000

3 Safety Valve Cracking pressure 40 cm of H2O 1 2,500 2500

4 PEEP Cracking pressure 0-20 cm H2O 1 2,500 2500

5 NRVs Inlet and outlet of ventilator tubes 2 1000

6 Adapters, clamps and fittings As required 5000

18000

Total cost: Rs. 55050 for a prototype. This is the cost of the prototype. We expect it to some down with volume and design optimization.

Note: We have not included the cost of a compressor here as required.

Pneumatic circuit (Explained)

Circuits explained (Please read disclaimer. High voltages and pressures are

dangerous.)

• The electrical circuit (In India) starts with a power supply to convert the 240V AC supply to a 24VDC supply that operates the electronics.

• The electronics in D2 is a Arduino board that controls a FESTO proportional valve through feedback obtained from two pressuresensors. Our current experience recommends that flow not be measured by this method but by using an actual flow sensor that has a high conductance. Control of pressure, volume, pressure regulated volume and the breathing rate can be done by the code that runs the Arduino. We are in the process of putting our code up for open source use.

• The pneumatic circuit starts from either the hospital air/oxygen supplies, cylinders or a compressor that could deliver 4 bar pressure. (Atmospheric pressure is 1 bar).

• These are routed through individual rotameters (flow meters) that allow for fixing the Air-Oxygen ratio.• The mixed supply is then regulated down to 40 millibar pressure by a pressure regulator. • This low pressure supply is then pulsed to provide inhalation pressure to the patient through the proportional valve.• A pressure limiting valve ensures that inhalation pressure does not exceed specifications.• The bypass orifice present in D1 is not required in D2 as the proportional valve is used to control exhalation pressure. • The PEEP valve ensures that a constant low PEEP pressure prevents the lungs from collapsing during exhalation. • Adapters that convert from the ¼” world of steel gas piping to the >1”world of medical plastic tubing are very important.• System design is crucial to ensure that the conductances in the circuits are kept high to deliver the required flows at the very low

pressure drops and provide the doctors with the pressure, volume and volumetric pulses they are used to.

CreditsAjay, Akshay, Anirudh, Anisha, Ankit, Harshavardhan, Hira, Justin, Kapil, Maithili, Manjunath, MM Naik, Narayanan, Nishant, Pandian, Prosenjit, Raghuveera, RP, Rohith, Rohith, Sagar, Saurabh, Surendra, Suresh, Sushobhan, Tanushree, Vasu, Vinay, …and many more from IISc, PSU, KAS, Manipal, Hydro Pneo and VT Vacuum.