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Computer Aided Designs for a Mechanical Ventilator  Apr 09, 2020

IISER Pune researchers are involved in a multi-institutional effort to produce open-source computer-aided-designs for a mechanical ventilator that is currently in use in hospitals. This work is being carried out in collaboration with Capt. (Retd.) Rustom Bharucha from Bharucha Instrumentation and Control, Pune, India; IUCAA, Pune; IISER Pune; IndoGenius, New Delhi; and King’s College London, United Kingdom.

Independently, IISER Pune researchers have also developed a prototype of a more advanced, mass producible ventilator, the details of which are available here.

Ventilators offer a crucial life support system for respiratory tract conditions and are essential in our ongoing battle against COVID-19. There is an increased demand for ventilators at this time. However, supply chain disruption (including export bans) as well as the cost and complexity of most ventilator designs pose significant challenges during the ongoing pandemic. The need of the hour is to find a ventilator with a proven design, which has already been used in hospitals and mass produced locally. 

The Bharucha Ventilator
The Bharucha ventilator has originally been developed by Capt. (Retd.) Rustom K. Bharucha, who has been making ventilators for decades. Unlike experimental ventilators that are also being explored, the Bharucha Ventilator has been used in hospitals and rural clinics, by over one hundred doctors on thousands of patients, over the last fifteen years. It can also be operated manually in the event of power failure and, unlike many designs, does not rely on pressurized piped oxygen or air.

The Bharucha ventilator is robust, relatively easy to make and purely mechanical with no electronics. The cost per machine when made by an individual buying parts locally should be less than Rs. 7000 ($95) and when mass produced could come below Rs. 3500 (~$50). This would make it one of the cheapest ventilators available.

Creating a Computer Aided Design (CAD) model
Dr. Naresh Sharma from IISER Pune's International Relations Office facilitated the contact between researchers at the institute, Dr. Umakant Rapol and Dr. Sunil Nair, with Dr. Prashant Jha, Kings College, London and Nick Booker, Co-Founder of OpenBreath. Tech and IndoGenius, who was looking to make Bharucha Ventilator available more widely. IISER Pune then teamed up with Dr. Suresh Doravari and student volunteers from IUCAA, Pune to create the designs using a model kindly lent by Capt. Bharucha. 

“The Bharucha ventilator is a beautiful example of frugal innovation, and offers us the possibility of incorporating additional functionalities with relatively minor design modifications. Our agenda as a team is to offer an open source solution of a proven machine that is a purely mechanical in nature – critical in a time where the large scale sourcing of electronic components appears to be a daunting task," says Dr. Sunil Nair.

Dr. Suresh Doravari said, “We hope that our efforts to make a CAD model of the design and releasing it open source will inspire adaptations and enhancements of the design to local needs.”

The Bharucha Ventilator
The Bharucha Ventilator
CAD Model of the Ventilator
CAD Model of the Ventilator
Mechanism of Action
The ventilator uses an AC motor - like a table fan, and that lifts weights, enabling the bellows to expand. It is the release of the weight that generates the pressure.  

The modifications made by the team are expected to improve the functioning of the ventilator. “By changing the weights, you can adjust the pressure. Additional catchments mean the bellows can expand more or less - which gives a manually adjustable volume. These modifications could make the current design more usable. We wanted a purely mechanical design to be available to the world as a Plan B Ventilator - ultimately decisions will be taken by local clinicians as to the manner in which it is used and modified,” says, Dr. Prashant Jha.

Speaking on the versatility of the design, Dr. Umakant D. Rapol said that the mechanics of the design is fairly simple and allows mass-production. It could also be produced in local machine shops with basic metal-working equipment, would accept generous machining tolerances in most parts of the equipment, in addition to a few robust sensors for monitoring flow, pressure and content of gases.

The team at IISER Pune is also looking at other solutions, and is evaluating the feasibility of modifying some existing designs to enable local production.


 

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