Power devices critical to open source ventilator design
Power devices are at the heart of an open source ventilator design developed by Renesas Electronics.
Engineers looked at several open-source ventilator designs, including the Medtronic PB560, to come up with a three board design that is both easy to assemble but also safe. It controls the tidal volume and mixture of gas delivered to the patient while monitoring the patient’s status. The ventilator is portable and can be used with or without gas tanks. In addition, a humidifier can be connected to the ventilator’s intake path for long term use.
The design uses 20 chips from Renesas, including low drop out regulator, buck boost DC-DC converter controller, and a battery balancing and monitoring chip to boost the battery life of the ventilator.
The ventilator system reference design to provide a portable unit that can be used in hallway or non-ICU use cases. The machine can provide high pressure oxygen to patients in assist control and pressure control modes. The assist control mode provides a certain tidal volume of gas to a patient with each inhale. The flow sensor (FS1023) would monitor the gas flow rate at the inhale tube and the tidal volume would be calculated by the MCU using the rate integrated with time. The oxygen valve would be controlled by the MCU and manage the oxygen ratio. The pressure control mode provides a certain pressure to the patient with each inhale.
There is one proximal air pressure sensor connected to the mask to monitor the inhale pressure and send that information to the RX23W MCU. The blower, which provides pressure and blows air into the system, is driven by a motor control board that is controlled by the RX23T MCU. It uses I2C communication with the RX23W, and the two microcontrollers monitor each other to ensure the system operates safely. A humidifier is added to the system to provide moist gas to the patient.
The system design implements a sensor board, a motor control board, and features Bluetooth connectivity that allows medical professionals to monitor several patients simultaneously via a tablet or other mobile device. Each board has its own microcontroller to control its specific task while monitoring the status of the connecting board. The ventilator solution also provides a system of checks and balances to enable regulatory approval and provide patient safety.
“Renesas’ engineers have created a ventilator system reference design to address the challenges our global community faces as we fight the COVID-19 pandemic,” said Chris Allexandre, Senior Vice President, IoT and Infrastructure Business Unit at Renesas. “Leveraging our broad product portfolio and system design expertise, we are enabling customers to accelerate their development of medical ventilator systems capable of operating in a home or hospital environment.”
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