The University of Johannesburg’s engineering team designed and printed mechanical ventilators to help with the forecast shortage as the country moves towards the COVID-19 pandemic’s peak.
Named AURA IMPRIMERE, meaning ‘A Breeze of Air provided by printing’, the 3D printed ventilators are portable and can be operated off-the-grid for up to one and a half hours. This is because of the battery system which can continue functioning when the electricity goes down.
“These unique 3D printable ventilators use a microcontroller to control the operation of the two motors. By adjusting the speed and direction of rotation of the motors, it is possible to obtain a pressure-time profile that is suitable for respiratory assistance of patients,” said Professor Tien-Chien Jen, UJ’s Head of Department of Mechanical Engineering Science and project team leader.
“The microcontroller monitors the pressure inside the Ambu bag by using a pressure sensor. If the pressure sensor picks up irregularities in the pressure, then the motor controller will intervene to correct these issues. It is also important that the mechanical arms of the ventilator operate in unison. Sensors that monitor the position of the ventilator arms are also used to enable the microcontroller to keep the mechanical arms of the ventilator in sync,” explained Jen.
This machine is based on a reciprocating engine piston and crank design. The motors were extracted from locally bought electric screwdrivers.
The ventilator allows for electronic components, such as a control resistor, variable resistor, and a small programmable computer to be used. These electronic components can customise the pulse needed for the patient and can vary the speed of the pulsation.
The crank design provides a linear motion for the slider relative to the slider base. Here the “fingers” are integrated that pushes the ambu bag and allow it to deflate.
“The Ambu bag comes in different sizes, and the invention can be custom changed with ease, on-site, according to the patient age, condition, and breathing necessity. This is due to the meshed base plates that allows the clamps, mechanism, electrical housing, etc. to be reoriented and placed as the consumer pleases. Inspired by “LEGO” type designs.”
The team has made their design open-source, meaning anyone with access to a 3D printer can make them.