Around the world, the coronavirus crisis has seen the demand for ventilators soar. Many manufacturers are therefore working at full speed to develop new ventilator systems, primarily for those countries that cannot afford expensive high-tech equipment.

However, there’s a catch: standardised tests are required before these systems can be produced on an industrial scale. And because a ventilator is also currently under development at ETH Zurich, researchers at the Chair of Product Development and Engineering Design have built a test rig that enables them to conduct an in depth examination of a wide range of ventilator systems. The test consists of an evaluation of the accuracy of controls and instruments including the alarm signals and the evaluation of the trigger signals for the assisted ventilation. In addition, the conformity of the patient connection with the corresponding standard and the usability are tested.

“Our tests are standardised and we check that the ventilators meet the relevant requirements,” says Marianne Schmid Daners, Senior Scientist. This means that ventilator manufacturers can test their systems at every stage of development.

Modelling infected lungs

Schmid Daners and her team use a dummy head and a mechanical lung (the “TestChest”) in the test rig, both provided by the Simulation Center at the University Hospital Zurich. Normally used to train hospital staff, the TestChest is now being used by the ETH researchers to accuratly represent the conditions in the lungs and thus to measure the pressure in both the lung and the ventilator, as well as the tidal volume.

The TestChest is based on a computer model that enables the researchers to simulate the corresponding lung characteristics and breathing patterns of patients suffering from COVID-19, for example. The dummy head allows the ETH researchers to check whether the masks fit properly. Moreover, testing must include the entire system, both ventilation and the associated connections.

The researchers can test different kind of systems, regardless of whether they were produced by commercial suppliers, research labs or private individuals. Some of the features they assess include the pressure generated by a ventilator, the respiratory volume and the supply of oxygen to the lungs.

Three systems put to the test

To date, the engineers have put three different ventilator systems through their paces on the test rig. Two came from external companies and one from a research group led by ETH Professor Kristina Shea. In fact, this project was the reason for setting up a test rig in the first place. Marianne Schmid Daners is involved in both projects. The team is currently developing a simple, low-cost ventilator for use in emergency situations (cf. ETH News article from 12.05.2020).

The test rig project came about as part of the helpfulETH initiative launched by the ETH Domain. “The test rig will be available to test innovative ventilator systems until further notice,” Schmid Daners says.