Modular PAPR - Modular filtered air supply for the protection of medical personnel and for respiratory support of patients

In the current project we are developing a reusable powered air-purifying respirator (PAPR) as infection protection for medical personnel. Following the concept of a modular design, the respirator was developed based on a scuba mask. Additional components are attached via connectors, which can be quickly manufactured on demand using rapid prototyping methods. Medical staff in hospitals must be protected especially against infection with the SARS-CoV-2 coronavirus. At the beginning of the pandemic, protective equipment became scarce in many places due to the rapid spread of the virus, so that disposable products had to be used several times. Today, the need for low-cost, rapidly manufacturable yet effective protective equipment remains, especially in pandemic hot spots and emerging and developing countries. In the anti‑corona project "Modular PAPR", Fraunhofer IGB is therefore developing a modular and reusable powered air‑purifying respirator which provides filtered, virus-free breathing air. For this purpose, first suitable electronic components were selected and a circuit was developed to control the incoming and outgoing air flow via fans. Subsequent flow measurements were performed to characterize the fans. We conducted initial tests regarding the filter effect with medical filters, various everyday filters (HEPA vacuum cleaner filters, pollen fleece) and textile fabrics. As expected, medical filters showed the best filter performance. However, similar performance was also achieved with some filters from the everyday range. To protect COVID‑19 patients from secondary infections and to reduce the viral load in the room air, the second development stage of the PAPR also filters the wearer's exhaust air. In the third development stage, our PAPR enables non-invasive individual respiratory support for patients with mild respiratory distress who do not yet require full ventilation. For this purpose, sensors for flow and pressure measurement are connectable to the printed circuit board. The key aspects in the development of the PAPR are its modular design and the use of components that are also available in large quantities in the corona crisis and were not originally intended for medical purposes. We have therefore selected a readily available scuba mask as the basis. All components are joined via connectors that can quickly be produced via rapid prototyping methods such as 3D printing and laser cutting.