Out of thin air

Another way of “making” oxygen is using concentrators, devices that selectively remove nitrogen — the gas that makes up 78% of our atmosphere — using a series of membranes, porous materials and filters. These started being produced in mid1970s, and the technology is very well established.

These devices turn air into a stream of oxygenenriched gas, typically above 95% (the rest is formed of mostly argon). This is usually good enough for respirators and ventilators. The benefit of a concentrator is it can be produced as a small device to be used in hospitals or care homes. Commercially available concentrators exist now, but they are expensive and difficult to produce in developing countries.

This is why scientists like me are looking for solutions. My team studies new types of materials that store and separate gases, some of which provide potentially affordable solutions for devices such as oxygen concentrators. We develop two main types of materials — zeolites (crystals of silicon, aluminium and oxygen) and metalorganic frameworks (usually called MOFs). Both are highly porous materials; you can imagine them as miniature, moleculesized sponges.

Like sponges, these porous materials adsorb more fluids than you’d intuitively imagine. Although the millions of pores inside zeolites and MOFs may seem tiny, their total surface area is monumental. In fact, one gram of certain recordbreaking MOFs feature a surface area of over 7000sq m.

Tiny amounts of zeolites and MOFs can store huge amounts of fluids, often gases, and they have been used in gas storage, purification, carbon capture and waterharvesting.

Some of my team, partnering with the engineering company Cambridge Precision, and the Centre for Global Equality, have started looking into whether they can be used to store oxygen. We’ve developed an initial prototype that works. We hope to have a final prototype in place in two months’ time, and after this we will need to seek medical approval.