That’s the question Ana Martins Costa and her colleagues at the University of Twente are exploring. Their answer: RenOx, a new kind of artificial organ that could one day support both lungs and kidneys. Replacing respiratory and renal function now requires two separate machines.
The idea for RenOx didn't come from a planned experiment. It came from a mistake. Marcus Hormes once forgot to connect one of the two sides of an artificial lung device to the oxygen supply. When he checked the results, the oxygenation efficiency was barely any different. Puzzled, he mentioned it to his colleague not in a meeting, but during a casual conversation at the swimming pool.
That colleague was Jutta Arens, now a professor at the University of Twente and Ana's promotor during her PhD. Years later, Jutta and collaborators kept thinking about what that forgotten connection might mean. Could you deliberately replace some of the gas-exchange membranes with dialysis membranes? Would the lung still work? And if it did, could it also clean blood at the same time? Years of research later, those questions became RenOx. "The greatest innovations often come from paying attention to the things that weren't supposed to happen," says Ana.
Why life support can still cause harm
When someone’s lungs fail and no other conventional treatments can be applied, doctors use a technology called ECMO (extracorporeal membrane oxygenation). This machine can be viewed as an artificial lung that keeps oxygen flowing into the blood. When a patient receives treatment with such an artificial lung, it is very common that their kidneys also fail. It is the second most common complication of this treatment, affecting up to 70% of patients. When this happens, dialysis can take over the job of filtering out toxins. But that requires a second machine.
“Patients on ECMO or dialysis are connected to large machines through multiple tubes,” says Ana. “And even though these systems are lifesaving, every additional component is a risk for bleeding, infection, or clotting. They make recovery difficult.” The human body is just not meant for all that artificial machinery in contact with blood. “The dialysis circuit on top of the ECMO circuit is a second, artificial, complex blood circulation system outside your body,” Ana explains. “And every extra tube or pump adds to the risks.”
One invention, two life-saving functions
RenOx takes an innovative approach. Instead of running the blood through two separate circuits, it combines both functions in a single, compact device. A hexagon with a few tubes on the outside and a large bundle of membranes (resembling miniaturised straws) that can both breathe and clean blood. “RenOx is a ‘two-in-one organ device,” says Ana.
At the heart of RenOx is a bundle of tiny fibre membranes, resembling a cluster of drinking straws. Blood flows around them while gases and waste move through the porous walls. Similar to how the natural lung’s alveoli and the kidney’s nephrons work. This design doesn’t just save space. It requires fewer connections to your body and just one pump instead of two, while also reducing the number of artificial surfaces that your blood touches, lowering the risk of clotting and infection.
From hospital bed to wearable life-support
Today, patients on ECMO can barely leave their beds. The complex machines that keep them alive also keep them tethered to the hospital. Ana and her collaborators hope that will change. They want to make life-support systems compact and safe, so that patients could one day have a portable option and hopefully go home and move freely while still connected to this artificial organ.
“Right now, patients on ECMO can hardly leave their beds. Multiple connections tie them to the life-support system,” says Ana. “We hope that, step by step, we can make these systems smaller, lighter, and safer. Hopefully, one day they will be small enough to carry.”
The researchers are already exploring miniaturised versions of RenOx and other artificial organs, such as the ArtPlac project. ArtPlac is a tiny artificial placenta designed to help premature babies whose lungs and kidneys are not yet fully developed. It’s a similar technology, adapted for the smallest and most fragile patients imaginable.
Engineering the next breath of life
The development of RenOx is not just about medical innovation. It’s about giving patients their freedom back. “Imagine being able to walk, talk, or even go outside while your artificial organs quietly do their job,” Ana says. “As engineers, we are working towards this kind of future”
Projects like this one show how biomedical engineering, materials science, and medicine come together at the TechMed Centre of the University of Twente to redefine what’s possible in healthcare. The road to a wearable artificial lung-kidney system is still long, but every new experiment brings that future closer.
