Researchers at the University of Pompeu Fabra in Spain have developed a device capable of performing calculations by printing cells (cells) on paper. For the first time, they have developed a living device that can be used outside the laboratory without the need for a specialist, and can be produced commercially at a low cost.

We currently have many electronic devices – such as computers and tablets – which have a lot of computing power. But despite their power, they represent very limited devices for detecting biological markers that indicate the presence of disease. For this reason, biological computers began to be developed several years ago – living cellular devices that can detect multiple markers and generate complex responses. In them, researchers use biological receptors that allow them to detect exogenous signals and, using synthetic biology, modify them to respond according to the information they find.

To date, cellular devices have been developed that must operate in the laboratory for a limited time under certain conditions and must be processed by a specialist in the field of molecular biology. Now a group of researchers from the University of Pompeu Fabra has developed a new technology for printing cellular devices on paper that can be used outside the laboratory.

Interestingly, they use different types of cells with nutrients as ink for drawing. The cells remain trapped in the paper, alive and functional, and there they continue to grow and can emit signals that travel through the paper and reach other cells. The reason this is done on paper (or other surfaces like fabric) is mostly practical. This is a cheap method and is easily adaptable to industrial use, and large quantities can be produced at very low cost.

“We wanted to develop a scalable model and thought about using a printing system similar to the one used for printing T-shirts. We make shapes according to our drawing, we saturate it with various cellular inks, like a buffer, put on paper, and the cells are deposited.”

Syrah Mogas-Diez from Pompeu Fabra University in Spain

The strong point is that these paper devices can be stored in the refrigerator or even frozen, since the cellular ink contains cryoprotectants that allow it to do so. Thus, unlike previous devices, they can be stored for a long time before use.

In this new approach, each element of the device is a group of cells, in this case bacteria, with minimal genetic modification that can detect different signals. The cells live in a strip of paper and communicate with each other, integrate signals and generate a particular response depending on the various combinations of signals detected. The elements do not change, but by changing their position in space with the help of the drawing they do on paper, you can create devices with different functions.

“So the order of the cells is software, the cells are the hardware, and paper is the physical substrate on which those cells are placed.”

Javier Masia from Pompeu Fabra University in Spain

The research team has developed various biosensors, one of which is designed to detect mercury. Compared to other existing systems, the system contributes to visually assessing the concentration of mercury without requiring a device in the laboratory to measure it. Depending on the amount of mercury present, more or fewer dots appear on the reactive strip that can be counted with the naked eye.