Scientists have proved that how electricity is transported in printed 2D materials, paving the way for the design of flexible devices for healthcare and beyond. The work identifies what properties of 2D material films need to be tweaked to make electronic devices to order, allowing the rational design of a new class of high-performance printed and flexible electronics. Silicon chips are the components that power most of our electronics, from fitness trackers to smartphones. However, their rigid nature limits their use in flexible electronics. Made of single-atom-thick layers, 2D materials can be dispersed in solution and formulated into printable inks, producing ultra-thin films that are extremely flexible, semi-transparent, and with novel electronic properties. This opens up the possibility of new types of devices, such as those that can be integrated into flexible and stretchable materials, like clothes, paper, or even tissues into the human body.

A study, in Nature Electronics, led by Imperial College London and Politecnico di Torino researchers reveals the physical mechanisms responsible for the transport of electricity in printed two-dimensional (2D) materials. However, without knowing which parameters to control to design printed 2D material devices, their widespread use has been limited. Now, the international research team has studied how electronic charge is transported in several inkjet-printed films of 2D materials, showing how it is controlled by changes in temperature, magnetic field, and electric field.

Former, researchers have built several flexible electronic devices from printed 2D material inks, but these have been one-off 'proof-of-concept' components, built to show how one particular property, such as high electron mobility, light detection, or charge storage can be realized. The team investigated three typical types of 2D materials: graphene (a 'semimetal' built from a single layer of carbon atoms), molybdenum disulfide (or MoS2, a 'semiconductor'), and titanium carbide MXene (or Ti3C2, a metal) and mapped how the behavior of the electrical charge transport changed under these different conditions. Lead researcher Dr. Felice Torrisi, from the Department of Chemistry at Imperial, said: "Our results have a huge impact on the way we understand the transport through networks of two-dimensional materials, enabling not only the controlled design and engineering of future printed electronics based on 2D materials but also new types of flexible electronic devices.”

The Co-author and Professor Renato Gonnelli, from Politecnico di Torino, Italy, said: "The fundamental understanding of how the electrons are transported through networks of 2D materials underpins the way we manufacture printed electronic components. By identifying the mechanisms responsible for such electronic transport, we will be able to achieve the optimum design of high-performance printed electronics."

These future devices could one day replace invasive procedures, such as implanting brain electrodes to monitor degenerative conditions that affect the nervous system. Other potential healthcare applications include wearable devices for monitoring healthcare -devices like fitness watches, but more integrated with the body, providing sufficiently accurate data to allow doctors to monitor patients without bringing them into the hospital for tests. They could also reveal how to design entirely new types of electrical components impossible using silicon chips, such as transparent components or ones that modify and transmit light in new ways.