Flexible electronics, which can be injected into synthetic cavities and living tissue through a needle with a diameter as small as 0.1 mm, are reported online this week in Nature Nanotechnology. The electronics, composed of a mesh of electrodes, unfold to their original shape in less than an hour following injection and have been used to monitor brain activity in live mice.

Flexible and stretchable electronics could allow for continuous monitoring and manipulation of the properties of 3D structures, such as biological tissue. Previous research has shown that these electronics can be surgically implanted; however, their controlled delivery to specific regions and non-invasive implantation has not yet been possible.

Now, Charles Lieber, Ying Fang and colleagues have designed mesh-shaped electronics that can be loaded into a syringe and injected into specific regions of synthetic cavities or living tissues. The authors show that once injected, the ‘rolled up’ electronics unfold to approximately 80% of their original configuration with no loss of function. The authors injected the electronics into two distinct brain regions in live mice and found that they produced no immune response over a period of five weeks and were able to network with healthy neurons. Also, when the electronics were injected into the hippocampus of the mice, the authors found that they could monitor brain activity with limited damage to the surrounding brain tissues.

In an accompanying News & Views, Dae-Hyeong Kim and Youngsik Lee write, “Further integration of the injectable electronics with other functional units and/or wireless components is expected to lead to promising pathways for innovations in implantable bioelectronics and continuous biomonitoring.”