Pop-Up Image
Device with a scaled-up FET sensor array for measuring electrical signals in a 3D cardiac tissue construct. (Credit: Yue Gu)

Engineers have developed a powerful new tool that monitors the electrical activity inside heart cells, using tiny “pop-up” sensors that poke into cells without damaging them. The device directly measures the movement and speed of electrical signals traveling within a single heart cell — a first — as well as between multiple heart cells. It is also the first to measure these signals inside the cells of 3D tissues.

The device could enable scientists to gain more detailed insights into heart disorders and diseases such as arrhythmia (abnormal heart rhythm), heart attack, and cardiac fibrosis (stiffening or thickening of heart tissue).

The device consists of a 3D array of microscopic field effect transistors, or FETs, that are shaped like sharp pointed tips. These tiny FETs pierce through cell membranes without damaging them and are sensitive enough to detect electrical signals — even very weak ones — directly inside the cells. To evade being seen as a foreign substance and remain inside the cells for long periods of time, the FETs are coated in a phospholipid bilayer. The FETs can monitor signals from multiple cells at the same time. They can even monitor signals at two different sites inside the same cell.

The team’s experiments led to an interesting observation: signals inside individual heart cells travel almost five times faster than signals between multiple heart cells. Studying these kinds of details could reveal insights on heart abnormalities at the cellular level.