Soft electrodes cozy up to cells

Abstract

Measuring the electrical activity of single cells gives biologists new insights into the heart and nervous system, but existing rigid electrodes made of metal or silicon can stress biological tissues and limit the quality of electrical measurements. Now, researchers have made squishy hydrogel electrodes that match the mechanical properties of living tissues and have shown that they can take better readings from heart and nerve cells (Proc. Natl. Acad. Sci. USA 2018, DOI: 10.1073/pnas.1810827115). The unnatural rigidity of flat electrodes or thin wires used to study the electrical activity of single cells can cause stress, leading cells to behave abnormally, including changing their gene-expression patterns. The material mismatch also prevents the cells from nestling up to the electrode and making strong contact. This physical gap causes impedance, or a muffled and noisy electrical signal. These problems are even more acute when working with cardiomyocytes, heart muscle cells that beat even