Researchers at University of California San Diego have developed a tiny ‘pop-up’ sensor that can measure the electronic signals propagating inside cardiac cells. The technology consists of tiny spike-like protrusions that can penetrate cell membranes without causing damage, and which can detect electrical signals within individual cells and between cells in 3D tissue samples. The device could provide new insights into cardiac diseases, including myocardial infarction and arrhythmias. Cardiac tissue is intrinsically dependent on electrical activity for correct function, and measuring this accurately on a single cell level and intercellularly could provide a wealth of information about the basis for numerous cardiac diseases. However, inserting tiny electrodes into individual cells is difficult and can cause damage. This newest technology aims to provide a less invasive way to achieve this. “Studying how an electrical signal propagates between different cells is important to understand the mechanism of cell function and disease,” said Yue Gu, one of the scientists that led the development of the new sensor. “Irregularities in this signal can be a sign of arrhythmia, for example. If the signal cannot propagate correctly from one part of the heart to another, then some part of the heart cannot receive the signal so it cannot contract.” The basis of the device is an array of tiny field effect transistors that the researchers have coated with a phospholipid bilayer. This coating allows them to penetrate inside the cell without eliciting a foreign body response, which would hamper long-term measurements of electrical activity. The tiny probes are sensitive enough to measure electrical signals within one cell but they can also track signals that travel through several cells. The device features a ‘pop-up’ structure, as the researchers bonded the transistors onto a pre-stretched elastomer sheet, and when they released the tension the transistors erected to form a 3D structure. “It’s like a pop-up book,” said Gu. “It starts out as a 2D structure, and with compressive force it pops up at some portions and becomes a 3D structure.” So far, the UCSD team tested the technology on cardiac cell cultures in the lab, and have already gained some insights into the speed at which signals propagate through individual cells and groups of cells. However, the device may also have potential in researching neurological diseases, and could allow researchers to study the electrical impulses within neurons. Source
