New Slap Bracelet-Like Sensor Studies Heart Cells in Unprecedented Detail

Researchers have created a new kind of sensor that wraps around cultured heart cell tissue, allowing them to study how these cells interact with one another as they would in the human body in response to different treatments.

New slap braclet sensors give entirely new perspective on 3D heart cell structures

Researchers at Carnegie Mellon University (CMU) and Nanyang Technological University in Singapore (NTU Singapore) have built what they call an organ-on-an-electronic-chip platform (OE-chip) that can measure the electrophysiology of cultured heart cells in a three-dimensional structure, offering scientists an unprecedented perspective on how these cells communicate with one another.

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Current methods for studying how different drugs affect heart cells have been limited by physical considerations. "For decades, electrophysiology was done using cells and cultures on two-dimensional surfaces, such as culture dishes," said Tzahi Cohen-Karni, Associate Professor of Biomedical Engineering and Materials Science & Engineering at CMU. "We are trying to circumvent the challenge of reading the heart's electrical patterns in 3D by developing a way to shrink-wrap sensors around heart cells and extracting electrophysiological information from this tissue."

The sensor the researchers have developed, described in a paper published in the journal Science Advances, starts out like a normal, flat, rectangular sensor onto which a cultured, three-dimensional structure of heart cells is placed.

Then, by etching off a bottom layer of germanium called the 'sacrifice layer,' the structural tension holding the sensor flat is broken the same way the tension holding a slap bracelet straight breaks when the curved side of the bracelet hits a person's wrist. Without this tension, the sensor rolls up into a barrel shape just like the slap bracelet does, wrapping itself around the tissue structure.

The researchers used structures known as cardiac spheroids to test their new sensor. These structures are elongated organoids made of heart cells and are about the width of two or three human hairs. By wrapping the sensor around the cell structure in this way, they are able to test the electrical signals that course through the cells with a level of precision that isn't possible with a two-dimensional sensor.

“Mechanics analysis of the roll-up process enables us to precisely control the shape of the sensors to ensure conforming contact between the sensors and the cardiac tissue,” said Jimmy Hsia, former CMU faculty member and now a professor and dean of the Graduate College of NTU Singapore. “The technique also automatically adjusts the level of the delicate ‘touch’ between the sensors and the tissue such that high quality electric signals are measured without changing in the physiological conditions of the tissue due to external pressure.”

The researchers hope that the the sensor will enable the testing of different drugs on processes in cultured heart cells that until now haven't been testable.

"This platform could be used to do research into cardiac tissue regeneration and maturation that potentially can be used to treat damaged tissue after a heart attack, for example, or developing new drugs to treat disease,” said Anna Kalmykov, a Ph.D. student in biomedical engineering at CMU and the lead author of the paper.