‘Pop-Up’ Electronic Sensors Could Detect When Individual Heart Cells Misbehave

AHA Publisher — Thu, 30 Dec 2021 08:00:24 +0000

University of California San Diego via Newswise – Engineers at the University of California San Diego 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, published Dec. 23 in the journal Nature Nanotechnology, 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). “Studying how an electrical signal propagates between different cells is important to understand the mechanism of cell function and disease,” said first author Yue Gu, who recently received his Ph.D. in materials science and engineering at UC San Diego. “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.” “With this device, we can zoom in to the cellular level and get a very high resolution picture of what’s going on in the heart; we can see which cells are malfunctioning, which parts are not synchronized with the others, and pinpoint where the signal is weak,” said senior author Sheng Xu, a professor of nanoengineering at the UC San Diego Jacobs School of Engineering. “This information could be used to help inform clinicians and enable them to make better diagnoses.” 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. “That’s what makes this device unique,” said Gu. “It can have two FET sensors penetrate inside one cell—with minimal invasiveness—and allow us to see which way a signal propagates and how fast it goes. This detailed information about signal transportation within a single cell has so far been unknown.” To build the device, the team first fabricated the FETs as 2D shapes, and then bonded select spots of these shapes onto a pre-stretched elastomer sheet. The researchers then loosened the elastomer sheet, causing the device to buckle and the FETs to fold into a 3D structure so that they can penetrate inside cells. “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.” The team tested the device on heart muscle cell cultures and on cardiac tissues that were engineered in the lab. The experiments involved placing either the cell culture or tissue on top of the device and then monitoring the electrical signals that the FET sensors picked up. By seeing which sensors detected a signal first and then measuring the times it took for other sensors to detect the signal, the team could determine which way the signal traveled and its speed. The researchers were able to do this for signals traveling between neighboring cells, and for the first time, for signals traveling within a single heart muscle cell. What makes this even more exciting, said Xu, is that this is the first time that scientists have been able to measure intracellular signals in 3D tissue constructs. “So far, only extracellular signals, meaning signals that are outside of the cell membrane, have been measured in these types of tissues. Now, we can actually pick up signals inside the cells that are embedded in the 3D tissue or organoid,” he said. 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, said Gu. “Say you’re measuring the signal speed in one cell, and the signal speed between two cells. If there’s a very big difference between these two speeds—that is, if the intercellular speed is much, much smaller than the intracellular speed—then it’s likely that something is wrong at the junction between the cells, possibly due to fibrosis,” he explained. Biologists could also use this device to study signal transportation between different organelles in a cell, added Gu. A device like this could also be used for testing new drugs and seeing how they affect heart cells and tissues. The device would also be useful for studying electrical activity inside neurons. This is a direction that the team is looking to explore next. Down the line, the researchers plan to use their device to record electrical activity in real biological tissue in vivo. Xu envisions an implantable device that can be placed on the surface of a beating heart or on the surface of the cortex. But the device is still far from that stage. To get there, the researchers have more work to do including fine-tuning the layout of the FET sensors, optimizing the FET array size and materials, and integrating AI-assisted signal processing algorithms into the device. To read the original article click here.

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Do You Have a Ticking Time Bomb in Your Chest That Could Cause a Stroke?

AHA Publisher — Wed, 03 Nov 2021 07:00:22 +0000

Walla! via The Jerusalem Post – More than 30,000 Israelis suffer from atrial fibrillation without knowing it. This is an arrhythmia, a fluctuation in the normal heart rate that is called a “ticking time bomb,” and it significantly increases the risk of having a stroke. A new questionnaire from the Ne’eman Association checks if you’re at risk of having a stroke. Approximately 90,000 Israelis suffer from atrial fibrillation, but 30,000 people don’t know that they have this condition. This means that they walk around with a ticking time bomb in their body that isn’t noticeable and can cause a stroke without any early warning signs. Now a new pilot from the Ne’eman Association seeks to diagnose these people and save their lives with a simple digital questionnaire for people over age 65. “Every year about 20,000 people suffer a stroke that can lead to disability and even death,” said Prof. Natan Bornstein, director of the Neurological Institute at Shaare Zedek Medical Center and chairman of the Israeli Stroke Society and the Ne’eman Association. “Of these strokes, only about 20% are caused by atrial fibrillation and occur in patients with no early symptoms, so in other words many of these cases were diagnosable and preventable.” What Is Atrial Fibrillation? Bornstein explained that atrial fibrillation is a heart rhythm disorder characterized by rapid and irregular contraction of the heart. Irregular heartbeat can cause blood to congeal in the heart and clot. The danger is that these blood clots will leave the heart and reach blood vessels in the brain. As a result, blood and oxygen supply to the brain may be blocked and cause a stroke.This is why atrial fibrillation is one of the major risk factors for stroke. The professor added that studies show that people over age 65 who have been diagnosed with atrial fibrillation are five times more likely to have a stroke as compared to the general healthy population. “Early detection of atrial fibrillation and appropriate drug treatment with anticoagulants can prevent a stroke and therefore it’s crucial to diagnose atrial fibrillation,” he said. The incidence of atrial fibrillation increases with age, and if people have diseases such as diabetes, hypertension, progressive heart failure, vascular disease, obstructive pulmonary disease and overactive thyroid gland, these increase the risk for atrial fibrillation in this age group. As mentioned, the Ne’eman Association, which works to reduce stroke and provides rehabilitative services, is now leading a unique pilot that will identify people at risk for atrial fibrillation by using a digital questionnaire and advanced heart rate monitoring technology, in order to save their lives. The pilot calls on people aged 65 and over to answer a digital questionnaire, which examines their level of risk for latent atrial fibrillation. Participants diagnosed at high risk using the questionnaire will receive at home, for free, an advanced heart rate monitoring device (called a Holter), which is connected 24/7 to a monitoring center in order to find a fibrillation. As part of the pilot, those who are at risk will receive the world’s smallest miniature monitoring device called MonitorNano, which runs an automated algorithm for detecting arrhythmias, which is pre-programmed to detect arrhythmias. The patient has nothing to do but carry it on his body. It’s the smallest wearable monitoring device in the world, only 12 mm thick and weighs only 18 grams. The data received from the monitor is transmitted to the center through the management application installed on a cell phone and analyzed by medical staff. “There is no doubt that if it’s possible to prevent a stroke, of course this is the preferred option,” concluded Pnina Rosenzweig, CEO of the Ne’eman Association. “Early testing to detect those at risk can save lives and this is a way to do so with a simple and free answer. It’s possible to get a professional and quality diagnosis of a significant risk factor and prevent a stroke.” To read the original article click here.

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‘Pop-Up’ Electronic Sensors Could Detect When Individual Heart Cells Misbehave

Do You Have a Ticking Time Bomb in Your Chest That Could Cause a Stroke?