Session: 04-17-01: Functional Soft Composites - Design, Mechanics, and Manufacturing

Paper Number: 173516

Stretchable, Conductive, Transparent Cardiac Array for Large-Area, Label-Free Electrical and Optical Studies 

Heart disease imposes an annual economic burden of approximately $219 billion in the United States and accounts for the deaths of about 655,000 Americans each year—roughly 1 in every 4 deaths. A key contributor to these alarming statistics is the limited availability of tools capable of spatiotemporally mapping and modulating cardiac metabolic and electromechanical activity. Such tools are essential for elucidating the complex pathophysiology of heart disease, enabling intraoperative and postsurgical monitoring, and guiding the development of effective and timely clinical interventions. Microelectrode arrays (MEAs) are widely used to probe cardiac excitation wave patterns and localize regions responsible for arrhythmias, while electrical pacemakers and defibrillators remain the cornerstone of clinical therapy for correcting abnormal heart rhythms. However, conventional MEAs are limited in their ability to assess critical cardiac parameters such as intracellular calcium dynamics and metabolic activity. Optical mapping complements these electrical techniques by enabling visualization of these key physiological processes and elucidating their roles in cardiac function under both healthy and diseased conditions. Soft and transparent microelectrodes that allow light to transmit through the microelectrodes in both directions for co-localized crosstalk-free electrophysiology and optical mapping to take the full advantages of each technique. However, significant challenges remain in developing organ-scale, stretchable, and transparent MEAs that are compatible with label-free optical modalities for comprehensive, multimodal mapping of cardiac dynamics. Here, we introduce ultrathin (10 µm), stretchable (up to 100% strain), and transparent (>80% transmittance) MEAs comprising up to 144 channels and covering a centimeter-scale field of view to address these limitations. Each microelectrode is composed of metal nanowires coated with a conductive polymer for electrical recording and pacing. These arrays demonstrate excellent channel uniformity (average 1-kHz impedance of 6.63 ± 0.73 kilohms) and mechanical compliance closely matched to cardiac tissue. We validated our transparent, stretchable MEAs both ex vivo and in vivo using rat models under various cardiac conditions. These devices enable high-resolution mapping of cardiac conduction across all four heart chambers on the curved and continuously moving epicardial surface. They also allow for localized pacing to assess cardiac function during disease progression and therapy. Importantly, the MEAs support synchronized, label-free optical imaging of the native metabolic marker NADH, enabling us to study the relationship between electrical activity and metabolism. Histology and blood analyses confirmed the devices’ biocompatibility. Altogether, our results highlight the potential of these MEAs as powerful tools for precise, multimodal cardiac mapping, with a clear path toward clinical applications.

Presenting Author: Luyao Lu George Washington University

Presenting Author Biography: Luyao Lu received his Ph.D. degree in 2015 from the University of Chicago. He was then a postdoctoral fellow at the University of Illinois Urbana-Champaign and Northwestern University from 2015 to 2018. He joined George Washington University in August 2018 where he is currently an Associate Professor in Biomedical Engineering. His research focuses on innovating bioelectronic technologies, including designing soft electric/semiconductor materials and devices and creating advanced classes of implantable, wearable, and lab-on-a-chip optoelectronic tools, for applications in basic physiology investigations, organs-on-chips, and personalized medicine. He is an author of >30 peer-reviewed publications (>8,000 cites). His research has been recognized by multiple awards, such as the NSF CAREER Award (2024).

Authors:

Luyao Lu George Washington University