Ex vivo cultured organoids, tissue slices, and isolated organs are essential models for studying disease mechanisms and evaluating drug responses. Real-time, multisite electrophysiological monitoring is critical for capturing their dynamic behavior. However, conventional microelectrode arrays are limited in dynamic environments due to rigid structures, fixed electrode layouts, and cable constraints. Advances in soft, stretchable electronics offer solutions, but most devices lack active repositioning capabilities. "Magnetically actuated soft robots provide non-contact actuation and high degrees of freedom in biological environments, yet integrating magnetic actuation with electrophysiological sensing remains underexplored." said the author Qianbi Peng, a researcher at Chinese Academy of Sciences, "In this paper, we present a soft electrode platform integrating magnetic actuation and electrophysiological sensing for high-fidelity, multisite monitoring on dynamic ex vivo tissue surfaces."
The soft electrode platform (MSE) utilizes a magnetically actuated design integrated with electrophysiological signal acquisition. Structurally, the MSE features a flower-like shape with a thickness of approximately 200 μm, consisting of three layers: a soft silicone elastomer base for flexibility and biocompatibility, a gold (Au) electrode layer for signal acquisition, and a silicone elastomer encapsulation layer to protect the electrodes and circuits. The platform operates in a closed-loop cycle of "locate-adhere-record-detach," with precise movement and attachment enabled by a magnetic tripolar design, allowing the electrodes to adhere firmly to the target tissue for stable signal acquisition. The MSE relies on external magnetic fields for movement and positioning, with a rotating magnetic field enabling movement and a static magnetic field used for electrode adhesion to the tissue. The electrode records high-fidelity electrophysiological signals on dynamic tissue surfaces, providing multisite monitoring by navigating between different target locations. The platform ensures stable contact with tissue and adapts to dynamic tissue changes, enabling high signal-to-noise ratio data acquisition.
The authors conduct detailed testing and verification of MSE. First, in terms of magnetic actuation, the MSE demonstrated excellent motion control. It was able to navigate accurately under a rotating magnetic field and adhere stably under a static vertical magnetic field. The navigation error was less than 0.5 mm, ensuring precise targeting. Additionally, the MSE's movement speed reached 15 mm/s, with a step-out frequency of 40 Hz under an 8 mT magnetic field, demonstrating excellent maneuverability. For electrophysiological signal acquisition, the MSE's electrodes successfully recorded stable signals from dynamic cardiac tissue. During multisite monitoring of the heart, the signal-to-noise ratios (SNR) were 22.07 dB, 26.03 dB, and 36.34 dB, with the highest SNR exceeding the clinical threshold of 30 dB, highlighting the platform's ability to capture high-quality signals. Moreover, the MSE exhibited excellent stretchability and durability. The electrodes withstood tensile strains of up to 160%, and after over 4,000 stretching cycles, the resistance change remained within 5%, indicating excellent mechanical and electrical stability. Surface morphology analysis revealed microgrooved patterns on the gold surface, enhancing both stretchability and stable contact with tissue interfaces. Overall, the MSE demonstrated outstanding performance in motion control, electrophysiological signal acquisition, stretchability, and durability, proving its potential as a multisite electrophysiological monitoring platform, especially for dynamic biological tissue surfaces.
Despite the excellent performance of the MSE, there are still some limitations. First, the current MSE system operates primarily within a 10 cm³ 3D Helmholtz coil setup, which limits the size of the controllable workspace. As a result, its application to larger organs, such as isolated rabbit hearts or human-derived organoid assemblies, remains constrained. Second, the open three-petal design of the MSE does not fully exploit the stretchability of the electrode material, even though it can withstand tensile strains of over 160%, which is sufficient for surface deformation of heart tissue. Moreover, the attachment quality of the MSE is currently inferred indirectly through impedance changes, which suffer from temporal delays and poor spatial resolution. For instance, localized detachment of a single petal may not be detected in time. "In future research, we will expand the workspace of magnetic field control, improve the design structure of MSE to enhance the contact stability between electrodes and dynamic organs, and integrate real-time feedback mechanisms to improve accuracy and control capabilities." said Qianbi Peng.
Authors of the paper include Qianbi Peng, Jianping Huang, Chenyang Li, Mingguo Jiang, Chenyang Huang, Jinxin Luo, Hanfei Li, Ting Yin, Mingxue Cai, Shixiong Fu, Guoyao Ma, Zhiyuan Liu, and Tiantian Xu.
This work was supported in part by the National Key R&D Program of China (grant 2023YFB4705300), the National Natural Science Foundation of China (grants U22A2064, 52473269, 62471462, and 62403448), the Shenzhen Science and Technology Program (grants JCYJ20220818101611025, RCJC20231211085926038, KQTD20210811090217009, and JCYJ20240813154939050), the Youth Innovation Promotion Association of CAS, the SIAT-CUHK Joint Laboratory of Robotics and Intelligent Systems, the National Natural Science Foundation of China (grant 62473360), and the Guangdong Basic and Applied Basic Research Foundation (grant 2025A1515010715).
The paper, "Magnetically Actuated Soft Electrodes for Multisite Bioelectrical Monitoring of Ex Vivo Tissues" was published in the journal Cyborg and Bionic Systems on Oct. 24, 2025, at DOI: 10.34133/cbsystems.0434.
