Implantable micro-Electrode Array for Long-term ECG Recording in Zebrafish
Zebrafish is an emerging model for cardiac electromechanical coupling owing to its regenerative capacity after 20% ventricular amputation. We hereby developed a micro-electrode array (MEA) for both long-term and real-time monitoring of zebrafish electrocardiogram (ECG) in response to injury and regeneration. The gold sputtered 5-lead MEA was formed on a parylene base by micro-fabrication processes (Fig. 1A). To test the MEA, we sedated Zebrafish in 0.04% tricaine methanesulfonate, followed by a 2-mm-long horizontal incision at 0.5 mm caudally to the heart. The MEA was embedded into the incision site so that the four working electrodes (WE) were close to the heart and the reference electrode (RE) positioned on the fish body. The entire device was then secured by medical epoxy (Fig. 1B). The ECG signal recording was performed by connecting the MEA to a differential amplifier and a computer loaded with Labview. The signal was processed using wavelet transform and thresholding algorithm. The ECG obtained from the top working electrode is shown in Fig. 1C. The processed data were comparable with ECG recorded by conventional electrodes in terms of signal-tonoise ratio (SNR) and patterns. The implantable devices remained attached to zebrafish for several days, allowing for reliable long-term and multi-site recordings for heart regeneration research.