Wearable flexible micro electrode for adult zebrafish long term ecgmonitoring

During the last decade, close resemblance between the zebrafish heart and human heart physiology has been discovered [1] andzebrafish (Danio rerio) has become an emerging animal model for studying side effects developmental drugs may impose on the heart [2][3]. More interestingly, contrary to human heart the zebrafish heart has a remarkable ability to “regenerate” after severe injury [4], making it also a popular model for studies of regenerative medicine. On the other hand, Electrocardiogram (ECG) is a widely used tool to monitor the physiological changes of the zebrafish heart. However, due to its in-water habitat, a long term ECG monitoring solution, although very much needed, was not present. All published adult zebrafish ECG recorded to this date have been done acutely with anesthetized fish. This work presents, for the first time a wearable flexible parylene (PA) micro-electrode that monitors the Adult Zebrafish ECG long term. We show here the design, fabrication and testing of the flexible electrode along with a micro-molded ultra-soft, density adjusted silicone jacket, allowing ECG recording to be carried under water, in the fish´s natural habitat with no need for anesthesia.