This paper presents several aspects of in vivo biocompatibility tests using the animal model, considering conductive electrodes based on cotton fabric and a conductive paste-based polymeric matrix with copper microparticles that offer the potential to be used in medical devices. Additionally, this work presents a potential application of the electrodes for temperature sensors using the Arduino development board. In addition, after performing in vivo tests, analysis of the primary irritation scores, animal irritation scores, and cumulative irritation index showed that the electrodes resulted in a negligible measurement of perceived skin irritation.