Our work presents a low-cost biosignal acquisition system, BITalino, based on the Arduino hardware platform; both the hardware and software components are detailed, together with experimental evaluation. This system was designed to be integrated in a biometric platform based on Electrocardiographic (ECG) signals, that will be used for identity recognition. The experimental evaluation revealed that this system is not only capable of ECG signal acquisition, for biometric purposes, but it can also be used as a generic platform for other biomedical applications, greatly extending its applicability. In this paper we describe the proposed platform, with special emphasis on the design principles and functionality. Future work will focus on further developing our hardware, targeting its integration in a prototype system for ECG-based biometric recognition.