Electrocardiograph of Twelve Derivations, Low Current Consumption, Powered and Communicated for USB

In this work we present the design and construction of a system for electrocardiography of twelve derivations, low power, suministred by Universal Serial Bus (USB) port, at same time the EKG signal is monitored in this port, the system consists on a circuit of three simultaneous channels that register the electric activity of the patient´s heart in twelve derivations by a 10 terminals cable. The initial amplification is made using the instrumentation amplifier AD 620, continues with a filter of 0.05 Hz in low frequencies and 120 Hz for high frequencies. Once carried out this process the final amplification is made, the electric isolation is by magnetic type, the USB communications are made using a commercial acquisition data system (ADS) model USB-1208 FS that has a resolution of 12 Bits, the program and the control interface for the data acquisition and display of signals coming from the USB port, was developed for the Windows XP operating system, and it was written in DELPHI 7.0 language, the system is powered with 5 V, demands 25 mA, has a CMRR 97dB, input dynamic range of 4 mVplusmn5% and bandwith of 0.05 Hz at 120 Hz, that which make it appropriate to clinical diagnostic.