An ECG monitoring system using android smart phone

An ECG monitoring system is implemented by using an android smart phone, an FPGA chip, a comparator, a resistor, a capacitor and an ECG front-end amplifier circuit. The FPGA chip includes a digital circuit block for delta modulator and a USB 1.1 PHY/LINK. The digital circuit block for delta modulator includes a sampler(D flip-flop), a sinc filter and a FIR filter. The delta modulator consists of the comparator, the resistor, the capacitor and the digital circuit block inside the FPGA. The sampler works at the clock frequency of 6MHz. The delta modulator accepts an analog input voltage up to 1.7kHz in the range from 0.2V to 1.2V and generates an 8bit output at the data rate of 23.4KS/s. The smart phone supplies a 5VDC voltage through a micro USB port to all the circuits including the FPGA chip, the comparator and the ECG front-end amplifier circuit. The measured ECG waveform is displayed on the smart phone, the heart rate is calculated by the smart phone. The measured ECG waveform and the calculated heart rate are stored in a flash memory in the smart phone.