FPGA-based 16-bit 20 MHz device for the inductive measurement of electrical bio-impedance

A novel FPGA based 16-bit 20 MHz real-time electrical impedance measurement device has been developed. While such device can have several applications, then one of the purposes is to measure and monitor the human cardio-respiratory activity signals by inductive magnetic induction based coupling, where a fine resolution in relatively high frequency range is needed. As such a small form-factor device with affordable price and low power consumption is not commercially available, for wearable personal healthcare, the first prototype of such instrumentation device was developed. The solution uses the Altera Max10 FPGA and the external fast operating 16-bit analog-to-digital and digital-to-analog converters (ADC and DAC) with complementary analog components for signal generation, conditioning and handling. The WiFi data communication is based on a separate ESP8285 chip. The overall solution was tested in the frequency range of analog signals up to 20 MHz, getting 4000 measurement results during every second, what is certainly enough for the real-time presenting of impedance waveforms of such physiological processes as breathing and heart beating.