Debug BioImpedance board

Version-1 of PCB+Firmware for assessing bioimpedance has been created, using AFE4300, ATMEL mc and C like coding. Impedance values are not consistently seen, they vary by many ohms. This needs to be understood and debugged. To do – 1. Validate existing calculations of segmental impedances in code. 2. Current implementation is using FWR mode for impedance measurement. Will change over to IQ mode make any difference? 3. For a constant resistor value, it would be a good idea to scope the SPI interface (DOUT) and check if the readings are reasonably stable 4. Since the body impedance measurements should not change much, it would help to get them to run the ADC at the lowest possible sample rates and check ? 5. Isolation - Check if the cables/connectors are thoroughly isolated from any nearby noise sources. 6. Establish differences in impedances when tested with electrodes made of different material - SS/Ag-coated SS. 7. Analog waveforms probably need to be studied to see signal integrity and to weed out noise. 8. Confirm frequencies to be used and help in derivation of various output vital stats. Of particular interest would be if Bone Mineral Content can be derived. 9. Study impact of electrode design, cable used, pressure applied on the impedance measurement to come up with a prescribed protocol. 10. Design a suitable simulator jig that can be used for calibration and testing.