Development of a Spontaneous Potential Measuring Device

The developed spontaneous potential (SP) measuring device involves design and construction of non-polarized porous pot as sensing unit, using high input impedance preamplifier with serial output 24 bits analog- to-digital converter, microcontroller and liquid crystal display (LCD) unit. The non-polarizing porous pots were molded using kaolin, clay and sawdust with Aluminum silicate as bound material in the ratio 67:33:1:12 by volume (59.3%, 29.2%, 0.01%, and 10.6%). After molding, it was sun dried for 48 hours and later poured water into it for 3 hours and finally oven dried at temperature 150°C for 6 hours during which the added saw-dust was burnt and created the needed porosity and hardened it. Concentrated solution of one molar Hydrated Copper Sulphate was used as the electrolyte with copper rod as the electrode, and both were put into the porous pot and then sealed off with copper lead points out for connectivity. High input impedance amplifier of ADS1220 analog-to-digital converter was used for the signal conditioner in a differential mode. ADS1220 input is equipped with an electromagnetic interference (EMI) filter to remove noise from electrical installation. The 24-bits serial output o ADC felt into the microcontroller (Arduino Mega 2560) for low voltage signal for measurement and display the value on LCD. The developed SP instrument was calibrated by using a Mastech Multimeter 69702 model and an available SP instrument. The Mastech multimeter and developed SP instrument were compared the correlation is 0.95 and with relative error of 0.00011. The standard deviation obtained was 0.0055. The developed SP instrument was compared with available SP device correlation value was 0.998 with average deviation of ±0.000124. The input resolution of the developed instrument is 0.24μV with minimum and maximum of -2.48 V and +2.48 V respectively.