Electroencephalogram (EEG) signals play a vital role in the prediction of mental disorders. The impedance between the EEG electrodes and the skin contact should be minimum to get low-noise EEG signals. This work focuses on an intelligent, wearable device capable of measuring the EEG signals in a non-invasive manner in parallel to ESI measurement. The device includes an analog front end (AFE) amplifier, back-end micro-controller (BEMC), and electrode-skin interface impedance (ESI) measuring unit. A novel technique is used for measuring ESI by connecting a fixed resistance at the input terminals of the low noise amplifier in a parallel manner and measuring the change in the signal. This unique technique is suitable in portable medical devices as it is safe and consumes negligible power (27mW). A PCB prototype is developed using the available commercial components. The designed prototype has a small form factor (52mm X 53mm), lightweight, and easily behind the ear wearable.