The application relates to an apparatus, electronic device and method. The apparatus comprises circuitry configured to provide a direct current signal to a subject. The circuitry is configured to enable switching between a first circuit loop and a second circuit loop. The first circuit loop is configured to enable charging of a capacitor to enable measurement of a first time constant to be obtained where the first time constant is indicative of a charging time of the capacitor. The second circuit loop is configured to enable discharging of the capacitor to enable measurement of a second time constant to be obtained where the second time constant is indicative of a discharging time of the capacitor. The first time constant and the second time constant enable an impedance of the subject to be estimated.
