Abstract: A device for detecting electrical impedance by utilizing a theory of excitation and response signals and method thereof, wherein the excitation signal is a square wave excitation current signal (1), the response signal on a target is transformed to a square wave signal with appropriate amplitudes by buffering, amplifying, RC filtering and differential amplifying, then is transformed to a digital signal at a proper time by an analog-to-digital converter. The response signal is sampled once when at high level and once when at low level for every circle by the ADC, and a sample V1 and a sample V2 are obtained respectively, difference of the samples is taken as a detecting result for one circle. An average value of the detecting result from a plurality of circles is taken as a final result. Information of electrical impedance is illustrated by the final result because the excitation current signal is constant.

Abstract: An electrical impedance detecting device of a portable electrical impedance imaging system by utilizing a theory of sending excitation signal and detecting response signal and a method thereof, wherein the excitation signal is a constant square wave excitation current signal, the response voltage signal on a target is transformed to a square wave signal with appropriate amplitudes by buffering, amplifying, RC filtering and differential amplifying circuits, and then is transformed to a digital signal at a proper time by an analog-to-digital converter. The response voltage signal is sampled once when at high level and once when at low level for every circle of the square wave signal by the ADC, and a sample V1 and a sample V2 are obtained respectively, difference of the sample V1 and the sample V2 is taken as a detecting result for one circle. An average value of the detecting result from a plurality of circles may be taken as a final result.