The Design of Contactless Conductivity Sensor for Biological Tissues

The magnetic induction measurement system could estimate the conductivity distribution on interesting region by contactless measuring the coupling field of receiver coil. Therefore, the magnetic measurement system could remove the effects of contact impedance between skin and electrode. For biological tissue measurement, the ratio between the primary and secondary field can be up to 10000:1. In order to extract the part of induced current, the primary voltage must be removed from the measured signal. In this paper, we propose a contactless conductivity sensor with the differential receiver coil alignment for the measurement of biological tissues. The performance of the contactless conductivity sensor could be improved by utilizing a differential receiver coil alignment to compensate the primary field. In our experiment, the sensitivity and one-dimension spatial resolution are applied to evaluate the performance of the proposed sensor. The experimental results show that the proposed sensor has high sensitivity to saline with different conductivity. The experimental results also show the feasibility of distinguishing the conductivity of biological tissues.