A New Impedance Sensor Based on Electronically Implemented Chaotic Coupled van der Pol and Damped Duffing Oscillators

Abstract

The chaotic behaviour of a system depends on the parameter values, and when the system exhibits such a chaotic behaviour, it is sensitive to the initial conditions. This feature can be used for manufacturing high sensitivity sensors. Sensors based on chaotic circuits have already been used for measuring water salinity, inductive effects, and both noise and weak signals. This article investigates an impedance sensor based on the van der Pol and Duffing damped oscillators. The calibration process is a key point and therefore the folding behaviour of signal periods was also explored. A sensitivity of 0.15 kΩ/Period was estimated over a range from 89.5 to 91.6 kΩ. This range can be adjusted according to the application by varying the gain of the operational amplifier used in this implementation. The development of this type of sensor might be used in medical and biological engineering for skin impedance measurements, for example. This type of chaotic impedance sensor has the advantage of sensing small disturbances and then rapidly detecting small impedance changes within biological materials.