Ramp-Response Time-Domain Dielectric Spectroscopy: Proof of concept numerical analysis

Dielectric Spectroscopy (DS) probes the interaction of matter with time-varying electric fields on frequencies ranging from mHz up to THz. In the lumpedelements approach, the high-frequency limit can reach the hundreds of MHz. DS has gained great interest in biomedical applications. Current methodologies for assessing the complex dielectric permittivity offer advantages and drawbacks. In this context, developing a new measurement approach may offer distinct advantages not found in existing techniques. We present a novel time-domain method, which entails placing the material of interest in a capacitor sample cell connected to a pair of Operational Transconductance Amplifiers (OTA) serving as a gyrator to invert its impedance. The system’s voltage response to a current ramp renders a step-response of the dielectric permittivity (i.e., in the time domain). Fitting the response voltage to dielectric models (e.g., Debye, Cole-Cole) provides the full spectrum model of the complex permittivity. The significance of this development lies in the directness of its results obtained rapidly while being cost-effective. It must be noted that the high-frequency limit of the system is constrained by the component specifications, primarily the OTA.