Time-Constant-Domain Spectroscopy: An Impedance-based Method for Sensing Biological Cells in Suspension

TL;DR

This paper presents a novel impedance-based, label-free method using the distribution of relaxation times to analyze biological cells in suspension, providing a robust electrical fingerprint for sensing and characterization.

Contribution

It introduces the time-constant-domain spectrum (TCDS) technique, enabling detailed analysis of biological cells without complex models or prior knowledge.

Findings

TCDS effectively differentiates cell types and compositions.

High sensitivity and resolution in detecting biological samples.

Impedance measurements from 1 kHz to 1 MHz are sufficient for analysis.

Abstract

Impedance measurement is a common technique to characterize and detect the electrical properties of biological cells. However, to decode the underlying physical processes, it requires complex electrical models alongside prior knowledge of the sample under study. In this work, we introduce an attractive label-free method for sensing biological cells in suspension based on the measurement of electrical impedance and the distribution of relaxation times (DRT) model. The DRT maps impedance data from the frequency-domain to a time-constant-domain spectrum (TCDS) being a useful and robust method for data analysis. We perform impedance measurements in the range from 1 kHz to 1 MHz to obtain the TCDS for sensing mimic samples as well as HeLa cells in suspension. Results show that the TCDS can be seen as an electrical fingerprint for the sample, as it can decode useful information about the composition and structure with high sensitivity and resolution.