**Author details**

*Biosensors for Environmental Monitoring*

**4.3 Biosensors for drug residue detection**

**5. Conclusion**

**Abbreviations**

ity of the electrodes are analyzed.

*I*(*t)* current response *V*(*t)* applied voltage (Δt) time interval φ phase shift *Z*(ω) impedance

*V*(*t)* voltage-time function *I*(*t)* current-time function

*R*<sup>s</sup> resistance of the electrolyte CPE constant phase element *R*ct charge-transfer resistance *W* the Warburg impedance *C*dl double-layer capacitance BSA bovine serum albumin Au-NPs gold nanoparticles MC-LR microcystin-LR

WHO World Health Organization NG nitrogen-doped graphene CFU colony-forming unit

DC direct current

et al. fabricated an impedimetric paper-based biosensor for the detection of bacterial contamination in water [73]. They used lectin *concanavalin A* as a bioselective element due to its stability to interact with mono- and oligosaccharides on bacterial

A good overview about aptamer-based EIS biosensors to determine different

Jacobs et al. use an EIS-based microdevice, coupled with a nanoporous membrane and functionalized antibodies, to detect erythromycin in different water sources—drinking water and river water [75]. The limit of detection in drinking water was found to be around 0.1 ppt. In milk the allowed maximum residue level for erythromycin is 40 ppb. In the river water, the sensitivity is usually lower because of the organic matter in it that can interfere with binding of erythromycin. The limit of detection in the river water samples was around 1 ppt. The overall impedance change was still large enough to show if the concentrations of erythro-

In this overview main challenges and limitations of impedance biosensors, including the complexity of impedance detection, susceptibility to non-specific binding, challenges with the sensitivity, limitations to small molecule, and reusabil-

cells. The detection limit was approximately 1000 CFU/ml.

groups of antibiotics in water samples is presented in Ref. [74].

mycin are in a range of suitable or unsuitable for drinking.

EIS electrochemical impedance spectroscopy

IUPAC International Union of Pure and Applied Chemistry

**60**

Kairi Kivirand1,2\*, Mart Min1 and Toonika Rinken<sup>2</sup>

1 Thomas Johann Seebeck Department of Electronics, Tallinn Technical University, Tallinn, Estonia

2 Institute of Chemistry, University of Tartu, Tartu, Estonia

\*Address all correspondence to: kairi.kivirand@ttu.ee

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
