In this paper, we describe an in situ sensor for estimating bacterial concentration in a lab-scale fermentor using impedance spectroscopy. We constructed the impedimetric biosensor using a gold-coated silicon wafer, PDMS polymer, and a borosilicate glass tube. An advantage of using these materials was that we could make a plug-type, disposable electrode. We compared the impedimetric differences between bacterial cells, culture media, and metabolic by-products. We measured real-time impedance changes of an E. coli solution at 0.01 MHz frequency of applied AC for 13 h, and correlated them with the bacteria concentration as estimated by a hemocytometer. In conclusion, impedance increased and reactance decreased during the measurement period, as the concentration of E. coli increased. The correlation between the E. coli concentration and the impedimetric data was linear.
Bibliographical noteFunding Information:
This work was supported by National Core Research Center (NCRC) for Nanomedical Technology of the Korea Science & Engineering Foundation (Grant no. R15-2004-024-01001-0) and Seoul Research & Business Development (Seoul R&BD Program, 11128).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry