Monitoring of bacteria growth using a wireless, remote query resonant-circuit sensor: application to environmental sensing

A new technique is presented for in-vivo remote query measurement of the co mplex permittivity spectra of a biological culture solution. A sensor compr ised of a printed inductor-capacitor resonant-circuit is placed within the culture solution of interest. with the impedance spectrum of the sensor mea sured using a remotely located loop antenna; the complex permittivity spect ra of the culture is calculated from the measured impedance spectrum. The r emote query nature of the sensor platform enables, for example, the in-vivo real-time monitoring of bacteria or yeast growth from within sealed opaque containers. The wireless monitoring technique does not require a specific alignment between sensor and antenna. Results are presented for studies con ducted on laboratory strains of Bacillus subtilis, Escherichia coli JM109, Pseudomonas putida and Saccaromyces cerevisiae. (C) 2001 Elsevier Science B .V. All rights reserved.