Biomass measurement of living Lumbriculus variegatus with impedance spectroscopy

Impedance spectroscopy is a useful tool for non-invasive and realtime measurements of cell suspensions and a variety of biologicaltissues. The objective of this study was the investigation of thedielectric properties of living aquatic worms ( Lumbriculusvariegatus) using impedance spectroscopy in a frequency rangebetween 100 Hz and 10 MHz. We demonstrate a linear relationbetween the worm biomass and the phase response of the signalthereby providing a quick and precise method to determine thebiomass of aquatic worms in situ. Possible applications for non-destructive online biomass monitoring of aquatic worms and otheraqueous organisms are discussed. Furthermore, we show thatgroups of worms fed different diets can be distinguished by themethod presented. These results reveal a close relationshipbetween the nutritional composition of the worms and themeasured phase response. We also demonstrate that the phaseresponse at 90 kHz does not depend on the worm size. In contrast,the response function for the signal at 440 Hz reveals a linearcorrelation of average individual worm size and phase. Therefore,we conclude that the measured phase response at 90 kHz qualifiesas a measure of the total amount of worm biomass present in themeasuring cell, whereas the phase measurement at 440 Hz can beused to estimate the average individual worm size