4.2 Chemical Sensors Using Biological Cells, Molecules, and Methods

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Figure 4.4: A rat taste neuron is grown on a silicon chip and used as a chemical sensor (adapted from [14]).

with a cell culture medium. NO was detected using double potential step chronoamper-

ometry; the specificity was excellent even while being in solution. The detection limit

was 25 nM and 80 nM of NO for a biofilm and separate cultured cells, respectively.

Instead of using cells, receptors and ion channels can be used directly as the sens-

ing element. Here, two examples with different transducer elements will be highlighted.

In one case, the goal was to detect two alcohols, 3-methyl-1-butanol and 1-hexanol, since

salmonella bacteria release them when infecting beef [20]. To that end, a peptide, part of

an odorant-binding protein from Drosophila called LUSH, was used as the sensing/bind-

ing element. The peptide was deposited on a quartz crystal microbalance (QCM) (see Sec-

tion 1.6) and allowed to self-assemble. The change of resonance frequency of the sensor

with and without bound alcohol was measured.