A sensor has been described for E. coli O157:H7 where the
target is captured on antibody modified paramagnetic nanobeads
then detected via impedance spectroscopy (Varshney,
Li, Srinivasan, & Tung, 2007). Although the assay time was
only 35 min the lower detection limitwas 4e5 log cfu/gwhich
is above that required for ground beef testing that requires
detection of 1 cfu/25 g (Table 1).