The stability and relative activity of the Fc12-PF6/MO/GOx bioelectrode were monitored over a period of 30 days, and the results are presented in Figure . Notably, during the first 10 days of the measurement period, the relative activity remained close to 100%. In contrast, the earlier system Fc12-Br/MO/GOx lost 60 % of its activity by day 10.