Fig. 8.

Contact resistance measurements under vacuum. a Micrograph of a single periplasmic fibre sheath on a SiO₂ electrode stretched across 11 consecutive Au contacts (each 100 µm wide) separated by non-conductive interspacings (each 100 µm wide). The inset shows a close-up of one bridged interspacing defined by the white rectangle. b Long-term current measurement across a single non-conductive interspacing at constant bias of 100 mV. The resistance across this non-conductive interspacing was repeatedly measured over a 4-week span and remained within 10% of the initial value. c Resistance across nine consecutive non-conductive interspacings as measured by two-probe (red line) and four-probe (blue) methods. The difference (green line) represents the contact resistance