Acetobacter Biofilm: Electronic Characterization and Reactive Transduction of Pressure

Abstract

The bacterial skin studied here is a several centimeter-wide colony of Acetobacter aceti living on a cellulose-based hydrogel. We demonstrate that the colony exhibits trains of spikes of extracellular electrical potential, with amplitudes of the spikes varying from 1 to 17 mV. The bacterial pad responds to mechanical stimulation with distinctive changes in its electrical activity. While studying the passive electrical properties of the bacterial pad, we found that the pad provides an open-circuit voltage drop (between 7 and 25 mV) and a small short-circuit current (1.5–4 nA). We also observed by pulsed tomography and spatially resolved impedance spectroscopy that the conduction occurs along preferential paths, with the peculiar side-effect of having a higher resistance between closer electrodes. We speculate that the Acetobacter biofilms could be utilized in the development of living skin for soft robots: such skin will act as an electrochemical battery and a reactive tactile sensor. It could even be used for wearable devices.

Electrical potential spiking of kombucha zoogleal mats

“…First, as proposed in [39], the waves of depolarisation, emerging due to metabolically triggered release of potassium, travelling in a bacterial film coordinate the cells’ metabolic states. The excitation wave, recorded as spikes, have been also observed in acetobacter colonies [32, 33].…”

“…If kombucha zoogleal mats acted as ‘continuous’ sheets with non-linear electrical properties and endogenous electrical activity the mats would be fertile substrate for future living electronics and computing devices. Pioneer experiments with acetobacter colonies [32, 33] successfully demonstrated that bacterial films can be used for sensing purposes.…”

Kombucha electronics

“…Electrical properties of kombucha mats can further advance ideas on electricity based integration, and possibly, protocognition of symbiotic organisms [8,9,10,11]. Similar bacterial cellulose mats, for example, produced by Acetobacter aceti colonies, have been shown to feature interesting electrical properties and pressure sensing capabilities [12].…”

Dynamics of electrical resistance of kombucha zoogleal mats

“…We have already demonstrated a potentially unique properties of kombucha mats via analysis of their electrical potential dynamics [33]. We have also shown that acetobacter colonies, which form thick bacterial films, can be used for sensing purposes [34, 35].…”