Abstract

Electroactive microbes can form conductive biofilms that serve as living electronic biomaterials, integrating the dynamic functionality of living cells with the input-output properties of electronic components. Creating these living electronics requires precise control over biofilm formation on solid-state electrodes to characterize and harness the electronic properties of the biotic-abiotic hybrids. However, native biofilm formation on electrode surfaces often results in films that are non-uniform or too thin for reliable and reproducible electronic measurements and applications. Here, a protocol is presented that utilizes a light-induced genetic circuit in the model electroactive bacterium Shewanella oneidensis to enable the precise spatial patterning of conductive biofilms on electrodes using light. This so-called biofilm lithography approach can be performed using either a simple projector or a light-emitting diode array. The controlled patterning allows for tunable biofilm conduction dependent on pattern size. By utilizing these defined geometries and measuring the resulting conduction currents through biofilms, this method enables accurate quantification of the intrinsic living material conductivity. Overall, this protocol presents a facile approach for controlling electroactive biofilm formation on electrodes, which may facilitate further advances in both studying and harnessing bioelectronics.