Organic Microbial Electrochemical Transistor Monitoring Extracellular Electron Transfer

Abstract

Extracellular electron transfer (EET) denotes the process of microbial respiration with electron transfer to extracellular acceptors and has been exploited in a range of microbial electrochemical systems (MESs). To further understand EET and to optimize the performance of MESs, a better understanding of the dynamics at the microscale is needed. However, the real-time monitoring of EET at high spatiotemporal resolution would require sophisticated signal amplification. To amplify local EET signals, a miniaturized bioelectronic device, the so-called organic microbial electrochemical transistor (OMECT), is developed, which includes Shewanella oneidensis MR-1 integrated onto organic electrochemical transistors comprising poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) combined with poly(vinyl alcohol) (PVA). Bacteria are attached to the gate of the transistor by a chronoamperometric method and the successful attachment is confirmed by fluorescence microscopy. Monitoring EET with the OMECT configuration is achieved due to the inherent amplification of the transistor, revealing fast time-responses to lactate. The limits of detection when using microfabricated gates as charge collectors are also investigated. The work is a first step toward understanding and monitoring EET in highly confined spaces via microfabricated organic electronic devices, and it can be of importance to study exoelectrogens in microenvironments, such as those of the human microbiome.

High‐Gain Chemically Gated Organic Electrochemical Transistor

“…Judicious side chain engineering [ 1–7 ] or blending with polyelectrolytes facilitates mass transport in aqueous environments to successfully interface with biological systems. [ 8 ] These unique properties enable their application in electrochemical devices, including biosensors, [ 9–12 ] actuators, [ 13 ] energy storage materials, [ 14 ] transistors, [ 15 ] or neuromorphic devices. [ 16 ]…”

“…[ 35 ] Another approach would be to utilize a polarizable OMIEC‐based gate electrode where the ET reaction is limited to the gate, allowing the gate's work function, and V T , to shift. [ 11 ] While this design circumvents some of the limitations of operating OECTs amperometrically, it remains suboptimal for sensing. For instance, as the ET reaction is conducted in an electrolyte shared by both the gate and channel, diffusion of redox‐active species may lead to additional unintended side reactions on either the channel, the gate, or both.…”

Nanomaterials Facilitating Microbial Extracellular Electron Transfer at Interfaces

“…successfully integrated microfabricated organic microbial electrochemical transistor with the exoelectrogenic bacteria S. oneidensis MR‐1 by depositing the bacteria onto the 0.25 mm 2 transistor gate. [ 153 ] This platform has a potential to capture very subtle differences in EET response from a small number of bacteria. Second, nanomaterials can provide a unique platform to investigate behavior of EAMs.…”

Neural Networks Predicting Microbial Fuel Cells Output for Soft Robotics Applications

“…Turing completeness with cellular automata has been reported using MFCs that make reference to additional pins - akin to transistors - which has been shown to solve the Game of Life algorithm, as an example where MFCs can be used as information processing units ( Tsompanas et al, 2017b ). Finally, advancements in materials science have made bacterial communities, such as Shewanella oneidensis, integration into organic electronics (PEDOT-PSS) possible, resulting in organic microbial electrochemical transistors ( Méhes et al, 2020 ), i.e. the building blocks of computation.…”