# Femtosecond Laser Micropore-Enhanced Miniaturised PCB-Based Microbial Fuel Cell Biosensor for Toxicity Detection

## TL;DR

A small, low-cost biosensor using a microbial fuel cell with a laser-treated anode detects toxic substances like formaldehyde.

## Contribution

A femtosecond laser micropore-enhanced PCB-based MFC biosensor for miniaturized toxicity detection is developed.

## Key findings

- Femtosecond laser processing created micropores on the anode without damaging the PCB or electrodes.
- Micropores increased surface area and hydrophilicity, improving microbial adhesion and sensor performance.
- A 0.1% formaldehyde solution significantly reduced the biosensor’s output power, demonstrating its sensitivity.

## Abstract

This study presents a low-cost, small-scale single-chamber microbial fuel cell (MFC) toxicity biosensor fabricated on a printed circuit board (PCB) and a 3D-printed chamber with a volume of 120 μL. The anode consists of a screen-printed carbon electrode on the PCB, while the air cathode is a carbon paper electrode. To address poor adhesion of microorganisms to the smooth anode surface, femtosecond laser processing was used to fabricate a micropore array with 40 μm pores on the electrode. This method can create micropores on the anode surface without damaging the screen-printed electrodes, the PCB substrate, or the pads. These micropores increase the anode’s surface area and hydrophilicity, allowing more microbial coatings to firmly adhere to its surface. In this study, the MFC utilised Rhizobium rosettiformans W3, extracted from activated sludge at a wastewater treatment plant, as the anode microorganism. Its aerobic nature simplifies the design of MFCs, enabling a single-chamber structure and miniaturisation. Using formaldehyde solution as a toxicity sample to test the biosensor’s performance, a 0.1% concentration significantly reduced the sensor’s output power.