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Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session E

Poster W2 - Optimization of Sensing and Actuation Capabilities of PCB-based Electrodes

Saturday, October 26, 2024

10:00 AM – 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Jason Chen (he/him/his)

MPower Fellow Graduate Assistant
Robert E. Fischell Institute for Biomedical Devices
College Park, Maryland, United States

Co-Author(s)

Quinton Burke, M. Eng

Research Engineer
Robert E. Fischell Institute for Biomedical Devices, United States
Chen-Yu Chen, PhD

Post-doctoral Fellow
Bentley Lab
Beltsville, Maryland, United States
JR

John Rzasa, PhD

Associate Research Engineer
Robert E. Fischell Institute for Biomedical Devices, United States

Primary Investigator(s)

WB

William Bentley, PhD

Distinguished Professor
University of Maryland, United States

Introduction: The growing accessibility of printed circuit boards, or PCBs, has spurred their research as a cost-effective alternative to commercial electrodes for electrochemistry. These PCBs can be customized through many electronic design programs available to academic institutions. The versatility of PCBs to function as electrodes is enabled by their modern manufacturing process. Specifically, a thin layer of gold is applied to the surface of the PCB as part of its ENIG finish that prolongs the lifespan of the PCB. Gold is ideal for electrochemistry due to its high conductivity and biocompatibility [1]. Our design features an all-gold working, counter, and reference electrode layout. A downside of PCB electrodes is their inconsistent build quality. These minor differences are usually insignificant when used as they were intended—in electronics—but they prove troublesome when repurposed as an electrode for sensitive electrochemistry applications [2]. Our aim is to provide a framework for designing, testing, and validating the efficacy of PCB electrodes to ultimately incorporate them into low-cost devices. We are not only calibrating these PCB electrodes for sensing, but also for actuating, targeting engineered E. coli that are responsive to hydrogen peroxide produced by the PCB electrode.

Materials and

Methods: The PCBs were designed in Autodesk Fusion 360 (San Francisco, California). The design files were then submitted to Digikey Red (Thief River Falls, Minnesota). The E. coli is deposited on the electrode with a thiolated polyethylene glycol (PEG-SH) hydrogel by supplying an oxidizing potential. Hydrogen peroxide, or H2O2, is then generated using a reducing potential. In response, the cells produce the quorum-sensing molecule autoinducer-1, or AI-1, whose concentration can be approximated using a cell-based luminescence assay. Ferrocene was used as a redox mediator for electrochemical analysis.

Results, Conclusions, and Discussions: Results and

Discussion:
A positive correlation between magnitude of charge supplied and the hydrogel thickness was found. Additionally, there was a correlation between hydrogel thickness and level of AI-1 produced, shown in Figure 1e. Our most recent results support a correlation between the magnitude of charge supplied and the amount of H2O2 generated, as well as between H2O2 levels and AI-1 levels. Gel thickness was indirectly characterized through the intensity of fluorescence of the deposited hydrogel labeled with fluorescein. H2O2 concentrations were approximated using Pierce peroxide assay.

Conclusions:
PCB electrodes must go through a quality assessment, such as running and comparing CVs, to ensure reliability prior to use; poor sensing capabilities often translated to poor actuation. The next steps involve verifying hydrogel and cell deposition, the production of hydrogen peroxide, and finally the production of AI-1 by the deposited cells. The validation of these steps brings us closer to the incorporation of PCBs into affordable sensor devices capable of characterizing their environment through CVs and providing feedback by generating more or less H2O2 and thus AI-1.

Acknowledgements (Optional): We would like to thank the MPowering the State Entrepreneurship Fellowship and the Gordon and Betty Moore Foundation for their support.

References:
[1] Waseem U. Understanding the ENIG finish: A comprehensive guide. Wevolver. October 31, 2023. Accessed July 20, 2024. https://www.wevolver.com/article/understanding-the-enig-finish-a-comprehensive-guide.
[2] Zupančič U, Rainbow J, Estrela P, Moschou D. Utilising Commercially Fabricated Printed Circuit Boards as an Electrochemical Biosensing Platform. Micromachines (Basel). 2021;12(7):793. Published 2021 Jul 3. doi:10.3390/mi12070793