Electrodeposition of PEDOT on Semi-Spherical PCBs for Enhanced Arthroscopy Probes

Biological systems are increasingly integrated with electronic technology. Arthroscopy probes, particularly those used for knee diagnostics [1], rely on microelectrode arrays to assess cartilage health by measuring its electromechanical response to pressure. The Arthro-BST™ probe, developed by Biomomentum Inc., is one such device that utilizes printed circuit board (PCB)-based microelectrodes. However, conventional metal electrodes suffer from high impedance, which limits efficient electrical signal transmission through tissues and affects measurement accuracy.

To address this challenge, poly(3,4-ethylenedioxythiophene) (PEDOT), an organic conductor with low impedance, high conductivity, electrochemical stability, and biocompatibility [2,3], has been investigated as a coating for microelectrodes. PEDOT was electrodeposited onto nickel-phosphorus (Ni-P) and gold/nickel-phosphorus (Au/Ni-P)-coated electrodes using a galvanostatic potentiometric method, forming a porous structure confirmed by scanning electron microscopy (SEM). PEDOT-coated microelectrodes exhibited a 100- to 1000-fold reduction in impedance at low frequencies (<100 Hz) compared to traditional metal electrodes, significantly enhancing their performance in electromechanical measurements.

Probe functionality was tested using a benchtop Arthro-BST arthroscopy setup. Comparative testing between PEDOT-coated probes and Electroless Nickel Immersion Gold (ENIG)-processed probes revealed that PEDOT-coated electrodes reached electrical equilibrium in PBS within 10 seconds, whereas ENIG electrodes required up to 3 minutes, an impractical delay for arthroscopy procedures. To assess the durability and adhesion of the PEDOT coating to metal substrates, an ongoing concern [4], the coated electrodes underwent autoclaving, sonication in phosphate-buffered saline (PBS), and aging at 60°C for 30 days. Furthermore, PEDOT coatings maintained stability under 100 cycles of mechanically controlled indentation, demonstrating their robustness for surgical applications. This study highlights the potential of PEDOT as a superior microelectrode coating for arthroscopy probes, offering reduced impedance, faster stabilization, and enhanced durability. The findings support the integration of PEDOT into clinical arthroscopy tools, improving efficiency, diagnostic accuracy, and overall surgical outcomes.

References:

1. Changoor, A., Coutu, J. P., Garon, M., Quenneville, E., Hurtig, M. B., & Buschmann, M. D. (2011). Streaming potential-based arthroscopic device is sensitive to cartilage changes immediately post-impact in an equine cartilage injury model. Osteoarthritis and Cartilage.
2. Rossetti, N., Luthra, P., Hagler, J. E., Jae Lee, A. H., Bodart, C., Li, X., & Cicoira, F. (2019). Poly(3,4-ethylenedioxythiophene) (PEDOT) coatings for high-quality electromyography recording. ACS Applied Biomaterials, 2(11), 5154-5163.
3. Bodart, C., Rossetti, N., Hagler, J. E., Chevreau, P., Chhin, D., Soavi, F., & Cicoira, F. (2019). Electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) coatings for implantable deep-brain-stimulating microelectrodes. ACS Applied Materials & Interfaces, 11(19), 17226-17233.
4. Wei, B., Liu, J., Ouyang, L., Kuo, C. C., & Martin, D. C. (2015). Significant enhancement of PEDOT thin film adhesion to inorganic solid substrates with EDOT-acid. ACS Applied Materials & Interfaces, 7(28), 15388-15394.