O akci
Bioelectronic implants have revolutionized medical research and treatment, enabling the study of the human brain and offering therapeutic solutions for neurological disorders affecting 1.3 billion people worldwide (1). Deep brain stimulation has effectively managed motor symptoms in Parkinson's patients (2), while responsive neurostimulation devices have reduced epileptic seizures (3). However, challenges related to size, biocompatibility, and long-term functionality prohibit these devices from reaching patients at scale. This has prompted the development of thin-film neurotechnology devices, providing flexibility and improved spatial resolution. However, translating these advances to clinical applications poses challenges, requiring long-term stability and efficacy demonstration.
Using a combination of accelerated aging and electrochemical degradation monitoring, we test the stability of conventional metal-based stimulation implants and compare them to our novel metal-free implants. Specifically we compare electrodes made of gold, electrodes coated with the conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), and electrodes made of PEDOT:PSS (metal free). Conducting polymer coatings are known to offer mixed ionic-electronic conductivity, which improves performance in neural applications. We show that pristine PEDOT:PSS electrodes outperform all other configurations, exhibiting little degradation over an extrapolated aging time exceeding two years. Based on these results, we explore different substrate and insulation materials to further extend the implant lifetime. We identify swelling of PEDOT:PSS as a slow degradation factor and suggest that electrodes made from PEDOT:PSS and polydimethylsiloxane (PDMS) may mitigate this. PDMS, used as a substrate and insulation material, shows promise due to its superior intrinsic strain properties surpassing popular polymers like polyimide and parylene C. I will discuss optimising fabrication methods to develop PDMS/PEDOT:PSS/PDMS devices using lithographic processes.
Finally, I will discuss a proof-of-concept application of these PDMS/PEDOT:PSS/PDMS devices in monitoring and modulating the gastrointestinal system. We demonstrate clinical relevance through the addition of disease specific chemical stimulants, blockers and through electrical stimulation induced contractions to aid gut motility. These devices have the potential to provide clinical insights into complex chronic disorders like irritable bowel syndrome and gastroparesis.
References:
1. Feigin, V. L. et al. Lancet Neurol (2019).
2. Kringelbach, M. L., et al. Nature Reviews Neuroscience (2017).
3. Stacey, W. C., et al. Nature Clinical Practice Neurology (2008).
