Biosensing Detection - Bioinspired Approaches for Human-Centric Technologies - page 88

Fig. 3.2 A P3HT layer is able to induce neuronal firing and to restore light sensitivity in explanted
blind retinas. Dose-response analysis of the mean ( s.e.m.) firing rate versus light intensity
performed in degenerate retinas over P3HT-coated Glass:ITO ( red dots ) or Glass:ITO alone ( open
dots ) shows sensitivity to irradiances compatible with physiological levels of illumination

[reproduced with permission from Ghezzi et al. ( 2013 )]

polymer is still only partially understood, its potential impact is clear-cut. The
advantages offered by organic semiconductors are manifold and rely on material
softness, reduced invasiveness, very low toxicity, and enhanced biocompatibility,
no need for external biasing, very limited and spatially confined heat production,
and reduced oxidation/reduction reactions at the interfaces, as a consequence of the
capacitive-like coupling between the artificial and the natural tissue. Another major
advantage is the spatial confinement of the stimulation, which could in principle
improve the limited resolution of traditional implants. There are however many
open issues, regarding in particular the long-term stability of the polymeric mate-
rial, the tolerability over prolonged time in vivo, and the optimization of the device
response, which represent an exciting challenge for material scientists, chemists,
and physicist community, working at the forefront of biomedical technology.

3.7 Perspectives of Bioelectronic Interfaces

The several examples of organic-based devices for biomedical and neuroscience
applications briefly summarized here above give a clear idea of the huge potential
offered by conjugated materials. Reported performances in some cases already
outmatch the ones of traditional inorganic devices, despite the fact that the field
is still in its infancy. There is indeed a lot of room for discovering new possible
applications, improving existing performances, and inventing new devices. Organic
transistors, for instance, would greatly benefit from adopting new-generation,
stable, and high-mobility n-type materials, recently reported in the literature, thus