Let There Be Light

Harnessing the interaction between light and matter has become an increasingly important approach when developing bio-inspired systems, such as optoelectronic synaptic devices. Where current optoelectronic devices rely on complex materials often lacking key biological features, organic photoelectrochemical transistors (OPECTs) leverage the properties of conjugated polymers, paving the way for more versatile devices that are better suited to biological systems.

Expanding on this, an international team of researchers led by Francesca Santorohas have developed an innovative OPECT device featuring an azobenzene-based organic neuro-hybrid building block to mimic the retina’s structure. The device is able to emulate visual pathways and dually operates with both optical and electrical functions, enabling light dependent conditioning and extinction processes that accurately mimic synaptic neural functions, including short- and long-term plasticity.

Here, we speak with one of the researchers, Ottavia Bettucci, who delves deeper into the work – and the potential of the innovative device.

Why did you aim to mimic the retina with your OPECT device?
 

Bioelectronics is a branch of science that combines biology and electronics through devices capable of interacting with biological systems. Our idea was to fabricate a device capable of not only interacting with biological cells, but also emulating some biological behaviors under an appropriate stimulus. Our stimulus was light.

How does the system work?
 

In the device there is a light-sensitive part, developed entirely by our team, which is made of an organic material – a polymer. This polymer can modulate the electrical current produced by the device when light interacts with it. In simple terms, this new material can act as the photoreceptor cells in our eye that transform light into electrical signals – which are subsequently transferred to the brain and allow us to see.

What makes this system different from others with a similar goal?
 

The new light-sensitive material we developed has non-toxic, organic components. It’s flexible and allows bidirectional ions–electrons communication, just like a biological system. Because of this, it can be integrated into biological systems that use electrical signals produced by ions to communicate. Such properties allow our device to work much better than conventional semiconductor components made of silicon, which are rigid and only work with electrons.

What are the potential applications of the device?
 

The development is, so far, only a proof-of-concept. However, with deeper investigation and optimization, it is possible that our chip could use the organic components to actively intervene in the communication pathways of cells. In doing so, the device could correct errors in the processing and transmission of information that occur in neurodegenerative diseases such as Parkinson’s or Alzheimer’s disease, or in issues with supporting organs that no longer function properly.

What lies beyond proof of concept?
 

The future steps of this project are varied. One such area would be studying similar materials to mimic different biological behaviors with different light triggers. However, the most interesting possibility is the potential of coupling our chip with biological neurons to prove that it could function as an artificial synapse.