First prototype realised by the University of Minnesota with a 3 D printer specifically customised for printing on hemispherical surfaces
A team of researchers at the University of Minnesota has succeeded in printing, for the first time, a series of photoreceptors arranged on a hemispherical surface. This achievement is an important step towards the realisation of a 'bionic eye', which in the future could actually be useful for restoring sight in blind people.
The research was published in Advanced Materialsa peer-reviewed scientific journal dealing with new developments in biomaterials.
To arrive at the 3 D prototype, the scientists made a hemispherical dome with the aim of understanding how to overcome the difficulties in printing electronic components on a curved surface. From this artefact, the researchers built a customised 3 D printer using an ink-base with silver particles and after numerous attempts succeeded in getting the ink dispensed to stay in place and consolidate evenly (whereas normally ink tends to slide along curved surfaces). In the final stage, the scientists used materials containing a semiconductor polymer to print the photodiodes, which can convert light into electrical impulses. Current was generated when photons were absorbed into the photodiode.
Once the technique was fine-tuned, the total duration of the entire printing process was reduced to one hour.
Dr. McAlpine commented that the most astonishing part of this experiment was the efficiency of 25% in converting light into electricity, achieved by 3 D-printing semiconductors.
Dr McAlpine and his team are known for integrating 3 D printing, electronics and biology into a single platform. A few years ago, the same team was in the international spotlight for the printing of a 'bionic ear', which was followed by 3 D printing of artificial organs similar to natural ones for surgical practice, a tissue based on electronic material that could be used as 'bionic skin', electronic components directly on the moving hand, and cells and prostheses to help people living with spinal cord injuries regain some functionality.
In the case of the bionic eye, Dr. McAlpine has a strong personal drive: "My mother is blind in one eye and every time I talk to her about my work she asks me 'When are you going to print a bionic eye for me?'
The next development steps include the realisation of a prototype with a larger number of photoreceptors, even more efficient in the impulse transmission process.
Source
Park SH, Su R, Jeong J, et al. 3D Printed Polymer Photodetectors. Adv Mater. 2018 Aug 28:e1803980. doi: 10.1002/adma.201803980.
Dr. Carmelo Chines
Direttore responsabile
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