A simple retinal prosthesis has been developed in cooperation between Tel Aviv University in Israel and Linköping University in Sweden. Fabricated utilizing cheap and widely-available natural pigments used in printing inks and cosmetics, it includes small pixels like a digital camera sensor on a nanometric scale. Researchers hope it may restore sight to blind people.
Researchers led by Eric Glowacki, chief researcher of the organic nanocrystals subgroup at the Laboratory of Organic Electronics, Linköping University, have developed a tiny, simple photoactive film that transforms light impulses into electric signals. These signals in turn stimulate neurons (nerve cells). The study team has chosen to concentrate on a particularly pressing application, artificial retinas which could later on restore sight to blind people. The Swedish team, specializing in nanomaterials and electronic devices, worked with researchers from Israel, Italy and Austria to optimise the tech. Experiments in eyesight restoration were completed by the group of Yael Hanein at Tel Aviv University in Israel. Yael Hanein’s group is a world-leader in the interface between electronics and the nervous system.
The outcomes have recently been released in the journal Advanced Materials.
The retina consists of several thin layers of cells. Light-sensitive neurons at the rear of the eye convert incident light to electrical signals, while other cells process the nerve impulses and transmit them along the optic nerve into an area of the brain called the”visual cortex.” An artificial retina might be surgically implanted into the eye if a person’s sight has been lost as a result of the light-sensitive cells becoming degraded, thus failing to convert light to electrical pulses.
The artificial retina is made up of thin circular film of photoactive material, and is much like an individual pixel in a digital camera sensor. Each pixel is truly microscopic – it’s roughly 100 times thinner than a single cell and has a diameter smaller than the diameter of a human hair. It consists of a pigment of semi-conducting nanocrystals. Such pigments are cheap and nontoxic, and are widely utilized in commercial makeup and tattooing ink.
“We have optimised the photoactive film for near-infrared light, since biological tissues, such as bone, blood and skin, are most transparent at these wavelengths. This raises the possibility of other applications in humans in the future,” states Eric Glowacki.
He describes the artificial retina as a microscopic doughnut, with the crystal-containing pigment at the center and a very small metallic ring around it. It functions with no external connectors, and the neural cells are triggered with no delay.
“The response time must be short if we are to gain control of the stimulation of nerve cells,” states David Rand, postdoctoral researcher at Tel Aviv University. “Here, the nerve cells are activated directly. We have shown that our device can be used to stimulate not only neurons in the brain but also neurons in non-functioning retinas.”
David Rand, Marie Jakešová, Gur Lubin, Ieva Vėbraitė, Moshe David-Pur, Vedran Đerek, Tobias Cramer, Niyazi Serdar Sariciftci, Yael Hanein, Eric Daniel Głowacki. Direct Electrical Neurostimulation with Organic Pigment Photocapacitors. Advanced Materials, 2018; 1707292 DOI: 10.1002/adma.201707292
Linköping University. “Organic printing inks may restore sight to blind people: Direct electrical neurostimulation with organic pigment photocapacitors.” ScienceDaily. ScienceDaily, 2 May 2018.
Linköping University. (2018, May 2). Organic printing inks may restore sight to blind people: Direct electrical neurostimulation with organic pigment photocapacitors. ScienceDaily. Retrieved June 5, 2018 from www.sciencedaily.com/releases/2018/05/180502104043.htm
Linköping University. “Organic printing inks may restore sight to blind people: Direct electrical neurostimulation with organic pigment photocapacitors.” ScienceDaily. www.sciencedaily.com/releases/2018/05/180502104043.htm (accessed June 5, 2018).