Head lights

Abstract

A team from Arizona State University have developed a novel way to treat neurological diseases. Their method exploits devices normally associated with display technology and neuro-stimulation. Electronics Letters takes a look at their findings. The team believe that their manuscript is the first reported and successful use of flexible OLED display technology to optically stimulate neural tissue OLEDs, Organic Light Emitting Diodes, are thin-film electroluminescent devices that emit light when a forward voltage bias is applied across a transparent anode and reflective cathode. Flexible OLED displays are manufactured on thin and flexible plastic substrates, instead of glass, and are rapidly becoming the mobile display technology of choice for the latest generation of smartphones. Somewhat surprisingly, the main advantage for flexible OLED display technology is not mechanical flexibility or bendability. Instead, by replacing the traditional rigid and thick glass substrates with over 35 times thinner flexible plastic substrates, the overall case thickness of a smartphone can be reduced by as much as 10 percent. Using thin and flexible substrates also makes it much easier to add functional and visually appealing curved edges to the display, while improving durability and reducing weight. Given these advantages, flex OLEDs appear poised to replace conventional glass substrate-based displays in mobile applications. OLEDs have also found a use in wearable electronics. Until now, wearable electronics have been manufactured using microelectronic components bonded to printed circuit boards. However, these conventional wearables are typically quite rigid and planar, while biological surfaces are usually curved, soft and pliable. As an alternative approach, wearable biomedical devices have been manufactured using an inherently biocompatible, thin and flexible plastic display substrate. To date, the team from Arizona has also adapted flexible OLED display technology to manufacture a prototype photoplethysmograph (PPG) sensor array for precision cardiac monitoring and a programmable fluorescent microarray for point-of-care medical diagnostics in smart bandages. In the Letter featured, the group used the emitted light from flexible OLEDs, instead of electrical neuro-stimulation, to optically excite genetically modified neural tissue in vitro. Optogenetics is a relatively new and experimental neuro-stimulation technique that genetically modifies neurons to respond to light. In their conceptual therapeutic configuration, individual OLED pixels in a conformable flexible display would be turned on to illuminate and optically stimulate selected and localised peripheral nerves. The team explored the viability of this technology as a non-invasive alternative to both prescription drugs and surgery to treat chronic inflammatory disease and mental health disorders. The team hope that this new therapy could be used to treat patients by optically stimulating selected branches of the auricular vagus transcutaneously via the outer ear using a high-resolution array of red OLEDs manufactured on a flexible plastic substrate, similar to a peel-and-stick adhesive bandage, as opposed to a surgically implanted device. Preliminary analysis combined with in-vitro experimental measurements indicated that the flexible red OLEDs are bright enough to induce therapeutic optical stimulation in optogenetically modified neural tissue. As an alternative to conventional prescription-drug-based treatments, direct neuromodulation of peripheral nerves promises drug-free treatment of chronic inflammatory disease and mental health disorders, including arthritis, systemic inflammatory response syndrome, inflammatory bowel disease, post-traumatic stress disorder (PTSD), anxiety, and depression. Essentially, this technology uses peripheral neuro-stimulation to treat a number of diseases by helping the body heal itself, as opposed to having to take a pill to treat the same condition. Their preliminary data and analysis indicates that an experimental optogenetics-based optical stimulation using OLED technology may be a viable alternative to electrical neuro-stimulation. A potential benefit of peripheral neuro-stimulation is the promise of far fewer side effects during patient treatment. From its start at Stanford about a decade ago, optogenetics is now being widely investigated in a large number of research labs across the world. Much of this early work has focused on advancing the understanding of a number of neurological and psychiatric diseases and disorders. The team believe that the future of optogenetics work will increasingly put an emphasis on diagnosis and patient treatment. Hopefully, this future work will eventually allow doctors to treat patients using new peripheral neuromodulation methods as a safe alternative to prescription drugs and with far fewer side effects. A new biophotonic alternative to conventional prescription-drug-based treatments for inflammatory disease and mental health disorders is presented